DNA and Genetic Inheritance

Question 1

DNA:

Answer 1

• the genetic material of a cell is composed of a chemical called DNA
• DNA is a polymer made up of two strands in a structure called a double helix
• DNA in the nucleus is contained in structures called chromosomes

Question 2

Gene:

Answer 2

• a small section of DNA on a chromosome
• each gene codes for a particular sequence of amino acids, together making a protein

Question 3

Genome:

Answer 3

• all the genes coding for all of the proteins within an organism

Question 4

Gamete:

Answer 4

An organism’s reproductive cell which ahs the number of chromosomes (23)

Question 5

Chromosome:

Answer 5

A structure found in the nucleus which is made up of a long strand of DNA

Question 6

Alleles:

Answer 6

The different forms of a gene - humans have two alleles for each gene as they inherit one from each parent

Question 7

Dominant allele:

Answer 7

Only one out of two is needed for it to be expressed and for the corresponding phenotype to be observed

Question 8

Recessive allele:

Answer 8

Two copies are needed for it to be expressed and for the corresponding phenotype to be observed

Question 9

Homozygous:

Answer 9

When both inherited alleles are the same (i.e. two dominant or two recessive)

Question 10

Heterozygous:

Answer 10

When one of the inherited alleles is dominant and the other is recessive

Question 11

Genotype:

Answer 11

The combination of alleles an individual has (e.g. Aa)

Question 12

Phenotype:

Answer 12

The physical characteristics that are observed in the individual (e.g. eye colour)

Question 13

Use of a Punnett Square Diagram:

Answer 13

• shows the probability of the offspring of two parents having certain genotypes and phenotypes
• uppercase = dominant characteristics
• lowercase = recessive characteristics