Download Unit 7: Heredity and Biotechnology

Unit 7: Heredity and Biotechnology
Name: _________________________ Hr________
I. Heredity – Every living thing inherits its traits from its parent(s). Genetics is the study of heredity.
A. Heredity – _____________________________________________
______________________________________________
B. Gene- __________________________________________________
__________________________________________________
C. Allele – Alternate versions of a trait (straight v. curly hair, widow’s peak or not)
D. Parental Generation (P1) – The parents to be mated or bred.
E. Filial Generation (F1) – The offspring of parental generation.
F. Pure/true breeding – When offspring (F1) always show same trait as parents (P1).
G. Hybrid – The offspring of 2 pure parents that have different traits (Red flower parent X white flower parent).
II. Mendel’s Experiments and Results (Gregor Mendel performed genetic studies on pea plants from the 1830’s - 1850’s)

Mendel crossed two different pure traits and saw that only one of the traits appeared in the F 1 generation. Then
the other trait reappeared in the F2 generation.

Mendel concluded that something inside the plant controlled which of the two traits appeared, he called it a factor.

What Mendel called a factor, we now call a

Mendel concluded that since there were two forms of every trait/characteristic that he studied (height, color, seed
texture, etc.) that there were two factors/genes controlling each trait (1 from each parent).
and know that they are coded for in DNA.
Mendel’s Principles (based on observational evidence without the help of microscopes, chemistry, etc...)
1. Dominance & Recessiveness – When 2 different factors for the same trait appear in an organism, 1 factor/“gene”
will dominate or be expressed, the other gene will not be expressed (a dominant
gene will “cover up” or “turn off” the recessive gene). **refers to alleles of same trait
Example: tall pea plant X short pea plant = tall pea plant (Tall is dominant to short in pea plants)
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2. Segregation – Since all organisms have 2 genes for each trait, then during the making of sex cells (meiosis) there
must be a separation of genes, one to each new sex cell (this separation/segregation occurs during
anaphase). **refers to alleles of same trait
3. Independent Assortment – Genes for different traits are not connected, they are sent to sex cells independent of
each other (just because the plant was tall it need not have round seeds) . By luck, the traits
Mendel studied were located on separate chromosomes. ** refers to different traits
Q: What could cause the Principle of Independent Assortment to be incorrect? _______________________
________________________________________________________________________________________
Linked genes do not assort independently.
The more closely located two genes are on
a chromosome, the more likely they are to
be inherited together. Genes that are found
on separate chromosomes or are far from each
other on a chromosome do assort independently.
This information has helped scientists build
chromosome maps such as the one below for
Drosophila melanogaster (the fruit fly).
Q: What can disrupt linkage? __________________________________________________________________
Q: What causes Genetic Variation? (a) __________________________________________________________
(b) _____________________________________________________________, (c) ______________________
Q: Why were pea plants (or zebra fish, yeast, bacteria, and fruit flies today) good organisms to study?
1. _________________________________________________
5. ___________________________________
2. _________________________________________________
6. ___________________________________
3. _________________________________________________
7. ___________________________________
4. _________________________________________________
8. ___________________________________
Q: Why is Gregor Mendel called the “Father of Genetics”? _________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
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III. Genetic Crosses
Dominant alleles will be symbolized with a capital letter (T);
recessive alleles with a lower case letter of the dominant allele (t).
A. Genotype – The actual genes an organism possesses (TT, Tt, tt) - one from each parent.
B. Phenotype – The expression of the genotype (result of specific genes being turned on) - TT = Tall, Tt = Tall, tt = short.
C. Homozygous –
D. Heterozygous –
E. Carrier – Describes the genotype of an individual that has a copy of, or carries, the recessive trait, which is not
expressed in the phenotype of the organism (being heterozygous for a trait).
F. Multiple Allele Trait – When more than two alleles determine the phenotype (Example: Blood = A, B, O).
G. Probability – The likelihood that a specific event will occur. It can be expressed as a decimal, percentage,
fraction, or a ratio.
Example: Flipping a coin.
What is the chance of flipping heads once?
What is the chance of flipping heads three times in a row?
_________________________________
______________________________________________
IV. Predicting the Outcomes of Genetic Crosses
Punnett Square – A tool used to predict the genotypes and phenotypes of genetic crosses.
How to set up a Punnett square:
1) Identify and abbreviate all known alleles (T = tall, t = short)
T
t
t
Tt
tt
t
Tt
tt
2) Write the genotype of the parents to be crossed (Tt x tt)
3) Draw a Punnett square and put one parent across the top and the other
down the side.
4) Complete the Punnett square. Place the parental alleles in the empty
boxes of their corresponding row/column.
5) List all genotypes and phenotypes in probability form.
Offspring Genotypes:
TT = 50%
tt = 50%
Offspring Phenotypes: Tall = 50%
Short = 50%
Tall height is dominant to short height in pea plants. Cross two parents who are both heterozygous for height.
Alleles =
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
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Codominance – When both forms of a trait are dominant. The resulting phenotype for a heterozygous offspring displays
both traits equally. Since neither one is recessive, neither one can “cover up” the other.
Example: White x Red = red + white speckles (Roan)
Both Red (R) and White (W) are dominant. RW would be both red and white and look roan. Cross a red horse with a
white horse.
Alleles =
Parental Genotype =
Offspring Genotype =
Offspring Phenotype =
Incomplete Dominance – When neither form of a trait is dominant. The resulting phenotype for a heterozygous offspring
is usually a mix.
Example: White x Red = Pink
Neither red (r) nor white (w) is dominant. In incomplete dominance, r & w together would look pink. Cross two pink
flowers.
Alleles =
Parental Genotypes =
Offspring Genotypes =
Offspring Phenotypes =
Multiple Alleles - For many genes there are more than 2 alleles in a population. This does not mean that an individual
has more than 2 alleles for 1 gene; an individual still inherits just 1 allele for each trait from each parent.
Alleles = A, B, O (A and B are both dominant, while O is recessive)
Blood Types:
AA (homo) or AO (hetero) = Type A
BB (homo) or BO (hetero) = Type B
AB = Type AB
OO = Type O
Cross a heterozygous Type A x homozygous Type B
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
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Genetic Problems involving Two Traits: Consider two traits at the same time. Each parent will pass on 1 allele for each trait.
Alleles: T = Tall, t = short; R = Round, r = wrinkled
Cross a pea plant that is homozygous dominant for Height & homozygous recessive for Seed Texture with a pea plant
that is heterozygous for both traits.
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
Polygenic Traits - Traits controlled by 2 or more genes (skin, hair & eye color in humans are determined by 4-6 genes).
V. Genetic Patterns
A. Sex Determination
1. Sex Chromosomes – Those chromosomes that determine the gender of an organism (XX = female, XY = male)
2. Autosomes – All “non-sex” chromosomes (22 pairs in human body cells).
B. Human cells - 2 sex chromosomes (either XX or XY) + 44 autosomes = 46 chromosomes per somatic cell
C. Sex-linked traits (those carried on the X chromosome, such as colorblindness or male pattern baldness):
N = Normal Vision, n = colorblind
Possible female genotypes: X N XN = Normal Vision, X
N
Xn = Normal Vision (carrier), X n Xn = Colorblind
Possible male genotypes: XN Y = Normal Vision, Xn Y = Colorblind
Q: What does “carrier” mean? Why can’t males be carriers for sex-linked traits? ___________________________
______________________________________________________________________________________________
Cross a normal vision male with a carrier female.
Parental Genotypes:
Offspring Genotypes:
Offspring Phenotypes:
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VI. Mutation – A change in the sequence of DNA that affects the genetic information; caused by mutagens.
 Examples of mutagens: ______________________________________________________________________
 germ/sex cell mutation – ___________________________________________________________________
 somatic cell mutation – ____________________________________________________________________
Types of Mutations
Normal Codon Sequence
1. Gene or Point Mutation – Mutation that only affects one gene.
THE CAT ATE THE RAT
a) Addition or Insertion - ___________________________________________
THE FAT CAT ATE THE
b) Subtraction or Deletion – ________________________________________
THE ATE THE RAT
c) Substitution or Missense – ______________________________________
THE COT ATE THE RAT
2. Chromosomal Mutation – Mutation that affects many genes on one or more chromosomes.
a) Deletion – ____________________________________
Diagrams of Chromosomal Mutations
_____________________________________________
b) Duplication – __________________________________
______________________________________________
c) Inversion – ____________________________________
______________________________________________
d) Translocation – _________________________________
______________________________________________
e) Nondisjunction – _______________________________
Draw Nondisjunction in the space below:
______________________________________________
Mutations can lead to a genetic disorder. A few examples of the
thousands of genetic diseases are described on the next page.
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VII. Genetic Disorders: Some diseases can be inherited from our parents through alleles that they pass down to us.
A. Chromosomal abnormalities
1. Down Syndrome: Caused by a trisomy (3) of chromosome 21; produces mild to severe mental retardation.
2. Turner’s Syndrome: Caused by a missing X chromosome (genotype XO). Women with Turner’s syndrome
are sterile because their sex organs do not develop during puberty.
3. Klinefelter’s Syndrome: Caused by an extra sex chromosome (genotype XXY). Men with this disorder have
underdeveloped sex organs, abnormally long legs and arms, and large hands.
B. Dominant Allele
1. Achondroplasia: The most common form of dwarfism.
2. Huntington's disease: Symptoms develop in people’s 30's when the nervous system begins breaking down.
C. Codominant Allele
1. Sickle cell disease: Sickle-shaped blood cells develop that can cause blockage in blood vessels.
D. Recessive Allele
1. Tay-Sachs disease: Results in nervous system breakdown and death in the early years.
2. Cystic Fibrosis: Excess mucus is present in the lungs, the digestive tract, and the liver. People with CF are
more susceptible to infections, respiratory and digestive problems.
E. Sex-linked Disorder
1.Hemophilia: Missing a protein necessary for blood clotting. People with this disease can die from a minor cut.
Q: Do all mutations lead to genetic disorders? Explain. _________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
VIII. Human Heredity
Pedigree – A family record that shows how a trait is inherited over several generations. It is useful in helping
determine the risk of having a child with a family disease
Pedigree Key
Male (no disease)
Male (diseased)
Male (carrier)
Female (no disease)
Female (diseased)
Female (carrier)
Mates
Death
Offspring
Siblings
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Pedigree Problem
Cystic Fibrosis is an autosomal (not sex-linked) recessive disorder caused by a defect in the CFTR gene. This gene
codes for a transport protein called a chloride ion channel that is important for producing sweat, digestive juices, and
mucus in our bodies. Defective CFTR proteins cause the body to produce unusually thick, sticky mucus that 1) clogs the
lungs and leads to life threatening lung infections; and 2) obstructs the pancreas and stops digestive enzymes from
helping your body break down and absorb food.
A man (III-3) comes from a family that has a history of cystic fibrosis in some offspring. In trying to determine whether or
not he carries an allele for CF, he constructed a pedigree of his family’s history in relationship to the condition.
Complete the pedigree below. In the spaces below each symbol, write as much of the genotype of each individual as you
can from the information provided. Heterozygotes do not show symptoms, so you must determine who is heterozygous
and divide their symbol to indicate that they carry one allele.
IX. Selective Breeding – Allowing only those organisms with desired traits (or without undesirable traits) to produce
offspring of the next generation

Inbreeding - ________________________________________________________________________________
Examples: _________________________________________________________________________________
Q: What problem(s) can result from inbreeding? _______________________________________________________

Hybridization - ______________________________________________________________________________
Examples: _________________________________________________________________________________
Q: What is the benefit of hybridization? _______________________________________________________________
_________________________________________________________________________________________________
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X. Genetic Engineering
A. Genetic Engineering – The transfer of DNA/genes from one organism to another.
1. It is also called recombinant DNA technology or gene splicing.
2. Genetic engineering can take place within a species (e.g. transferring genes between humans) or between
species (e.g. transferring genes between humans and bacteria).
Q: Why is it possible to transfer genes between different species and still have the gene function properly?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
B. Transgenics – _______________________________________________________________________________
1. Transgenic Microorganisms – Produce a variety of important substances useful for health and industry.
Examples: ________________________________________________________________________________
2. Agrogenetics
a. Transgenic Animals – Used to study genes, improve food production, and make desired products.
Examples: _______________________________________________________________________________
b. Transgenic Plants – Used to increase the amount of food produced and increase hardiness of crops.
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C. Steps of Genetic Engineering
1. Scientists identify the gene (_____________________________________________________________________)
that they want to transfer. They then collect a sample of the DNA containing that gene. DNA extraction is the
removal of DNA from cells by lysing the membrane and separating the DNA from other cell parts.
2. Restriction enzymes, also known as endonucleases, are added to the sample of DNA.
a. Each enzyme identifies its own recognition sequence where it will cut DNA.
b. Researchers choose restriction enzymes that will cut before and after the gene they want to transfer.
c. The restriction enzyme cuts the DNA at the specific sequence.
Examples of Restriction Enzymes and their Recognition Sequences
3. The DNA fragment for the desired gene must then be separated from the rest of the DNA by gel electrophoresis.
The pieces of DNA are called RFLP’s (Restriction Fragment Length Polymorphisms).
a. A mixture of DNA fragments is placed at one end of a porous gel.
b. ____________________________________________________________________
c. The negatively charged DNA molecules move toward the positive end of the gel.
d. The smaller fragments move faster through the gel toward the positive end than the larger fragments.
e. Once the fragments are spread out enough on the gel, a pattern of bands is revealed.
Well
Results of Gel Electrophoresis: Different combinations of RFLP’s can be made by using different restriction
enzymes. Since each organism or individual has a unique DNA sequence, the RFLP’s that result from cutting the
DNA with restriction enzymes makes a pattern on the gel that is unique to that individual. This pattern of DNA
fragments is called a DNA fingerprint (much like bar codes used for scanning merchandise).
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4. Once the desired gene fragment is separated from the others and then cut from the gel, it can be recombined with
the DNA of the second organism to continue the genetic engineering.
a. Often the gene is to be moved to bacteria, so it can be reconnected with a small loop of bacterial DNA called
a plasmid.
b. The plasmid must be cut with the same restriction enzymes that were used on the gene fragment.
c. The sticky ends, which are overhanging ends of DNA, are complementary in the 2 pieces of DNA that will be
combined (the gene and the plasmid).
d. Ligase enzymes seal the sugar-phosphate backbone of the two pieces of DNA, creating recombinant DNA
from two organisms.
5. Plasmids or viruses are then used as a vector, a genetic vehicle that carries foreign DNA into a host cell
6. The recombinant DNA inside the host cell reproduces new cells that contain copies of the inserted gene. These
new copies of the gene are considered clones, so this process is called cloning.
Q: What are some uses for cloning? _________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
XI. Genome Sequencing – Process of locating all the genes on a chromosome of an organism and determining the
nucleotide or base sequence for each gene.

Define Genome: ____________________________________________________________________________

In DNA sequencing, a complementary DNA strand is made using a small portion of fluorescently labeled (glowing
colors) nucleotides. Each time a labeled nucleotide is added in place of a normal nucleotide, replication of that
strand stops producing a short fluorescently color-coded DNA fragment. When the mixture of fragments is
separated on a gel, the DNA sequence can be read directly from the gel based on those fluorescent colors.

The number of completed genomes is approaching 200! The list includes members of all 6 kingdoms
(Archaebacteria, Eubacteria, Protists, Fungi, Plants, & Animals), viruses, and cellular organelles.
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Steps and Apparatus for Genome Sequencing
A different color fluorescent
dye is used for each base
(A,C,G,T).
When a dyed base is added
to a strand instead of a
normal one, that strand is
finished and shows the color
of the last base added.
The color and length of each
fragment produced allows
us to “read” the sequence of
the strand of DNA.
b. Human Genome Project – An international effort to map and sequence the human genome.
- The project began in 1990 under the leadership of James Watson, of DNA fame, at a cost of $3,000,000,000+
- A draft sequence was completed in 2000, and a final sequence was announced in 2003.
Q: What are some uses for the information gained from the Human Genome Project? _______________________
______________________________________________________________________________________________
XI. Making Copies of DNA with Polymerase Chain Reaction – a man-made process of producing clones of DNA
sequences in a machine
1. After sequencing a desired gene, primers are made.
A primer is a single-stranded sequence of DNA
nucleotides complementary to the beginning of the
gene/DNA sequence to be copied.
2. Ingredients required:
 Template DNA (to be copied)
 Primer (for the strand to be copied)
 Nucleotides (to build all the new strands)
 DNA Polymerase (to put the nucleotides together!)
3. Heat is used to break the H-bonds between the two
DNA strands. The mixture is then cooled.
4. As the temperature decreases, DNA polymerase uses
the primers as a starting point to add nucleotides to
build copies of the desired gene.
5. The solution is heated and cooled repeatedly, and
each time the # of copies of the gene doubles.
Q: How many cycles must be completed to make a
million gene copies using PCR?
_______________
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XII. Applications of Genetic Engineering
A. Reproductive Screening – ____________________________________________________________________
__________________________________________________________________________________________
Example: amniocentesis, chorionic villi sampling, fetal cell sorting, fetoscopy
B. DNA Fingerprinting – the identification of organisms using sequences of DNA that vary widely between
organisms. An organisms DNA is cut using
restriction enzymes. The RFLP’s are then
separated by electrophoresis. The pattern
created may be unique for each individual, if
the proper region of DNA is chosen.
Example Problem:
Is Jack the father of Payle? _____________
How do you know? ___________________
___________________________________
Example Problem:
Scientists found members of a plant species they did
not recognize. They wanted to determine if the unknown species was related to one or more of four known species, A, B,
C, and D. The relationship between species can be determined most accurately by comparing the results of gel
electrophoresis of the DNA from different species. The chart below represents the results of gel electrophoresis of the
DNA from the unknown plant species and the four known species.
Q: What determines
how far a fragment
will move in the gel?
________________________
–
+
← Well
________________________
________________________
+
= RFLP
1. Which Plant Specie(s) has the smallest fragment of DNA? _________________________
2. Which Plant Specie(s) has the largest fragment of DNA? _________________________
3. Which Plant Specie(s) is most closely related to the unknown plant? _________________________
4. Which Plant Specie(s) is least closely related to the unknown plant? _________________________
Q: What are the uses of DNA Fingerprinting?
1) ____________________________________________________________________________________________
2) ____________________________________________________________________________________________
3) ____________________________________________________________________________________________
4) ____________________________________________________________________________________________
5) ____________________________________________________________________________________________
6) ____________________________________________________________________________________________
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C. Gene Therapy – A therapy used to cure a diseased individual by correcting or replacing a mutated gene.
1. A normal gene is cut out using restriction enzymes and copied by PCR.
2. The copies are introduced into the diseased individual.
3. Methods for introducing the gene include
a. using non-harmful viruses (vector) to deliver gene to a cell’s DNA
b. intravenous (IV) injections into the bloodstream
c. direct insertion into affected cells
Gene Therapy for Sickle Cell Disease
D. Cloning of Dolly the Sheep and other Organisms (success rate for this experiment was 1 out of 277 attempts -0.003%)
Process of Cloning the First Mammal
A donor cell is taken from
a sheep’s udder.
Donor
Nucleus
These two cells are fused
using an electric shock.
Fused Cell
Egg Cell
The nucleus of the
egg cell is removed.
An egg cell is
taken from an adult
female sheep.
The fused cell
begins dividing
normally.
Foster/Surrogate Mother
Embryo
Cloned Lamb
The embryo
develops normally
into a lamb—Dolly
The embryo is placed
in the uterus of a
foster mother.
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XIII. Bioethics
A. Bioethics includes people’s response to the ever growing understanding and use of gene technologies and cell
reproduction.
B. Because of the wide variety of cultures and societies, there is a wide variety in personal ethics, causing many
bioethical beliefs and concerns. This can lead to spirited debate about biological issues.
C. Examples of bioethical issues: stem cell research, genetically engineered foods
Q: Who determines which technologies are carried out in a society? ______________________________________
______________________________________________________________________________________________
Pros and Cons of Genetic Engineering (Though very legitimate, do not use personal morals for answers please).
Genetic Engineering Application
Pros
Mammal Cloning
(sheep, pigs, humans)
* Replacement organs (i.e. – new
heart or liver for those suffering from
liver or heart failure) without rejection
Cons
* False positives
DNA Fingerprinting
* Human error
Human Genome Project
Reproductive Screening
(amniocentesis)
Agrogenetics
Gene Therapy
Stem Cell Research
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Who Controls Your DNA?
April 16. Cpl. John C. Mayfield and Cpl. Joseph Vlacovsky were found guilty of disobeying a lawful order. The U.S.
Department of Defense requires DNA samples for a database that could be used to identify soldiers’ remains. The two
Marines refused.
At their court martial, the two Marines argued that DNA samples could be examined for genes related to disease or even
behavior and, therefore, the database was an invasion of privacy. As a result of the concerns raised by this case, the U.S.
Department of Defense has changed its policies. It now destroys DNA samples upon request when an individual leaves
military service. Do people have a right to control their own DNA samples?
The Viewpoints
DNA Information Is Not Private
As the court recognized, the U.S. Department of Defense had good reasons for requiring that DNA samples be taken and
stored. Furthermore, DNA sequences are no more private and personal than fingerprints or photographs, which are taken
by private and government agencies all the time. An employer has a right to take and keep such information. Individuals
should have no reason to fear the abuse of such databases.
DNA Information Is Private and Personal
The use of DNA for personal identification by the military may be justified. An individual’s genetic information, however, is
a private matter. A recent study at Harvard and Stanford universities turned up more than 200 cases of discrimination
because of genes individuals carried or were suspected of carrying. Employers with DNA information might use it to
discriminate against workers who carry genes they suspect might cause medical or behavioral problems. Individuals must
have the right to control their own DNA and to withhold samples from such databases.
You Decide
1. What are the major issues regarding DNA databases?
2. Are there any circumstances in which an employer might be justified in demanding DNA samples from its
employees? Why might an employee wish to withhold such samples?
3. Should the control of DNA databases be a matter of law, or should it be a matter to be negotiated between
people, their employers, and insurance companies?
4. Suppose you were a doctor working as a consultant to a health insurance company. The insurance company is
trying to decide whether to test adults for cystic fibrosis alleles before agreeing to insure their families. What
advice would you give to the company about this?
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