KEY
Unit 3 Test Review
Biology 1/5/11
Everything we have covered is fair game for the test, but your KUD is an extremely valuable
resource as a study guide. Go through each section to see what you need clarification on, and
then check your notes to review that material. I have outlined some sample topics and question
below for your practice, and would encourage you to look over old quizzes as well as class
notes.
What is the most basic unit of life? A cell.
Describe cell theory. Cells are the most basic unit of life, and all cells come from other cells.
Discuss similarities and differences between prokaryotic and eukaryotic cells.
Prokaryotic cells are smaller and simpler than eukaryotic cells, and they lack a nucleus.
Eukaryotic cells are comparatively larger, more complex, and can form multi-cellular organisms.
Use words and pictures to show the process social amoebas go through when they start
running out of food and try to find a new place to live. Explain how “cheaters” fit in to the
situation. (I’m going to skip the drawing)
Amoebas send out messages when they begin to starve, telling the group to get together. The
amoebas clump together to form a slug-like complex. The slug moves along to a higher/sunnier
location and turns into a stalk/tower with a clump on top. The clump breaks off and floats to a
new (and hopefully better) location. The amoebas that were part of the stalk are stranded and
end up dying.
Cheaters are amoebas that always go to the top instead of staying in the stalk. The reaction to
this is that other amoebas won’t let them join the group/slug in the first place.
Division of labor allows for specialized cells to exist in what types of organisms? Multi-cellular.
Does surface area or volume increase faster as the size of an object increases? Volume.
Use the word bank to write in the correct organelle. There are more words than definitions. (1.5 pts
each)
Cell wall, Chloroplast, Chromoplast, Cilia, Cytoplasm, Cytosol, Cytoskeleton, Endoplasmic
reticulum, Flagella, Golgi apparatus, Leucoplast, Lysosome, Mitochondria, Nucleus, Plasma
membrane, ribosomes
A. Long cellular appendages specialized for locomotion.
Flagella.
B. The organelles in eukaryotic cells that carry on cell respiration and are the site of ATP synthesis.
Mitochondria.
C. The entire contents of the cell, except for the cell nucleus. Cytoplasm.
D. An organelle found in plants and photosynthetic protists; the site of photosynthesis. Chloroplasts.
E. An extensive membranous network in eukaryotic cells. It is composed of ribosome-studded and
ribosome-free regions. Endoplasmic reticulum.
F. A cell vesicle that contains digestive enzymes. Lysosome.
G. An organelle consisting of two subunits and functioning as the site of protein synthesis. Ribosomes.
H. A plastid in plant tissues that is potentially capable of developing into a chloroplast. Leucoplast.
I. The membrane-bound organelle that houses chromosomes in eukaryotic cells. Nucleus.
What is the difference between gametes and somatic cells? Gametes are cells used for sexual
reproduction (egg and sperm) and somatic cells are cells of the body.
What is an autosome? An autosome is a type of chromosome that doesn’t determine
male/female (the first 22 chromosomes in a human cell).
What is an example of a sex chromosome? A sex chromosome is an X or a Y chromosome, it
determines whether a person is male or female.
Describe the roles of two enzymes associated with DNA replication.
DNA helicase opens up/separates/unzips the original strand of DNA. Next, DNA polymerase
comes in and adds nucleotides onto the exposed pieces to make two new copies of the DNA.
Draw and label an image that includes the following terms: Chromatin, Chromatid, Centromere,
Chromosome pair.
Chromatin is the tightly coiled DNA/protein material inside (ChromatIN is Inside), while the
chromatid is the term for one half of the paired pieces. The chromatids are joined at the center
known as the centromere (CENTromere is in the CENTer). The whole thing is called a
chromosome pair.
What does semi-conservative replication mean when discussing DNA synthesis? When DNA is
replicated, the strand is split down the middle. One half goes to one copy, the other half goes to
the other.
Draw a detailed diagram of a strand of DNA undergoing replication. Include properly paired
nucleotides, 3’ and 5’ labels, and indicate the leading and lagging strands. (Check your notes for
a drawing)
The “pointy” end of the DNA should be labeled as 3’, and the “flat” end is the 5’ (Five is Flat). As
replication proceeds, there will be a leading strand and a lagging strand. The leading strand is
the piece of DNA that can add on new nucleotides right as the original A-C G-T pairs are broken.
This will be the strand that has the pointy 3’ end pointing into the spot where DNA helicase is
opening the original strand.
Draw out the four phases of mitosis in the order that they occur. (See notes for pictures)
Prophase: Chromosomes are doubled up and condensed inside the cell.
Metaphase: Centrioles one either end of the cell act like anchor points for mitotic spindles,
which line all of the chromosomes up in the center of the cell.
Anaphase: The mitotic spindles pull the chromosomes into 2 pieces, one set for each side of the
cell.
Telophase: The spindles detach, nuclear envelopes start forming around the new sets of
chromosomes, and the cell begins to split into two (cytokinesis).
Discuss how cyclins and kinases work together to help regulate the cell cycle. Add a picture if
you think it will make your description easier to understand. (See notes for pictures)
A kinase is an enzyme that performs a specific task associated with a phase of the cell cycle.
This could be something involved with cell growth, DNA replication, or part of mitosis. The
active site (the part of the kinase that does the work) is tucked away and inaccessible when it is
not in use (the cell wouldn’t want to grow or replicate DNA while it is in Gap-0, for example).
However, when the time comes for the kinase to do its job, the cell produces a bunch of
proteins called cyclins that float around and bind with the kinase in a way that opens it up and
exposes the active site. While the active site is exposed, the kinase helps the cell to carry out
the processes associated with that particular phase. Once the phase is over, the cyclins go away
and the kinases close back up.
What is cancer? Cancer is a group of diseases characterized by uncontrolled cell division.
What is metastasis? Give an example of how it occurs. Metastasis is the spreading of cancer
throughout the body. If a few cancerous cells from a tumor get into the bloodstream, they can
be carried through the body and deposited somewhere else and potentially start a new tumor.
What is the difference between oncogenes and proto-oncogenes?
Oncogenes are genes that have mutated to become cancerous. These genes speed up the cell
cycle and increase cell division. Before the gene gets mutated, it is a proto-oncogene and helps
to control and regulate the cell cycle correctly.
How many copies of a tumor suppressor gene does a cell need in order to function correctly?
A cell normally has two copies of tumor suppressor genes, but it can function with only one.
Draw a diagram of the cell cycle that includes all of the phases and checkpoints we discussed in
class. (See notes for pictures)
I’ll start at the beginning of G1.
G1 is a growth phase. The cell has just come out of mitosis and during Gap-1 it grows to normal
size. There is a “side-loop” off of G1 known as Gap-0, which is a developmental rest point for
the cell. During G0 the cell doesn’t grow or replicate DNA, it just performs its function in the
body.
At the end of G1 there is a checkpoint called the Restriction Point. The cell checks to make sure
everything is okay before it begins DNA Synthesis (S-phase). During S-phase DNA is
replicated/doubled.
After S-phase the cell cycle transitions to Gap-2, which is another growth phase. During this
time the cell has to bulk up to a larger size because it is preparing to go into mitosis/cytokinesis
which will split it in half. At the end of G2 there is a checkpoint to make sure everything is all set
and ready for mitosis to begin.
The phases of mitosis have already been addressed, but one thing to keep in mind is that there
is another checkpoint between metaphase and anaphase. The cell is making sure mitosis is
going smoothly.
Name a common risk factor/cancer pairing that we have discussed in class.
UV exposure (sun/tanning bed) and Skin cancer
Cigarette smoke and Lung cancer
HPV and cervical cancer
Hepatitis B and liver cancer