Module 6: Mutations + Hox Genes Flashcards
What is an Operon?
A cluster of genes under the control of a promoter.
Give one example of apoptosis in the development of an embryo:
- Formation of Synapses
- Separation of digits (e.g toes or fingers)
Name all the kingdoms that use homeobox genes:
Fungi, Animalia and Plant.
Explain how the failure of a control mechanism can prevent the separation of fingers.
Transcription factors not produced, and-so transcription of the hox gene may not occur -> Molecules signaling apoptosis aren’t produced-> apoptosis does not occur.
Gene:
A specific segment of DNA whose nucleotide sequence codes for a specific protein.
Locus:
The location of a gene on a chromosome.
Alleles:
alternative forms of the same gene which occupy the same locus on a pair of homologous chromosomes.
Genotype:
The genetic constitution of an organism comprising all the genes possessed by an individual.
Phenotype:
The observable characteristic that is the consequence of a genotype.
Mutations:
Random and spontaneous changes to the base sequence
Somatic mutation:
Mutation on non-reproductive cell -Only affects the individual organism
Germ-line mutation:
Mutation on gametes that are inheritable.
Causes of Mutations:
Spontaneous, chemicals, radiation, viruses `
Example of beneficial mutation:
Sickle cell anaemia is a germline mutation that causes anaemia but makes the victim resistant to malaria.
Degenerate DNA:
Multiple codons code for the same amino acid.
Substitution Mutation:
A base pair is spontaneously replaced with another - this affects only one base triplet codon - effects at protein level.
Deletion Mutation:
A base pair/gene is discarded -> alters the reading frame of the gene -> irreversible
Addition Mutation:
A base pair is inserted into the DNA or duplicated - > caused by transposable elements or errors - > may alter splicing -> causes a frameshift
Homozygous:
individuals who carry two identical alleles.
What are the 3 types of substitution mutation:
Nonsense Mutation, Missense Mutation, Silent Mutation
Nonsense Mutation;
Premature stop codon results in a shorter unfinished protein.
Silent Mutation:
Change in DNA sequence does not affect sequence of amino-acids forming protein, due to degenerate DNA.
Missense Mutation:
A genetic alteration where a single base pair substitution alters genetic code to produce a different amino acid.
Why are chromosomal mutations severe:
Large regions of DNA are lost and damaged.
What are introns?
Non-coding regions.
What are exons?
Coding Regions.
