16 - Gene Mutation and DNA Repair

16 - Gene Mutation and DNA Repair - Chapter 16 Gene...

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

View Full Document Right Arrow Icon
Chapter 16 Gene Mutation and DNA Repair I. Consequences of Mutation a. Chromosome mutations: changes in chromosome structure b. Genome mutations: changes in chromosome number c. Single-gene mutations: small changes in DNA structure that occur within a particular gene d. Gene Mutations Are molecular changes in the DNA sequence of a gene i. Permanent alterations of DNA within a gene ii. Point mutation: change in a single base pair within the DNA 1. substitutions a. Transition: change of a pyrimidines to another pyrimidines or a purine to another purine (A to G) i. more common than transversion b. Transversion: purines and pyrimidines are interchanged 2. deletions e. Gene mutations can alter the coding sequence within a gene i. Silent mutations: those that do not alter the amino acid sequence of the polypeptide even though the nucleotide sequence has changed ii. Missense mutations: base substitutions where an amino acid change does occur 1. sickle-cell anemia, mutates in B-globin gene a. glutamic acid is changed to valine iii. Nonsense mutations: change form a abnormal codon to a termination codon 1. causes translation of polypeptide to terminate early and truncates it 2. polarity: when a nonsense mutation occurs in a bacterial operon and inhibits expression of downstream genes iv. frameshift mutations: addition or deletion of a number of nucleotides that is not divisible by three, completely different amino acid sequence occurs downstream from the mutation v. except for silent mutations, new mutations are more likely to produce polypeptides with reduced
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 04/07/2008 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas at Austin.

Page1 / 2

16 - Gene Mutation and DNA Repair - Chapter 16 Gene...

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