BIOL 1406.007 Chapter 6
lysosomes
- autophagy - macromolecule digestion
smooth ER
- lipid synthesis - calcium ion storage - poison detoxification
The structure of a chloroplast is closely tied to its function as the site of photosynthesis Some of the following statements are true for chloroplasts? Select the three that apply.
- They have membranous sacs called thylakoids that are surrounded by a fluid called storma - They contain the green pigment chlorophyll - They are the sites of reactions that convert solar into chemical energy
The primary role of _____ is to bind animal cells together.
desmosomes
Where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the endoplasmic reticulum?
in mitochondria
Many cell organelles, most notably the nucleus, are anchored by _______, which are assembled from a diverse class of proteins.
intermediate filaments
The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the ___.
intermediate filaments
prokaryotic only
nucleoid
Where is a bacterial cell's DNA found?
nucleoid region
_____ are surface appendages that allow a bacterium to stick to a surface.
Fimbriae
The DNA-containing region of this bacterial cell is indicated by the letter _____.
D
Which of the following options best depicts the flow of information when a gene directs the synthesis of a cellular component?
DNA → RNA → protein
In bacteria, DNA will be found in ________.
the nucleoid
A small surface area to volume ratio is desirable for the cell to transport enough nutrients and waste across the plasma membrane to meet its metabolic needs.
False
As a cell increases in size, the surface area increases proportionately more than the volume.
False
plant cell only
cellulose cell wall, chloroplast, central vacuole
Which organelle often takes up much of the volume of a plant cell?
central vacuole
animal cell only
centriole
Which structure below is independent of the endomembrane system?
chloroplast
Thylakoids, DNA, and ribosomes are all components found in ________.
chloroplasts
In a liver cell detoxifying alcohol and some other poisons, the enzymes of the peroxisome remove hydrogen from these molecules and ________.
combine the hydrogen with oxygen molecules to generate hydrogen peroxide
Which of the following is a junction found in animal cells that establishes a barrier that prevents leakage of fluid across layers of cells?
tight junctions
Which of these cell junctions form a barrier to the passage of materials?
tight junctions
Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.
transferring of information from DNA to messenger RNA
Cells require which of the following to form cilia or flagella?
tubulin
Which of the following are part of the endomembrane system? Select/check all that apply.
- Gogli apparatus - lysosomes - Rough ER
All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes?
- insulin - lysosomal enyzme - ER protein
Golgi apparatus
- protein modification and sorting - cisternal maturation
both plant and animal cells
-mitochondrion - endoplasmic reticulum - plasma membrane - golgi apparatus - cytoskeleton - nucleus
The cellular organization and extracellular environments of plants and animals are very different. Drag the labels to their appropriate locations in the table below. Use only pink labels for the pink targets. Labels may be used more than once.
1. Membrane protein complexes that strengthen the adhesion between adjacent cells, like rivets, to protect against pulling forces. DESMOSOMES AND ANIMAL 2. Small channels that form across the plasma membranes of adjacent cells; especially important in intercellular communication. GAP JUNCTIONS AND ANIMAL 3. Membrane proteins that create a watertight seal between cells. TIGHT JUNCTIONS AND ANIMAL 4. Small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between cells. PLASMODESMATA AND PLANT 5. A polysaccharide that is used to synthesize cell walls, which protect cells and help maintain their shape. CELLULOSE AND PLANT 6. Long fibers of proteins found in the extracellular matrix that provide structural support for cells. COLLAGEN AND ANIMAL
1 meter = _____ centimeters.
100
What is the approximate volume of the budding cell?
14 µm3
Approximately how much additional cytoplasm will the budding cell have to synthesize as it grows to the size of the mature cell?
19 µm3
Approximately how much additional area of plasma membrane will the budding cell have to synthesize as it grows to the size of the mature cell?
22 µm2
What is the approximate surface area of the budding cell? (Remember that you approximated the diameter of the budding cell to be 3 µm.)
28 µm2
What is the approximate diameter of the budding cell?
3 µm
The shape of a yeast cell can be approximated by a sphere, so you can calculate the volume of each cell using the formula for the volume of a sphere:
33 µm3
Note that the scale bar under the photo is labeled 1 μm (micrometer). The scale bar works the same way as a scale on a map, where, for example, 1 inch equals 1 mile. In this case the bar represents a much smaller distance.
4 µm
As the new cell grows, its plasma membrane needs to expand to contain the increased volume of the cell. Calculate the surface area of each cell using the formula for the surface area of a sphere: A=4πr2A=4πr2 What is the approximate surface area of the mature parent cell? (Remember that you approximated the diameter of the mature parent cell to be 4 µm.)
50 µm2
The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____.
C
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
cell wall
_____ aid in the coordination of the activities of adjacent animal cells.
Gap (communicating) junctions
Compare the following two organisms: - Organism A is a single-celled organism with a surface area-to-volume ratio of 4.5. - Organism B is a multicellular organism with a surface area-to-volume ratio of 3.2. Which organism's surface area to volume ratio will better support its cellular interior(s), and why?
Organism A because it has the higher surface area to volume ratio.
You have a cube of modeling clay in your hands. Which of the following changes to the shape of this cube of clay will decrease its surface area relative to its volume?
Round the clay up into a sphere.
Suppose you discovered a new multicellular organism that is shaped like a cube. The organism measures 3 cells tall, 3 cells wide, and 3 cells deep. You measure one cubed cell to be 2 arbitrary units per side. Can you calculate this organism's surface area to volume ratio?
Surface Area = 648 units^2 Volume = 216 units^3 SA to Vol ratio = 3
When the budding cell matures, it will be approximately how many times greater in volume and how many times greater in surface area than its current size?
The new cell will be approximately 2.4 times its current volume and 1.8 times its current surface area
Which of the following expresses the concept of emergent properties?
The parts of a car, once assembled, result in a structure that can provide transportation.
A cell's growth is limited by its surface area to volume ratio.
True
Multicellularity in large organisms results in more, smaller cells and thus a higher surface area to volume ratio.
True
The surface area of a cell is determined by the surface area of the plasma membrane, the selective boundary through which materials enter and exit the cell.
True
A newly discovered unicellular organism isolated from acidic mine drainage is found to contain a cell wall, a plasma membrane, two flagella, and peroxisomes. Based just on this information, the organism is most likely ________.
a motile eukaryote
Proteins that are secreted from a eukaryotic cell must first travel through the endomembrane system.
a. endoplasmic reticulum b. cis glory cisternae c. medial corgi cisternae d. trans golgi cisternae 3. plasma membrane
eukaryotic only
lysosome, mitochondria, nucleolus
chloroplast
makes sugar by converting light energy into chemical energy
Membrane phospholipids
may have ʺkinksʺ in their tails, each caused by the presence of a double bond between carbons.
During muscle contraction, myosin motor proteins move across tracks of ___.
microfilaments
The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of _______.
microfilaments
Centrosomes are sites where protein dimers assemble into ___.
microtubules
in eukaryotic fagella, the fibers that slide past one another due to the activity of dynein proteins are ___.
microtubules
Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely malfunctioning in this disease?
mitochondria
Which organelle is the primary site of ATP synthesis in eukaryotic cells?
mitochondrion
Which structure is common to plant and animal cells?
mitochondrion
Golgi apparatus
modifies and packages proteins
Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from ________.
nearly any eukaryotic organism
Scientists can track the movement of proteins through the endomembrane system using an approach known as a pulse-chase experiment. This experiment involves the "pulse" phase: Cells are exposed to a high concentration of a radioactively labeled amino acid for a short period to tag proteins that are being synthesized. the "chase" phase: Any unincorporated radioactively labeled amino acids are washed away and large amounts of the same, but unlabeled, amino acid are added. Only those proteins synthesized during the brief pulse phase are radioactively tagged. These tagged proteins can be tracked through the chase period to determine their location in the cell. The data below were obtained from a pulse-chase experiment in which cells were examined at different times during the chase period. The numbers represent the radioactivity (measured in counts per minute) recorded at each of the indicated sites. The higher the number, the greater the radioactivity.
phagocytosis
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.
plasma membrane
Mitochondrion
produces chemical energy (ATP) that can power the cell
What is a function of a bacterium's capsule?
protection
rough ER
protein synthesis
Examination of a cell by transmission electron microscopy reveals a high density of ribosomes in the cytoplasm. This observation suggests that this cell is actively producing large amounts of which of the following molecules?
proteins
Which of the following frequently imposes a limit on cell size?
ratios of surface area to volume
central vacuole
regulates cytoplasm composition, creates internal pressure, and stores cell compounds
In a bacterium, where are proteins synthesized?
ribosomes
Which of the following are found in plant, animal, and bacterial cells?
ribosomes
both prokaryotic and eukaryotic
ribosomes, plasma membrane, flagella
Which of the following is the most common pathway taken by a newly synthesized protein that will be secreted by a cell?
rough ER → Golgi → transport vesicle → plasma membrane
plant cell wall
strong, protective structure made from cellulose fibrils
A cell with a predominance of smooth endoplasmic reticulum is likely specialized to ________.
synthesize large quantities of lipids
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle is most likely defective in this condition?
the lysosome
