genetics (inheritance)

Question 1

what is a gene?

Answer 1

sequence of bases on a DNA molecule that codes for a protein, resulting in a characteristic

Question 2

what is an allele?

Answer 2

different version of a gene- code for different versions of the same characteristic

Question 3

what is a genotype?

Answer 3

genetic makeup of an organism- the alleles that it has

Question 4

what is a phenotype?

Answer 4

expression of an organism’s genotype an its interaction with the environment- an organisms characteristics

Question 5

what does dominant mean?

Answer 5

allele whose characteristics appears in the phenotype even when there’s only 1 copy

Question 6

what does recessive mean?

Answer 6

allele whose characteristic appears in the phenotype if two copies are present

Question 7

what does co dominant mean?

Answer 7

alleles that are both expressed in the phenotype- neither is recessive

Question 8

what is a locus?

Answer 8

fixed position of a gene on a chromosome, allels of a gene are found at the same locus on each chromosome in a pair

Question 9

what is a homozygote?

Answer 9

organism that carries two copies of the same allele

eg) BB or bb

Question 10

what is a heterozygote?

Answer 10

organism that carries 2 different alleles

eg) Bb

Question 11

what is a carrier?

Answer 11

person carrying an allele which is not expressed in the phenotype, but that can be passed onto the offspring

Question 12

what chromosomes do females have?

Answer 12

2 X chromosomes

Question 13

what chromosomes do males have?

Answer 13

an X and a Y chromosome

Question 14

when is a characteristic sex linked?

Answer 14

the allele that codes for a characteristic is located on a sex chromosome

Question 15

why are most genes on the sex chromosomes only carried on the X chromosome?

Answer 15

Y chromosome is smaller so carries fewer genes

Question 16

why are males more likely to show recessive phenotypes for sex linked genes?

Answer 16

males only have one X chromosome
often only have 1 allele for sex linked genes
express this characteristic even if it is recessive

Question 17

what is an autosome?

Answer 17

chromosome that isn’t a sex chromosome

Question 18

why are genes on the same autosome linked?

Answer 18

as they are on the same autosome, they stay together in independent segregation

Question 19

what happens when are two genes on an autosome more closely linked?

Answer 19

crossing over is less likely to split them up

Question 20

what is epistasis?

Answer 20

when an allele of one gene masks the expression of the alleles of other genes

Question 21

what is a species?

Answer 21

group of similar organisms that reproduce to give fertile offspring

Question 22

what is a population?

Answer 22

group of organisms of the same species living in a particular area at a particular time

Question 23

what is the gene pool?

Answer 23

complete range of alleles present in a population

Question 24

what does the Hardy Weinberg principle predict?

Answer 24

that the frequencies of alleles in a population won’t change across generations

Question 25

what conditions is the Hardy Weinberg principle true under?

Answer 25

large population
no immigration 
no emigration
no mutations 
no natural selection 
random mating