D1.3 Mutations and Gene Editing Flashcards
mutation types, mutagens, loci, knockout, diseases, CRISPR
mutations
random, rare change in DNA, some have no effects
types of mutations
substitutions, deletions, insertions, point mutation (1 nucleotide modified)
locus
fixed position of a gene on a chromosome
achromatopsia
mutation of GNAT2 gene on chromosome 1, which controls production of protein transducin, which enables colour vision
genome
all DNA in the nucleus and mitochondria of an animal cell
phenotype
observable qualities based on genotype and environment
polymorphism
occurrence of two different phenotypes
genotype
combination of alleles inherited, codes for phenotype
single-nucleotide polymorphism
substitution point mutation, results in alleles and explains some diseases
missense mutation
substitution mutation that results in 1 different amino acid coded for
nonsense mutation
substitution mutation that results in stop codons
what causes sickle cell disease and what are its effects?
substitution mutation of gene for haemoglobin results in valine amino acid to be produced instead of glutamic acid, causes red blood cells be shaped like sickles and weakness, fatigue, shortness of breath, and malaria resistance
what causes huntington’s and what are its effects?
insertion mutation when trinucleotide repeat expansion of CAG results in HTT gene on chromosome 4 becoming mHTT gene, causing more glutamine production and trouble walking, speaking, and holding
only under what conditions does huntington’s show?
after 40 years old and when there are over 40 repeats of CAG
trinucleotide repeat expansion
when a set of 3 nucleotides repeats, expanding the polysaccharide region
frameshift mutation
when insertions/deletions occur in non-multiples of 3, altering entire sequence
chemokine
chemicals that tell leucocytes where an infection is, picked up by leucocyte receptors
what forms leucocyte receptors?
co-receptor molecule C-C chemokine receptor type 5
how does HIV-1 infect an individual?
enters CD4 leucocytes through receptors, so those with working CCR5 genes on chromosome 3 are at risk; if it destroys the leucocytes, it becomes AIDS
what mutation makes an individual resistant to HIV-1?
delta 32 mutation (CCR5-∆32) deletes 32 nucleotides, creating a stop codon for the gene CCR5, preventing formation of receptor
what are mutagens and some examples?
chemicals that cause mutations (eg enzymes that transform bases, benzene that causes leukaemia)
what can cause mutations?
mutagens and radiation
what percentage of DNA is actually coding?
1-2%
example of non-coding DNA
satellite DNA found in centromere, structural purposes; much more likely to be mutated than coding DNA (1 every 1000 base pairs vs 1 every 500 mil)
