Lesson 7: Variation in Heredity

Question 1

mendel’s research involved the crossing of what type of plants?

Answer 1

what he called “typical” and “atypical” plants

Question 2

typical being..

Answer 2

homozygous dominant

Question 3

atypical being..

Answer 3

homozygous recessive

Question 4

what is complete dominance

Answer 4

when one version/allele masks the other version
- when one allele is expressed in the phenotype even if there is another allele present
- the dominant allele’s phenotype is expressed even if the genotype is heterozygous

Question 5

what is incomplete dominance + example

Answer 5

when 2 alleles interact with one another and neither masks the other but instead result in a BLENDED phenotype
EX: snapdragons (flowers)
- there are two alleles for flower colour including red and white
- NEITHER ARE DOMINANT, so neither allele can mask the other

Question 6

what is codominance + example

Answer 6

another example of what can happen when two alleles interact with one another
- both mask the other, so both show up in a mixed, not blended phenotype
EX: shorthorn cattle
- there are two alleles for hair colour including red and white
- both are dominant, so both hair colours appear

Question 7

what is human blood type inherited through: dominant, codominant, incomplete..

Answer 7

codominance and dominance

Question 8

what are the blood types

Answer 8

A, B, O, AB

Question 9

how does codominance and dominance work in blood types?

Answer 9

these blood types are inherited through 3 possible alleles: Ia, Ib, and i
^the a and b are subscripts
- each of these alleles codes for a different enzyme that places different types of sugars on the surface of red blood cells

Question 10

what is the genotype and # of sugars present for blood type A

Answer 10

• IA IA or IA i
• one type of sugar

Question 11

what is genotype and # of sugars present for blood type B

Answer 11

• IB IB or IB i
• one type of sugar

Question 12

what is genotype and # of sugars present for blood type AB

Answer 12

• IA IB
• two types of sugars

Question 13

what is genotype and # of sugars present for blood type O

Answer 13

• ii
• no sugars

Question 14

the IA and IB alleles are what to each other?

Answer 14

codominant to each other

Question 15

the IA and IB are completely what to the i allele

Answer 15

dominant to the i allele

Question 16

blood type A antigens and safe transfusions

Answer 16

• A antigens
• TO: A, AB
• FROM: A, O

Question 17

blood type B antigens and safe transfusions

Answer 17

• B antigens
• TO: B, AB
• FROM: B, O

Question 18

blood type AB antigens and safe transfusions

Answer 18

• A and B antigens
• TO: AB
• FROM: A, B, AB, O
• universal recipient

Question 19

blood type O antigens and safe transfusions

Answer 19

• no antigens
• TO: A, B, AB, O
• FROM: O
• universal donor

Question 20

CODOMINANCE IN BLOOD TYPES

Answer 20

if you give both one of A and one of B, the resulting CODOMINANCE will produce BOTH A and B antigens, which is type AB

Question 21

DOMINANCE IN BLOOD TYPES

Answer 21

The O allele is RECESSIVE, so either of the other blood types will override it when they are paired, resulting in either type A or type B (dominates type O blood)

Question 22

what happens when someone is given the wrong blood type (for ex, blood b is given blood a)

Answer 22

their antibodies will reject the foreign antigens and attack them, potentially causing the transfused blood to clot