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
what is substitution?
one or more bases are swapped for others
what are the three types of substitution mutation?
silent, nonsense, mis-sense
what is morphogenesis?
the regulation of the pattern of anatomical development
what is morphogenesis controlled by?
homeobox genes
what are homeobox genes?
-has a sequence of 180 base pairs
-codes for homeodomains (protein segments which act as transcription factors)
-they are ancient and highly conserved
-they switch genes on and off
what genes control the development of the body plan?
homeobox genes
what does the fact that homeobox have high levels of conservation suggest?
that their activity is fundamental to the development of a working body so any mutation would be fatal
what are hox genes?
one specific group of homeobox genes (only in animals)
what are the 3 types of symmetry?
radial, bilateral, asymmetry
what is radial symmetry?
organisms with a top and a bottom but no left or right side
what is bilateral symmetry?
organisms have a left right and a head and tail end
what is asymmetry?
organisms have no lines of symmetry
what type of genes are homeobox genes?
regalotory
what is apoptosis?
programmed cell death
what is apoptosis triggered by?
transcription factors made by hox genes
what is an operon?
A cluster of genes under the control of a promoter
what is a gene?
section of DNA coding for a polypeptide
what structural detail of a polypeptide is altered by gene mutations
sequence of amino acids
