mutation - ANSWER-a change in the DNA / nucleotide sequence
,Somatic cells - ANSWER-liver, brain, any cell in body that is not a
gamete
Germline cell - ANSWER-zygotes, sperms, - reproductive / sex cells
somatic mutation - ANSWER-non heritable, does not occur in germ-line
cells, is not passed onto progeny, is passed onto all descendants of that
cell
**only current offspring will carry mutations
** most cancers
germline mutation - ANSWER-heritable, occurs in germ-line cells, and
is passed on/present in all cells of the offspring
what regions of the DNA are affected by germline and somatic
mutations, respectively? - ANSWER-both types of mutations may affect
the protein coding regions or the non-coding regions
what is the effect of mutations in protein coding regions? - ANSWER-
affects the polypeptide sequence (defective), and may impact protein
function
what is the effect of mutations in non-coding regions? - ANSWER-in
non-coding RNA: impacts gene expression
Gene regulatory areas: increases inhibition process of transcription +
gene expression tome
*genes expressed @ beginning of liver --> timing may be impacted
loss of function mutation + the 2 types - ANSWER-reduces or abolishes
protein function.
1. null (amorphic): complete loss of protein function
2. hypomorphic: incomplete, reduced activity (supressed)
,Loss of Function - Dominant (Haplo insufficient) - ANSWER--
mutation in 1 gene - other gene is affected - not sufficient - function is
lost
Loss of Function - Recessive (Haplo sufficient) - ANSWER-- mutation
in one gene - other gene is functional - proteins are still function+
perform fine @ basic physiological level
gain of function mutation + the 3 types - ANSWER-increased activity or
new function; or expression in the wrong place/time
1. hypermorphic: more protein or increased activity
2. neomorphic: generates a new function
3.dominant negative/anti-morphic: prevents the normal protein from
performing its homeostatic function
are loss-of-function and gain-of-function mutations usually dominant or
recessive? - ANSWER--loss of function: can be either
-gain of function: almost always dominant
TP53 (p53) - ANSWER-Tumor suppressor protein 53
transcription factor that acts as the gatekeeper of cell cycle progression;
stopping the cell cycle if there is DNA damage - prevents cells from
proliferating
what is Tp53 supposed to do when there is damaged DNA? - ANSWER-
promote apoptosis genes, promote DNA repair genes, and inhibit cell
cycle genes
p53 forms - ANSWER-tetramer - 4 proteins - exactly the same
DBD + function - ANSWER-the DNA binding domain, important for
Tp53 to bind to DNA and regulate transcription
, What happens when there is a loss of function of DBD? - ANSWER-
reduction in DNA binding capacity, abolished gene expression,
increased proliferation of mutated cell
**cancer cells --> inhibit/ignore p53
what type of mutation causes a mutant p53 protein? - ANSWER-
dominant negative/anti-morphic mutation
what happens when there is a mutant p53 protein? - ANSWER--
suppresses the function of wild type p53
-does the opposite of what's supposed to happen: inhibits apoptosis
genes, inhibits DNA repair genes, and promotes cell cycle genes
**lecture diagrams
spontaneous mutation - ANSWER-occurs randomly with no known
cause
- spontaneous manners ( replication errors, transposons)
induced mutation - ANSWER-arises due to exposure to mutagenic
agents and radiation
- mutagenic agents - increase mutation rates several fold compared to
spontaneous mutations
what happens more often, spontaneous or induced mutations? -
ANSWER-induced
point mutation + types - ANSWER-change in a single nucleotide, or a
few base pairs. types: substitution, deletion, insertion
chromosomal rearrangement - ANSWER-large deletions, large
insertions, inversions, or translocations. at the chromosomal level,
sometimes deletions and insertions happen together
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