Module 6 - Cellular Control Flashcards
what is a mutation?
a random unpredictable change in DNA
what can a mutation affect?
-small part of DNA molecule (gene mutation)
-large pieces of chromosomes/number of chromosomes present (chromosome mutation)
what is a gene mutation?
change in the base sequence of a DNA molecule
what are the three types of point mutation?
substitutions, insertions, deletions
what are the likely effects of a simple substitution?
-no effect due to the degenerate nature of the code
-introduction of a stop codon
what is deletion?
section of chromosome breaks off and gets lost within the cell
what is translocation?
a section of one chromosome breaks off and joins another non-homologous chromosome
what are the causes of mutation?
what increases the rate of mutation?
mutagens
what are the four stages where gene expression can be controlled or regulated?
Transcriptional control, Post-transcriptional control, Translation control, Post-translational control
what is chromatin?
a mixture of DNA and proteins that form the chromosomes found in eukaryotic cells
what two enzymes does E.Coli code for?
-lactose permease (which cell to take up lactose)
-lactase (enables cell to hydrolyse lactose to glucose and galactose)
what is a chromosomal mutation?
mutation that affects the whole chromosome or a number of chromosomes in a cell
what is a frameshift?
caused by insertions and deletions, all triplets downstream will be different giving the protein a different sequence of amino acids and different tertiary structure
what is the exon?
the expressed region within the gene
what is the intron?
the intragenic region (region within the gene)
how are the introns removed from a gene?
they are spliced
what is pre-transcriptional control?
-it produces pre-mRNA which is processed to form mature mRNA
-cap and tail are added to mature mRNA by spliceosomes removing introns
what happens in RNA editing?
-it can undergo deletion, addition or substitution which allows a single length of DNA to produce a range of different strands of mRNA
how does degradation of mRNA affect the rate of protein synthesis?
the more resistant the molecule the longer it will last in the cytoplasm therefore increasing the rate of protein synthesis
how does the binding of inhibitory proteins to mRNA affect the rate of protein synthesis?
it prevents mRNA from binding to ribosomes and the synthesis of proteins
what does the activation of initiation factors do in regards to the rate of protein synthesis?
aid binding of mRNA to ribosomes
what structural detail of a polypeptide is altered by gene mutations?
the amino acid sequence
