Chapter 2.7 Flashcards
(9 cards)
What is an allele?
Alleles are alternative forms of a gene for a particular characteristic.
Each allele is characterised by a slightly different nucleotide sequence.
What is a phenotype?
A phenotype is the characteristics that result from the expression of an organism’s genotype.
A phenotype depends on the environment and genotype.
Eg Chemicals, Radiation, temperatures lifestyles and weight.
What is Homozygous?
Homozygous means having two identical allele for a characteristic within the genotype.
What is heterozygous?
Heterozygous means having 2 different alleles for a characteristic within the genotype.
What are the modes of inheritance?
Complete dominance: it is a type of inheritance in which the dominant trait requires only one allele to be present for its expression. The dominant allele gene will mask the recessive allele gene.
Co-Dominance: it is a type of inheritance where both different alleles show equal dominance, thus both genotypes phenotype characteristic will be expressed by the individual (organism).
Incomplete Dominance: is a type of inheritance
Partial dominance and Incomplete dominance.
What is the difference between a dominant gene and a recessive gene.
A person to show the recessive phenotype must have the genotype of both recessive alleles Eg bb.
A dominant gene will always dominate or take over the phenotype, the dominant gene will show its expression in the characteristic of the individual and overrule the recessive gene. The recessive gene is masked under the dominant gene and thus does not show itself.
What is the difference between homozygous and heterozygous?
A homozygous characteristic of an individual means that their genotype will have the same type gene alleles. Eg BB
A heterozygous characteristic of an individual means that their genotype will have different alleles. Eg Bb
What is the difference between a phenotype and genotype?
A genotype is genetic instructions (contained in DNA) inherited from parents at a particular gene locus. (One from each).
A phenotype is the characteristic expression of the genotype.
What is a carrier of a recessive gene mean?
A carrier refers to a person who is heterozygous for a particular trait, where the dominant characteristic is expressed and the recessive one is masked. This means they still carry the recessive trait but is being overruled by the dominant gene.
