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UNIT 1: A VIEW OF LIFE A READING TEXTS I WHAT IS BIOLOGY? Biology is a natural science concerned with the study of life and living organism, including their structure, function, growth, origin, evolution, distribution, and taxonomy Biology is a vast subject containing many subdivision, topics and disciplines Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology Cells are the basic unit of life New species and inherited traits are the product of evolution Genes are the basic unit of the heredity An organism regulate its internal environment to maintain a stable and constant condition Living organism consume and transform energy Subdisciplines of biology are recognized on the basis of the scale at which organism are studied and the methods used to study them: biochemistry examines the rudimentary chemistry of life: molecular biology studies the complex interactions of systems of biological molecules: cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues, organs, and organs systems of an organism; and ecology examines how various organisms interact and associate with their environment II THE CHARACTERISTICS OF THE LIVING ORGANISMS Organisms are composed of cells The cell theory , one of the fundamental unifying concepts of biology, states that all living organisms are composed of basic units called cells and of substances produced by cells Although they vary greatly in size and appearance, all organisms are composed of these small building blocks Some of the simplest life forms such as bacteria, are unicellular: they consist of a single cell In contrast, the body of the human or a maple tree is made of a billions of cells In these complex multicellular organisms, life processes depend on the coordinated functions of the components cells Viruses are not considered organisms They can carry on life activities and reproduce only by using the metabolic machinery of the cells they parasitize, and so are said to be on the borderline between living and nonliving things Living organisms grow and develop Some nonliving things appear to grow Crystals may form in a supersaturated solution of the salt; as more of the salt comes out of the solution, the crystal may enlarge However, this is not growth in the biological sense Biologists defined as an increase in the amount of living substance in the organism Growth can result from an increase in the size if the individual cells, the number of cells, or both Growth maybe uniform in the various parts of an organism, or it may be greater in some parts than in others, causing the body proportions to change as growth occurs Metabolism includes the chemical processes essential to growth, repair, and reproduction In all living organism, chemical reactions and energy transformations take place that are essential to nutrition, growth and repair of cells, and conversion of energy into usable forms The sum of all chemical activities of the organism is its metabolism Metabolic reactions occur continuously in every living organism, and they must be carefully regulated in maintain a balanced internal state The tendency of organisms to maintain a relatively constant internal environment is termed homeostasis, and the mechanisms that accomplish the task are know as homeostatic mechanisms Movement is a basic property of cells Although not necessarily locomotion (moving from one place to another), is another characteristic of living organisms The living materials within cells is in continuous motion, and organisms move as they interact with the environment Most animals move very obviously; they wiggle, crawl, swim, run, or fly Locomotion may result from the slow oozing of the cell, from the beating of tiny hair-like extension of the cell called cilia or longer structures know as flagella, or from the contraction of muscles A few animals, such as sponges, corals, and oysters, have free-swimming larval stages but not move from place to place as adults Even these adults, described as sessile, remain firmly attached to some surface, they may have cilia or flagella These structures beat rhythmically, moving the surrounding water that brings food and other necessities to the organism Organism respond to stimuli All forms of life respond to stimuli, physical or chemical changes in their internal or external environment Stimuli that evoke a respond in most organisms are changes in the color, intensity, or direction of light; changes in temperature, pressure or sound; and changes in the chemical composition of the surrounding soil, air or water In simple organisms, the entire organism may be sensitive to stimuli Certain single- celled organisms, for example, respond to bright light by retreating In complex animals such as polar bears or humans, certain cells of the body are highly specialized to respond to certain types of stimuli For example, cells in the retina of the eye respond to light Although their responses may not be as obvious as those of animals, plants respond to light, gravity, water, tough, and other stimuli The streaming motion of the cytoplasm in plant cells may be speeded up or stopped by changes in the amount of light Many plant responses are carried out by different rates of growth of various parts of the plant body A few plant, such as the Venus flytrap of the Carolina swamps, are remarkably sensitive to tough and can catch inserts Their leaves are hinged along the midrib and they have a scent that attracts insects The present of an insect on the leaf, detected by trigger hairs of the leaf surface, stimulates the leaf to fold When the edges come together, the hairs interlock to prevent escape of the prey The leaf then secretes enzymes that kill and digest the insect The Venus flytrap is usually found in soil that is deficient in nitrogen The plant obtains part of the nitrogen require for its growth from the insect prey it “eats” Organisms reproduce In simple organisms such as amoeba, reproduction may be asexual- that is , without sex When an amoeba has grown to a certain size it reproduce by splitting it in half to form two new amoebas Before it divides, an amoeba make a duplicate copy of its hereditary material (genes) and distributes one complete set to each new cell Except for size, each new amoeba is similar to the parent cell (The new amoeba may not be identical to each other or to the parent cell because mutations may occur) In most plants and animals, sexual reproduction is carried out by the reproduction of specialized egg and sperm cells that fuse to form a fertilized egg The new organism develops from the fertilized egg Offspring produced by sexual reproduction are the product of the interaction of various genes contributed by both the mother and the father Such genetic variation provides raw material for the vital processes of evolution and adaptation Populations evolve and become adapted to the environment The ability of a population to evolve (change) and adapt to its environment enables it to survive in a changing world Adaptation are traits that enhance an organism’s ability to survive in a particular environment They may be structural, physiological, behavioral, or a combination of all three The long, flexible tongue of a frog is a adaptation for catching insects, and the thick fur coat of the polar bear is an adaptation for surviving frigid temperatures Every biologically successful organism is a complex collection of coordinated adaptations produced through evolutionary processes III ESSENTIAL CHARACTERISTICS OF LIFE There are many characteristics processed by living organisms in common By these characteristics we can distinguish living things from nonliving things Feeding or nutrition Every organism must take in food from its surroundings The function of food id to provide energy for living process and to provide the raw materials necessary for growth Green plants possess chlorophyll and can make their own food by photosynthesis This is a form of autotrophic nutrition Animals and fungi cannot make their own food They have to obtain food from other organisms, digesting the organic compounds by enzymes and absorbing the products into the body This is called heterotrophic nutrition Respiration All living processes require energy which is released from food The energy is released during the breakdown of certain energy-rich compounds in the food by the process of respiration During respiration, oxygen is usually required and carbon dioxide and water are given off as by-products Respiration occurs in every cell of the body in both plants and animals Excretion There are many chemical processes, such as respiration, taking place inside the cells of an organism These are collectively called metabolism Some of the by products of metabolism are of no use to the organism and may even be harmful if allowed to accumulate The removal of such waste substances from an organism is called excretion In mammals, carbon dioxides is excreted by the lungs during breathing out or exhalation and nitrogenous wastes (mainly urea) are excreted by the kidney as the urine Plants not process excretory organs They usually get rid of metabolic wastes by turning them into harmless substances which are stored within the body Leaf fall also eliminates metabolic wastes in some plants Growth Every organism gets bigger and more complex as it gets older Nonliving things also grow, such as crystals, by the addition of new material to their external surface Living organisms, however, grow from within by the formation of new living matter or protoplasm For this to take place, they must obtain food by autotrophic or heterotrophic nutrition 5 Reproduction The lifespan of organisms are limited They eventually die through aging, diseases, predation or accidents However, they have the ability to perpetuate their own species They produce offspring by sexual or asexual reproduction The resulting offspring have similar characteristics as their parents In asexual reproduction, a part of the parent becomes separated and develops into a new individual In sexual reproduction, two individuals of opposite sexes are involved The male gamete (sperm) fuses with and fertilizes the female gamete (ovum) to form a zygote The zygote becomes an embryo which later develops into a new individual Irritability (or sensitivity) Living organisms have the ability to detect changes in both the internal and external environments (we call these changes stimuli) and respond to them For example, the superficial blood vessels in the skin of a mammal dilate in respond to a rise in body temperature in order to increase the rate of heat loss If your eyes are exposed to bright light, the iris responds by diminishing the pupil diameter Green plants can also detect external stimuli such as light and water, but they respond more slowly than animals Movement Animals move from place to place (locomotion) to search for food and escape from their enemies Plants on the other hand, can manufacture their own food by photosynthesis from raw materials obtained in one place, and most of them are anchored into the soil by roots Their movements are comparatively slow, being restricted to bending growth responses of the shoot and the root B COMPREHENSION EXERCISES I Decide the following statements are true or false One of the functions of food is to provide energy for living process Willows can make their own food from other organisms, and digest the organic compounds There are kinds of reproduction During respiration, plants require CO2 and give off O2 Respiration occurs in every cell in the body of the animals, but plants The iris dilates is an example of adaptation of mammals in respond to the rise of temperature Viruses are organisms that can carry on life activities The tendency of organisms to maintain a relatively constant internal environment is termed homeostatic mechanisms II Fill in each gap proper words / a word to make meaningful statements The sum of all the chemical activities of the organism is its The tendency of organisms to maintain a constant internal environment is termed A(n) is a physical or chemical change in the internal or external environment that causes a response in an organism and flagella are used by some organisms for locomotion A population must be able to to changes in its environment in order to survive An organism that cannot synthesize its own food from inorganic materials and must eat producers The basic unit of life Living things grow by increasing of cells Metabolism can be described a the sum of all the that take place in the organism 10 is the tendency of organisms to maintain a constant internal environment 11 In general, living things reproduce in one of two ways 12 The process by which living thing become adapted to their environment, or change, is called III Choose the correct answer Which of the following is not a characteristic of all living organisms? a living things respond to stimuli b living things exhibit movement and locomotion c living things reproduce d living things grow and develop Biology is the: a study of plants b study of animals c study of life d study of inorganic and organic life Which of the following life forms carry on cellular respiration? a bacteria b fungi c plants d animals e all of the above Fertilization is the: a union of two sex cells to form a zygote b transfer of pollen to the ovule c transfer of pollen to the antheridium d growth of the embryo into a new individual The characteristic (s) common to all living things include (s) a reproduction b autotrophic synthesis c heterotrophic synthesis d growth e adaptation The characteristic of living organisms that involves such processes as growth, repair, chemical synthesis and reproduction is referred to as: a development b metabolism c adaptation d homeostasis The function of homeostasis in a living organism is to: a provide for unlimited growth b allow unrestricted movement c allow for adaptation to a harmful environment d maintain a uniform or constant internal environment An example of evolution is the appearance of giraffes with long necks The long neck gave these giraffes a selective advantage because it allowed them to: a drink easier b see predators easier d have better homeostasis c reproduce easier e eat the leaves at the top of the tree Adaptation are traits that enhance an organism’s ability to survive in a particular environment They may be: a behavior b physiological c structural d All above are correct 10 Reproduction that involves different parents joining to form a new individual Includes a combination of new traits a growth b sexual reproduction c asexual reproduction d reproduction 11 Organism that can use sunlight energy to synthesize complex food molecules are known as: a heterotrphs b autotrops c consumers d producers 12 The cell theory states that all living organisms: a grow and develop b respond to stimuli c are composed of basic unit called cells d cam move from one place to another 13 An example of evolution is the appearance of giraffes with long necks The long neck gave them a selection advantage because it allows them to: a drink easier b see predator easier c reproduce easier d eat the leaves at the top of the tree 14 Organisms can reproduce by asexual reproduction and sexual reproduction A benefit of sexual reproduction is that: a more offspring can be produced b the offspring are all identical to the parents c the interaction of the genes brings about variation d evolution will occur at a slower rate when you have parents * GRAMMAR NOTE: TO/ IN ORDER TO/ SO AS TO + V-INFINITIE UNIT 2: BOTANY A READING TEXTS I AN INTRODUCTION TO PLANT BIOLOGY - Plants are living organisms belonging to the kingdom Plantae They include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae The scientific study of plants is known as botany - Botany, sometimes referred to as plant science or plant biology, is the branch of biology that deals with the scientific study of plant life The word botany is referring to pastures, meadows, grass, fodder Botany is considered to be one of the oldest sciences as it began with the effort of early humans to identify edible, poisonous and medicinal plants When scientists first began grouping similar types of living things together, all organisms were identified as either plants or animals Botany covered all organisms not classified as animals As science has progressed, many organisms that were one included in the study of botany are no longer technically considered to be a part of the plant kingdom, such as fungi, lichens, bacteria, viruses and single-celled algae Botanists continue, however, to study these some of these life forms and so it is common to see organisms such as fungi, lichens certain bacteria and photosynthetic protists covered by botanical studies II THE IMPORTANCE OF BOTANY - The study of plants is of great importance to humans Plants generate the oxygen we breathe, are a major part of the food consumed by humans and animals, and are used to create fibers, fuels and medicines essential to our lives Plants absorb carbon dioxide, which is important in lowering greenhouse gasses, and are crucial to the water cycle - Nearly all the food we eat comes (directly and indirectly) from plants like this American long grain rice.Virtually all foods eaten come from plants, either directly from staple foods and other fruit and vegetables, or indirectly through livestock or other animals, which rely on plants for their nutrition -Fundamental life processes: Plants are convenient organisms in which fundamental life processes (like cell division and protein synthesis) can be studied, without the ethical dilemmas of studying animals or humans 10 Amphibian species are in decline around the world due to a variety of threats including of invasive species, habitat destruction, disease, climate change and toxins Reptiles Reptiles are cold-blooded vertebrates that diverged from ancestral amphibians about 340 million years ago during the Carboniferous Period Early reptiles included organisms such as Hylonomus, Petrolacosaurus, Archaeothyris and Paleothyris The oldest evidence of reptiles is a set of footprints found in Nova Scotia Two characteristics distinguish early reptiles from amphibians: scales and the ability to lay hard-shelled amniotic eggs Reptiles include turtles, squamates, crocodiles and tuataras There are about 8,000 species of reptiles alive today Of the four reptile groups, the squamates (amphisbaenians, lizards and snakes) are the most diverse with nearly 7,600 species Mammals Mammals are vertebrates that evolved from therapsid reptiles during the Jurassic Period about 200 million years ago The first mammals, known as morganucodontids, were nocturnal insect eaters that resembled modern-day shrews For the better part of 130 million years, mammals remained small and lived in a world dominated by the dinosaurs But around 65 million years ago, a drastic shift in climate caused the extinction of more than two-thirds of the animal species on the planet, including the dinosaurs Mammals survived this bout of climate change and in its wake, diversified and colonized the many newly-available habitats Today, mammals are remarkably varied, with some 5,400 species occupying every continent on the globe Birds Birds evolved from reptiles during the Mesazoic Era about 150 million years ago Today, more than 9,000 species inhabit virtually every terrestrial habitat on the planet Birds have a number of characteristics that sets them apart from other vertebrates such as feathers, bills and a furcula Birds, best known for their ability to fly, are unmatched in their command of the skies Albatrosses glide over the vast open sea, hummingbirds hover motionless in mid-air, and birds of prey capture prey with pinpoint accuracy But not all birds are aerobatic experts Some species such as ostriches, kiwis and penguins, lost their ability to fly long ago in favor of lifestyles suited more for land or water *Decide the following statements are true or false The ancestors of invertebrates are micro-organisms There are more than 90% of all species alive today are invertebrates The common thing of all invertebrates are lack of backbone 19 Fishes used to be jawless Amphibians used to live in the water Amphibians are increasing quickly today There are groups of reptiles in total All mammals eat insects in the evening Feathers, bills, furculla are typical characteristics of birds 10 All birds can fly 11 All animals which can fly are birds 12 Only reptiles can lay eggs 13 The first reptiles live in Nova Scotia 14 There are more than 5000 species amphibians alive today 15 Fishes are ancestors of amphibians 20 UNIT 4: HUMAN BODY The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs By the time the human reaches adulthood, the body consists of close to 100 trillion cells,[1] the basic unit of life These cells are organised biologically to eventually form the whole body I SYSTEMS Cardiovascular system The cardiovascular system comprises the heart, veins, arteries and capillaries The primary function of the heart is to circulate the blood, and through the blood, oxygen and vital minerals are transferred to the tissues and organs that comprise the body The left side of the main organ (left ventricle and left atrium) is responsible for pumping blood to all parts of the body, while the right side (right ventricle and right atrium) pumps only to the lungs for re-oxygenation of the blood The heart itself is divided into three layers called the endocardium, myocardium and epicardium, which vary in thickness and function Digestive system The digestive system provides the body's means of processing food and transforming nutrients into energy The digestive system consists of the - buccal cavity, esophagus, stomach, small intestine, large intestine ending in the rectum and anus These parts together are called the alimentary canal (digestive tract) Integumentary system The integumentary system is the largest organ system in the human body, and is responsible for protecting the body from most physical and environmental factors The largest organ in the body, is the skin The integument also includes appendages, primarily the sweat and sebaceous glands, hair, nails and arrectores pili (tiny muscles at the root of each hair that cause goose bumps) Lymphatic system The main function of the lymphatic system is to extract, transport and metabolise lymph, the fluid found in between cells The lymphatic system is very similar to the circulatory system in terms of both its structure and its most basic function (to carry a body fluid) Musculoskeletal system The human musculoskeletal system consists of the human skeleton, made by bones attached to other bones with joints, and skeletal muscle attached to the skeleton by tendons Bones An adult human has approximately 206 distinct bones: 21 Nervous system The nervous system consists of cells that communicate information about an organism's surroundings and itself 60 mph II 20 LITTLE KNOWN FACTS ABOUT THE HUMAN BODY A human being loses an average of 40 to 100 strands of hair a day A cough releases an explosive charge of air that moves at speeds up to Every time you lick a stamp, you're consuming 1/10 of a calorie A fetus acquires fingerprints at the age of three months A sneeze can exceed the speed of 100 mph Every person has a unique tongue print According to German researchers, the risk of heart attack is higher on Monday than any other day of the week After spending hours working at a computer display, look at a blank piece of white paper It will probably appear pink An average human drinks about 16,000 gallons of water in a lifetime 10 A fingernail or toenail takes about months to grow from base to tip 11 An average human scalp has 100,000 hairs 12 It takes 17 muscles to smile and 43 to frown 13 Babies are born with 300 bones, but by adulthood we have only 206 in our bodies 14 Beards are the fastest growing hairs on the human body If the average man never trimmed his beard, it would grow to nearly 30 feet long in his lifetime 15 By age sixty, most people have lost half of their taste buds By the time you turn 70, your heart will have beat some two-and-a-half billion times (figuring on an average of 70 beats per minute.) 16 Each square inch of human skin consists of twenty feet of blood vessels 17 Every human spent about half an hour as a single cell 18 Every person has a unique tongue print Every square inch of the human body has an average of 32 million bacteria on it 19 Fingernails grow faster than toenails 20 Humans shed about 600,000 particles of skin every hour - about 1.5 pounds a year By 70 years of age, an average person will have lost 105 pounds of skin EXERCISE: All Life begins with a single _ A) tissue B) cell C) organ D) microbe The control center of a cell is the _ 22  A) chromosome B) cytoplasm C) cell membrane D) nucleus Skin, ears, and kidneys are examples of _ A) organs B) cells C) tissues D) organ systems The _ system removes waste products from the body A) Excretory B) All of these C) Integumentary D) Digestive A group of similar cells performing the same function is a(n) A) cell B) tissue C) organ D) system The type of joint in your knee is a _ joint A) hinge B) ball & socket C) gliding D) fixed The type of joint found in your shoulder is a _ joint A) hinge B) fixed C) ball & socket D) gliding One important function of bones is to produce _ A) tendons B) ligaments C) blood cells D) cartilage Breathing, heart beating, and food digesting are examples of activities using _ type of muscles A) cardiac B) voluntary C) striated D) involuntary 10 Walking, running, and carrying a book involve using _ type of muscles A) striated B) cardiac C) voluntary D) involuntary 11 Cardiac muscle tissue can be found in your _ A) Heart B) Liver C) Stomach D) Brain 12 Skin helps the body maintain a steady _ through perspiration and enlarging of blood vessels A) Tan B) Pace C) Temperature D) Heart beat 13 Digestion begins in the _ A) large intestine B) mouth C) small intestine D) stomach 14 The human heart has _ chambers (rooms) A) Three B) Two C) Five D) Four 15 The top chambers of the heart are called the _ A) Septum B) Atrium C) Aorta D) Ventricle 16 The bottom of the heart is called the _ A) Aorta B) Septum C) Ventricle D) Atrium 17 Arteries, Veins, and capillaries are the _ in the circulatory system A) organs B) vessels C) cells D) tissues 18 This blood type is called the "universal donor: A) Type AB B) Type O C) Type B D) Type A 19 The main organ in the respiratory system is the _ A) Diaphragm B) Bronchi C) Trachea D) Lung 20 In which structure is blood filtered within the kidneys? A) bladder B) ureter C) nephron D) gland 21 Water, urea, and other wastes are eliminated in a fluid called _ A) protein B) urine C) perspiration D) carbon dioxide 22 The _ makes urea and breaks down old red blood cells A) Urethra B) Pancreas C) Kidneys D) Liver 23 Axon, cell body, and dendrites are parts of a _ cell A) Prokaryotic B) Epithelial C) Cardiac D) Nerve 23 24 A nerve cell is also called a(n) _ A) epithelial B) neuron C) prokaryotic D) cardiac 25 The central nervous system includes: A) Brain B) Nerves C) Spinal Cord D) Brain & Spinal Cord 26 The peripheral nervous system includes : A) Brain B) Spinal Cord C) Nerves D) Brain & Spinal Cord 27 The part of the brain responsible for thinking and memory is the _ A) Cerebellum B) Medulla C) Spinal Cord D) Cerebrum 28 The part of the brain responsible for involuntary actions such as breathing and heart beat is the A) Spinal Cord B) Cerebellum C) Cerebrum D) Medulla 29 The endocrine gland that helps regulate blood glucose levels: A) Pancreas B) Adrenal C) Pituitary D) Thyroid 30 The endocrine gland helps control other glands and regulates blood pressure: and water balance A) Adrenal B) Pituitary C) Thyroid D) Pancreas 24 UNIT 5: CELLULAR ORGANISM I Parts of the cell Cell Diversity Cells with different functions often have different shapes As these pictures show, cells come in many different shapes How are the shapes of these cells related to their functions? Four Common Parts of a Cell Although cells are diverse, all cells have certain parts in common The parts include a plasma membrane, cytoplasm, ribosomes, and DNA The plasma membrane (also called the cell membrane) is a thin coat of lipids that surrounds a cell It forms the physical boundary between the cell and its environment, so you can think of it as the ‘‘skin’’ of the cell Cytoplasm refers to all of the cellular material inside the plasma membrane, other than the nucleus Cytoplasm is made up of a watery substance called cytosol, and contains other cell structures such as ribosomes Ribosomes are structures in the cytoplasm where proteins are made DNA is a nucleic acid found in cells It contains the genetic instructions that cells need to make proteins These parts are common to all cells, from organisms as different as bacteria and human beings How did all known organisms come to have such similar cells? The similarities show that all life on Earth has a common evolutionary history II Biological membranes Membranes are composed of lipids, proteins and sugars 25 Biological membranes consist of a double sheet (known as a bilayer) of lipid molecules This structure is generally referred to as the phospholipid bilayer In addition to the various types of lipids that occur in biological membranes, membrane proteins and sugars are also key components of the structure Membrane proteins play a vital role in biological membranes, as they help to maintain the structural integrity, organization and flow of material through membranes Sugars are found on one side of the bilayer only, and are attached by covalent bonds to some lipids and proteins Three types of lipid are found in biological membranes, namely phospholipids, glycolipids and sterols Phospholipids consist of two fatty acid chains linked to glycerol and a phosphate group Phospholipids containing glycerol are referred to as glycerophospholipids An example of a glycerophospholipid that is commonly found in biological membranes is phosphatidylcholine (PC) (Figure 1a), which has a choline molecule attached to the phosphate group Serine and ethanolamine can replace the choline in this position, and these lipids are called phosphatidylserine (PS) and phosphatidylethanolamine (PE), respectively Phospholipids can also be sphingophospholipids (based on sphingosine), such as sphingomyelin Glycolipids can contain either glycerol or sphingosine, and always have a sugar such as glucose in place of the phosphate head found in phospholipids (Figure 1b) Sterols are absent from most bacterial membranes, but are an important component of animal (typically cholesterol) and plant (mainly stigmasterol) membranes Cholesterol has a quite different structure to that of the phospholipids and glycolipids It consists of a hydroxyl group (which is the hydrophilic ‘head’ region), a four-ring steroid structure and a short hydrocarbon side chain (Figure 1c) Figure 1.Schematic representations of three types of membrane lipid (a) Phosphatidylcholine, a glycerophospholipid (b) Glycolipid (c) A sterol The sugars attached to lipids and proteins can act as markers due to the structural diversity of sugar chains For example, antigens composed of sugar chains on the surface of red blood cells determine an individual's blood group These antigens are recognized by antibodies to cause an immune response, which is why matching blood groups must be used in blood transfusions Other carbohydrate markers are present in disease (e.g specific carbohydrates on the surface of cancer cells), and can be used by doctors and researchers to diagnose and treat various conditions III Comparison between plant and animal cells Comparison chart 26 Differences — Similarities — Animal Cell versus Plant Cell comparison chart Animal Cell Cell wall Absent Shape Round (irregular shape) Vacuole One or more small vacuoles (much smaller than plant cells) Centrioles Present in all animal cells Chloroplast Animal cells don't have chloroplasts Plant Cell Present (formed of cellulose) Rectangular (fixed shape) One, large central vacuole taking up 90% of cell volume Only present in lower plant forms Plant cells have chloroplasts because they make their own food Cytoplasm Present Present Ribosomes Present Present Mitochondria Present Present Plastids Absent Present Endoplasmic Present Reticulum (Smooth and Rough) Present Golgi Apparatus Present Present Plasma Membrane Only cell membrane Microtubules/ Present Microfilaments Flagella May be found in some cells Cell wall and a cell membrane Present May be found in some cells 27 Animal Cell versus Plant Cell comparison chart Animal Cell Lysosomes Lysosomes occur in cytoplasm Nucleus Present Cilia Present Plant Cell Lysosomes usually not evident Present Most plant cells not contain cilia III Exercises Match a part of a cell in column A with its function/ definition in column B COLUMN A COLUMN B organelle basic unit of structure and function in living things Cell part of a cell with a specific function cytoplasm It is a flexible covering that protects the inside of a cell from the environment outside a cell nucleus an membrane bound organelle that contains DNA cell membrane a thick fluid inside the cell in which the organelles are suspended chloroplast strong layer around the cell membrane in plant, algae, and some bacteria cells cell wall An organelle in the cells of plants and some other organisms that captures energy from sunlight and uses it to produce food 28 UNIT 6: ENERGY AND METABOLISM I Energy and Metabolism All living organisms need energy to grow and reproduce, maintain their structures, and respond to their environments Metabolism is the set of life-sustaining chemical processes that enables organisms transform the chemical energy stored in molecules into energy that can be used for cellular processes Animals consume food to replenish energy; their metabolism breaks down the carbohydrates, lipids, proteins, and nucleic acids to provide chemical energy for these processes Plants convert light energy from the sun into chemical energy stored in molecules during the process of photosynthesis Bioenergetics and Chemical Reactions Scientists use the term bioenergetics to discuss the concept of energy flow through living systems such as cells Cellular processes such as the building and breaking down of complex molecules occur through step-by-step chemical reactions Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed All of the chemical reactions that take place inside cells, including those that use energy and those that release energy, are the cell's metabolism 29 Most energy comes from the sun, either directly or indirectly Most life forms on earth get their energy from the sun Plants use photosynthesis to capture sunlight, and herbivores eat those plants to obtain energy Carnivores eat the herbivores, and decomposers digest plant and animal matter Cellular Metabolism 30 Every task performed by living organisms requires energy Energy is needed to perform heavy labor and exercise, but humans also use a great deal of energy while thinking and even while sleeping For every action that requires energy, many chemical reactions take place to provide chemical energy to the systems of the body, including muscles, nerves, heart, lungs, and brain The living cells of every organism constantly use energy to survive and grow Cells break down complex carbohydrates into simple sugars that the cell can use for energy Muscle cells may consumer energy to build long muscle proteins from small amino acid molecules Molecules can be modified and transported around the cell or may be distributed to the entire organism Just as energy is required to both build and demolish a building, energy is required for both the synthesis and breakdown of molecules Many cellular process require a steady supply of energy provided by the cell's metabolism Signaling molecules such as hormones and neurotransmitters must be synthesized and then transported between cells Pathogenic bacteria and viruses are ingested and broken down by cells Cells must also export waste and toxins to stay healthy, and many cells must swim or move surrounding materials via the beating motion of cellular appendages like cilia and flagella II Process of Photosynthesis Photosynthesis in plants occurs in two stages These stages are known as the lightdependent reactions and the Calvin Cycle Light-dependent Reactions The first stage of photosynthesis is the light dependent reactions These reactions take place on the thylakoid membrane inside the chloroplast During this stage light energy is converted to ATP (chemical energy) and NADPH (reducing power) Light-dependent Reactions Light is absorbed by two Photosystems called Photosystem I (PSI) and Photosystem II (PSII) These protein complexes contain light harvesting chlorophyll molecules and accessory pigments called antenna complexes The photosystems are 31 also equipped with reactions centers (RC) These are complexes of proteins and pigments which are responsible for energy conversion The chlorophyll molecules of PSI absorb light with a peak wavelength of 700nm and are called P700 molecules The chlorophyll molecules of PSII absorb light with a peak wavelength of 68Onm and are called P68O molecules The light dependent reactions begin in PSII  A photon of light is absorbed by a P680 chlorophyll molecule in the light harvesting complex of PSII  The energy that is generated from the light is passed from one P680 chlorophyll molecule to another until it reaches the reaction center (RC) of PSII  At the RC is a pair of P680 chlorophyll molecules An electron in the chlorophyll molecules becomes excited as a result of a higher level of energy The excited electron becomes unstable and is released Another electron is released following the capture of another photon of light by the light harvesting complex and the transfer of energy to the reaction center  The electrons are transported in a chain of protein complexes and mobile carriers called an electron transport chain (ETC) Plastoquinone is the mobile carrier that transports the electrons from the reaction center of PSII to the Cytochrome b6f Complex as shown in the diagram above  The electrons lost from PSII are replaced by splitting water with light in a process called Photolysis Water is used as the electron donor in oxygenic photosynthesis and is split into electrons (e-), hydrogen ions (H+, protons) and oxygen (O2) The hydrogen ions and oxygen are released into the thylakoid lumen Oxygen is later released into the atmosphere as a by-product of photosynthesis  While the electrons pass through the ETC via Plastoquinone, hydrogen ions (protons) from the stroma are also tranferred and released into the thylakoid lumen This results in a higher concentration of hydrogen ions (proton gradient) in the lumen  As a result of the proton gradient in the lumen, hydrogen ions are transferred to ATP synthase and provide the energy needed for combining ADP and Pi to produce ATP  Cytochrome b6f transfers the electrons to Plastocyanin which then transports them to Photosystem I 32 III Exercises What are the primary photosynthetic pigments? What are the accessory photosynthetic pigments? Paper chromatography is a technique for , dissolved What pigments do? The distance a pigment travels on the chromatography paper is dependent on? How many bands of color should appear on the chromatography paper? What are the colors you should expect to see on the band? What pigment is yellow? What pigment is yellow-orange? 10 What pigment is blue-green? 33 ... of all animals, both living and extinct I CHARACTERISTICS OF ANIMALS All animals are eukaryotes: sinh vật nhân chuẩn All living organisms can be sorted into one of two groups depending on the basic