Mutations and Evolution More on Biochemistry and Vertebrate Evolution From:

Mutations and Evolution

More on Biochemistry and Vertebrate Evolution

From:http://www.bishops.ntc.nf.ca/science/biology/mutations/

Mutation: damage to genetic materialA mutation to genetic material usually is NOT beneficial.About 1 in 1,000,000 times the mutation can lead to a beneficial variation (this is part of the evolutionary process).

A. Defintion

I. What are Mutations? How do they relate to evolution?

1. There are many possibilities for errors to occur:

Human genes are--on average--3000 nucleotides long.

There are about 30,000 genes in a complete set of human DNA: 46 DNA strands per cell in humans--each with about 140 million base pairs.

B. Why do mutations occur?

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2. Mutagens are things that cause mutations, they include:• High Temperatures • Toxic Chemicals (pesticides, etc)• Radiation (nuclear and solar)Many common place items are capable of causing mutations: microwave, fruit from the store, radar, cellular phones….

B. Why do mutations occur?

C. Types of mutations1. Chromosomal: affecting whole or a part of a chromosome

2. Gene: changes to the bases in the DNA of one gene (this is our focus)

1. Point mutation - when a base is replaced with a different base.

CGG CCC AAT to CGG CGC AAT Guanine for Cytosine

D. Gene mutations

2. Frame Shift mutations• A frame shift mutation results from a base deletion

or insertion. Each of these changes the codon that follow the mutation.

CGG CCC AAT to…

CGG CGC CAA T (all new codons!)

• Frame shift mutations have greater effects than a point mutation because they involve more codons (recall how important codons are to protein synthesis)

D. Gene mutations

Inserted!

a. Insertion - when a base is added

CGG CCC AAT to CGG CGC CAA T Guanine is added

b. Deletion - the loss of a base

CGG CCC AAT to CGG CCA A T loss of Cytosine

D. Gene mutations

E. What mutations do1. Mutations effect protein synthesis. During transcription mutated DNA will produce faulty mRNA leading to the production of a bad protein.

2. The Frame shift changes the mRNA produced.mRNA from DNA as expected……..GGG CCC TTT AAACCC GGG AAA UUU

Mutated DNA (insertion)

GGC GCC CTT TAA ACCG CGG GAA AUU UAll the codons are changed, this in turn changes the amino acids of the protein!

E. What mutations do

Resulting polypeptide:

Pro-Gly-Lys-Phen

Resulting polypeptide:

Pro-Arg-Glu-Phen-? Different!

3. Protein shape determines how a protein will function--mutations change the protein. • A point mutation leads to change in one amino acid. This change can change the protein shape enough to distort the whole protein (as in sickle cell disease).• More often, it is a frame shift mutation, which changes several codons, that distorts the protein’s structure.






4. Differences in DNA amongst living creatures is due to mutation. It is due to billions of years of mutations that the variety of life exists on earth.








II. Why study mutations and biochemistry?

• DNA differences due to mutation can be “read” to help establish evolutionary classification of organisms. So, DNA holds the key to understanding many evolutionary relationships

• DNA is the key to understanding many aspects of health and disease

• Genetic alteration of DNA is a major issue of modern and future human society

• Biotechnology and medicine are common career options

• You will be doing biotechnology lab work in this class





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