Cellular Control Flashcards
(25 cards)
gene mutation
random change to genetic material
during DNA replication before division
somatic mutation
during mitotic division so not passed to offspring
point mutation
3 types?
1 base pair replaces another
silent, missense, nonsense
silent mutation
triplet still codes for same amino acid
missense
change to base triplet changes amino acid sequence (primary), so change tertiary so can’t function
nonsense
becomes termination triplet
truncated protein not function
indel mutation
nucleotides inserted/deleted from DNA
may cause frameshift which is when different groups of 3 form and all subsequent triplets are altered
number of __________ increases _________ across generations
if________ then = disease
CAG triplets
at meiosis
above critical number
transcription factors
how does it work?
protein/short non-coding RNA that combines with specific site on DNA to inhibit/activate transcription of gene
regulate gene expression
bind to specific promoter regions so aid/stop RNA polymerase
post-transcriptional gene regulation
introns (non-coding) and exons (coding) transcribed to primary mRNA
edited to remove RNA introns, exons joined (endonuclease)
some introns encode proteins/become non-coding RNA involved in gene regulation
post-translational gene regulation
activation of proteins by phosphorylation
signalling molecule activates transmembrane protein
which activates G protein
which activates adenyl cyclase
which catalyses ATP to cAMP
which activates PKA (protein kinase A)
which catalyses phosphorylation of protein and hydrolysis of ATP
activates enzymes in cytoplasm
PKA may phosphorylate another protein (CREB) which enters nucleus and acts as transcription factor
operon
group of genes that function as single transcription unit
in prokaryotes
lac O lac Z lac Y P I Lac I
operator region code for B-galactosidase code for lactose permease promoter region codes for repressor protein (Lac I)
E.coli normally metabolises ________.
if only ______ is present then what occurs?
glucose
lactose
lactose binds to lac I can't bind to lac O RNA polymerase binds to P lac Z and lac Y transcribed enzymes for lactose metabolism (B-galactosidase and lactose permease) produced
lactose permease
allows lactose to enter cell
B-galactosidase
hydrolyse lactose to glucose and galactose
homeobox sequence (6)
180 base pairs involved in regulating patterns of anatomical development
in animals, plants, fungi
make up homeobox genes
encodes 60 amino acid homeodomain sequence within a protein
base sequences very similar and regulate development and differentiation
conserved - remain in all descendent species throughout evolutionary history
homeodomain sequence
bind to DNA and regulate transcription of adjacent genes
homeo-domain containing proteins are transcription factors and fold to H-T-H (2 alpha helices connect by turn)
part of it recognises TAAT sequence of enhancer region from gene to be transcribed, enhancer region (initiates/enhances transcription)
Hox genes
subset of homeobox genes
only in animals
formation of anatomical features in correct locations
What do Hox genes do?
and extra info about them (4)
regulate embryo development along anterior-posterior axis
arranged in clusters, 4 if 4-limbed
expressed in order along axis-sequential and temporal order
encode homeodomain proteins that act as transcription factors
regulated by gap genes and pair-rule genes (these genes regulated by maternal mRNA from egg cytoplasm)
mitosis regulated by ______________
homeobox and Hox genes
_______ constant?
cell divides limited times before dies
Apoptosis
and how?
programmed cell death
enzymes break down cytoskeleton
cytoplasm dense with tightly packed organelles
protrusions from membrane(blebs)
chromatin condense, nuclear envelope breaks, DNA breaks
cell breaks to vesicles, ingested by phagocytes
What induces apoptosis?
nitric acid makes inner mitochondrial membrane more permeable to H ions to interrupt proton gradient and proteins into cytoplasm bind to apoptosis inhibitor
