Grinblat Study Guide

Grinblat Study Guide - Biology 151 2011 Genetics Learning...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Genetics Learning Objectives Part 1: Molecular and Genomic Levels Last updated: 10/28/11 DNA as the genetic material • Essential properties of deoxyribonucleic acid (DNA) as genetic material: stable, can be copied accurately, contains information, can be transmitted. • DNA is a component of chromosomes • Chromosomes, composed of protein and DNA, are physical units of heredity (demonstrated in Hershey-Chase experiment; DNA but not protein enters bacteria when bacteriophage infects) • DNA is a polymer of monomeric units called nucleotides. A nucleotide is composed of 1. a 5 carbon sugar, deoxyribose. 2. a triphosphate group, attached to the sugar at the 5 prime carbon. 3. a nitrogen-containing base, attached to the sugar at the 1 prime carbon. • There are 4 nitrogenous bases in DNA: two 1-ringed (C and T), two 2-ringed (G and A) • single stranded DNA = a chain of nucleotides, covalently bonded, grows in one direction only (5’ phosphate group attaches to 3’ carbon). • Chargaff’s rule: in all species examined, proportions of A=T and proportions of G=C • Watson and Crick (Franklin): DNA is double-stranded, hydrogen bonds hold the two strands together • Two DNA strands are antiparallel and form a helix Basic mechanism of DNA replication. • DNA is copied – replicated – using a semi-conservative model (demonstrated in MeselsonStahl experiment). • Bacteria have one circular double-stranded DNA chromosome, with one origin of replication. • In eukaryotes, large linear chromosomes contain many origins of replication used at the same time. • Steps in replication: helix unwinds - a replication bubble forms. Replication fork = junction between the open and closed regions, replication bubble = open DNA between two adjacent forks. • Helicase unwinds DNA: single strand binding proteins (SSBPs) keep it single stranded:. • Primase: makes a short RNA copy of DNA • DNA polymerase extends the chain, and then replaces RNA primers with DNA. • DNA polymerase cannot initiate a new strand, it can only add onto an existing 3’ OH group. • Only the leading strand is synthesized continuously toward the replication fork. The opposite strand (lagging strand) is made away from the replication fork, in small fragments called Okazaki fragments • DNA ligase makes covalent bonds between adjacent Okazaki fragments • Simple definition of a gene: one gene makes one protein = the central dogma of biology. . • Gene --> protein --> phenotype • DNA produces protein indirectly, through an intermediate molecule – ribonucleic acid, RNA. • In bacteria, transcription and translation are coupled (i.e. can occur almost simultaneously) • Eukaryotic cells uncouple transcription and translation: transcription takes place in the nucleus, translation in the cytoplasm. RNA and the basic mechanism of transcription
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/13/2011 for the course ZOO 151 taught by Professor Peralta during the Fall '07 term at Wisconsin.

Page1 / 13

Grinblat Study Guide - Biology 151 2011 Genetics Learning...

This preview shows document pages 1 - 2. Sign up to view the full document.

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