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Human Heredity 14-1
1. How do biologists make a karyotype?
They photograph cells in Mitosis and cut out
the chromosomes from the photographs and
then group the chromosomes together in parts.
2. The following is true about human
chromosomes:
A. The X and Y chromosomes are known as
sex chromosomes because they determine an
individual’s sex.
C. All the chromosomes except the sex
chromosomes are autosomes.
#3
4. Why is there a chance that half of the zygotes will be
female and half will be male?
All the egg cells inherit an X chromosome from the
Mother. Half of the sperm cells carry an X chromosome and
the other half carry a Y chromosome.
5. What does a pedigree chart show?
relationships within a family
6. A person who expresses the trait = a
7. A male = c
8. A person who does not express the trait = c
9. Represents a marriage = b
10.A female = a
11.Connects parts to their children = d
12.Give two reasons why it is impossible to
associate some of the most obvious human
traits with single genes:
a. a. Many traits are polygenic
b. Many traits are strongly influenced by
environmental factors
13. Why is it difficult to study the genetics of
humans?
Humans have long generation times, a
complex life cycle, and relatively few offspring.
14. The following is true about human blood group
genes:
A. the Rh blood group is determined by a single
gene.
D. Individuals with type O blood are homozygous
for the i allele (ii) and produce no antigen on the
surface of red blood cells.
15. True or False: Many human genes have become
known through the study of genetic disorders.
TRUE
16. PKU = c
17. Tay-Sachs Disease = A
18.Achondroplasia = B
19.Hungtington’s = D
20.What is the normal function of the protein
that is affected by cystic fibrosis?
The protein allows chloride ions to pass
across biological membranes.
21. A change in just one DNA base for the gene
that codes for the protein __________ causes
sickle-shaped red blood cells.
hemoglobin
22. What is the advantage of being heterozygous
for the sickle cell allele?
People who were heterozygous are generally
healthy and are resistant to malaria.
23. What makes an allele dominant, recessive,
or codominant?
It depends on the nature of the gene’s
protein product and its role in the cell.
Human Chromosomes 14-2
1. The following is true about human genes and
chromosomes:
B. Chromosome 22 contains long stretches of
repetitive DNA that do not code for proteins
D. Human genes located close together on
the same chromosomes tend to be inherited
together.
2. What are sex-linked genes?
They are genes that are located on the X or Y
chromsome.
3. True or False: The Y chromosome does not
contain any genes at all.
False
4. Colorblindness Inability to distinguish certain colors
Defective version of any one of three genes
associated with color vision
Hemophiliablood does not clot normally
Duchenne Muscular Distrophyprogressive weakening and loss of skeletal
muscle
5. True or False: All X-linked alleles are expressed
in males, even if they are recessive.
True
6.
7. How does the cell “adjust” to the extra X
chromosome in female cells?
In female cells, one X chromosome is
switched “off”
8. What is Barr body?
It is a dense region in the nucleus that is formed by
the turned off X chromosome
9. True or False: Barr bodies are found only in
males.
False
10. If you see a white cat with orange and black
spots, is it most likely a male or a female?
Female. In cells in some parts of the body one
X chromosome that has allele for orange spots is
switched off, whereas in other parts of the body,
the other X chromosome with the allele for
black spots is switched off.
11. What occurs during nondisjunction?
Homologous chromosomes fail to separate
12. True or False: If nondisjunction occurs, gametes
may have abnormal numbers of chromosomes.
True
13. The condition in which an individual has three
copies of a chromosome is known as
____________, which means “three bodies”
trisomy
14. True or False: Down syndrome occurs when an
individual has two copies of chromosome 21.
False. Down syndrome = Trisomy 21
15. Down syndrome is characterized by
mental retardation
16. Why does an extra copy of one chromosome
cause so much trouble?
scientists do not know
17. The following is true about sex chromosome
disorders:
A. A female with the karyotype 45,X has
inherited only one X chromosome and is sterile.
D. The Y chromosome contains a sexdetermining region that is necessary for male sexual
development.
Human Molecular Genetics 14-3
1. Biologists search volumes of the human
genome using _______________.
sequences of DNA bases
2. Why might prospective parents decide to
have genetic testing?
Genetic tests can determine whether parents
risk passing alleles for genetic disorders to their
children.
3. The following is true about genetic testing:
B. Labeled DNA probes can be used to detect
specific sequences found in disease-causing
alleles.
C. Some genetic tests use changes in
restriction enzyme cutting sites to identify
disease-causing alleles.
D. DNA testing makes it possible to develop
more effective therapy and treatment for
individuals affected by genetic disease.
4. What is DNA fingerprinting?
It is the identification of individuals by a method that
analyzes sections of DNA that have little or no known
function but vary widely from one individual to another.
5. Small sample of DNA is cut with a
__restriction______ enzyme.
The fragments are separated by size using
__gel_electrophoresis__.
Fragments with highly variable regions are detected with
a __DNA_probe__, revealing a series of DNA bands
of various sizes.
The pattern of bands produced is the _DNA_fingerprint_,
which can be distinguished statistically from the
pattern of any other individual in the world.
6. The following are sources of DNA samples:
A. blood B. sperm D. hair
7. True or False: DNA evidence is not reliable
enough to be used to convict criminals.
False
8. What is the Human Genome Project?
It is an ongoing effort to analyze the human
DNA sequence.
9. The following is true about the Human
Genome Project:
C. Researchers completed the genomes of
yeast and fruit flies during the same time they
sequenced the human genome.
D. a working copy of the human genome was
completed in June 2000.
10. What were the three major steps in the process
of sequencing the human genome?
a. Widely separated regions of DNA on each
chromosome were sequenced
b. Random fragments of DNA were sequenced
c. Computers found overlapping regions between
the fragments and positioned them relative to
the known markers.
11. What is an open reading frame, and what is it
used for?
A series of DNA bases that will produce an mRNA
sequence. Scientists use it to locate genes.
12. The mRNA coding regions of most genes are
interrupted by __________.
introns
13. List three other parts of the gene that
researchers look for
a. promoter
b. “start” site for transcription
c. “stop” site for transcription
14. Why are biotechnology companies
interested in genetic information?
They are trying to use this information to
develop new medicines and treatments for
diseases.
15. True or False: Human genome data are top
secret and can be accessed only by certain
people.
False
16. What is gene therapy?
The process of changing the gene that causes
a genetic disorder.
17. The following is true about gene therapy:
A. When the normal copy of the gene is
inserted, the body can make the correct protein,
which eliminates the disorder.
C. Viruses are often used to carry the normal
genes into cells.
18. True or False: All gene therapy experiments
have been successful.
False
19. What other changes could be made to the
human genome by manipulating human cells?
Biologists could try to engineer taller people,
change eye color, appearance, etc. They could
even clone human beings.
20. What is the responsibility of society in biology?
Society will have to learn to wisely use the tools
that science has given it. It will have to develop an
ethical consensus of what should and should not be
done with the human genome.
21. True or False: Scientists should be expected to
make all ethical decisions regarding advances in
human genetics.
False
2. Autosomes
1. Karyotype
3. Sex chromosome
4. Karyotype = c
5. Sex chromosome = e
6. Autosomes = g
7. Pedigree = a
8. sex-linked gene = f
9. Nondisjunction = b
10. DNA fingerprinting = d
Pedigree Practice
1. Given the following genotypes, describe the
phenotypes (normal or albino)
AA = _______normal______
Aa = ______normal_______
aa = _____albino_________
Pedigree Practice
2. aa x Aa
Aa, Aa, aa
3. How many children does this family
have? __3____
What are the sexes of the children?
___female____
Pedigree Practice
4. Aa x aa
aa , Aa, Aa - Aa
aa
5. How many children does the original couple have? _3_
6. How many grandchildren does the original couple have? _1__
What is the sex of the grandchild? __male__
Pedigree Practice
7. Aa x Aa
aa, Aa - Aa
aa - Aa, aa, Aa or AA *
aa
*When two hetorzygotes are crossed (Aa x Aa)
offspring may be unknown and can be either AA
or Aa.
Pedigree Practice
8. How many children does the original couple have? _2__
9. How many grandchildren? ____3__
10. Rats can produce a lot more offspring than humans,
making a pedigree more difficult to manage. A researcher has
four female white rats named April, May, June, and July. One
night, the cage was left open in the lab and a brown rat got
into the female's cage. Six weeks later, the rats had litters of
babies of varying colors. Two of the offspring managed to
reproduce before the researcher was able to sort out the
mess. Determine genotypes of the rats in this pedigree.
Pedigree Practice #10
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