9- Genetic diversity and adaptation

Question 1

mutation

Answer 1

change to the quantatity or base sequence of DNA in an organism

Question 2

gene mutation

Answer 2

change in nucleotide bases or sequence of bases

Question 3

substitution

Answer 3

a nucleotide is replaced by a nucleotide that has a different base
new triplet may code for a different amino acid
polypeptide produced will differ in a single amino acid
of amino acid is involved in forming bonds to form the tertiary structure of the final protein, then the replacement amino acid may not from the same bonds
different shape of protein which may mean that it doesn’t function properly

Question 4

deletion

Answer 4

a nucleotide is lost from the DNA sequence
causes triplets to be read in a different order

Question 5

changes in whole sets of chromosomes

Answer 5

occurs when organisms have three or more sets of chromosomes rather than two

Question 6

changes in the number of individual chromosomes

Answer 6

individual homologous pairs of chromosomes fail to separate during meiosis (non-disjunction)
results in gamete having one more or one less chromosome

Question 7

meiosis 1

Answer 7

homologous chromosomes pair up and their chromatids wrap around each other
by the end of this division homologous pairs have separated with one chromosome of each pair going into one of the two daughter cells

Question 8

meiosis 2

Answer 8

chromatids move apart
at the end of meiosis 2 four cells have been formed

Question 9

how does meiosis cause genetic variation

Answer 9

independant segragation
crossing over
different alleles for the same gene

Question 10

independent segregation

Answer 10

arrangement of homologous pairs is random
combination of chromosomes from paternal and maternal origin that go into daughter cells at meiosis 1 is random

Question 11

crossing over

Answer 11

chromatids of each pair become twisted around eachother
tensions are created and portions of chromatids break off
equivalent portions of homologous chromosomes exchanged
new combinations of maternal and paternal alleles produced

Question 12

formula for the possible combinations of chromosomes in daughter cells

Answer 12

2 to the power of n
n=number of homologous pairs

Question 13

genetic diversity definition

Answer 13

total number of different alleles in a population

Question 14

natural selection definition

Answer 14

the process that leads to evolution in populations

Question 15

evolution defintion

Answer 15

change in allele frequency over many generations in a population

Question 16

describe the process of natural selection

Answer 16

1. new alleles for a gene are created by random mutation
2. if the new allele increases the chances of the individual to survive in that environment they are more likely to survive and reproduce
3. this reproduction passes on the advantageous allele to the next generation
4. as a result over many generations, the new allele increases in frequency in the population

Question 17

directional selection

Answer 17

one of the extremes has the selective advantage
occurs when there is a change in the environment
modal trait changes

Question 18

stabilising selection definition

Answer 18

modal traits have selective advantage
occurs when there is no change in the environment
modal trait remains the same
standard deviation increases as individuals with extreme trait decrease