Lecture 4/2

Question 1

What is a hemolytic reaction?

Answer 1

when antibodies signal cell destruction of red blood cells

Question 2

which blood types are antibodies made against?

Answer 2

type A and B

Question 3

which blood type is a universal donor?

Answer 3

O

Question 4

which blood type can accept any other blood type?

Answer 4

AB

Question 5

what are the 3 most common antigen (protein) types on the surface of a RBC that will trigger an immune response?

Answer 5

ABO, Rh, and Kell

Question 6

which antigen on a RBC protects against malaria?

Answer 6

Duffy

Question 7

what percentage of the population is Rh-?

Answer 7

~15%

Question 8

what are the 2 blood supplies in the placenta?

Answer 8

maternal-placental and fetal-placental

Question 9

do the two blood supplies in the placenta cross?

Answer 9

not usually

Question 10

when is a time that it is likely fetal blood will escape from placenta?

Answer 10

it could happen during pregnancy, but is more likely to happen during birth

Question 11

if an Rh- mother is pregnant with an Rh+ baby, what can happen during the second Rh+ pregnancy?

Answer 11

the mother’s immune system will have developed antibodies against Rh+ and the mother’s immune system could cross the placenta and destroy fetal red blood cells

Question 12

what is the treatment for a mother pregnant with a baby of a different Rh? Who is commonly given this treatment?

Answer 12

RhIg (Ig=immunoglobin) injections – these are antibodies against Rh+ during early pregnancy to prevent the mother from mounting her own defense/immune response. These injections are given routinely to Rh- mothers

Question 13

what do half and half ratios of phenotype indicate about the parents?

Answer 13

one must be heterozygous

Question 14

if the numbers in a phenotype ratio don’t add up to 4 or 16, what does that tell us about the genotypes?

Answer 14

there is (at least) one lethal GT

Question 15

can something be dominant but also be lethal when homozygous?

Answer 15

yes, it will just be the dominant phenotype when heterozygous

Question 16

are lethal alleles dominant or recessive?

Answer 16

they can be either

Question 17

what is the inheritance of huntington’s disease?

Answer 17

autosomal dominant, late-onset lethality

Question 18

what is pleiotropy?

Answer 18

one gene contributes to multiple, seemingly unrelated characteristics/phenotypes

Question 19

what is an example of pleiotropy?

Answer 19

variant 370A in the ectodysplasin A receptor in East Asian and Native American people is correlated with thicker hair, missing lower wisdom teeth, and shovel teeth

Question 20

what happens when 370A variant is put into mice?

Answer 20

thicker hair and an increased density of sweat glands

Question 21

when in development is it likely that a gene that affects multiple unrelated characteristics will be around?

Answer 21

early, before things have been designated

Question 22

why can mutation of one gene contribute to multiple, seemingly unrelated characteristics?

Answer 22

mutations of a gene that functions early in a developmental pathway affect later development possibilities

Question 23

can a gene have different functions at different times of development?

Answer 23

yes, this is also considered pleiotropy

Question 24

what does hemoglobin do?

Answer 24

it transports oxygen in RBCs

Question 25

what makes up hemoglobin?

Answer 25

globin (2 subunits, alpha and beta globin) and an iron molecule

Question 26

what genes encode alpha globin

Answer 26

Hbalpha

Question 27

what gene encodes beta globin

Answer 27

Hbbeta

Question 28

what is the result of mutations in alpha or beta globin genes?

Answer 28

alpha or beta thallasemia

Question 29

what happens in thallasemia?

Answer 29

excessive killing of red blood cells, which leads to anemia, bone deformities, and heart failure

Question 30

how does the body respond to thallasemia? what does that lead to?

Answer 30

makes more RBCs, leads to iron overload which causes liver and heart failure

Question 31

what is the clinical treatment for thallasemia?

Answer 31

blood transfusions, but iron overload causes liver and heart failure -- a new drug (desferoxamine) eliminates iron OR stem cell transplant from a relative

Question 32

sickle cell disease is caused by the most common mutation in which gene?

Answer 32

beta globin S

Question 33

is sickle cell considered pleiotropic? why?

Answer 33

yes, it deforms RBCs, causes anemia, heart failure, and resistance to malaria

Question 34

is sickle cell lethal?

Answer 34

it can be recessive lethal (heart failure)

Question 35

what is the dominance pattern of sickle cell disease?

Answer 35

it is different for the different phenotypic aspects of the disease -- there are rare dominant alleles

Question 36

what is the treatment for sickle cell?

Answer 36

bone marrow transplant from matched relative can cure, OR hydroxyurea to stimulate fetal Hb production

Question 37

what is epistasis?

Answer 37

when the effects of one gene masks/suppresses another

Question 38

what is the epistatic result from an AB x B cross? what is it called?

Answer 38

O blood type, called Bombay phenotype, hh

Question 39

how does the bombay phenotype come about?

Answer 39

if you don't have fucosyltransferase, you can't put the sugar on the sugar, which causes an O blood type appearance

Question 40

what are the two enzymes involved in putting sugars on the sugar for blood type?

Answer 40

fucosyltransferase and glycosyltransferase

Question 41

Bombay phenotype is which antigen?

Answer 41

H

Question 42

What sort of blood transfusion can an hh person receive? why?

Answer 42

only blood from other bombay patients because their body makes antibodies against A and B types and also against H antigen

Question 43

why is bombay phenotype considered epistatic?

Answer 43

the H phenotype masks/is epistatic to the ABO phenotype

Question 44

what is the difference between epistasis and dominance patterns on alleles of the same gene?

Answer 44

for epistasis, it is 2 different genes (not even on the same chromosome) and one phenotype is masking the other

Question 45

what is the phenotypic ratio for the bombay phenotype?

Answer 45

6:4:3:3 (2 genes -- H antigen and ABO)

Question 46

what are multigenic traits?

Answer 46

more than one gene contributes to a trait

Question 47

for the purple pigment in sweet pea flowers, why is there a 9/16 ratio (and 7/16 for white)?

Answer 47

there are two enzymes involved in creating the purple pigment, BOTH enzymes must be available as precursors

Question 48

what is complementation?

Answer 48

heterozygosity of 2 recessive alleles in 2 genes in a pathway gives the WT phenotype

Question 49

if a pea flower with no enzyme A is crossed with a flower with enzyme A but no enzyme B, what color is the resulting flower?

Answer 49

purple

Question 50

what are the epistatic relationships for the purple/white flowers?

Answer 50

bb masks/is epistatic to A-phenotype and aa masks/is epistatic to B-phenotype

Question 51

what does a complementation test do?

Answer 51

it determines whether mutations are in the same gene or in different genes -- can only test recessive mutations

Question 52

what phenotypes do you need in order to test complementation?

Answer 52

recessive

Question 53

if a complementation test of whitexwhite gives only white flowers, are the mutations on the same gene or different genes?

Answer 53

same gene

Question 54

if a complementation test of whitexwhite gives only purple flowers, are the mutations on the same gene or different genes?

Answer 54

different genes

Question 55

are alleles of the same gene in the same complementation group or different

Answer 55

same

Question 56

are different genes that give the same phenotype in the same or different complementation groups

Answer 56

different complementation groups

Question 57

if you supplement a1a1 plant with B substrate, will it make pigment?

Answer 57

yes

Question 58

complementation test: mutant 1 x mutant 2 = mutant phenotype: complement? complementation group? same gene?

Answer 58

same gene, do not complement. mutants form one complementation group

Question 59

complementation test: mutant 1 x mutant 2 = WT phenotype: complement? complementation group? same gene?

Answer 59

mutations do complement and are alleles of different genes, mutants are part of 2 complementation groups