4-3 Genetic diversity can arise as a result of mutation or during meiosis

Question 1

What is a mutation?

Answer 1

• Changes in DNA during replication or any change in the base sequence or quantity of DNA.

Question 2

What are the two types of mutation?

Answer 2

• Substitution, this is when one nucleotide in the DNA sequence is replaced by another, the effect of the change in an amino acid depends on the orle of the original amino acids in the shape and function of the protein, a substitution may not always be harmful as the substituted nucleotide may code in the triplet for the same amino acid.
• Deletion, a deletion event is when a nucleotide in the DNA sequence is lost, the loss of a single nucleotide can have a significant impact as it leads to a frame shift, resulting in completely different amino acids being coded for.

Question 3

What are the two mutations found in chromosomes?

Answer 3

• Polyploidy, three or more sets of chromosomes instead of two.
• Non-disjunction, chromosomes fail to separate properly, so one more or less chromosome.

Question 4

What is meiosis?

Answer 4

• Meiosis is a form of cell division that gives rise to four daughter cells that are genetically different and have half the number of chromosomes found in the parent cell.

Question 5

What is the role of meiosis?

Answer 5

• The main role of meiosis is the production of haploid gametes, as cells produced by meiosis have half the number of chromosomes.

Question 6

What are two causes of genetic variation?

Answer 6

• Independent assortment of chromosomes, there are various combinations of chromosome arrangement, during meiosis 1 homologous chromosomes line up in pairs, the arrangement of these pairs is random, meaning that the division into the daughter cells Is also random.
• Crossing over of chromatids, when pais of chromosomes line up they can exchange some of their genetic material, crossing over occurs when one chromosome may swap places with the same part of its homologous pair leading to a different combination of alleles on the gene.

Question 7

What are the stages of meiosis?

Answer 7

• Meiosis 1, homologous chromosomes pair up whereby crossing over at the chiasmata may take place, the cell then divides whereby each daughter cell contains once chromosome from each homologous pair.
• Meiosis 2, the chromatids of each chromosome are separated producing 4 haploid daughter cells.