chapter 22 - inheritance

Question 1

what were mendels two conclusions

Answer 1

• law of segregation: two alleles for each trait separate when gametes form; parents pass only one allele for each trait onto offspring
• law of independent assortment: genes of different traits are inherited independently of each other

Question 2

what is a cross / hybrid cross

Answer 2

• C: the mating of two organisms

- HC: only one pair of contrasting characteristics is studied

Question 3

what is a gene

Answer 3

• the factor that determines an inherited characteristic

- located on chromosomes

Question 4

what is an allele

Answer 4

• an alternative form of a gene, an individual only usually has 1 or 2 alleles for each gene

Question 5

what is dominant vs recessive

Answer 5

• D: the allele that masks the effect of an alternative allele
• R: the allele that is masked by the effect of an alternative allele

Question 6

what is homozygous, heterozygous and hemizygous

Answer 6

• homo: when an individual has the same alleles for a particular characteristic (purebred)
• hetero: when an individual possesses different alleles for a particular characteristic (hybrid)
• hemi: individuals have only one allele for a gene (sex linked)

Question 7

what are genotype vs phenotype

Answer 7

• G: genetic makeup of an individual as determined by the alleles for the characteristic being considered
• P: physical appearance of an individual determined by the expression of alleles for that characteristic

Question 8

who was Gregor Mendel

Answer 8

• first known geneticist, father of genetics
• Australian monk, born in 1822
• did most of his study on pea plants

Question 9

what is a punnet square

Answer 9

• diagram showing the gene combinations that might result from a genetic cross
• used to calculate the probability of inheriting a particular trait

Question 10

what is chromosome 23

Answer 10

• sex chromosomes, females have two X’s, males have one X and one Y

Question 11

what are chromosomes 1-22

Answer 11

• autosomes, non-sex chromosomes

Question 12

what are sex linked characteristics

Answer 12

• traits / genes that are carried / located on the sex chromosomes

Question 13

males and sex-linked traits

Answer 13

• males XY
• only men inherit the Y chromosome, only men inherit Y-linked traits
• males is hemizygous for X-linked traits
• men cannot be carrier of X-linked traits, they have it or they don’t

Question 14

females and sex-linked traits

Answer 14

• female XX
• pass on X to their sons
• can be carriers of a certain characteristic or trait

Question 15

what are X-linked traits

Answer 15

• traits carried on the X chromosome

- males and females can inherit X-linked traits, both inherit an X chromosome

Question 16

what are Y-linked traits

Answer 16

• traits carried on the Y chromosome
• Y chromosome is small and doesn’t carry many genes
• y-linked diseases are very rare
• only passed from father to son

Question 17

what is co-dominance

Answer 17

• situation in which both alleles of a gene contribute to the phenotype of the organism
• no dominant of recessive genes

Question 18

what are multiple alleles

Answer 18

• when there are more than two alleles for a particular characteristic

Question 19

example of co-dominance and multiple alleles

Answer 19

• blood types / groups

Question 20

explain the different types of blood groups

Answer 20

• A: antigen a, I^A I^A or I^A i, receives from A and O, donates to A and AB
• B: antigen b, I^B I^B or I^B i, receives from B and O, donates to B and AB
• AB: antigens a and b, I^A I^B, receives from A, B, AB and O (universal receiver), donates to AB
• O: no antigens, i i, receives from O, donates to A, B, AB and O (universal donor)