Genetics Flashcards
What is a gene?
A part of the DNA molecule of a chromosome that directs the synthesis of a specific polypeptide chain
What is a genome?
All the genes carried by a cell or organism
What is an allele?
A characteristic controlled by a pair of factors, on inherited from each parents
What is the law of uniformity?
When 2 homozygotes with different alleles are crossed, the Fl generation will all be identical heterozygotes
What is the law of segreation?
Each individual posses 2 genes for each specific characteristic, only one will be passed on at any give time
What is the law of independent assortment?
Members of different gene pairs will segregate independently from one another
What is a genotype?
The genetic makup
What is the phenotype?
The appearance of an individual, which allele is physically expressed
What is a good way to predict segregation of genes?
Punnet square
What does it mean when phenotypes are discrete?
The phenotypes are clearly defined, like flies where only have red or white eyes, never pink
What does it mean by quantiative phenotypic traits?
Shows a continuous variation over a range of phenotypes
Polygenic expression is possible - where 2 or more genes contribute to outcome
How to differences in alleles arise?
Mutations in the gene sequence
What are mutations in alleles called and what does it denote?
Single nucleotide polymorphism (SNPs) and constitutes one base pair change
When is a mutation considered an allele?
When 1% or more of the population has it, otherwise is known as a rare variant
Describe a metacentric chromosome:
Equally long “short” and “long” arms because the centromere is in the center
Describe a submetacentric chromsome:
Shorter appearing “short” arms because the centromere is close to the short end, providing unequal chromatids
Describe a acrocentric chromosome:
Has almost no “short” arms, which are replaced by satellites because the centromere is all the way at one end
What is heterochromatin?
The “dark bands” on a chromosome indicating tightly packed chromatin (DNA)
What is euchromatin?
The “light bands” on a chromosome indicating light packed chromatin (DNA)
How would you name an area on a chromosome which is chromosome 4, long arm, region 2, band 6?
4q26
How would you name a reciprocal translation in a male between the long arm of chromosome 6 region 4 band 1 with the short arm of chromosome 3 region 8 band 3?
46, XY, t(6;3)(q41;p83)
What is the gene pool?
All of the alleles for every gene in a given population
What is a population?
Groups of individuals of the same species that occupy the same enviornment and can inbreed with one another
How do you calculate allele frequency?
of copies of a specific allele in a population
divided by
total # of all alleles for the gene in population
How do you calculate genotype frequency?
of individuals within a particular genotype in a population
divided by
total number of individuals in a population
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1
What does HW say about gene frequencies?
All subsequent generations will have the same proportion of genotypes and allele frequencies
What are the conditions for HW?
- No new mutations
- No natural selection
- Population is large enough that allele frequency doesn’t change due to sampling error
- No migration
- Random mating
What is it called when genetic variation occurs in a population?
Microevolution
What are the 2 traits that influence natural selection?
Characteristics that make organism better adapt to their environment and more likely to survive to reproduce
Traits directly associated with reproduction will produce more viable offspring
