Mutations, Gene expression and Cancer Flashcards
what is the genetic code described as
universal
degenerate
non-overlapping
what does universal mean
same 3 bases on mRNA codon for the same amino acids in all organisms
what does non-overlapping mean
the ribosome reads each base only once in the codons
what does degenerate mean
more than one triplet codes for an amino acids
what is the term for 3 bases on DNA
triplet
what is the term for 3 bases on tRNA
anticodon
types of mutations
substitution
addition
deletion
inversion
translocation
(chromosomal mutations)
duplication mutations
what are the types of mutagenic agents
high energy ionising radiation
DNA reactive chemicals
Biological agents
types of stem cells
Totipotent
Pluripotent
Multipotent
Unipotent
what is the process of which cells become specialised
cell differentiation
where are totipotent cells found
zygote and early embryo (upto 8 cell stage)
where are pluripotent cells found
embryonic and fetal stem cells
where are multipotent found
adult stem cells
where are unipotent cells found
used in the formation of single type of cells eg. cardiomyocytes
how many cells can totipotent cells differentiate into
any type of cell
how many cells can pluripotent cells differentiate into
most types of cells
how many cells can multipotent cells differentiate into
some types of cells
how many cells can unipotent cells differentiate into
only one type of cell
eg. heart stem cells differentiate into cardiomyocytes
What is a promoter region
one or more base sequences found upstream of a gene that control the expression of that gene
what is a transcription factor
proteins which when activated, bind to the promoter region of a gene stimulating RNA polymerase to begin transcription the target gene
why does RNA interference occur
-protein synthesis uses large amounts of ATP
-overproduction of a specific protein is a waste of valuable ATP
-if a cell has synthesised enough of a specific protein
two types of interfering RNA
microRNA
small interfering RNA
How does interfering RNA work
inheritable changes in gene expression without changes to their DNA base sequence
Inheritable changes are caused by changes in the gene’s environment that inhibit transcription by:
-increased methylation of DNA
-decreased acetylation of histones
process of methylation of DNA
CH3 is linked to CG bases on the promoter region upstream of the gene
process of interfering RNA
microRNA and siRNA are complementary to RNA
degenerates the RNA
translation is reduced
process of acetylation of histones
-acetyl groups on histone tails
-histones are not tightly packed
-promoter region is left exposed
