Cellular Control Flashcards
What is a mutation?
A random change in the base sequence of the DNA
What are transcription factors?
Proteins that bind to specific DNA sequences to initiate the transcription of genes into mRNA
Define operon.
A cluster of genes controlled by a single promoter
What are the components of an operon?
Regulatory genes - encode proteins that regulate expression of structural genes
A promoter region - site where RNA polymerase binds to initiate transcription
Operator region - sequence where repressor proteins can bind
Structural genes - genes that code for proteins
What is the function of the lac operon in E. coli?
Controls the metabolism of lactose
allows lactose to be used as an energy source when glucose is absent
What is the lacI?
a regulatory gene that codes for a repressor protein that inhibits transcription when no lactose is present
What happens when lactose is present in E. coli?
Lactose binds to repressor protein
Repressor protein changes shape so it cant bind to operator
RNA polymerase can bind to the promoter region
Structural genes can be transcribed
What happens when lactose is absent in E. coli?
The repressor protein binds the the operator
This prevents RNA polymerase from binding to the promoter region
Transcription is inhibited
What are the 3 structural genes of the lac operon?
lacZ:
Beta-galactosidase - breaks down lactose into glucose and galactose
lacY:
Lactose permease - transports lactose into cells
lacA:
What is the function of cAMP in the lac operon when lactose is present?
cAMP levels increase and binds to cAMP receptor protein (CRP)
CRP-cAMP complex increases transcription of lac operon
lactose is metabolised
What is the function of cAMP in the lac operon when lactose and glucose are present?
Glucose reduces cAMP levels
CRP-cAMP cannot form
lac operon transcription decreases
Structural genes are not transcribed so enzymes are not produced
What is splicing?
The removal of introns from mRNA before translation, occurring only in eukaryotes
What do Hox genes control?
The general organization of an organism’s body, including the arrangement of body parts
True or False: Hox genes are highly conserved throughout evolution.
True
What are the two processes that contribute to the development of the body plan?
- Mitosis
- Apoptosis
Define apoptosis.
The process of controlled cell death where cells self-destruct without causing harm
What are the types of mutations?
Substitution - one base replaced for another
Insertion - one or more bases are added
Deletion - one or more bases are removed
Inversion - a sequence of bases are reversed
What is a frameshift mutation?
A mutation caused by insertion or deletion that alters the reading frame of the genetic code
What can result from a neutral mutation?
- Change in base without amino acid change
- Change to a similar amino acid
- Mutation coding for an unimportant amino acid
What is an example of a beneficial mutation?
Antibiotic resistance in bacteria
What are examples of harmful mutations?
- Cystic fibrosis
- Cancer
