cell cycle , cellular ageing , cell death and gene expression Flashcards
what is a gene ?
A functional region of DNA which codes for a sequence of RNA
what is an allele ?
An individual variant of a gene
What is an exon ?
Portions of a gene product which are removed via splicing of RNA
what is an intron?
Portions of a gene product which are retained following splicing
what is the genotype?
The genes (and alleles of them) in a cell/organism
what is the phenotype?
The physical features of an organism resulting from its genotype
what is a mutation ?
Changes in the genetic sequence
how is RNA produced from DNA?
Transcription
what are the forms of RNA?
messanger RNA
transfer RNA [tRNA]
ribosomal RNA [rRNA]
short interferring and micro RNA [siRNA and miRNA]
what is a substitution mutation ?
one base is replaced with another
What are the 3 types of substitution mutations ?
Silent: New code is for same amino acid
Missense: The new code changes an amino acid
Nonsense: The new code is a STOP codon and stops the protein being produced
What does the frameshift mutation do?
Frameshift: The triplet code is disrupted, so all amino acids after the mutation
change
what are the types of frameshift mutations ?
Addition: A new base is added, shifting the rest forwards
Deletion: A base is removed, pulling the rest backwards
Mutations
what is a germline mutation ?
cells that will give rise to gametes
have genes that can be passed on
can be passed down through families
what is a somatic mutation ?
mutation does effect other cells only the ones it divides into
cannot be passed
what is proliferation ?
growth
replace dead / injured cells
happens in mitosis
when is proliferation vital?
plays a key role from embryogensis to whole organism
crititical in the maintenance of adult tissue homeostasis
why do some cells divide at specific times ?
enviroment = nutrience , temp , ph , oxygen
interactions with other cells and signalling molecules
intracellular signalling
what are the four stages of dividing cells ?
G1
S phase
G2
M phase
also G0 - for resting cells
what happens in G1 ?
preparation for DNA synthesis [ s phase]
what happens in G2 ?
preparation for cell division [ m phase ]
If DNA damage is detected, the cell will not be able to proceed through the cell cycle until that damage is repaired. If it can not be repaired, what process will occcur ?
apoptosis
What happens during s phase ?
DNA replication occur
DNA helicase breaks hydrogen bonds between DNA strand separating them
DNA polymerase catalyses addition polymerisation of DNA nucleotides
New nucleotides are added to the 3’ (“3 prime”)
end of the new strand. New nucleotides are
attached via their 5’ (“5 prime”) end
how is cell cycle controlled ?
fixed amount of time for each event
information from cell cycle event and external environment
