CAS BI 105 Lecture Notes - Lecture 19: Frameshift Mutation, Nonsense Mutation, Silent Mutation
30 Apr 2018
School
Department
Course
Professor
Mutation and Gene Regulation
Mutation - mistakes made in the copying/transfer of making DNA and RNA
Gene Regulation - regulate which cells are more likely to be made into proteins/transcripts
Mutation Types
•Occasionally mistakes are made
•Point mutation - one nucleotide replaced with another (ex: C is replaced with a T)
•Missense Mutation - one amino acid is substituted for another
•Nonsense mutation - premature stop codon
•Frame-shift mutation - all/most amino acids are changed
•Mutations can be harmful or have no affect
How do we get mutations?
•Many mutations spontaneously arise during DNA replication
•These can be detected and deleted by DNA repair enzymes (polymerase and others)
•Some slip by
•Other mutations can be induced by exposure to mutagens
•Mutagen - a substance that causes mutations
•ex: UV Rays/X Rays (radiation-induced)
•ex: Exhaust/Chemicals in cigarette smoke (chemical-induced)
Mutation Functions (consequences)
•Silent mutations - no change to function
•Loss-of-function mutations - something you could do before but can’t do now
•Gene is not expressed
•Gene no longer codes for a functional protein
•Gain-of-function mutation - something you could not do before and can do or do more of now
•Mutation in the cell cycle control gene now results in more cell division
•Replication of genes on the chromosome leads to a greater expression
Chromosomal Mutations
•Large chunks of DNA can be duplicated/moved/mutated/deleted when there are changes to the
chromosome
•Chunks of DNA from one chromosome move to another chromosome
Genetic Regulation
•Almost every cell in the body has the complete genome
•Not all genes are needed all the time
•Not all genes are needed in every cells
•ex: liver cell and brain cell (need different complements of genes)
Cell Differentiation
•The process by which cells become specialized for their role in the body
•Stem cells —> can be translated into any cell type
•Cells become more specialized until they have unique properties
•^can also lose properties which will convert them into
different cells
•When a cell is fully differentiated, it can only perform a
few select tasks
find more resources at oneclass.com
find more resources at oneclass.com
