Mechanism of Inheritance

Question 1

What is a karotype

Answer 1

1. A karotype is an individual’s complete set of chromosomes
2. A normal human cell has 46 chromosomes or 23 homologous pairs of chromosomes
3. A gamete (sperm and ovum) has half the number of chromosomes
   - fusion of nuclei of male and female gametes restores the full set of chromosomes

Question 2

Definition of a gene

Answer 2

A gene is a basic unit of inheritance. It is a sequence of nucleotides, as part of a DNA molecule

Question 3

Function of gene

Answer 3

Each gene controls the formation of one polypeptide

Question 4

Definition of an allele

Answer 4

An allele is an alternative form of a gene, found on the same relative location (locus) in a pair of homologous chromosomes, which controls one characteristic

• each individual has two alleles for each gene, one on each homologous chromosome
• an allele can be dominant or recessive

Question 5

What is a dominant allele

Answer 5

An allele which expresses itself and give the same phenotype in both homozygous and heterozygous conditions

Question 6

What is a recessive allele

Answer 6

An allele which expresses itself in only in the homozygous conditions and not in a heterozygous condition