Biology 111 Exam 3 Study Guide
Dr. Michael Nicodemus
The exam will consist of one or two matching sections and a short answer section. All of the
potential short answer questions are listed below. All of the words that may be used in the
matching section are listed. There is a glossary available on Canvas to which I will be adding
words as the semester progresses. In this glossary, you will find all the words and their
definitions that may be on the tests. For words with more than one definition, the number of the
definition used on the test is given. Anything italicized below will not be given in the question on
the test.
Short Answer
 Name and describe the levels of organization in DNA from individual monomers
(nucleotides) to all of the DNA in an organism (genome).

Using a labeled drawing and description, explain transcription.
A gene (DNA INSTRUCTION) is unzipped and mRNA is paired with the complimentary DNA
nucleotides bty letter.
Once completed, DNA zips back up, The mRNA breaks away, than leaves the nucleos and enters
the cytoplasm

Using a labeled drawing and description, explain the three stages of translation.
Once an mRNA has rec ivied its “recipe” The three stages of Translation take place
Initiation The mRNA moves into the ribosome, where the complimentary tRNA is met with the
mRNA,
Elongation Enter second tRNA, first exits, third entrees ext, going alone the length of the
mRNA
Termination- Once a stop codon is reached, the newly formed protien is released/

Using a labeled drawing and description, explain DNA replication.
Each strand of the DNA molucule is used in the creation of a new double strand. Replication
begins with double strand dna being seperated, and each one is used as a parent.

Draw and label a section of DNA, showing components and bonds.

Using labeled drawings, name and describe all of the steps of the cell cycle.
G1 2 G2
 Using labeled drawings, name and describe all of the steps of mitosis.
Prophase- Chromosones become visible and condense, becomning shorter and thicker
Metaphase – Double stranded Chromosomes line up along the equater of the cell.
Anaphase – sister chromiteids begin to seperate
Telephase – the two groups of crhomosons reach either end of the cell, spindle disappears.

What is a karyotype? How many chromosomes does a “normal” human have? What
does it mean for chromosomes to be homologous? Using a labeled drawing and
description, explain how an animal could get an abnormal number of chromosomes.
Describe one genetic disease that is caused by having an abnormal number of
chromosomes.
the number and visual appearance of the chromosomes in the cell nuclei of an
organism or species.
23
Two sets of each chromosome, possible different alleles
Down syndrome

Describe what genotypes, phenotypes, and alleles are. What are the two main factors
that influence phenotype? What does it mean to say that an allele is dominant?
What does it mean to say that an allele is recessive?
Alleles are different types of the same gene, ie white vs brown fur
Genotype- genetic makeup of something
Phenotype – Phisical cheriterstics that something receives
a dominant allele will cover a recessive allele

Name and describe two “principles” of Mendelian genetics.

Start with true breeding parents, one dominant and one recessive. Give the
phenotype and genotype of each (chose any trait you like). Give the phenotype and
genotype of the offspring of those parents. Using a Punnett square, show the
genotypes and phenotypes of all possible offspring of a cross between two of the
offspring from the F1 generation and the proportions of each.
Segregation a During reproduction, the inherited factors (now called alleles) that
determine traits are separated into reproductive cells by a process called meiosis and
randomly reunite during fertilisation.
true breeding
Inheritance involves the passing of discrete units of inheritance, or genes, from parents
to offspring.
Wb Wb – white fur brown fur

Using a drawing and description, show how a testcross works. Describe the two possible
outcomes in terms of offspring and what that means in terms of the genotype of the
parents.
the cross of an organism with an unknown dominant genotype with an organism
that is homozygous recessive for that trait

Describe gene linkage. Why are genes sometimes linked? How does that relate to the
Principle of Independent Assortment? Describe how gene linkage can be used for gene
mapping.
Gene linkage: two alleles located close to each other on a chromosome are likely to
segregate together even when recombination occurs, chances are they won't get
separated.
chromosome mapping: making a 'map' of where genes are on a chromosome. This is
done by figuring out which genes are closest to each other and which are farther apart
based on how frequently they get separated during recombination.

What is codominance? Using a Punnett square, show the phenotypes and genotypes of
the offspring of a cross between two heterozygous parents (chose whatever trait you like).
N S
Situation in which two different alleles for a genetic trait are
both expressed.
SNS SS
SNS SS

Describe the three alleles for blood type. Describe how they relate to each other in
terms of dominance. Name the four blood types and show the all the genotypes for
each.
ABO O .O.
<.O.>

What is polygenic inheritance? How does it work? Describe an example of polygenic
inheritance.
Inheritance from multiple genes alaa skin color.
 What is epistasis? How does it work? Describe an example of epistasis.
Epistasis. When one gene masks a second gene. Keys car milk
 What is pleiotropy? Name and describe an example of pleiotropy.
Pleiotropy refers to the phenomenon in which a single gene controls several distinct,
and seemingly unrelated, phenotypic effects.
A classic example of pleiotropy is the human disease PKU (phenylketonuria). This
disease can cause mental retardation and reduced hair and skin pigmentation, and can
be caused by any of a large number of mutations in a single gene that codes for an
enzyme (phenylalanine hydroxylase) that converts the amino acid phenylalanine to
tyrosine, another amino acid.

Name the chromosomes involved in sex determination in humans and what
combinations lead to what sex. Describe genetic diseases that are more prevalent in
males. Why are they more prevalent?
Xy xx female xy male. Pretty much all of them due to the double chance of reciving them

What is mitochondrial disease? Why is it only inherited through the mother?
Mitochondrial deases result from a failure of the mitochondria/
Girls will always pass on a mtDNA mutation (genetic error or defect) and boys will
never pass on a mtDNA mutation.

What is a mutation? Describe ways that mutations can happen in terms of the genetic
code.
These genetic changes are not present in a parent’s egg or sperm cells, or in the fertilized egg, but
happen a bit later when the embryo includes several cells. As all the cells divide during growth
and development, cells that arise from the cell with the altered gene will have the mutation, while
other cells will not
A gene mutation is a permanent alteration in the DNA sequence that makes up a gene

What is a chimæra? Describe ways a chimæra can happen.

What is a mutagen? Give some examples of mutagens.
a single organism composed of genetically distinct cells. Taking the cells from one
species and splicing them with the other species
an agent, such as radiation or a chemical substance, that causes genetic mutation
Vocabulary
Allele
Anaphase
Base pair
Base substitution
Biodiversity
Carrier (3)
Centromere
Chimæra
Chromatid
Chromosome
Codominance
Codon
Covalent bond
Crossing-over
Cytokinesis
Cytoskeleton
Dihybrid cross
DNA
Dominant
Down Syndrome
Enzyme
Epistasis
Evolution
Fertilization
Frameshift
Gamete
Gene
Gene linkage
Genome
Genotype
Helix
Hemoglobin
Heredity
Heterozygous
Homozygous
Hybrid
Hydrogen bond
Interphase
Karyotype
Klinefelter Syndrome
Meiosis
Membrane
Metaphase
Mitochondria
Mitosis
Monohybrid cross
Mosaic (1)
mRNA
Mutagen
Mutation
Nonsense mutation
Nucleotide
Nucleus (2)
Penetrance
Phenotype
Pleiotropy
Polygenic
Prophase
Protein
Punnett square
Recessive
Replication (2)
Ribosome
rRNA
Sickle-cell anemia
Silent mutation
Species
SRY
Sterile
Swyer Syndrome
Telophase
Testcross
Thymine
Transcription
Translation
Transposon
tRNA
Uracil