Inheritance Flashcards
What is a gene?
sequence of bases on a DNA molecule that codes for a protein which results in a characteristic
What is an allele?
one or more alternative versions of the same gene
What is a genotype?
genetic constitution of an organism
What is a phenotype?
expression of the genetic constitution - organism’s characteristics
What is a dominant allele?
an allele whose characteristics appears in the phenotype even when there’s only one copy
What is a recessive allele?
an allele whose characteristics only appears in the phenotype if two copies are present
What is co-dominant?
alleles that are both expressed in the phenotype
What is a locus?
fixed position of a gene on a chromosome
What is a homozygote?
an organism that carries two copies of the same allele e.g. BB or bb
What is a heterozygote?
an organism that carries two different alleles e.g. Bb
What is a modification?
any change to the phenotype that doesn’t affect the genotype and isn’t inherited
What are multiple alleles?
a gene that has more than two allelic forms
What is monohybrid inheritance?
inheritance of a single gene
What is pure breeding?
where a single gene is consistently bred in an organism - homozygous
What is sex-linked?
when the allele that codes for a characteristic is said to be located on a sex chromosome
Why are males more likely to inherit sex linked diseases?
the Y chromosome is smaller than the X chromosome and carries fewer genes
they only have one X chromosome and only have one allele for sex-linked genes
only one copy of allele they express the characteristic of the allele even if its recessive
What is a gene pool?
all of the alleles of all the genes of all individuals in a population at any one time
What is allelic frequency?
number of times an allele occurs within the gene pool
What is the Hardy-Weinberg principle?
mathematical equation that can be used to calculate the frequencies of the alleles of a particular gene in a population
What five conditions must be met for HWP?
no mutations arise population is isolated no artificial selection population is large mating within the population is random
What is the equation for HWP?
p2 + 2pq + q2 = 1
p2 = homozygous dominant
2pq = heterozygous
q2 = homozygous recessive
