HEREDITY
Final Exam Study Guide
Name:_______________________________________________________
period:_____
1. What is DNA replication?
A new strand of DNA is made using an existing piece of DNA as a
template.
a. Where does it occur? In the nucleus
b. Why is it called “semiconservative”?
Each new piece of DNA contains one strand from the original
DNA and one “new” strand (generated from adding nucleotides
complementary to the original strand.)
2. What is transcription?
A piece of mRNA is made using a DNA template.
a. Where does it occur? In the nucleus
3. What is translation?
 A protein is made using an RNA template.
 mRNA carries the message in CODONS.
 tRNA transfers amino acids to the strand in the
correct order using ANTICODON to codon
matching.
a. Where does it occur? cytoplasm
b. What organelle is involved? Ribosome (made of rRNA)
4. Why do replication and transcription ALWAYS have to occur in the nucleus of a eukaryotic cell?
DNA cannot leave the nucleus. (And both require a DNA template)
a. Would this be true in a prokaryote? NO- they do not have a nucleus, just a nucleoid region
Use the codon chart to answer the questions that
follow. (Choose A, B, C or D)
Match the following consequences to the
mutation that would cause them.
A. the amino acid sequence would be shorter
than expected
B. the identity of one amino acid would change
C. the identity of more than one amino acid
would change
D. the amino acid sequence would remain
unchanged
5. _B___ If the original strand of AUG CCA UUG CAU was changed to AUG CAA UUG CAU
6. _A___ If the original strand of AUG CCA UUG CAU was changed to AUG CCA UAG CAU
7. __D__ If the original strand of AUG CCA UUG CAU was changed to AUG CCA UUA CAU
8. _C___ If the second C in CCA was deleted from the original strand of AUG CCC AUU GCA U
9. What is a germ cell? How does it differ from a somatic cell?
Somatic cells refer to those cells that make up the body (aka body cells). These cells contain the
diploid number of chromosomes. In humans this number is 46. Germs cells are those cells
associated with the gametes of an organism. These cells have half the number of chromosomes and
are haploid. In humans, this number is 23.
10. How would getting a mutation in a germ cell affect organisms differently than a mutation in a
somatic cell?
Germ cell mutations can be passed from parent to offspring. Somatic cell mutations are not
11. Compare and contrast a point vs frameshift mutation. Which usually causes more damage to the
protein?
Both mutations will alter the sequence of nitrogen bases in the DNA. A point mutation
changes/replaces one nitrogen base with another in the sequence of DNA. This may or may not alter
the amino acid that will be coded for. A frameshift mutation will add or delete nitrogen bases
changing how the codons will be read at the ribosome. A frameshift mutation will change all of the
amino acids after the point of insertion or deletion.
Use this diagram to answer the next few questions.
12. What macromolecule is being made through the process pictured above? ____Protein___________.
13. Which organelle is closely associated with the process represented in the diagram?_Ribosome____
14. Which amino acid would be added to the chain at the position of codon CUU?__Leucine_________.
15. When writing the offspring ratios for dihybrid crosses, what order will you always report in?
Dominant, Dominant: Dominant, recessive: recessive, Dominant: recessive, recessive
16. What parent combinations will give you the following ratios:
a. 3:1
__Aa x Aa__________________
b. 2:2
__Aa x aa__________________
c. 9:3:3:1
__AaBb x AaBb_____________
d. 1:1:1:1
__AaBb x aabb______________
17. We studied many different patterns of inheritance. Briefly describe each type below. Be able to
read a pedigree for each type
a. Simple Mendelian traits (T= tall, t= short) Involves the inheritance of one trait. For example
tall plants are crossed with short plants. If tall is dominant, predict the genotypic ratios of the
F1
b. Dihybrid Crosses Involves the inheritance of two traits. For example tall plants with yellow
seeds are crossed with short plants with green seeds.
c. Sex-linked traits (on the X chromosome) This involves the inheritance of traits located on
the X chromosome. These traits include color blindness and muscular dystrophy. Males are
more likely to express these recessive conditions because males only need one of the
recessive alleles whereas females need two.
d. Incomplete Dominance: When two organisms are crossed for a particular characteristic, an
intermediate phenotype may result. For example, when a red flower is crossed with a white
flower, pink flowers are produced.
e. Codominance When two organisms are crossed for a particular characteristic, both
characteristics appear in the phenotype. For example, when a red flower is crossed with a
white flower, red and white flowers are produced.
f. Multiple Alleles: More than two alleles exist for a particular trait. For example, in human
blood types individuals can be blood type A, B, O, or AB
18. Your liver cells perform a very different function from you nerve cells. They have very different
shapes, make different proteins and even have a different life span. If every cell in your body has the
same DNA, how do you think these differences could occur?
Different genes are turned on or off in these different cells causing them to perform different
functions.
19. Watson and Crick expanded on research performed by Rosalind Franklin to discover the structure of
DNA. Explain the following terms they used to describe its structure.
a. Complementary base pairs A always pairs with T and G pairs with C
b. Double Helix The structure of DNA is composed of two strands that twist resembling a
twisted ladder. This unique shape is known as the double helix.
c. Genetic Code for making proteins Genes are segments of DNA. These segments of DNA
contain the information needed to make proteins.
20. In corn, purple kernels (D) are dominant over yellow (d), & smooth kernels (G) are dominant over
shrunken (g). How many phenotypes are there?(n=__4_) Degrees of Freedom: ((n-1)= __3__)
An ear of corn is found to have 381 kernels.
216 are purple, smooth
79 are purple, shrunken
65 are yellow, smooth
21 are yellow, shrunken
Based on these results, it was suspected that both parents were heterozygous for each trait. A Chi
Square analysis was performed on the data. The null hypothesis and results are show below.
Null Hypothesis: There is no significant difference between the expected 9:3:3:1 and observed
ratio. Any difference is due to chance.
Observed
Expected
purple, smooth
purple, shrunken
yellow, smooth
yellow, shrunken
216
214
79
71.5
65
71.5
21
24
Calculated Chi Square value x2= 1.771
21. Should you accept or reject the null hypothesis? Explain why? With three degrees of freedom and a
x2 value of 1.771 we need to accept the null hypothesis due to the fact it is below the critical value at
.05. The observed data “fits” the predicted
ratio.
22. Which man is the biological father of this
baby? Male 1 Use the following gel
electrophoresis.
23. The gel electrophoresis below shows the DNA
banding patterns for a blood stain found at a crime
scene and 4 suspects. Which of them is probably
the culprit? John
24. How were these bands created? (What are they
actually made of? What is the name of the enzyme
used to cut it?) The bands are segments of DNA.
In order to produce these bands a long strand of
DNA was cut using restriction enzymes. The
resulting fragments were then pulled through a gel
like substance that separated the different
fragments based on their length. The smallest
fragments are at the bottom of the gel and the
longest fragments remain close to the top.
25. Below is another gel. How is the gel pattern created? (Why do some pieces move farther than
others? Why are some bands thicker than others?) The thicker bands in the gel represent many
fragments of DNA that are the same size accumulating in the same location in the gel.
26. In Meiosis we studied a concept called
independent assortment. The picture below
illustrates this using eye color and hair color.
Explain how this creates diversity among
organisms and determine what combinations of
gametes can be formed in this example
brown hair
blue eyes
blonde hair
brown eyes
When the homologous chromosomes pair up during meiosis I they can alter their arrangement resulting
in different gametes. For example, the chromosome containing the blonde hair gene doesn’t always
need to line up on the right side of the cell above the chromosome containing the brown eye gene. It
could have just as easily positioned itself on the left side of the cell along with the blue eye gene.
27. Some traits are called “linked” because they occur on the same chromosome and therefore are often
inherited together. One such linkage is red hair and light complexion.
How would this change the
possible combinations in the gametes? Draw a picture to help illustrate the difference.
If genes are linked and located on the same chromosome, they do not segregate and separate
independently of eachother.