prelim 1 outline

prelim 1 outline - NS 3200- Human Biochemistry Prelim 1:...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
NS 3200- Human Biochemistry Prelim 1: Study Guide- Replication: DNA replication involves 3 steps: A. Initiation B. Elongation C. Excision-ligation (proofreading, patch up) Transcription: DNA to RNA Translation: mRNA to protein Base Nucleotides: Purines- A,G: Pyrimidines C,T (no T in RNA, U instead) Purines are larger than Pyrimidines If there is a pentose sugar attached to the nucleotide, its called a nucleoside Bases are hydrophobic G-C bond has 3 hydrogen bonds compared to A-T, which has 2. This requires a higher temperature to ‘melt’ the C-G base pair Chargaff’s rule: concentration of A=T, C=G Read DNA from 5’ to 3’ Always add nucleotides directionally through the 3’ hydroxyl end Dominant form of DNA is B-conformation. (A-conformation is overwound) Modification of bases: methylation can regulate or turn off gene expression Chromosomes and Chromatin: Components of Chromatin: made up of DNA, protein, and a small amount of RNA Euchromatin- transcribed chromatin; Heterochromatin is not transcribed (condensed) Chromatin becomes highly condensed to form chromosomes Basic Elements of Chromosome: autonomously replicating sequence (ARS); the centromere (spindle attachement site during nuclear division); and the telomeres(ends), which are involved in completion of DNA replication Composition of a Nucleosome: a nucleosome core contains two molecules of each histone (2A, 2B, 3, and 4) with DNA wrapped around the histones. Histone 1occupies the linker region between nucleosomes Acetylation of DNA packing: acetylation on the lysine reduces the positive charge and this weakens the electrostatic attraction between histones and the DNA. In general, acetylation of histones leads to activation of gene expression and deacetylation reverses the effect. Only eukaryotes contain chromatin. Prokaryotes do not have chromatin, histones, nuclear membrane and cell organelles 1
Background image of page 1

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

View Full DocumentRight Arrow Icon
Basic Elements of a Gene: Gene: a gene consists of all the DNA sequences necessary to produce a single polypeptide or RNA product. Thus, the gene may not consist of contiguous sequences and need not code for a protein. Only one DNA strand codes for the protein, this is called the sense strand. The other strand does not code for the protein and is referred to as the anti-sense strand. A gene has both. Defining regions of a gene: Promoter : sites at which RNA polymerases and other regulatory proteins bind to DNA. Cis-acting elements: Specific sequences that bind trans-acting factors that influence gene expression. Transcriptional start site: Site on the DNA at which mRNA synthesis begins Translational start codon: consists of the three nucleotides “ATG” Introns: Intervening sequences in a gene that do not code for protein sequence and are removed during mRNA maturation Exons: DNA sequence that code for protein Termination codon: the end of the coding region of a gene Polyadenylation site: DNA sequence at the 3’ end of a gene that signal for adenosine nucleotide addition in the mRNA Transcriptional termination site:
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/09/2011 for the course NS 3200 taught by Professor Staff during the Spring '08 term at SUNY Buffalo.

Page1 / 10

prelim 1 outline - NS 3200- Human Biochemistry Prelim 1:...

This preview shows document pages 1 - 3. Sign up to view the full document.

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