Genetics

Question 1

Deoxyribonucleic acid (DNA)

Answer 1

1. DNA is a double stranded molecule made from 2 chains of nucleotides
2. Each nucleotide consists of a sugar, phosphate group and a base
3. 4 bases are present A, C, G and T
4. Base pairings are A and T, C and G
5. The DNA wraps around proteins called histones to form chromatin
6. Chromatin is super coiled to form the chromosomes

Question 2

Chromosomes

Answer 2

1. Most cells in the body contain identical copies of the bodies genetic material within the cell nucleus
2. This is not normally visible until the cell prepares to divide
3. The compact strands of DNA are called chromosomes
4. Each chromosome is one of a pair, one being inherited from the mother and another from the father
5. There are 23 pairs of chromosomes
6. Pairs 1-22 are called autosomes
7. Pair 23 are called the sex chromosomes, x and y
8. Chromosomes belonging to the same pair are called homologous pairs
9. The y chromosome is much shorter than the x, xy is male and xx is female
10. A cell containing 46 pairs chromosomes is called a diploid
11. A gamete contains half this number, 23 in total, and is called a haploid
12. The genome is the name given to all genetic material contained within a cell

Question 3

Genes

Answer 3

1. Along the length of each chromosome there are discrete sections called genes that code for the production of proteins
2. These proteins are responsible for all structures and some behaviour within the body
3. Genes normally exits in pairs, one copy on each of the homologous chromosomes

Question 4

Messenger RNA

Answer 4

1. DNA is too large to leave the nucleus
2. MRNA is used to carry the genetic instructions from the nucleus into the cytoplasm to the ribosomes where specific proteins are made from amino acids

Question 5

Gene expression

Answer 5

1. All cells except gametes and red blood cells contain a full set of genes
2. Each cell is able to selectively use the genes required for its particular function
3. As a result the cell only make the proteins required for its function

Question 6

Cell division

Answer 6

1. Mitosis is cell division leading to the formation of 2 Identical diploid daughter cells which occurs in tissues
2. Meiosis is cell division to produce gametes, which leads to the formation of 4 haploid daughter cells which occurs in the ovaries and testis

Question 7

Mutations

Answer 7

1. Mutations are alterations in the genetic code
2. Some occur during the copying of the genetic material during replication, other may be caused by external factors such as chemicals or radiation
3. Some mutations may be lethal, may alter structure or be passed onto the next generation