Chapter 12 Review
Name:
Franco - KEY
Who did what?
Who proposed that heredity factors carried on chromosomes?______SUTTON________________
Who hypothesized chromosomes responsible for heredity?_____WEISMANN___________________
Who called these small parts “genes”?______JOHANNSEN______________________________
Who’s work was rediscovered?____________MENDEL_____________________________________
Who was the first to see chromosomes?_________FLEMMING______________________
Who proposed the chromosome theory?_________SUTTON________________________________
Genetic Disorders: (match)
Turners syndrome
- occurs mostly in African Americans
Klinefelter’s syndrome
- contains an extra 21st chromosomes
Huntington’s disease
- degeneration of muscles
PKU
- excessive mucous produced in the lungs
Hemophilia
- only one X chromosome
Sickle Cell Anemia
- contains an XXY
Cystic fibrosis
- failure of brain to develop in infancy
Tay Sachs
- sex-linked blood clotting disorder
Down syndrome
- destroys the central nervous system
Muscular Dystrophy
- deterioration of brain tissue
Problems:
A man who is not bald marries a women who is heterozygous for baldness. What is the chance of having a
bald child?
bb x Bb
Xb
XB
X
Yb
Bb (XX)
Bb (XY)
bb (XX)
bb (XY)
b
½ chance of having a bald child (including son and daughter)
A mother with Type AB blood marries a man with Type B blood. What are the genotypes of the parents if
one child has Type AB and the other with Type A? IAIB x IBi
IB
IA
i
IAIB
IAi
IBIB
IBi
IB
In humans the gene from normal blood clotting, H, is dominate to the gene for hemophilia, h. This is a sexlinked trait found on the X chromosome. A woman with normal blood clotting has four children. They are a
normal son, a hemophiliac son, and two normal daughters. The father has normal blood clotting. What is
the probable genotype for each member of the family? XHXh x XHY
XH
XH
Xh
XHXH
XHXh
XHY
XhY
Y
This is a sex-linked trait. A normal clotting female whose father was a hemophiliac, marries a man who
has normal clotting blood. What are the expected genotypic and phenotypic ratios? XHXh x XHY
XH
XH
Xh
XHXH
XHXh
XHY
XhY
Y
Genotypic ratio = 1 XHXH : 1 XHXh : 1 XHY : 1 XhY
Phenotypic ratio = 2 normal females : 1 normal male : 1 hemophiliac male
Windows peak (W) is dominant to the No widows peak (w). A science class wanted to find the frequency of
the 2 alleles in their school’s population. A survey showed the following results: 388 non widows peak
and 812 who had a widows peak. Find the following information, show the math you have to do - you
may use a calculator to actually do the math.
Use these equations: p2 + 2pq + q2 = 1 and p + q = 1 (answers to nearest .001)
frequency of homozygous recessive ___________
388 non = w = q
812 with peak = W = p
q2 = 388/1200 = .322
frequency of gene (w) __________
frequency of gene (W) __________
q = (.322)1/2 = .567
1 - .567 = .433
frequency of heterozygous genotype ___________
2 x p x q = 2 x .433 x .567 = .491
number of students that are heterozygous _________ (nearest whole student)
.491 x 1200 = 589
A.
B.
----------------------C.
_______Homologous________ What is the name of the area marked C?
_______Holandric________ What is the name of the area marked B?
Sex-linked (non-homologous) What is the name of the area marked A?
Night/total colorblindness Name a trait found in humans that the gene for it would be located in area C?
TDF/hairy pinnae
Name a trait found in humans that the gene for it would be located in area B?
Defective tooth enamel, hemophilia, muscular dystrophy, R/G colorblindness Name a trait found in
humans that the gene for it would be located in area A?
The chromosome on the right is called the _______Y_________ chromosome.
The chromosome on the left is called the ________X________ chromosome.
A scientist wishes to find out how many people in the United States have attached earlobes. Will the
scientist check the ears of every person in the country? Explain what he would do.
No, the scientist could take a sample from a population and use the Hardy-Weinburg theory.
A set of fraternal twins separated at birth and reared in different environments was studied to determine
to what extent environmental factors shape development. What problem do you see in the reliability of
such a study?
They are fraternal twins, not identical twins. Due to this, they have different DNA so there are too
many variables to account for.
Define multiple alleles. What alleles are present for blood types? Name the blood types.
Multiple alleles are a variety of alleles of the same gene that affect traits. Multiple allele traits are
controlled by 3 or more alleles of the same gene. The alleles present for blood types are IA, IB, and i.
The blood types possible are A, B, AB, and O.
Explain why skin color is considered a polygenic trait?
Skin color is a polygenic trait because there is a continuous variation in the trait. Each gene has a
small additive effect.
Explain why baldness is a sex-influenced trait and describe the inheritance pattern.
Baldness is a sex-influenced trait because testosterone causes an increased expression in the
trait. Inheritance pattern:
Phenotypes
Bald
Normal hair
Pattern baldness
Male
Female
BB and Bb
BB
bb
bb and Bb
Define nondisjunction
The failure of homologous chromosomes to separate properly in the formation of gametes
Give the name of the following disorders:
XXY = Klinefelter syndrome
trisomy #21 = Down syndrome
XXX = Super female
XO = Turner syndrome
What are the following:

amniocentesis Removal of some amniotic fluid at 14-16 weeks in order to analyze fetal cells and

proteins or make a karyotype
chorionic villi biopsy Sample of tissue between uterus and placenta at 8-10 weeks to make a
karyotype (from chorion)


ultra sound Sonogram (use sound waves)
genetic screening Used for those with a history of genetic disorders. Make a karyotype, examine
blood for presence or absence of certain proteins

genetic counseling Medical guidance informing parents of potential problems for offspring

erythroblastosis fetalis Destruction of the fetus’ RBC due to the mother being Rh – and the first
and second babies being Rh +.

Rhogam shot (When mother is Rh – and first and second child are Rh +) Injection given to mother
within 72 hours of childbirth in order to destroy any Rh + blood antigens the mother may have
gotten from the child (contains anti Rh antibodies)
Classify each of these genetic disorders under its proper heading.
PKU
Down syndrome
hemophilia
sickle-cell anemia
Klinefelter’s syndrome
baldness
Genetic Disorders on autosomes
Nondisjunction
polydactaly
Turner’s syndrome
color blindness
Sex linked or Sex influenced traits
PKU
Down syndrome
Baldness
Sickle-cell anemia
Turner syndrome
Color blindness
polydactaly
Klinefelter’s syndrome
hemophilia
Explain fully why type A blood cannot be transfused into a type B person.
Type A blood has A antigens on its surface. Due to this, when it is introduced to a type B person (who
has antibodies towards type A), the type B person will begin to fight off and agglutinate the type A
blood.
For erythroblastosis fetalis to occur, what is the Rh factor for the mom, dad and baby?
Mom _____-_____
Dad ____+______
Baby _____+______
Can Rh positive blood be transfused into an Rh negative person? Not multiple times. There is little
problem on the first transfusion, but the subsequent transfusion could be fatal due to the production of Rh
antibodies.