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Central Dogma of Molecular Biology. Genetic information flows in one direction – from DNA to RNA to proteins. Bellringer What do these words mean to you? Write a short 2 word definition for each. 1. Mutation 2. Duplication 3. Deletion 4. Insertion 5. Translocation 6. Inversion
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Central Dogma of Molecular Biology • Genetic information flows in one direction – • from DNA to RNA to proteins.
Bellringer What do these words mean to you?Write a short 2 word definition for each • 1. Mutation • 2. Duplication • 3. Deletion • 4. Insertion • 5. Translocation • 6. Inversion • 7. Substitution
KEY CONCEPT Mutations are changes in DNA that can affect phenotype
Mutations are changes to DNA that may be • Harmful • Helpful • Have no effect.
When Mutations Occur • Errors can occur during: DNA Replication Protein Synthesis Meiosis .
Causes of Mutations 2. Mutagens – Environmental factors that cause changes in DNA Examples: - Radiation - Chemicals in environment .
The effect mutations have on an organism’s physical characteristics depends on: • The number and type of genes involved • Type of cell the mutation occurs in – somatic or sex
Mutations in Somatic Cells: • Affect only the organism they occur in. • Cannot be passed to offspring.
Mutations in Sex (Germ) cells: • May be passed to offspring
Two Categories of Mutations: 1.Single Gene– affects one gene – usually caused by an error in DNA replication 2. Chromosomal – affects chromosomes – usually error in meiosis . Usually more harmful since many genes are affected.
Types of Chromosomal Mutations • Translocation • Duplication • Nondisjunction • Deletion • Inversion
TRANSLOCATION(“transfer location”) • Piece of one chromosome breaks off and moves to a nonhomologouschromosomes.
DUPLICATION. • Two or more copies of the same gene on a chromosome .
NONDISJUNCTION • Homologous chromosomes don’t separate in Anaphase I • Sister chromatids don’t separate in Anaphase II
Deletion • Section of chromosome containing one or more genes is removed
Inversion • Section of a chromosome flips its position
Single Gene Mutations • Usually occur in DNA replication • Affect one gene and the protein made from it
Frameshift Mutation • Caused by adding or removing 1-2 bases • Changes the reading frame • .
Type of Frameshift Mutation .Deletion - one or more bases are deleted; shifts the reading frame
Type of Frameshift Mutation Insertion - one or more bases are added; shifts the reading frame
mutated base Point Mutations • One nucleotide is replaced by another.
Nonsense point mutation • Change codes for a STOP codon • Full protein not made • “NO” STOP
Missense Point Mutation * Codes for wrong amino acid* May be harmful or beneficial – depends…
Silent point mutationDoes not result in a different amino acid or protein made.DNA changes but its expression (phenotype) does not.
Results of mutations may be: • Harmful – needed protein isn’t made • Have NO EFFECT – are not harmful or helpful • Beneficial are favored by natural selection – rarely occurs
Mutations increase genetic variety Natural selection favors mutations that provide survival advantage.
Laron Syndromemutation that causes dwarfism also protects against cancer and diabetes. • ABC Evening News - Laron Syndrome
Mutations in body cells do not affect offspring. • Only Mutations in sex cells affect offspring. • Natural selection favors mutations that provide an adaptation that has survival advantage