Mutations

DNA Mistakes

• DNA is a molecule that replicates, works and copies with very high accuracy

• DNA has enzymes that make sure that it works with a high level of accuracy and detail

• DNA can often work without mistake

DNA Mistakes

• DNA can however make mistakes

• When a DNA makes a mistake in its own sequence of base pairs its is called a mutation

• A mutation can change the base pairs in DNA for the rest of DNA

DNA Mistakes

• The process of making mutations is called mutagenesis

• Mutagenesis is often the result of physical or chemical agents that can damage DNA called mutagens

Substitution

• One of the types of mutations makes mistakes between the base pairs

• When a base pair does not correctly match put with its complement it is a substitution mutation

Example

Original Phrase:The cat ran over the hat.

Mutation:cat bat

New Phrase:The bat ran over the hat.

Substitution• If a substitution mutation

is made, however there is no change in the amino acid sequence it is called a silent mutation

• This is because the mutation in not seen

• If the mutation does change the amino acid sequence it is called a missense mutation

Results of Mutations• Often times mistakes can

change the stop codons for proteins

• This means proteins either end early or don’t end at all

• When a stop codon is changed and it changes the shape of an amino acid sequence it is called a nonsense mutation

• This type of mutation can permanently change the organism

Substitution

• By substituting a base pair for a different base pair will change the codon in the mRNA

• By changing the codon there is a different amino acid that is coded

• This changes the overall protein that is stored in DNA

Insertion and Deletion• Sometimes extra base pairs

can be added or deleted from the DNA strand

• These additions or decreases in base pairs can affect the entire molecule of DNA

• This can change the message of DNA

• These are called frameshift mutations

Example

Original Phrase:The cat ran over the hat.

Mutation:ran rn

New Phrase:The cat rno vert heh at.

Insertion and Deletion• By adding and deleting base

pairs there is a change in the overall codons for the protein

• It could change some or all of the amino acids in the protein

• Depending on where the insertion and deletion happens it could ensure that the protein never starts or stops

Video

http://www.youtube.com/watch?v=kp0esidDr-c

Results of Mutations

• Mistakes in DNA often present themselves in single base pairs

• One single base pair can change the message for an entire protein

• These changes can change the proteins that DNA codes for

Results of Mutations

• People often think about mutations in the way that the media presents mutations

• People often think that mutation give people different personalities or powers

http://www.youtube.com/watch?v=DI7q6DF6D54

Results of Mutations

• Many times when a cell undergoes a mutation a cell becomes of less value

• The cell cannot create a functional protein in a segment of DNA

• This makes the cell less effective

Results of Mutations

• Mutations also often lead to the death of a cell

• Without an essential protein a cell will die

• If the cell is very important, it could lead to the death of the organism

Mutations in Evolution

• Mutations are not all bad

• If the mutations give the organism some benefit the organism could live

• The organism might actually benefit from the overall mutation

Practice