DNA and chromosomes

• DNA and Chromosomes Chromosome in Cells DNA (deoxyribonucleic acid) AGTC Human 46 chromosomes 22 homologs, x, or x/y Genes are carried by Chromosomes Two plant cells visualized by light microscope, DNA stained with DAPI Experimental procedures demonstrating that DNA is the genetic material 1940s • Genetic information is carried in the linear sequence of nucleotides in DNA • Genetic information contains instructions to synthesize proteins • DNA forms double helix with two complimentary strands holding together by hydrogen bonds between A-T (2 bonds) and G-C (3 bonds) • DNA duplication occurs using one strand of parental DNA as template to form complimentary pairs with a new DNA strand. • DNA is in nucleus in eucaryotes The Structure and Function of DNA 1953 Watson and Crick determined the structure of DNA DNA and its Building Nucleotides: Guanine (G), Adenine (A), Cytosine (C), Thymine (T). Polarized strand, 5’->3’ Base inside, sugar outside DNA and its Building Antiparallel strands DNA Pairs A always pairs with T, and G with C, A-T two hydrogen bonds, G-C three hydrogen bonds DNA Double Helix 10.4 nucleutides/turn; 3.4 nm between nucleutides DNA to Protein Genome: the complete set of information in an organism’s DNA Total length of DNA about 2 meters long in a human cell, encoding about 30000 proteins To carry the genomic information to daughter cells DNA Duplication Using itself as template [...]... Chromosome Complex of DNA and protein is called chromatin 44 homologous chromosomes and 2 sex chromosomes Complementary DNA with different Dyes The arrangement of the full chromosome set is called karyotype Banding Pattern of human chromosomes Giemsa Staining Green line regions: centromeres Encoding ribosome The organization of genes of a human chromosome Conservation between human and mouse genomes Usually... compartmentalized DNA activity Nuclear pores allow communication Nuclear lamina and cytoskeleton mechanically support the nucleus Chromosomal DNA and its Packaging • A gene is a nucleotide sequene in a DNA molecule that act as a functional unit for protein production, RNA synthesis • Introns and Exons • Chromosome: single long DNA contains a linear array of many genes • Human genome contains 2.3x109 DNA nucleotide... chromosome 1 and mouse chromosome 4 mouse human centromere Cell Cycle DNA molecule not only carries genetic information, but also undergoes conformational change Chromosomes exist through the cycle Mitotic and interphase chromosome Single chromosome can only be visible during mitosis Chromosomes at interphase and M phase Three important DNA sequences Telomere, replication origin, centromere DNA Molecules... 2.3x109 DNA nucleotide pairs, with 22 different autosomes and 2 sex chromosomes • Chromosomal DNA: replication origins, telomeres, centromeres • Histones form the protein core for DNA wrapping • Nucleosome: repeating array of DNA- protein particles • Modification of Chromatin and nucleosomes: histone H1, ATP-driven chromatin remodeling complexes, and enzymatically catalyzed covalent modification of the... The Assembly of the Core Histones Notice the long tails of the octamer The bending of DNA in a nucleosome 1 Flexibility of DNAs: A-T riched minor groove inside and G-C riched groove outside 2 DNA bound protein can also help Zigzag model of the 30-nm chromatin fiber Irregularities in the 30-nm fiber Flexible linker, DNA binding proteins Structural modulators: H1 histone, ATP-driven Chromatin remodeling... for nucleosome formation and disruption Covalent Modification of core histone tails Acetylation of lysines Mythylation of lysines Phosphorylation of serines Histone acetyl transferase (HAT) Histone deacetylase (HDAC) Summary • DNA, Chromosome • Centromere, telomere, replication origin • Nucleosome, Chromatin, • Histone: H1, H2A, H2B, H3, H4 • Histone octamer, DNA packaging • DNA binding proteins, Histone... and M phase Three important DNA sequences Telomere, replication origin, centromere DNA Molecules are highly condensed in chromosomes Nucleosomes of interphase under electron microscope Nucleosome: basic level of chromosome/chromatin organization Chromatin: protein -DNA complex Histone: DNA binding protein A: diameter 30 nm; B: further unfolding, beads on a string conformation Nucleosome Structures Histone . between A-T (2 bonds) and G-C (3 bonds) • DNA duplication occurs using one strand of parental DNA as template to form complimentary pairs with a new DNA strand. • DNA. DNA strand. • DNA is in nucleus in eucaryotes The Structure and Function of DNA 1953 Watson and Crick determined the structure of DNA DNA and its Building Nucleotides: