Inheritance, selection and speciation Flashcards
What is a gene?
A sequence of bases on a DNA molecule that codes for a polypeptide which results in a characteristic
What is an allele?
Different version of the same gene
What is meant by genotype?
The genetic composition of an organism
What is meant by phenotype?
The expression of genotype in an organism and it’s interaction with the environment
What is meant by a dominant allele?
It is always expressed in the phenotype of an organism
What is meant by a recessive allele?
An alleles whose characteristic will only appear in the phenotype if two copies are present- homozygous recessive
What are co-dominant alleles?
Alleles that are both expressed in the phenotype and neither one is recessive
What is meant by homozygous?
Two copies of the same allele , either dominant or recessive
What is meant by heterozygous?
When an organism carries two different alleles, usually one dominant and one recessive and can often be described as a “carrier”
What are gametes?
Sex cells i.e. egg and sperm. They only contain one allele for each gene
What is monohybrid inheritance?
The inheritance of a single characteristic/gene controlled by different alleles
What sex chromosomes do female mammals have?
XX
What sex chromosomes do male mammals have?
XY
How many pairs of chromosomes do humans have?
23
What is the name given to genes/ alleles found on either the X or Y chromosome?
Sex linked
What is meant by a species?
A group of similar organisms that can breed together to produce fertile offspring
What is meant by the gene pool?
The range of alleles present within a population of a species
What is meant by allele frequency?
How often an allele occurs in a population
What are the equations of the Hardy Weinburg equations?
p² + 2pq + q² = 1
P + q = 1
What can the Hardy Weinburg equations
Allele and genotype frequency , percentage of population with a certain genotype
What does each part of the Hardy Weinburg principle mean?
P = frequency of dominant allele Q = frequency of recessive allele 2PQ = frequency of heterozygous genotype p² = frequency of homozygous dominant genotype q² = frequency of homozygous recessive genotype
What does the Hardy Weinburg principal predict?
The proportion of dominant and recessive alleles of any gene in a population remains the same from one generation to the next, provided certain conditions are met
What conditions does the Hardy Weinburg equations need to meet?
- No mutations
- population is isolated
- no selection of any sort
- population is large
- random mating occurs
What is meant by selection?
Process that results in the best-adapted organisms in a population to survive, breed and pass on their favourable alleles to the next generation
