Biology 6.1 Flashcards
Point mutation
The bases substitute
Are made up of silent, missense and nonsense mutations
Indel mutation
Bases are inserted and deleted
This causes frameshift
The bases aren’t inserted in groups of 3
Silent mutation
The base trirplet changes but still codes for the same amino acid
This is because the code is degenerate
Missense mutation
The base triplet changes and codes for a different amino acid
Nonsense mutation
The base triplet changes and codes for a stop/termination triplet
What are transcription factors?
They control when genes are on or off
They bind to a specific promoter region
What are introns?
They are non coding regions in primary mRNA
What are exons?
Coding regions in mRNA
They are expressed
What happens in post transcriptional gene regulation?
The mRNA in edited and the introns are removed by splicing
Then the exons are joined by the endonuclease enzyme
What are homeotic genes?
Genes that control anatomical development
What are homeobox genes?
They are 180 base pairs that code for the homeodomain sequence
What is the homeodomain sequence?
- A strand of 60 amino acids that act as transcription factors
- They bind to promoter or enhancer regions and promote or inhibit transcription of the homeotic genes
- They are made up of 3 alpha helices
What are hox genes?
- Genes that are only in animals
- Highly conserved
- They control where body parts grow along anterior-posterior axis
What is colinearity?
Sequential temporal order of gene expression
How are hox genes regulated?
Regulated by gap genes and pair rule genes
What is the lac operon?
An operon that works in E. coli bacteria, that can produce enzymes needed to break down lactose if glucose isn’t present
What enzymes does the lac operon code for?
Lactose permease
Beta galactosidase
What happens at the lac operon when glucose is present?
- Regulatory Gene (I) codes for a repressor protein
- THe repressor protein binds to operator
- THis means RNA polymerase can’t bind to promoter region
- No MRNA made so genes Lac Z and Lac Y are off
What are the genes that code for the enzymes?
Lac Y and Lac Z
What happens at the lac operon when only lactose is present?
- Lactose binds to repressor protein
- This means the repressor protein can’t bind to operator
- RNA polymerase can bind to promoter
- MRNA is made so enzymes break down lactose
How are proteins activated?
- Signalling molecule binds to receptor
- The G protein activated
- Adenyl cyclase enzymes turn ATP to cAMP
- CAMP activates PKA
What does PKA do?
- Catalyses phosphorylation of enzymes
- Hydrolyses ATP
- Phosphorylates CREB which is a transcription factor
How does apoptosis work?
- Cytoskeleton breaks down
- Blebs (small protrusions) form
- DNA/ nuclear envelope break down
- Cell turns into vesicles
- Phagocytes ingest vesicles
How is apoptosis controlled?
By signalling molecules
- Cytokines
- Hormones
- Growth factors
- Nitric oxide
