key
Name: _________________________________
Unit 6: Human Genetics
Per. ______
Part A
gene expression
genome
repressor proteins
activation in eukaryotes
by degree of uncoiling of DNA
cell differentiation
morphogenesis
cancer
o tumors
 benign
 malignant
 metastasis
cancer (cont.)
o carcinoma
o sarcoma
o lymphoma
o leukemia
causes of cancer
o carcinogens
o mutagens
o oncogens
o viruses
Part B
1. sex determination
Thomas Hunt Morgan
sex-linked genes
linkage groups
chromosome mapping
mutation
o chromosome
 deletion
 inversion
 translocation
 nondisjunction
o gene
 point mutations
 substitutions
 sickle-cell anemia
 frame shift mutations
Part C
genetic engineering
restriction enzymes
plasmids
transplanting genes
recombinant DNA
transgenic organisms
DNA fingerprints
gel electrophoresis
human genome project
genetically engineered vaccines and crops
2. human genetics
o pedigrees
o Huntington’s Chorea
multiple alleles
polygenic traits
sex-linked
o colorblindness
o hemophilia
o Duchenne muscular dystrophy
sex-influenced traits
nondisjunction
o Down Syndrome
genetic screening/counseling
o amniocentesis
o PKU
Part A: Gene Expression
1. Control of Gene Expression
protein

activation of a gene that results in the formation of a

when transcription occurs a gene is “expressed” or “turned-on”
ex. gene for blue eyes is “expressed” only in the iris of the eye
genome: the complete genetic material contained in an individual

 repressor protein: inhibits a gene from being expressed (“turns off the gene”)
2. Gene Expression and Development

Cell Differentiation: development of cells with
o controlled

by gene expression
specialized -function
Cancer:
uncontrolled, abnormal cell division
 benign: no threat unless compressing a vital organ; in a single mass
o tumor: abnormal group of cells from
ex. fibroid cyst in uterus or breast, warts


malignant: abnormal cells
body
 metastasis:
Kinds of Cancer:
spread
invade and destroy healthy tissue elsewhere in
of cancer beyond original site
o carcinoma: skin, lining of organs
ex. lung cancer, breast cancer
o sarcomas:
bone and muscle tissue
o lymphomas: solid tumors in blood-forming tissue and may cause

o leukemia: uncontrolled production of white blood cells
Causes of Cancer:
o mutations that alter expression of genes
 spontaneous
leukemia

caused by carcinogens (substance that increases the risk of cancer)

ex. smoking, asbestos, radiation
viruses (HPV)
o mutagen: agents that cause
mutations
Part B: Inheritance Patterns and Human Genetics
1. Chromosomes and Inheritance
 sex determination
o Thomas Hunt Morgan
o used Drosophila melanogaster
= fruit fly
o why did he use fruit flies?
Large number of offspring
 Only 4 pairs of chromosomes
 Chromosomes are large an easy to see

o of
4 pairs


of chromosomes, one pair different in males than in females
females: two chromosomes identical
males: one chromosome looked like female and the other was shorter and Yshaped
o Morgan called these

sex chromosomes
XX (female)
XY (male)
Cross a male with a female and give genotype and phenotype ratios:
X
Y
X
X
XX
XX
XY
XY
Are Chromosomes the Same in Male and Female?
Chromosomes in Female and Male.
X
X
X
Y
1. How many chromosomes are in the body cells of a male fruit fly? (Note: the large dots are
chromosomes, too.)
8
2. How many chromosomes are in the body cells of a female fruit fly? 8
3 pairs
4. In the female fruit fly, how many of the pairs consist of two chromosomes that look alike? 4 pairs
3. In the male fruit fly, how many of the pairs consist of two chromosomes that look alike?
5. What names are given to each of the two unlike chromosomes in the male? X and Y
6. What is the name given to the two similar corresponding chromosomes in female? X and X
Self Test
Complete the following statements.
1. The number of chromosomes in the body cells of a fruit fly is 8
2. The male fruit fly has two sex chromosomes, called X and Y
3. The female fruit fly has two sex chromosomes, called X and X
4. A male fruit fly makes two kinds of sperm cells; one kind has the X chromosome, the other has the Y
5. The sex chromosome found in every egg is the X
6. When an egg is fertilized, a female will result if the chromosome combination is
XX
7. A male will result if the chromosome combination is XY
8. In any population, the proportion of males to females is about 50/50
fertilized
10. The sex in humans and fruit flies that has unlike sex chromosomes is the male
9. The sex of the offspring is decided at the moment when the egg is
1. Chromosomes and Inheritance (cont.)

o

location of genes on a chromosome
the farther apart two genes are, the more likely they will be separated by
Chromosome map: diagram showing the
crossing over
Mutations: a change in DNA
o Germ cell mutation: occurs in the organism’s
gametes (sex cells); do not affect the
organism; may be passed on to offspring
o Somatic mutations: body cell mutations; will affect the organism; not passed on; two
types:
 Chromosome Mutations: change structure of a chromosome or loss of entire
chromosome
 deletion: loss of a piece of chromosome
 inversion: segment breaks off and reattaches in reverse order
 translocation: segment breaks off and attaches to another nonhomologous chromosome

 non-disjunction: failure of a chromosomes to separate correctly
ex. extra chromosome or lacks a chromosome
Gene Mutations: change in DNA of a single gene
 point mutation: substitution, addition or deletion of one nucleotide of a
codon
 substitution: one nucleotide replaced by a different nucleotide
ex. sickle cell anemia caused by a T being substituted by A; causes
defective hemoglobin; sickle shaped red blood cells
 frame shift mutation: occurs when an addition or deletion causes the
shifting of the group of three making a codon
2. Human Genetics

difficult to study. Why? We grow over very long periods of time; harder to
take care of; small amount of offspring


Pedigree analysis
o pedigree: family record that shows how a trait is inherited over generations
Genetic traits and disorders
o Single-allele traits:
 Dominant:
 Huntington’s Disease: forgetfulness and irritability in 30s-40s; loss of
muscle control, spasms, mental illness, death
 Achondroplasia: dwarfism
many fingers or toes
Cataracts: clouding of the lens of the eye
 Polydactyly:


Recessive:
 Albinism: lack of pigment in hair, skin, eyes
 Cystic Fibrosis: abnormal cellular secretions of thick mucus which
accumulates in lungs
 Phenylketonuria (PKU): inability to metabolize phenylalanine in milk;
PP and Pp = normal; pp= PKU
 build-up causes mental retardation
 babies tested; those with PKU not given phenylalanine in diet
 Tay-Sachs Disease: causes death by deterioration from lack of
enzyme to breakdown fatty deposits on nerve and brain cells
o Multiple Alleles: traits controlled by 3 or more alleles of the same gene

ABO blood groups controlled by 3 alleles: IA, IB, i

each person’s blood contains 2 of these alleles

IA, IB are co-dominant (both expressed when together) and are both
dominant to the i
 A type = IA IA,IAi
 B type = IB IB, IBi
 AB type = IAIB
 O type =

ii
Which cross could result in all four blood types in the offspring? Show results
of cross below:
IA
i
IB
IA IB
IB i
i
IA i
i i
Pedigree Studies
Pedigrees are not reserved for show dogs and race horses. All living things, including humans, have
pedigrees. A pedigree is a diagram that shows the occurrence and appearance, or phenotype, of a
particular genetic trait from one generation to the next in a family. Genotypes for individuals in a
pedigree usually can be determined with an understanding of inheritance and probability.
In this investigation, you will
(a) Learn the meaning of all symbols and lines that are used in a pedigree.
(b) Calculate expected genotypes for all individuals shown in pedigrees.
Procedure
Part A. Background information
The pedigree in Figure 20-1 shows the pattern of
the inheritance in a family for a specific trait. The trait
being shown is earlobe shape. Geneticists recognize two
general earlobe shapes, free lobes and attached lobes
(Figure 20-2). The gene responsible for free lobes (E) is
dominant over the gene for attached earlobes (e).
In a pedigree, each generation is represented by a
roman numeral. Each person in a generation is numbered.
Thus, each person can be identified by a generation numeral
and individual number. Males are represented by squares
whereas females are represented by circles.
Part B. Reading a Pedigree
In Figure 20-1, person’s I-1 and I-2 are the parents. The
line which connects them is called a marriage line. Person’s
II-1, 2 and 3 are their children. The line which extends
down from the marriage line is the children line. The
children are placed left to right in order of their births.
That is, the oldest child is always on the left.
1. What sex is the oldest child? FEMALE
2. What sex is the youngest child?MALE
Using a different pedigree of the same family at a later time
shows three generations. Figure 20-3 shows a son-in-law as
well as a grandchild. Generation I may now be called
grandparents.
3. Which person is the son-in-law?II-1
4. To who is he married?II-2
5. What sex is their child? FEMALE
Part C. Determining Genotypes from a Pedigree
The value of a pedigree is that it can help
predict the genes (genotype) of each person for
a certain trait.
All shaded symbols on a pedigree
represent individuals who are homozygous
recessive for the trait being studied.
Therefore, person’s I-1 and II-2 have ee
genotypes. They are the only two individuals who
are homozygous recessive and show the
recessive trait. They have attached earlobes.
All un-shaded symbols represent
individuals who have at least one dominant gene.
These persons show the dominant trait.
To predict the genotypes for each person
in a pedigree, there are two rules you must
follow.
Rule 1: Assign two recessive genes to any person
on a pedigree whose symbol is shaded. (These
persons show the recessive trait being studied.)
Small letters are written below the person’s
symbol.
Rule 2: Assign one dominant gene to any person
on a pedigree whose symbol is un-shaded. (These
persons can show the dominant trait being
studied.) A capital letter is written below the
person’s symbol.
These two rules allow one to predict some of the
genes for the persons in a pedigree. Figure 20-4
shows the genes predicted by using these two
rules.
To determine the second gene for the
persons who show the dominant trait, a Punnett
square is used. In Figure 20-4, we already know
that the grandfather (I-1) is ee, if the
grandmother (I-2) were EE; could any ee
children like (II-2) be produced? A Punnett
square shows this combination to be impossible.
Thus, the grandmother must be heterozygous of
Ee.
6. (a) Do the following Punnett squares to show
the possible outcomes of persons I-1 & I-2.
(b) Can an Ee parent and an ee parent have
the results in generation II? yes
(c) Can an EE parent and an ee parent have
the results shown in Generation II?no
7. (a) Predict the second gene for person II-3.
(Read the Punnett square.) Ee
(b) Predict the second gene for persons II-4.
Ee_
(c) Could child II-3 or II-4 be EE? no
Explain. Dad can only give the e gene to the
children in row II.
To predict the second gene for person II-1, a
different method must be used, since he could
be either EE or Ee.
8. (a) Do the following Punned squares to show
the possible outcomes of persons II-1 &
II-2.
(b) Can and EE person married to an ee
person (II-2) have children with free earlobes?
yes
(c) Can an Ee person be married to an ee
person have children with free earlobes? yes
In this case, the second gene from person
II-1 cannot be predicted using Punnett squares.
Either genotype Ee or EE may be correct. When
this situation occurs, both genotypes are written
under the symbol (Figure 20-5)
Predicting the second gene for III-1 results
in her being heterozygous. Although her mother
must provide her with one recessive gene, she
has free lobes, so the second gene must be
dominant (Figure 20-5).
At some time in the future, if II-1 and
II-2 have many more children, one might be able
to predict the father’s second gene. For
example, if they have ten children and all show
the dominant free lobes, one could safely
conclude that he is EE. If, however, they have
some children with attached earlobes (ee), then
he must be Ee
When both parents show a dominant trait
and their child or children all show a dominant
trait, one cannot predict the second gene for
anyone if only a small family is available.
Examine the pedigree:
9.
(a) Which Punnett square, A, B, or C, would
best
fit this
family?
B
(b)
Explain.
It is the
only
punnett square that produces ee children.
Analysis
1. Draw a pedigree for a family showing two
parents and four children.
(a) Include a marriage line and label it.
(b) Include a children’s line and label it.
(c) Make the oldest two children boys and the
youngest two girls.
2. Fill out the following pedigree. Find the
genotype for each person. Use B & b.

Sex Linkage:
o more genes are carried on the SEX chromosome = X-linked genes
o sex-linked genes are on one chromosome; these are linked = inherited together
ex. Red hair and freckles


Polygentic Traits:
ex. skin color is influenced by 3-6genes; control the amount of pigment (melanin) in the skin
X-linked Traits:
o Colorblindness: recessive; inability to distinguish colors (red/green)
o Cross a carrier female with a normal male:
XCY
XcY
XCXC
XCXc
XcXc
o Hemophilia: recessive; bleeders disease; impaired ability of blood to clot


o Duchenne Muscular Dystrophy: weakens and destroys muscle cells
Sex-Influenced Traits: male or female hormones may influence gene expression
ex. baldness controlled by gene B; dominant in males but recessive in females
BB= bald in male and female
Bb= bald in male, normal in female; caused by testosterone
Non-Disjunction Disorders: failure of chromosomes to separate in meiosis
o Monosomy X aka turners syndrome: 45 chromosomes; underdeveloped, sterile females
o Trisomy X: XXX; super females; some retarded
o Klinefelter’s syndrome: XXY; normal egg x XY sperm
 sterile, underdeveloped males
o XYY: tall aggressive males, criminals?
o Down Syndrome: Trisomy 21
 extra chromosome 21
 mild to severe retardation, facial features, muscle weakness, heart defects,
short stature

Detecting Human Genetic Disorders
o Genetic screening: exam of person’s chromosomes
ex. karyotype: picture of chromosomes
blood test
amniocentesis: testing of amniotic fluid from embryo
chorionic villi sampling: sample tissue between mother’s uterus and placenta
o Genetic counseling: talk to patients about genetic disorders and risks of having
affected children
Part C: DNA Technology
1. The New Genetics
 DNA technology can be used to cure diseases, make better crops, animals or drugs
 Manipulating Genes:
o to isolate and transfer specific DNA segments, restriction enzymes
o are used to cut a piece of DNA
o single chains of DNA are crated with sticky-ends
o sticky ends bind to complementary sticky ends from recombinant form out of DNA
from 2 organisms
o cloning vectors: carrier used to clone a gene and transfer it to another organism

o plasmid: ring of DNA in a bacterium
Transplanting Genes:
o plasmids are used to clone a gene so that bacteria will produce a specific protein
ex. insulin
diagram:
see page 32
o Steps:
1. restriction enzymes cut the segment of DNA from a human cell that contains the
insulin gene and the circular plasmid in the bacteria
2. recombinant DNA is formed by combining the human and bacterial DNA
segments
3. The loop of DNA is inserted into a bacterial cell
4. The bacterial cell will produce the insulin and be duplicated every time it divides
o Transgenic organism: host receiving the recombinant DNA
2. DNA Technology Techniques
 DNA Fingerprints:
o pattern of bands that make up fragments from an individual’s DNA
Uses:
 comparing different species to determine how closely related

compare blood, tissue at crime scene with a suspects blood

establish relatedness or paternity

Making a DNA Finger Print
1. DNA segment cut into pieces by restriction enzymes
2. gel electrophoresis separates the DNA fragments by size and charge
diagram: see page 33

DNA fragments are placed in wells in a gel
 an electric current is run through the gel
 DNA fragments (- charge) migrate to the positive charged end of gel, not
at the same rate

 smaller fragments migrate faster
3. Make visible only bands being compared by using radioactive probes and photographic
film
Human Genome Project:
o Goals:
 determine the nucleotide sequence of the entire human genome (100,000 genes)

map the location of every gene on each chromosome
3. Practical Uses of DNA Technology
 Producing Pharmaceutical Products: that are safer and less expensive than produced by
conventional means
 Genetically Engineered Vaccines:
o vaccine: solution containing a harmless version of virus or bacterium

o new DNA technology can prevent a pathogen (disease causing agent) from harming
someone that has received a vaccine (only rare cases)
Increasing Agricultural Yields:
o produce disease- resistant, weed- resistant, and insect- resistant crops
o improves the quality and quantity of the human food supply
o isolate genes from nitrogen-fixing bacteria and transplant to plants so they can be
grown in nitrogen-poor soil without fertilizers