Cellular control 6.1 Flashcards
What is a mutation?
A change to the order of the bases of the DNA
What are the types of mutations?
- substitution
- Insertion
-Deletion
What is a substitution mutation?
One or more base pairs replace another
What is an insertion mutation?
One or more nucleotides are inserted from a length of DNA which can cause a frameshift
What is a deletion mutation?
One or more nucleotides are deleted from a length of DNA which can cause a frameshift
What are the three types of substitution reactions?
- silent
- misssense
- nonsense
What is a silent mutation?
When there is no change because the same amino acid has been coded for due to its degenerate nature
What is a missense mutation?
When a different amino acid sequence has been coded for
What is a nonsense mutation?
When the mutation ends up coding for a stop codon instead of an amino acid
What is a frameshift?
What are the effects of mutations?
- neutral
- harmful
- beneficial
What does a neutral effect to a mutation mean?
It means that a normal functioning protein is still synthesised so the phenotype is unchanged
What does a harmful effect to a mutation mean?
It means that proteins are not synthesised or non-functional so the phenotype is negatively impacted
What does a beneficial effect to a mutation mean?
It means that the proeins are synthesised with a new and useful characteristic in the phenotype
What are the causes of mutations?
- X-rays
- radiation exposure
- UV light
- cigarette smoke
What is a transcription factor?
- a protein or a short non-coding RNA that can combine with a specific site on a length of DNA and onhibit or activate transcription of the gene
- found in inactive forms and are activated by hormones or growth factors
What is an operon?
A section of DNA that contains a group of genes that function as a single transcription unit
What do activators do?
Start transcription
Whats do repressors do?
Stop transcription
Where do TF bind?
The promoter
What happens to a TF when a gene does not need to be expressed?
The site on the TF that binds to the DNA (promoter) is blocked by an inhibitor protein to prevent transcription
What are the two types of operons?
- structural
- regulatory
What do structural operons code for?
Code for structural/ functional proteins such as enzymes like collagen and keratin
What do regulatory operons code for?
mRNA which codes for a protein which is a repressor protein and binds to the operator which overlaps into the promotor to prevent the TF from binding
