Gene Expression and Protein Synthesis Part 4 - (Week 4) Flashcards
1
Q
What is involved in completing and targeting the functional protein?
A
- sometimes translation = not sufficient to make a functional protein
- polypeptide chains = modified after translation/targeted to specific sites in the cell
- post translational modifications (e.g. phosphorylation) - required before the protein can begin doing its particular job in the cell
2
Q
What is protein folding?
A
- physical process where a protein chain acquires its native 3-dimensional structure, usually biologically functional
- protein’s shape = linked closely with its function + the ability to predict this structure unlocks a greater understanding of what it does = how it works
3
Q
How are genes important in completing and targeting functional proteins?
A
A gene determines primary structure (amino acid sequence) + primary structure in turn determines shapes
4
Q
What are mutations?
A
- alterations in the DNA & nucleotide sequence
- sustainers of life + can cause problems
- source of all genetic variation + providing raw material for evolution
- source of many diseases + disorders
- useful for probing fundamental biological processes
5
Q
What are the types of mutation?
A
- base substitutions
- insertions & deletions (frameshift mutations/ inn-frame insertions & deletions)
6
Q
Other info about mutation:
A
- effects of them vary widely
- beneficial, no effect, harmful or lethal
- may cause genetic disorders or cancer
- used as a tool to understand what genes do
7
Q
What happens in a missense mutation?
A
- new codon encodes a different amino acid, there is a change in the amino acid sequence
- you have a shorter protein causing mistakes due to changes in the expression
8
Q
What is a nonsense mutation?
A
- new codon is a stop codon, there is premature termination of translation
9
Q
What happens in a silent mutation?
A
- new codon encodes the same amino acid, there is no change in the amino acid sequence
10
Q
What are the 3 basic types of gene mutations?
A
- base substitution (alters a single codon)
- base insertion (alters the reading frame + may change many codons)
- base deletion (alters the reading frame + may change many codons)
11
Q
What are the phenotypic effects of mutations?
A
- loss of function (resulting in reduced/ abolished protein function)
- gain-of-function (confers new/enhanced activity to a protein)
- conditional (mutant allele causes a mutant phenotype in only a certain environment (restrictive), causing a wild-type phenotype in some different environment (permissive))
- lethal (affects survival of organism)
12
Q
What is an oncogene?
A
- any gene that encodes a protein able to induce cancer
13
Q
Where are most oncogenes derived from?
A
- normal cellular genes (producing protein products that enhance cell division/ inhibit normal cell death
- conversion of a proto-oncogene into an oncogene involving a gain-of-mutation
- hyperactive = means functioning on its own
14
Q
Where do transcription & RNA processing happen?
A
- the nucleus
15
Q
Where does translation occur?
A
- ribosomes
