Biomarkers- Genetics Flashcards
Definition of a gene
Region of DNA that contains all of the information required to produce a functional protein or RNA
Definition of gene locus
The unique position of a gene on the chromosome
Definition of genome
All the genetic material (DNA) of an organism
Definition of genotype
The genetic constitution of a genome or individual locus
Definition of phenotype
The expressed features of the genome as a result of the interaction between the genotype and environment
Definition of genetics
The study of single genes and their effects
Definition of genomics
The study of all the genes in the genome how they interact and their interactions with environmental factors
Definition of epigenetics
The study of reversible, heritable mechanisms that influence gene expression without changing the DNA sequence
Definition of wildtype
The most common form of the gene within a population
Definition of allele
Alternative form (version) of a gene which has one or more differences in its nucleotide sequence
Definition of biallelic
Genes have two alleles
Definition of polyallelic
Genes have multiple alleles
Definition of homozygous
When copies of the gene (alleles) on each pair of a homologous chromosome are identical
Definition of heterozygous
When copies of a gene (alleles) on each pair of homologous chromosomes are different
What is co-dominance in blood groups
When both A and B are expressed because they are dominant
What enzyme is A blood
Transferase A
What enzyme is B blood
Transferase eB
What enzyme is O blood
Inactive transferase
What blood can AB blood types receive
A, B and O
Who can receive O blood
Anyone
What is incomplete dominance
When both alleles are expressed but one allele has more effect than the other
eg. T = straight hair and t = curly hair
Tt= wavy hair
What is polymorphism
A difference in DNA of equal or greater to 1% in a population
Definition of mutation
A difference in DNA that is associated with disease
Definition of haplotype
A set of DNA variations or group of alleles that are inherited together
What are germline cells
Cells that contain and transmit genetic information from generation to generation
What are somatic cells
All cells other than germline cells
Why are offspring genetically different from parents in humans
Independent assortment of homologous pairs of chromosomes during meiosis
Why are offspring genetically different from parents
- Independent assortment of homologous pairs of chromosomes during meiosis
- Random fertilisation
How does crossing over allow for genetic difference
Homologous chromosomes exchange information by recombination during meiosis
How does damaged chromosome ends lead to genetic variation
Causes chromosomes to fuse and incorrect separation during meiosis
Leads to gene amplification and loss
What are variations in DNA caused by
Errors in DNA replication
Damage to DNA caused by the environment
When are variations in DNA maintained in the germline DNA
They are not harmful
Provide an advantage
How do variations have a phenotypic effect
They must occur in the regulatory or coding region of a gene
How do variations effect the regulatory region of a gene
Altered efficiency of:
Transcription
Translation
Splicing
How do variations effect the coding region of a gene
- Alter the amino acid sequence of a protein and its function
- Affect the rate of folding of the protein
- Have an affect on protein stability
What are the 5 types of genetic variation
- Single nucleotide polymorphism
- Base deletion or insertion
- Microsatellites
- Minisatellites
- Copy number variations
What causes single nucleotide polymorphism
Base substitution in 1 in every 1000 bp
What is a synonymous SNP
No change to the amino sequence
What is a non synonymous- conservative missense SNP
Conservative change in the amino acid sequence because the side chains of bases are similar
What is a non synonymous- nonconservative missense SNP
Nonconservative change in the amino acid sequence because side chains of bases are different
What is a non synonymous- nonsense SNP
Change in the bases that encodes for a stop codon
What is another word for base insertion or deletion
Indels
How does base insertion occur
When strand slippage occurs in newly synthesised DNA, a base is inserted