LS: I will be able identify and describe the different types of mutations.

Mutations Mutations are changes in the genetic material (changes in the genes) The DNA code can have a base(or more than one) missing, added, or exchange in a codon. Mutations occur at a frequency of about 1 every 1 billion base pairs Everybody has about 6 mutations in each cell in their body!

Can we see mutations? Mutations are not always seen. The affected gene may still function. Mutations may be harmful. Mutations may be beneficial. Mutations may have no effect on the organism. Mutations may be harmful. Mutations may be beneficial. Mutations may have no effect on the organism.

How are mutations beneficial? Mutations are a major source of genetic variation in a population’s increasing biodiversity. Some variation may help them to survive better.

When will I see a mutation? Only mutations in gametes (egg and sperm) are passed onto offspring Mutations in body cells only affect the organism in which they occur and are not passed onto the offspring Only mutations in gametes (egg and sperm) are passed onto offspring Mutations in body cells only affect the organism in which they occur and are not passed onto the offspring

Types of Mutations Point mutation: occurs when the base sequence of a codon is changed. (ex. GCA is changed to GAA) There are 3 types: Substitution Deletion Insertion There are 3 types: Substitution Deletion Insertion Deletion and Insertion are also Frameshift mutations!

Ex: Substitution Substitution Mutations Normal DNA: CGA - TGC - ATC Alanine - Threonine - Stop Mutated DNA: CGA - TGC - TTC Alanine - Threonine - Lysine What has happened to the DNA?

Do these look the same? THE FAT CAT ATE THE RAT THE FAT HAT ATE THE RAT Do these phrases make sense? What happened? Changes the thought of the sentence. The effect will depend on where the substitution happened.

Ex: Insertion Mutation Normal DNA: CGA - TGC - ATC Alanine - Threonine - Stop Mutated DNA: CGA - TAG - CAT - C Alanine - Isoleucine - Valine What has happed to the DNA?

Further explanation!! An insertion mutation adds to the sequence: 1.Causes the triplet “frames” to shift 2.It always affects the amino acids and, consequently, the protein formed An insertion mutation adds to the sequence: 1.Causes the triplet “frames” to shift 2.It always affects the amino acids and, consequently, the protein formed

Ex: Deletion Mutated DNA: CGA - TCA - TC Alanine - Serine What has happened to the DNA?

Further explanation!! A deletion removes from the sequence. 1.Causes the triplet “frames” to shift 2.It always affects the amino acids and, consequently, the protein formed A deletion removes from the sequence. 1.Causes the triplet “frames” to shift 2.It always affects the amino acids and, consequently, the protein formed

1. ____________ are changes in the ___________ material. 2. Mutations are a major source of genetic __________. 3. In a ____________ mutation one nucleotide is replaced for another. 4. In a ____________ mutation a nucleotide is removed from the sequence. 5. In a ____________ mutation a nucleotide is added to the sequence. LET’S RECAP…

Missense vs. Nonsense Mutations A point mutation in which a single nucleotide change results in a codon that codes for a different amino acid Missense Mutation A Point mutation in a sequence of DNA that results in a premature stop codon. Nonsense Mutation

How do these mutations affect the organism? Substitution has the least affect: a. Changes only one amino acid or it may change no amino acid Substitution has the least affect: a. Changes only one amino acid or it may change no amino acid Least affected Example: Sickle cell anemia 1.Only one amino acid changes in the hemoglobin 2.The hemoglobin still functions but it folds differently changing the shape of the red blood cell

Insertion and deletion a.Affect many amino acids b.Consequently affecting the whole protein Insertion and deletion a.Affect many amino acids b.Consequently affecting the whole protein Greatest affect Example: Huntington’s Disease (caused by insertion mutation) a.People with this disorder have involuntary movement, loss of motor control b.Eventually there is memory loss and dementia c.The disease is terminal d.Located on chromosome 4

The greatest affect on the organism! When the mutation occurs in the gamete (egg or sperm) or early in embryonic development (in stem cells or first few days)

Chromosome Mutations Chromosomal mutation: a mutation involving a long segment of DNA There are 5 Types Deletion Inversion Translocation Nondisjunction Duplication

Deletion vs. Duplication Deletion 1. A segment breaks off and is lost Deletion 1. A segment breaks off and is lost Duplication 1. Occurs when a gene sequence is repeated on the chromosome Duplication 1. Occurs when a gene sequence is repeated on the chromosome

Inversion vs. Translocation Inversion 1.Chromosome segment breaks off 2.The segment then flips around backward 3.The segment then reattaches Inversion 1.Chromosome segment breaks off 2.The segment then flips around backward 3.The segment then reattaches Translocation 1.Involves two chromosomes that aren’t homologous 2.Part of one chromosome is transferred to another chromosome Translocation 1.Involves two chromosomes that aren’t homologous 2.Part of one chromosome is transferred to another chromosome

Nondisjunction 1.Failure of chromosomes to separate during meiosis 2.Causes gamete to have too many of too few chromosomes 3.Disorders: 1.Down Syndrome – three 21 st chromosomes 2.Turner Syndrome – single X chromosome 3.Klinefleter’s Syndrome – XXY chromosomes

Causes of Mutation Inherited 1.Hereditary mutations or germline mutations 2.This type of mutation is present throughout a person’s life in virtually every cell in the body Acquired 1.Or somatic mutations 2.Occur in the DNA of individual cells at some time during a person’s life 3.Caused by environmental factors 4.Can’t be passed on to the next generation

Causes of Mutations Mutations are caused by either natural errors or an environmental event A mutagen is something that causes the DNA code to change—X-ray, chemicals, UV light, radiation, etc.

1. During a ___________ mutation a premature stop codon is formed. 2. ________________ results when two non-homologous chromosomes exchange segments. 3. ________________ is the failure of chromosomes to separate during meiosis. LET’S RECAP…