Topic: Genetic Changes

Aim: How can genetic information be altered?

Thought Questions

• How is reading the DNA like a recipe?

• What happens when recipes go wrong?

• How does a wrong recipe relate to having the wrong “DNA” recipe?

What is a mutation?

• A genetic change/alteration that occurs on or within DNA.

• Results in a different transcription and translation message ultimately a different protein– Consequences: the protein may be the wrong protein

that the cell needs• Passed on through sex cells ONLY, not somatic cells• Mutations can be harmful when expressed, but can be

hidden

Agents that Cause Mutations:

• Environment– Mutagens: factors in the environment that can

cause a mutation– Long term radiation exposure ( UV from the sun,

radioactivity) cancer related– Chemical exposure ( formaldehyde, benzene, cigarette

smoke) – pH, physical manipulation, temp Example: Temp.

influenced : Himalyan Rabbit expresses genes in the winter( low temps) to make black fur for warmth.

*** Environment can influence genetic expression

Temperature Influences Trait

Rabbit expresses genes for a dark coat on particular parts of its body. When an ice pack is placed on its back, it too turns black

WHY DID THIS HAPPEN?

Types of Mutations

A- Chromosomal Mutations: changes that occur on sections of the chromosome or the complete chromosome structure. Ex: Inversion and Translocation

B- Gene (Point) Mutations: changes that occur on individual base(s) of the nucleotidesEx: Substitution, Addition, Deletion, Point Inversions

Types of Chromosomal Mutations- Inversion

• Segment of the chromosome breaks off and reinserted in the same place but in the reverse direction relative to the rest of the chromosome

Types of Chromosomal Mutations- Translocation

Information from one of two homologous chromosomes breaks and binds to the other. Known as “jumping genes”

Gene Mutations- Substitution

Substitution (point) mutation = when one base is replaced with another

Results in transcription and translation

of a different amino acid than expected.

Sickle Cell Anemia disease where substitution occurs on one base

Sickle Cell Anemia

• Disease where an individuals red blood cells are sickle in shape due to a substitution mutation that occurs in the DNA sequence of their red blood cell. Valine is substituted for glutamic acid

Results of sickle cell anemia

Gene Mutation- Addition

• Addition (point) mutation = when bases are added to the DNA sequence

• Results in the frame shift (bases move down) from the nucleotide sequences. Different (sometimes wrong or unwanted) amino acids are created into proteins

Gene Mutations- Deletion

• Deletion= nucleotides are deleted, which affects the coding of proteins that use this DNA sequence

Results of Addition & Deletion Mutations

Addition and Deletion mutations cause the DNA sequence to be read incorrectly Frameshift Mutation

RESULTS OF ALL TYPES OF MUTATIONS

• Overexpression of protein instruction

• No expression of protein instruction

• Expression of wrong protein instruction

Human Diseases Caused By Mutations

1) Sickle Cell Anemia - substitution mutation

2) Huntington’s Disease - addition mutation

3) Tay-Sachs Disease - deletion mutation

4) PKU- phenylketonuria- chromosomal mutation

PKU-phenylketonuria

• Missing enzyme that helps to breakdown phenylalanine. Genes are not expresses to make the enzyme phenylalanine hydroxylase

Recipe for a Ham & Cheese Sandwich (Normal)

1) Take 2 pieces of ham and place it on one slice of bread.

2) Add one slice of cheese on top of the ham.

3) Place one piece of lettuce on top of the cheese.

4) Place mayo on the second piece of bread.

5) Close the sandwich with the mayo on the inside.

Enjoy!

Name the mutation

1) Takke 2 pieces of hham and place it on one slice of bread.

2) Add one sliccce of cheese on top of the ham.

3) Ppplace one piece of leettuce on top of the cheese.

4) Place mayyyo on the seccond pieeece of bread.

5) Clossse the sandwich with the mayo on the inside.

Enjoyyyyyyy!

Name the mutation

1) Place mayo on the.

2) Take 2 pieces of ham and on top of the ham. place it on one slice of bread.

3) Add one slice of cheese

4) Place one piece of lettuce on top of the cheese.

5) second piece of bread Close the sandwich with the mayo on the inside.

Enjoy!

Name the mutation

1) Take 2 pieces of ham and place it on one slice of bread.

2) Place mayo on the second piece of bread.

3) Close the sandwich with the mayo on the inside.

Enjoy!