Inheritance Flashcards
(20 cards)
Gene
A specific sequence of nucleotides, as part of the DNA molecule, which codes for the synthesis of one specific polypeptide.
Gene locus
(Plural gene loci)
The specific position/location of a gene along the length of a chromosome.
Allele (of a gene)
An alternative form of a gene, with each allele having a slightly different nucleotide sequence.
Genotype
The genetic composition of all the alleles of genes in an organism.
Phenotype
The observable physical/physiological trait of an organism. The phenotype is the result of the expression of an organism’s genotype and the influence of environmental factors.
Dominant
The allele of a gene that is expressed in the phenotype of a homozygote and a heterozygote. The allele of a gene that is expressed in the phenotype under homozygous and heterozygous conditions.
The allele B for black hair is dominant to the allele b for brown hair.
Recessive
The allele of a gene that is expressed in the phenotype of a homozygote. The allele of a gene that is expressed in the phenotype only under homozygous condition.
The allele b for brown hair is recessive to the allele B for black hair.
Homozygote
(noun)
(adj homozygous)
An organism that has two same alleles of a gene at a particular locus on a pair of homologous chromosomes.
E.g., BB / bb
Heterozygote
(noun)
(adj heterozygous)
An organism that has two different alleles of a gene at a particular locus on a pair of homologous chromosomes.
E.g., Bb
Heterozygote
(noun)
(adj heterozygous)
An organism that has two different alleles of a gene at a particular locus on a pair of homologous chromosomes.
E.g., Bb
Codominant
Both alleles of a gene that is expressed in the phenotype of a heterozygote.
Both alleles of a gene that is expressed in the phenotype under heterozygous conditions.
E.g., A person with blood group AB (phenotype) has the genotype IAIB. The alleles of IA and IB are codominant to each other.
Autosomes (adj autosomal)
Any of the 22 numbered pairs of chromosomes found in most human cells. (Basically non-sex chromosomes from 1-22)
Meanwhile, chromosome number 23 (X & Y) are sex chromosomes.
Monohybrid Inheritance
Inheritance of one characteristic controlled by the alleles of one gene
Mutation
Change in the nucleotide sequence of DNA, or in the structure of a chromosome, or the number of chromosomes of an organism
Variation
Difference in characteristics shown by organisms belonging to the same natural population or species
Discontinuous Variation
A phenotypic variation that falls into two or more distinct, non-overlapping classes with clear-cut differences and no intermediates between them
- Usually controlled by usually one gene
- Relatively unaffected by environmental conditions
Continuous Variation
A phenotypic variation where certain characteristics within a population exhibit a complete range from one extreme phenotype to the other without any break
- Produced by additive effects of many genes on a single phenotypic character
- Affected by environmental factors
Natural Selection
Differential survival or, and reproduction by organisms best fitted to the environment
Evolution
The change in heritable phenotype traits of biological populations over successive generations
Environmental Factors
Organisms which are adapted to: disease, predators, mating, and resistance to certain deleterious factors in the environment, will be able to survive better.
