Module 1 Part 1 Flashcards
How are mutations classified
- heritability
-how they arise
-effects on gene function
-mutation type
define mutation
a change in the DNA sequence
define germ line mutation
heritable mutation from egg and sperm
define somatic mutation
mutation which is non heritable from the body cells
define protein coding region
mutation will affect polypeptide sequence
define non coding regions
mutation will affect gene regulatory regions; non coding RNA
- might still affect protein function during gene expression
what is germline mosaicism
genetically non identical germline cells (sperm, oocytes)
- mutation causes differences in offspring
what is somatic mosaicism
genetically non identical somatic cells
- post zygotic
- one mutated cell gives rise to daughter cells with same mutation
Describe the case study of genetic mosaicism discussed in class
blaschkoid congenital ichthyosiform erythroderma
- linear erythematosquamous plaques
- no growth/developmental delays
- hair and teeth not affected
RECESSIVE MUTATION
what gene is affected in blaschkoid congenital ichthyosiform erythroderma
gene ABCA12
define allele
gene variants which CAN result in mutation
define wildtype allele
the more abundant allele- present at greater frequencies
define mutant allele
the more rare allele
define spontaneous mutation
- occur randomly with no cause
- due to low level errors
- occur less frequently
describe an induced mutation
-arise due to exposure to physical and chemical mutagenic agents (radiation)
- mutagenic agents increase mutation rates greatly
describe loss of function mutation
reduces or abolishes protein function
what are the two types of loss of function mutations
- null (amorphic); complete loss of function
-hypomorphic; incomplete; reduced activity
define haplo insufficient genes
dominant gene
define haplo sufficient genes
recessive genes
- loss of function in which one normal allele is not enough for normal function
- more than 660 genes cause human disease as a result
describe a gain of function mutation
increased activity or new function; also for expression in wrong place or time
describe hypermorphic gain of function mutation
more protein or more efficient protein
describe neomorphic gain of function
generates a novel function
describe a dominant negative or anti morphic gain of function
prevents the normal protein from performing its homeostatic function
what is TP53
a transcription factor that functions as the gatekeeper of cell cycle progression
what does p53 do
arrests cell cycle progression if there is DNA damage- prevents it from proliferating
where do most p53 loss of function mutations occur
in the dna binding domain
what do some mutations in p53 result in
gain of function mutation
what does p53 actively supress
WT p53
what do mutant p53 cells exibit same phenotype as
p53 null cells
what are the three categories of mutations
single nucleotide, chromosomal re arrangements, change in chromosome number
what are the different types of nucleotide mutations
- substitution
- deletion
- insertion
what ar the different type of chromosomal re arrangement mutations
- large deletions
- large insertions
- inversions
- translocations
what is an example of changes in chromosome number
aneuploidy
what is the central dogma
DNA to RNA to Protein
define the genetic code
the set of nucleotide triplicates (codons) that code for amino acids or translation stop signal
what are point mutations
single base pair substitutions
what are three types of point mutations
nonsense: code for stop codon which can stop protein
missense: code for different amino acid, resulting in non functional or protein with different function
silent mutation: code for same or different amino acid but there is no functional change in protein
