Genetics

Question 1

DNA(deoxyribonucleic acid)

Answer 1

Found in Nucleus of all cells

Question 2

What are the components of DNA

Answer 2

Sugars
Phosphates
Bases

Question 3

DNA structure

Answer 3

Adenine pairs with thymine

Cytosine pairs with guanine

Question 4

Nucleotide

Answer 4

Sub-unit of the DNA molecule

Consists of one sugar, one phosphate and one base

Question 5

Chromosome

Answer 5

DNA wrapped around proteins called histones

Found in somatic cells ( pairs of chromosomes) and gametes ( single chromosomes)

Question 6

What is a gene?

Answer 6

Section of DNA that controls a trait

Genes for a particular trait occur at a particular point in the chromosome

Question 7

Homologous pair

Answer 7

A pair of chromosomes containing the pair of genes for a particular trait

Question 8

Alleles

Answer 8

Alternative forms of a gene
Inherited pairs of alleles control and determine the characteristics
Many genes have 2 alleles (dominant and recessive)

Question 9

Genotype

Answer 9

Genetic make-up of an individual

Inherited

Question 10

Phenotype

Answer 10

Observed expression of the alleles for the characteristic

Determined by the genotype and environment.

Question 11

What is monogenic inheritance?

Answer 11

Individual receives ONE pair of alleles for a trait. E.g. Blood grouping
Either present or absent
2 alleles for the trait
Only 2 phenotypes

Question 12

What is polygenic inheritance?

Answer 12

Many pairs of genes control the trait

There is continuous variation in the trait ( hair colour)

Question 13

What assumptions is polygenic inheritance based on?

Answer 13

1. Each gene has 2 kinds of alleles (contribution or non contributing)
   There is no dominance
   The effect of each contributing alleles is additive

Question 14

What is a mutation?

Answer 14

Permanent change to a gene or chromosome leading to a new characteristic in an organism