Cellular Control Flashcards
Name the three types of Gene mutation
Substitution
Insertion
Deletion
What is a substitution gene mutation?
Where a nucleotide is replaced
What is an Insertion gene mutation?
Nucleotide/s inserted into amino acid sequence causing frameshift
What is a Deletion gene mutation?
Nucleotide/s deleted from amino acid sequence causing frameshift
What is a point mutation?
Where only one base is affected
Name the three types of point mutation
- Silent mutation, no change in amino acid sequence
- Missense mutation, one amino acid is changed in sequence
- Nonsense mutation, triplet becomes stop codon
What is Gene expression regulation about? Give an example.
- Some genes constantly expressed
- Others only expressed when needed
E.g. Lac operon triggered by presence of lactose to synthesise enzymes that break down lactose
What is the Lac operon and what parts do what?
- Section of E.coli DNA
- structural part codes for the enzyme
- operon part switched structural genes on/off
- Promoter region, where RNA polymerase binds to begin transcription
Name the three parts of the Lac operon
Structural part
Operon part
Promoter region
What happens to the Lac operon in the ABSENCE of lactose?
- Regulator gene expressed
- Repressor protein is synthesised and binds to operator region
- RNA polymerase cannot bind to the promoter region
What happens to the Lac operon in the PRESENCE of lactose?
- Lactose changes the shape of the Repressor protein
- Repressor breaks away from operator
- RNA polymerase can bind to promoter
What are Homeobox genes/what do they do?
Genes that regulate body part development
What are Hox genes?
A subset of homeobox genes, found only in animals, involved in the formation of anatomical features in correct locations of the body plan
Why/how are homeobox genes so highly conserved?
- Highly important
- If absent, organism would die/natural selection
In what direction are the homeobox genes expressed?
Anterior to Posterior
What is Apoptosis?
Programmed cell death in multicellular organisms
Outline the process of Apoptosis?
- Enzymes break down cytoskeleton
- Cytoplasm now dense with organelles
- Blebs form
- Chromatin condenses, envelope breaks down, DNA broken into fragments
- Cell breaks into vesicles that are phagocytosed so cell debris doesn’t damage other cells
What is Apoptosis responsible for during development?
- Separation of digits
- Removes harmful/ineffective T-cells in development of the immune system
What are Introns?
Non-coding pieces of DNA which are not expressed
What are Exons?
Coding/expressed regions of DNA, separated by introns
When all the DNA of a gene has been transcribed it is called primary RNA, why? What happens to it?
Both introns and exons are transcribed, so are in this RNA, and it hasn’t been edited yet.
- The RNA introns (corresponding to the DNA introns) are removed
What happens after the RNA introns have been removed from the primary RNA?
The remaining RNA exons (corresponding to the lengths of DNA exons are joined together)
What enzyme may be involved in the editing/splicing process of primary RNA?
Endonuclease enzyme
How a length of DNA (with its introns and exons) is spliced can effect what?
The particular protein it codes for
What is a Transcription factor?
A protein or short non-coding RNA that can combine with a specific site on a length of DNA and either inhibit/Activate transcription of the gene
Give an example of regulation of gene expression at the transcription level
The whole Lac operon thing
Post-translational regulation of gene expression involves the activation of what?
Proteins
How are many enzymes activated in post-translational regulation of gene expression? Give an example.
By being Phosphorylated
- The whole formation of cAMP from ATP sequence is catalysed by the enzyme Adenyl Cyclase
