In-class introduction to basic Punnett square set-up and problem solving, Part 1 Problem-solving tips: · A Punnett square allows you to predict the possible genetic outcome of children based on the genetic make-up of the parents. · First, read the problem and figure out whether the trait of interest or genetic disorder is found on the dominant allele or the recessive allele because that will have an impact on how you interpret the results of the Punnett square. · Select a letter to represent the trait or disorder and define the dominant and recessive alleles. For example: For eye color, B (dominant) = brown eyes and b (recessive) = blue eyes. For achondroplasia (dwarfism), A (dominant) = achondroplasia and a (recessive) = normal allele. · If it is a sex-linked question, remember to include the sexual genotypes of the parents (XX for mom and XY for dad). · Write down all possible genotypes & phenotypes and use this information to help you set up the Punnett square. 1. Practice question on a human trait. In reality, eye color is controlled by multiple genes and is a complex trait. For simplicity, we’ll assume that brown eyes are dominant to blue eyes. Answer the questions below. a) Select a letter for this trait and define the dominant and recessive alleles. B (dominant) = b (recessive) = b) Write down all possible genotypes and phenotypes for individuals in the population Possible genotypes (the 2 alleles an individual has) Possible phenotypes (the physical appearance of a trait) Homozygous dominant individuals Homozygous recessive individuals Heterozygous individuals c) Set up the Punnett square and solve this problem. Kristy is heterozygous and Mark has blue eyes. What percentage of their offspring will have blue eyes? Kristy's genotype Mark's genotype a) Select a letter for this genetic condition and define the dominant and recessive alleles. F (dominant) = f (recessive) = b) Write down all possible genotypes and phenotypes for individuals in the population Possible genotypes (the 2 alleles an individual has) Possible phenotypes (the physical appearance of a trait) Homozygous dominant individuals Homozygous recessive individuals Heterozygous individuals c) Set up the Punnett square and solve this problem. Kristy and Mark are carriers for cystic fibrosis. The term carrier is only used when a condition is on the recessive allele. Carriers are heterozygous individuals who are normal and show no symptoms of the disorder, but they have the ability to pass on the mutated recessive allele to their offspring. What percentage of their children will be normal? What percentage of their children will be carriers? Kristy's genotype Mark's genotype 2. Practice question on a genetic condition. Cystic fibrosis (CF) is an autosomal, recessive condition that results in mucus buildup in the lungs and digestive system organs. As a result, CF .

1. In-class introduction to basic Punnett square set-up and problem
solving, Part 1
Problem-solving tips:
· A Punnett square allows you to predict the possible genetic
outcome of children based on the genetic make-up of the
parents.
· First, read the problem and figure out whether the trait of
interest or genetic disorder is found on the dominant allele or
the recessive allele because that will have an impact on how you
interpret the results of the Punnett square.
· Select a letter to represent the trait or disorder and define the
dominant and recessive alleles. For example: For eye color, B
(dominant) = brown eyes and b (recessive) = blue eyes. For
achondroplasia (dwarfism), A (dominant) = achondroplasia and
a (recessive) = normal allele.
· If it is a sex-linked question, remember to include the sexual
genotypes of the parents (XX for mom and XY for dad).
· Write down all possible genotypes & phenotypes and use this
information to help you set up the Punnett square.
1. Practice question on a human trait. In reality, eye color is
controlled by multiple genes and is a complex trait. For
simplicity, we’ll assume that brown eyes are dominant to blue
eyes. Answer the questions below.
a) Select a letter for this trait and define the dominant and
recessive alleles.
B (dominant) =
b (recessive) =

2. b) Write down all possible genotypes and phenotypes for
individuals in the population
Possible genotypes
(the 2 alleles an individual has)
Possible phenotypes (the physical appearance of
a trait)
Homozygous dominant individuals
Homozygous recessive individuals
Heterozygous individuals
c) Set up the Punnett square and solve this problem. Kristy is
heterozygous and Mark has blue eyes. What percentage of their
offspring will have blue eyes?
Kristy's genotype
Mark's genotype

3. a) Select a letter for this genetic condition and define the
dominant and recessive alleles.
F (dominant) =
f (recessive) =
b) Write down all possible genotypes and phenotypes for
individuals in the population
Possible genotypes
(the 2 alleles an individual has)
Possible phenotypes (the physical appearance of
a trait)
Homozygous dominant individuals
Homozygous recessive individuals
Heterozygous individuals
c) Set up the Punnett square and solve this problem. Kristy and
Mark are carriers for cystic fibrosis. The term carrier is only
used when a condition is on the recessive allele. Carriers are
heterozygous individuals who are normal and show no
symptoms of the disorder, but they have the ability to pass on
the mutated recessive allele to their offspring. What percentage
of their children will be normal? What percentage of their

4. children will be carriers?
Kristy's genotype
Mark's genotype
2. Practice question on a genetic condition. Cystic fibrosis (CF)
is an autosomal, recessive condition that results in mucus
buildup in the lungs and digestive system organs. As a result,
CF individuals have difficulty with breathing and bowel
movement is obstructed.
Cs/1.PNG
Cs/2.PNG
Cs/3.PNG
STUDY GUIDE on DNA, biotechnology, & gene expression

5. Readings: Ch. 5 (Sections 5.1-5.7; 5.12-5.17)
NOTE: Students are responsible for the following information
on the lecture exams: any and all information discussed in class,
presented in the PowerPoint slides, and specified in the study
guides and handouts.
Key terms to be familiar with for DNA replication &
biotechnology
Nucleic acid
Deoxyribonucleic acid (DNA)
Double helix
Phosphate-sugar backbone
Nucleotide
Phosphate
Ribose
Nitrogenous bases
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Complementary
base-pairing
Genome
Chromosome
Gene
Allele
Nucleotide sequence or base sequence
Hydrogen bonds
DNA replication
Helicase
Single strand binding proteins
DNA polymerase
Topoisomerase
DNA ligase
Nuclease
UVA rays

6. UVB rays
Melanin
Xeroderma pigmentosum
Biotechnology and genetic engineering
Genetically modified organisms
DNA fingerprinting
Watson and Crick
Rosalind Franklin
Study Qs: Complete questions discussed in class on a weekly
basis.
1. Nucleic acids make up the category of biological molecules
responsible for storing genetic information. Deoxyribonucleic
acid (DNA) is an example of a nucleic acid.
a. A molecule of DNA is constructed by linking together simple
building blocks called nucleotides. What are the three
components of a nucleotide? Label them in the diagram below.
b. Which two components of the nucleotide form the “back
bone” of the DNA double helix? What is the function of this
backbone?
c. What single component of the nucleotide is variable
(changeable) and has four possibilities: adenine (A), guanine
(G), cytosine (C), and thymine (T)? What is the function these
variable parts of the DNA double helix?
2. Explain the arrangement of the two DNA strands relative to
each other.
3. The DNA double helix consists of two separate DNA
molecules that are joined together by chemical bonds between
the nitrogenous bases. What types of chemical bonds unite the
two strands of the double helix? Describe their properties.
4. In order for one DNA strand to bind to its complementary
DNA strand and form a helix, specific base pairing is seen
between the nitrogenous bases. Memorize the following

7. complementary base-pairing rules used in DNA replication
(note: a different set of rules will be used during transcription).
DNA
DNA
A
T
T
A
C
G
G
C
a. Identify and explain which of the base pairs is stronger.
Which bonds (A-T or C-G) would you expect to find at the
beginning of a genes that would enable easier access to genetic
information?
5. Distinguish among the following terms (use your textbook):
a. Genome:
b. Chromosomes:
c. Gene:
d. Allele:
6. Cell division occurs during the growth and development of
our bodies; it also allows us maintain all organs by replacing
damaged or worn out cells. Before a cell divides, it must
replicate its DNA so that all future cells have their own set of
genetic instructions.
a. Outline the steps in DNA replication, including the function
of the following:
· Helicase
· Single-strand binding proteins
· DNA polymerase

8. · Topoisomerase
b. Explain why DNA replication is termed a semi-conservative
process.
7. When is DNA mismatch repair used? What enzyme is
involved in this repair process?
8. When is DNA excision repair used? What enzymes are
involved in this process?
9. As a last resort, what are cells programmed to do when their
DNA is damaged beyond any type of repair?
10. Review your notes on the effect of UVA and UVB radiation
on skin cells.
11. Xeroderma pigmentosum (XP) is a genetic disease caused by
the inability of afflicted individuals to repair DNA damage that
is caused by exposure to the sun’s ultraviolet rays.
a. Exposure of ultraviolet radiation alters the shape of our DNA
by causing an abnormal bond to form with the DNA molecule
itself. Describe the type of bond that forms.
b. In a normal person, what type of DNA repair is used to
correct damage that is caused by sunlight?
c. Explain why individuals with XP are unable to use this DNA
repair process.
d. What are the symptoms of XP?
e. What are ways to manage this genetic condition?
12. Biotechnology is a branch in science where living systems
are modified to create products that somehow benefit the human
population. Review your lectures notes and PowerPoint slides
when answering the following questions:
a. How is biotechnology in the form of DNA fingerprinting used
in crime scenes and paternity tests?

9. b. How can producing genetically modified foods be beneficial
to humans?
c. What are the concerns and side effects of genetically
modified foods?
d. How can biotechnology be used to help those with chronic
disease? Refer to the insulin example.
e. How can biotechnology be used in early diagnosis of genetic
diseases ( NOVA Science video).
Key terms to be familiar with for gene expression (DNA to
proteins)
Transcription (noun)
Transcribe (verb)
Translation (noun)
Translate (verb)
Promoter region
Terminator region
Introns
Exons
Codon
Start codon
Stop codon
RNA polymerase
Uracil (U)
Transfer RNA (tRNA)
Ribosome
Amino acids
Proteins
Gene
5’ Methylated cap
3’ Poly-A tail
Study Qs: Complete questions discussed in class on a weekly
basis.

10. 13. Define and understand all of the above terms.
14. Write down where each of the following structures is
located (i.e., nucleus, cytoplasm, or both):
DNA
mRNA
Ribosomes
tRNA
RNA polymerase
15. Describe the purpose and the process of transcription. In
your answer, define and explain the function of the following
key terms: nucleus, DNA, mRNA, RNA polymerase, promoter
region, terminator region, gene of interest, introns, exons, 5’
methylated cap, 3’ Poly-A tail. You should also memorize the
following complementary base-pairing rules for transcription
(which are different from DNA replication):
DNA
mRNA
A
U
T
A
C
G
G
C
16. Describe the purpose and the process of translation. In your
answer, define and explain the function of the following key
terms: mRNA, amino acids, proteins, codon, start codon, stop
codon, tRNA, ribosomes, cytoplasm.

11. 17. Given a DNA sequence, be able to transcribe it into mRNA,
and be able to use the genetic code table to translate it into an
amino acid sequence of a protein. Refer to activity in the
human and cow gene for insulin.
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