9-Genetic Diversity and Adaptation

Question 1

Mutation

Answer 1

Any change to the quantity/base sequence of DNA of an organism.

Question 2

Substitution of Bases

Answer 2

A gene mutation where a nucleotide in a DNA molecule is replaced with another nucleotide. If the C in GTC is replaced by G to become GTG then a new amino acid is coded for and the polypeptide chain will be different.

Question 3

Deletion of Bases

Answer 3

A gene mutation where a nucleotide is lost from the normal DNA sequence. This affects the whole polypeptide chain, not just one amino acid because after a nucleotide is omitted then every amino acid coded for after it will be different.

Question 4

Gene Mutation

Answer 4

Change in sequence of bases in DNA

Question 5

Chromosome Mutation

Answer 5

Change in structure/number of whole chromosome.
Either: CHANGE IN WHOLE SET OF CHROMOSOMES
CHANGE IN NUMBER OF INDIVIDUAL CHROMOSOMES

Question 6

Change in Whole Sets of Chromosomes

Answer 6

When organisms have 3 or more sets of chromosomes rather than the usual 2 (polyploidy).

Question 7

Change in Number of Individual Chromosomes

Answer 7

When individual homologous pairs of chromosomes fail to separate in meiosis (non-disjunction) so gamete has one more or one less chromosome.

Question 8

Process of Meiosis

Answer 8

FIRST DIVISION (MEIOSIS I)- Homologous chromosomes pair up and chromatids wrap around each other. Genetic Recombination (crossing over) occurs. At the end homologous pairs have separated and one chromosome from each pair goes into 1 of 2 daughter cells.
SECOND MEIOTIC DIVISION (MEIOSIS II)- Chromatids move apart. At the end 4 daughter cells have formed, each containing 23 chromosomes.

Question 9

Genetic Recombination (crossing over)

Answer 9

1) Chromatids of each pair become twisted around one another. During this twisting, tensions are created and portions of chromatids break off.
2) The broken portions rejoin with chromatids of its homologous partner. Usually equivalent portions of homologous chromosomes are exchanged.
3) This produces new genetic combinations of maternal and paternal alleles.