Presentation on theme: "12.4 MUTATIONS I. Kinds of Mutations"— Presentation transcript:
1 12.4 MUTATIONS I. Kinds of Mutations Mutations are changes in the genetic materialA. Gene mutations – changes in a single gene1. point mutation – changes in one or a few nucleotides
2 3 TYPES OF MUTATIONS a. substitution – one base is changed to another * usually affects only one amino acidb. insertion or deletion – a base is added or removed from DNA sequence
3 FRAMESHIFT MUTATIONSi. Insertion & Deletion are known as frameshift mutations because the reading frame of the genetic message is shifted when a base is added or removedii. may change every amino acid that follows the point of mutationiii. can alter a protein so much that it can not function
4 Gene Mutations: Substitution, Insertion, and Deletion
5 CHROMOSOMAL MUTATIONS B. Chromosomal mutation – changes in the number or structure of chromosomes1. Four types of chromosomal mutations:a. Deletion – all or part of chromosome is lost
6 CHROMOSOMAL MUTATIONS b. Duplication – produces extra copies of parts of a chromosomec. Inversion – reverses the direction of parts of chromosomesd. Translocation – part of one chromosome breaks off and attaches another chromosome
8 MUTATIONS II. Significance of Mutations A. many mutations are neutral and have little or no effect on expression of a gene or function of protein1. mutations allow genetic diversity in a species
9 MUTATIONSB. harmful mutations are the causes of many genetic disorders or even cancerbeneficial mutations produce proteins that can be helpful in different environments
10 MUTATIONSMeiosis is a process where gametes (sex Cells) half the number of chromosomes.a. Nondisjunction occurs when a complete set of chromosomes fails to separate during Meiosis.gametes (sperm & egg) may produce triploid (3N) or tetraploid (4N) organisms
11 What happens if nondisjunction occurs? The gamete will die or result in conditions known as trisomy or monosomy.Trisomy - a person has more than 2 copies of the same chromosome.Monosomy – a person only has one copy of a chromosome.
12 How can you tell that? Take a picture of the chromosomes This is known as a karyotype.