Module 6 Section 1 - Cellular Control Flashcards
A change to the base (nucleotide) sequence of DNA.
What are the three types of gene mutations?
What is a substitution mutation?
When one or more bases are swapped for another, e.g. ATGCCT becomes ATTCCT
What is a deletion mutation?
When one or more bases are removed, e.g. ATGCCT becomes ATCT
What is a insertion mutation?
When one or more bases are added, e.g. ATGCCT becomes ATGACCT
How does a mutation cause a modification in a protein (3) ?
- The order of DNA bases in a gene determines the order of amino acids in a particular protein.
- If a mutation occurs in a gene, the primary structure of the protein it codes for could be altered.
- This may change the tertiary structure of the protein so it doesn’t work properly, e.g. active sites denatured.
Why can some mutations have a neutral effect on a protein’s function? Give 3 ways.
- Although the base in a triplet changes, the amino acid that the triplet codes for doesn’t change. Some amino acids coded for by more than one triplet. (e.g. TAT and TAC = tyrosine)
- The mutation produces a triplet that codes for a different amino acid, but the amino acid is CHEMICALLY SIMILAR to the original.
- The mutated triplet codes for an amino acid NOT INVOLVED with the protein’s function.
Give an example in which a mutation can have a beneficial effect?
e.g. some bacterial enzymes can be mutated so that it BREAKS DOWN a wide range of antibiotics, so causes bacteria to be resistant to these antibiotics and increases its chance of survival.
Give an example in which a mutation can have a harmful effect?
e.g. cystic fibrosis is caused by a deletion of three bases in the gene that codes for CFTR which means that it beaks down and leads to excess mucus production.
What are the three levels that gene expression can be regulated/controlled?
- TRANSCRIPTIONAL Level
- POST-TRANSCRIPTIONAL level
- POST-TRANSLATIONAL level
What is gene expression controlled by at the transcriptional level?
What are Transcription Factors?
Proteins that bind to DNA and switch genes on or off by increasing or decreasing the rate of transcription.
What are Transcription Factors that increase the rate of transcription called? And vice versa?
Increases rate of transcription = ACTIVATORS
Decreases rate of transcription = REPRESSORS
How can the shape of a transcription factor that binds to DNA be altered?
What does this mean in terms of the how the synthesis of some proteins are controlled?
By binding of some molecules, e.g. some hormones and sugars
This means the amount of certain molecules in an environment or a cell can control the synthesis of some proteins by affecting transcription factor binding.
How do transcription factors perform in EUkaryotes?
They bind to specific DNA sites near the start of their TARGET genes - the genes they control the expression of.