Lecture 5 - BIOC 212 EXAM II LECTURE 5; W, Oct 26th NUCLEIC...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
BIOC 212 EXAM II LECTURE 5; W, Oct 26th NUCLEIC ACIDS & PROTEIN SYNTHESIS Ruthann Nichols; 2:30-4:30 pm, F, 3340 MSRB 3, office hours; nicholsr@umich.edu Nathan Raynard, GSI, 3-5 pm, Th, 3340 MSRB 3, office hours; nraynard@umich.edu Reading Material, Chapter 26, pp. 808-830 Nucleic acids are chemical messengers of an organism’s genetic information. Deoxyribonucleic acid (DNA) is a polymer of deoxyribonucleotides which carries genetic information. 26.1 DNA, Chromosomes, and Genes Genetic information drives the development of an organism; exact duplication of genetic information is essential for development. Lecture Goals 1. What is the composition of nucleic acids, DNA, and RNA? 3. What is the structure of DNA? 5. How is DNA reproduced? 7. What are the functions of RNA? 5. How do organisms synthesize messenger RNA? A chromosome is a structure in the cell nucleus which carries the genetic information; a complex of proteins and DNA; visible during cell division. A gene is the portion of the chromosome that controls a specific inheritable trait; a segment of DNA that directs synthesis of a single polypeptide (protein).
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chromatin is a complex of nucleic acid and basic proteins (histones) that is dispersed in the nucleus and condensed into chromosomes in cell division. Why are histones basic? Each chromosome contains a different DNA molecule. The DNA is duplicated so each cell receives a complete copy of the genetic information ( semiconservative replication) . Each DNA molecule is composed of many genes, individual segments of DNA containing instructions to synthesize a polypeptide. When a cell is NOT dividing its nucleus is occupied by chromatin , which is a compact, orderly tangle of DNA , the carrier of genetic information, twisted around organizing proteins called histones . During cell division , chromatin organizes itself into chromosomes (figure; right).
Background image of page 2
Nucleosomes are the basic unit of DNA packaging within a nucleus; they consist of a segment of DNA wound around a histone core. Nucleosomes are the repeating units of chromatin. Nucleosomes fold into higher order structures to form a chromosome in order to compact DNA and create an added layer of regulatory control which ensures correct gene expression. Nucleosomes may carry epigenetic information in the form of covalent modifications of histones . Histones (H2, H3, H4) are basic proteins in cell nuclei which package DNA into nucleosomes. Histones act as spools around which DNA winds to fit large genomes inside cell nuclei: the compacted molecule is 40,000 times shorter than an unpacked molecule. Posttranslational modifications alter histone interaction with DNA and nuclear proteins.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 24

Lecture 5 - BIOC 212 EXAM II LECTURE 5; W, Oct 26th NUCLEIC...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online