Explain The Basic Terminology Of Genetics Flashcards
Define chromosomes
Chromosomes are composed of tightly coiled DNA and become visible when a cell is actively dividing.
Define chromatids
A chromatid is a single DNA molecule on a chromosome
Define gene
A segment of chromatin that contains the code for a particular protein.
Define genotype
Refers to the genes possessed by an individual - one set inherited from the father and one from the mother
Define phenotype
Refers to an individuals observable characteristics- eye colour etc which is determined by the interaction between genotype and environmental factors
Define autosomal
DNA which is inherited from any of the pairs of chromosomes numbered 1-22, as opposed to sex chromosomes
Define allele
A single copy of a gene
Define homozygous allele
Refers to a pair of alleles that have the same effect e.g two alleles encoding for blue eyes
Define heterozygous allele
Refers to a pair of alleles that have different effects, e.g one allele encodes for blue eyes and the other encodes for brown eyes
Define dominant allele
Mask the effects of the recessive allele and produces the same effect whether two alleles are present or only one. The dominant allele will always be expressed.
Define recessive allele
Do not have an effect when they are paired with a dominant allele, because they only have an effect when there’s two recessive alleles within an individuals genome
Define Co-dominance alleles
Co dominant alleles have equal dominance in a heterozygous person
Define mutation
A Change in the genetic material of a cell brought about by a range of mechanisms including inaccurate replication, errors in translation or transcription, or DNA damage via exposure to environmental factors.
Define locus
The physical site or location of a specific gene on a chromosome
Define homologous gene
A gene inherited by two species that evolved from the same ancestor.
