gentic diversity- mutations, meiosis

Question 1

what is genetic diversity

Answer 1

• the total number of different alleles in a population
• the greater number of alleles that all members of a species possess, the greater genetic diversity

Question 2

gene mutation

Answer 2

a change to one or more nucleotide bases, or a change in the sequence of the bases within a gene

Question 3

chromosome mutation

Answer 3

a change in the structure or number of whole chromosomes

Question 4

in which cells would a mutation have to occur in order to be inherited

Answer 4

gametes/ cells producing gametes

Question 5

factors that cause mutations

Answer 5

spontaneous
radiation
chemicals biological agents

Question 6

what do we call something that increases the rate of mutations

Answer 6

mutagenic agent

Question 7

gene mutation types

Answer 7

deletion and insertion of bases
substitution

Question 8

which type of mutation causes a frame shift

Answer 8

deletion and insertion

Question 9

example of a genetic disease caused by substitution mutation

Answer 9

sickle cell anaemia

Question 10

why might a substitution mutation not cause any change to the amino acid in a polypeptide

Answer 10

the code is degenerate
may result in a trip,et which codes for the amino acid

Question 11

chromosome mutations

Answer 11

changes in the structure or number of whole chromosomes

Question 12

polyploidy

Answer 12

where organisms have three or more whole sets of chromosomes
commonly seen in plants

Question 13

non disjunction

Answer 13

when individual homologous pairs fail to separate during meiosis
resulting gamete either has one more or one fewer chromosome

Question 14

what does the process of mitosis result in

Answer 14

2 daughter cells
genetically identical
same number of chromosomes
often diploid

Question 15

what does meiosis result in

Answer 15

4 daughter cells
genetically different
half the number of chromosomes
haploid
gametes

Question 16

meiosis brings out genetic variation due to

Answer 16

crossing over - new combinations of maternal and paternal alleles
independent segregation of homologous chromosomes

Question 17

diploid

Answer 17

chromosomes occur in homologous pairs

Question 18

what are homologous chromosomes

Answer 18

two chromosomes carrying the same genes
chromosomes may carry different allele of the genes

Question 19

allele

Answer 19

alternative form of a gene

Question 20

the first division of meiosis

Answer 20

division 1
separates the homologous chromosomes

Question 21

prophase 1

Question 22

prophase 1

Answer 22

chromosomes coil up and become visible
spindle fibres form
nuclear membrane and nucleolus disappear
homologous chromosomes pair up- synapsis
chromatids of the homologous warp around each other many times- crossing over
portions of the chromatids break off and re join with the chromatids on the homologous chromosome- recombination
the points where this exchange of genetic material takes place are called chiasmata

Question 23

metaphase 1

Answer 23

homologous pairs of chromosomes line up on the equator of the cell
chromosomes of each pair orientating randomly either side- independent segregation

Question 24

anaphase 1

Answer 24

one of each homologous pair moves to each pole

Question 25

telophase 1

Answer 25

two daughter cells form each containing only one pair of homologous chromosomes

Question 26

the second division meiosis 2

Answer 26

separates the chromatids

Question 27

population

Answer 27

group of individuals of the same species that live in the same place and can interbreed to produce fertile offspring

Question 28

gene pool

Answer 28

all of the alleles that exist in a population at a specific time

Question 29

allele frequency

Answer 29

the number of times an allele appears within a populations gene pool allele of interest/total number of alleles

Question 30

natural selection

Answer 30

1. random mutation, new allele, advantage, variation 2. increased survival 3. pass advantageous alleles to next generation, increased reproductive success 4. next generation will have advantageous allele, survive and reproduce 5. frequency of the advantageous allele in the gene pool will increase

Question 31

selection

Answer 31

organisms that are better adapted to their environment survive and reproduce

Question 32

phenotype

Answer 32

the physical and chemical characteristics of an organism

Question 33

directional selection

Answer 33

selection for a particular characteristic may favor individuals that vary in one direction away from the mean of the original population

Question 34

how would a mutation make the bacterium resistant to penicillin

Answer 34

new protein was an enzyme called penicillinase that hydrolysed the penicillin before it was able to kill the bacteria

Question 35

how does stabilising selection affect the genetic diversity of a population

Answer 35

less diverse- phenotypes at the extremes are eliminated