Cellular control Flashcards
What is a mutation
random change in base pairing of nucleotide chain(mRNA)
How can genes be expressed 4 ways
Transcriptional control- genes turned off or on
Post transcriptional- Mrna modified and types of proteins produced are regulated
Translational- translation stopped/ started
Post translational- proteins modified after synthesis which changes function
How are genes controlled at a transcriptional level
-rate of transcription
which is controlled by transcription factors
What is a transcription factor
Proteins that bind to DNA and switch them on and off
what are activators and repressors
TFs that start/stop transcription of certain genes
How do TF bind in eukaryoes
TF bind to promoter site of the DNA which then allows RNA polymerase to bind allowing transcription
What is an operon in prokaryote
section of genes controlled by a promoter allow for singular gene expression
What is an operon made up of
Structural genes- code for proteins
control elements - (promoter where RNA poly binds to and operator where transcription factor binds to)
Regulatory gene- codes for activator or repressor molecule
What is lac operon
Specific gene mechanism in bacteria which is used to synthesise an enzyme to break down the lactose in absence of lactose the regulatory gene syntheses a protein in which blocks the operator site for RNA to bind when lactose is present it bind onto this regulatory protein and causes it to change shape so it can no longer bind onto the operator region which then allows RNA poly to bind onto the promoter region
Post transcriptional control
Introns- non coding
extrons- coding
Introns are spliced out to pre mRNA to make mature mRNA
Post translational control
activation from other molecules bind to their surface eg cAMP changes 3D shape of proteins to activate it
What is a body plan
general structure of an organism
What are Hox genes
Proteins that control body plan development
What are homeobox sequences
region in hox genes that are highly conserved meaning they change very little during the evolution of the organisms that contain it
What do homeobox sequences code for
homeodomain protein that binds DNA as a TF, genes that are involved in development activating and repressing them
What is apoptosis
High controlled programmed cell death
How does apoptosis occur
Enzymes in a cell begin to break down the organelles
The nucleus begins to break down and the cell fragments
phagocytes engulf the cell and digest it
How is mitosis/apoptosis involved in bodily development
Mitosis develops body parts whilst apoptosis refines them and removes unwanted structures
What can affect development due to genes
internal/ external stress which can affect apoptosis and mitosis and cause abnormal growth or cell death
What causes mutations
Spontaneous change can be caused by mutagenic agents which increase chances of mutation(UV light, ionising radiation and chemicals)
What are the types of mutation
Substitution- One or more bases are swapped for another ATGCCT, ATTCCT
Silent- due to degenerative nature of nucleotide sequence protein created is the same
Missense- when the substitution causes a stop codon to be prematurely coded for
Nonsense-when the change in base leads to a new protein being made
Deletion- ATGCCT, ATCT removal of bases
Insertion- When one or more bases are added ATGCCCT, ATGACCT
What is a frame shift
addition/ deltion of bases can cause the base triplets to shift affects amino acids produced and the protein
What are physical mutagens
iomizing rays which breaks strands of DNA and the repair can cause muations
What are chemical mutagens
Chemicals that alter bases by converting them Cytosine to uracil
