BIOL 110 Week 6 KEY
1. Label the diagram and define the organelles.
a. Plasma membrane- The membrane at the boundary of every cell that acts as a selective
barrier, thereby regulating what enters and
exits the cell.
b. Nucleus- An organelle, present in
eukaryotic cells, which contains
chromosomes.
c. Nuclear membrane- the membrane that
separates the nucleus from the cytoplasm
d. Ribosome- An organelle found in the
cytoplasm whose function is to aid in protein
synthesis.
e. Endoplasmic reticulum- The ER functions
as a manufacturing facility within the cell,
producing many different types of
molecules.
f. Rough ER- A type of ER studded with
ribosomes that specializes in protein
synthesis.
g. Smooth ER- A type of ER without
ribosomes which produces molecules other
than proteins.
h. Golgi apparatus- The Golgi apparatus is an
organelle whose function is to direct
distribution of molecules produced in the ER
to destinations within and without the cell.
i. Lysosome- A membrane-enclosed organelle, full of hydrolytic enzymes, found in eukaryotic cells
j. Food vacuole- A membrane-enclosed organelle that serves as a food storage space.
k. Central vacuole- A large, versatile type of vacuole found in plant cells that serves as a storage space
for several types of molecules, including proteins, water, pigments, and, in some plants, poisons.
l. Contractile vacuole- A vacuole, present in some protists, that can pump out excess water from the cell.
m. Chloroplast- An organelle found in plant cells that is the site of photosynthesis.
n. Mitochondria- An organelle found in plant and animal cells that provides energy to the cell through
cellular respiration.
o. Cytoskeleton- A network of microtubules, microfilaments, and intermediate filaments present in the
cytoplasm that serve both mechanical and transport functions; the skeleton and also “muscles” for the
cell.
p. Flagella/cilia- Cellular appendages attached to the cell membrane in animal cells that aid in
movement; flagella often appear singly and work through a “whiplike” motion, while cilia are smaller,
far more numerous, and work with a coordinated back-and forth motion.
2. List the four components of cellular respiration, where it occurs in the cell, and list major
products consumed and produced in each step.
a. Glycolysis: Requires 2 ATP to “get started”, produced 4 ATP and NADH, the glucose is
turned into 2 pyruvate atoms for every glucose atom. Glycolysis occurs in the cytoplasm
of eukaryotes and prokaryotes.
b. Pyruvate processing: Pyruvate is processed to release one molecule of carbon dioxide,
and the remaining two carbons are used to form the compound acetyl CoA, NADH if also
produced. Occurs in the matric of the mitochondria or the cytoplasm of prokaryotes.
c. Citric acid cycle: Acetyl CoA is oxidized to two molecules of carbon dioxide, 3 NADH, an
ATP and FADH2 is produced, the cycle runs twice for each glucose molecule oxidized.
Occurs in the matrix of the mitochondria or the cytoplasm of prokaryotes.
d. Electron transport and oxidative phosphorylation: Electrons from NADH and FADH2
move through a series of proteins called the electron transport chain (ETC). The energy
released in this reaction is used to create a proton gradient across a membrane; there
become a positive charge in the inner membrane of the mitochondria. This chemical
potential energy is changed into kinetic energy in the ATP synthase protein this is called
oxidative phosphorylation. Oxygen is used and water is produced.
3. Label the fermentation diagram
Fermentation occurs when there is no oxygen
available to produce ATP. There is less ATP
production and instead of carbon dioxide being
a waste product lactate is which forms lactic
acid.
4. What happens in Photosystem II?
Excited electrons from the antenna complex resonance energy to the reaction center. From
there pheophytin is reduced by electrons in photosystem II. Plastoquinone (PQ) receives
electrons from photosystem II and carries them across the lumen side of the thylakoid and
delivers them to more electronegative molecules in the cytochrome complex. Hydrogen is
stripped from the molecules on the stroma side and dropped of to the lumen side to create a
high chemical potential energy. This potential energy of the hydrogen concentration is used in
the ATP synthase molecule to form ATP. Very similar to the ETC in cellular respiration.
5. What happens in Photosystem I?
Pigments in the antenna complex absorb photons and pass the energy to the photosystem I
reaction center. Electrons are excited from the energy, the reaction center pigments are
oxidized. The high-energy electrons are passed through a series of carriers inside the
photosystem, then to a molecule called ferredoxin, and then to the enzyme NADP+ reductase.
NADP+ reductase transfers two electrons to NADP+ to form NADPH. This has a similar function as
NADH and FADH2 produced by the citric acid cycle. NADPH allows cells to reduce carbon dioxide
to carbohydrates in the Calvin cycle.
6. Define the Z-scheme.
It is a model for how photosystems I and II interact.
7. What is the C4 pathway?
The C4 pathway is in mesophyll cells that contain PEP carboxylase. A three carbon compound is
fixed to PEP carboxylase to create a four carbon organic acid. The C4 pathway increases the
carbon dioxide concentration. This helps improve the efficiency of the Calvin cycle.
8. What are CAM plants and what happens inside of them?
CAM occurs in plants that regularly keep their stoma closed on hot, dry days and open them on
cool nights. Much like the C4 pathway the CAM pathway creates higher concentrations of carbon
dioxide. The difference is that carbon dioxide is stored at night and used during the day.
9. What are the three types of cell junctions?
 Tight junctions: Specialized proteins in the plasma membrane line up and bind to one
another. This is matched in the nearby cell. The proteins bind to each other and create a
water tight seal between the two cells. This won’t allow solutions or any harmful object
to pass through.
 Desmosomes: It is a connection that forms bridges between anchoring proteins inside
adjacent cells. Intermediate filaments are involved and connect to the anchoring protein
inside the cell. They help support the connection and diffuse energy and forces placed
onto the cell. This is gap junction is the reason why if one cell is compressed or pulled
they don’t all fall apart.
 Gap junctions: They are made up of membrane proteins that line up to form a channel
between the cytoplasms. This is how cells can communicate between each other by
sharing their cytoplasm. This allows for diffusion across many cells and for
communication to occur between distant cells.