Genetics And Inheritance

Question 1

Gene

Answer 1

Sequence of DNA nucleotides that code for a polypeptide chain which is a sequence of amino acids

Question 2

Genotype

Answer 2

Genetic constitutions of an organism

Question 3

Gene pool

Answer 3

All the alleles in a population

Question 4

Population

Answer 4

All the individuals living in the same area at the same time that interbreed to produce fertile offspring’s

Question 5

Phenotype

Answer 5

Observable characteristics determined by its genotype and its interactions with the environment

Question 6

Allele

Answer 6

Different versions of the same gene

Question 7

Loci/locus

Answer 7

Position of gene / allele within the chromosomes

Question 8

Homozygous

Answer 8

Two copies of a gene are the same allele

Question 9

Heterozygous

Answer 9

Two copies of a gene are different alleles

Question 10

Dominant allele

Answer 10

Allele will always be expressed and contribute to phenotype

Question 11

Recessive allele

Answer 11

Allele will only be expressed and contribute to phenotype if homozygous

Question 12

Co dominant alleles

Answer 12

Both alleles always expressed and contribute to phenotype

Question 13

Diploid

Answer 13

2 copies of a gene

Question 14

Haploid

Answer 14

Only one copy of a gene

Question 15

Sex linkage

Answer 15

A genes whose locus in on the X chromosome

Question 16

Monohybrid

Answer 16

A genetic inheritance cross diagram of a characteristic determined by one gene

Question 17

Dihybrid crops

Answer 17

A genetic inheritance cross diagram for a characteristic determined by 2 genes

Question 18

Epistasis

Answer 18

When one Gene affects the expression of a another Gene within the phenotype

Question 19

Autosomal linkage

Answer 19

Genes that are on the same pair of homologous chromosomes ( nit the sex chromosome)

Question 20

Chi squared test

Answer 20

To see if differences between observed and expected values are significantly different in categorical data

Question 21

Hardy- Weinberg principle

Answer 21

Frequency of Allele of a particular gene will stay constant from one generation to the next providing no mutation, migration , selection, mating is random and population is large

Question 22

Why is named model good for studying

Answer 22

Small sample size so simple nutrient medium so less cost

Question 23

The actual percentage of q,p,2pq is lower than expected why?

Answer 23

Individuals with this allele do not reproduce and die therefore don’t pass on allele to future generations

Question 24

Evidence for allele bring recessive/dominant

Answer 24

Look for 2 shaded in parents and one colourless child or vice versa
This means parent must be heterozygous as child is homozygous recessive

Question 25

Evidence for not being on X chromosomes

Answer 25

Look for infected father and homozygous recessive daughter. Daughter is XX therefore one from mum and one X from dad. Allele for males always expressed on X sex chromosomes therefore daughter should have been infected Or homozygous recessive mother and disease carrying son

Question 26

Why are males more likely to get the disease than females?

Answer 26

Males only need to be expressed on one X chromosome whereas as females need allele to be expressed on both xx chromosome

Question 27

The observed ratio is distinctly different to expected phenotype ratio. The data shows to phenotypes with large number of individuals with two phenotypes and very low number of individuals. Explain why.

Answer 27

Individuals of genotype… produce mainly gametes of… Because … and… genes are linked Crossing over during meiosis one causes few .. and… Leading to fewer re-combinant genotypes so if you are individuals in next generation with .. …

Question 28

Why may genetic cross give different phenotypic ratios to what is expected?

Answer 28

Small sample size Epistasis Crossing over Random fusion of gametes

Question 29

2 Heidy Weinberg equations

Answer 29

P + Q= 1 P2 + 2PQ + Q2 = 1 2pq = heterozygous