Genetics Flashcards
What is fitness?
Relative ability of an organism to survive and pass on genes
What is phenotype?
Set of observable characteristics resulting from an interaction of the genotype and environment
What is genotype?
Set of genes in our DNA responsible for traits
How is genotype frequency calculated?
No of people with certain genotype/total number in sample
How is allele frequency calculated?
No of times a certain allele is seen/total no of alleles
What is the Hardy-Weinberg equilibrium?
Allele frequencies remain constant from generation to generation
What assumptions underlie the Hardy-Weinberg principle?
Mutation can be ignored Migration is negligible Mating is random No selective pressure Population size is large Allele frequencies equal in the sexes
What is natural selection?
Gradual process by which biological traits become more or less common in a population due to their fitness
What is negative selection?
Reduces fitness and decreases in frequency
What is positive selection?
Increases fitness and increases in frequency
What is genetic drift?
Random fluctuation of allele frequency in a small population
What is the founder effect?
Reduction of genetic variation when a small subunit of a large population establish a new colony
What is the first law of Mendelian inheritance?
Law of segregation
During gamete formation, alleles segregate from each other so each gamete carries only one allele for the gene
What is the second law of Mendelian inheritance?
Law of independent assortment
Gametes for different traits can segregate independently during the formation of gametes
What is the third law of Mendelian inheritance?
Law of dominance
Some alleles are dominant while others are recessive
What is non-Mendelian inheritance?
Any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws
What is penetrance?
Frequency which which a trait is manifested by individuals carrying the gene
What are genetic modifiers?
Genes which have on effect on the level of expression of another gene
What happens in genomic imprinting?
Only one working copy of a gene- one has been silenced
Child is mono-allelic
What is uniparental disomy?
When a child has 2 copies of a chromosome from one parent and none from the other
What are gyogenic genes?
2 maternal genomes
What are androgenic genes?
2 paternal genomes
What is special about mitochondrial inheritance?
All mitochondrial DNA inherited from mother
What is homoplasmy?
Uniform mitochondrial DNA with no disease
What is herteroplasmy?
2 or more forms of mitochondrial DNA that can cause disease
What are proto-oncogenes?
Normal gene that regulates for cell growth and differentiation
What does a photo-oncogene mutation cause?
Forms an oncogene that accelerates cell division
What are tumour suppressor genes?
Genes that act as “brakes” by inhibiting the cell cycle and/or inducing apoptosis
What are mismatch repair genes?
Corrects errors made during DNA replication e.g. single base mismatches
What causes genetic retinoblastoma?
A mutation in the RB1 tumour suppressor gene
What is BRCA1?
Checkpoint meditato involved in DNA damage signalling and repair
Mutation increases risk of primary breast cancer and ovarian cancer
What is BRCA2?
Repairs DNA by homologous recombination
Mutation increases risk of breast cancer and ovarian cancer
What are some hereditary colorectal cancer syndromes?
Familial adenomatous polyposis
MYH associated polyposis
