Cell Biology Exam 1

Chloroplasts can be thought of as mitochondria working in reverse because they make sugars from _____ and produce _____ while mitochondria breakdown sugars to _____ and consume _____.

carbon dioxide, oxygen

You discover a protein, MtA, and find that it binds to the plus ends of microtubules in cells. The hypothesis that best explains this localization is ________________.

MtA binds to GTP-bound tubular on microtubules.

Histones are the proteins found in nucleosomes. Mutations that convert a cell histones into a _____ protein would eliminate the ability of the cell to form a nucleosome.

Negatively charged Uncharged

Bacteria do not have organelles. How are they able to carry out photosynthesis?

They use their cell membrane to carry out photosynthesis.

Eukaryotic cells manufacture cytoskeletal proteins that help to maintain the cells shapes and functions. What would you predict about these proteins?

They would be manufactured on free ribosomes in the cytoplasm.

You find a previously uncharacterized organism and are studying the exocytic pathway. Your experiments show that dynein i s the motor protein responsible for transport of newly synthesized proteins between the ER and Golgi apparatus. Which motor protein do you conclude is responsible for retrograde transport of vesicles between these compartments.

kinesin

Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestos caused by the inhalation of asbestos fibers. Cells will phagocytize asbestos, but are not able to degrade it. As a result, asbestos fibers accumulate in

lysosomes

The filaments associated with adherin junctions maintain the shape of this structure

11 - microvilli

Microfilaments function in

muscle contraction maintenance of cellular shape in animal cells cell division

In addition to microtubule motor proteins, _____ are also involved in vesicular transport.

myosins

The "9 + 2" pattern of the flagella is nine _____ of microtubules and two additional microtubules in the center called the _____.

outer doublets; central pair

In a chloroplast, the storm is the

site where carbon dioxide is converted to sugars

Viral replication occurs in

the intracellular state only

The host range of a virus is determined by

the proteins on its surface and that of the host

Microscopic beads are coated with kinesis and subjected to an in vitro mobility assay. In which direction and along what cytoskeletal element are they seen to move?

toward the ply end of the microtubule

Retroviruses

transcribe DNA from RNA include the virus that causes AIDS may cause cancer

A pathologist use a(n) _____ to examine the cytoplasm of a cell for changes that result from viral infection.

transmission electron microscope

This organelle sorts proteins for the transport to different cellular locations

5 - Golgi complex

The enzyme tellers is found in this organelle

8 - nucleus

Which of the following is not a tenet of the cell theory?

All cells have a membrane-bound nucleus

You discover a fungus that contains a strange star-shaped organelle not found in any other eukaryotic cell you have seen. On further investigation, you find the following. 1. The organelle possesses a small genome in its interior. 2. The organelle is surrounded by two membranes. 3. Vesicles do not pinch off from the organelle membrane. 4. The interior of the organelle contains proteins similar to those of many bacteria. 5. The interior of the organelle contains ribosomes. How might this organelle have arisen?

ER

Intermediate filaments are made from elongated fibrous proteins that are assembled into a rope-like structure Figure Q17-10 shows the structure of an intermediate filament subunit. You are interested in how intermediate filaments are formed, and you create an intermediate filament subunit whose a-helical region is twice as long as that of a normal intermediate filaments by duplicating the normal a-helical region while keeping a globular head at the N-terminus and a globular tail at the C-terminus; you call this subunit IFad. If you were to assemble intermediate filaments using IFad as the subunit, which of the following predictions describes the most likely outcome?`

Filaments assembled using IF as will form dimers that are twice as long as dimers assembled from normal intermediate filaments.

Which of the following statements describes chromatin?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

What would happen if you were to inject fluorescently labeled tubular into a non-dividing cultured cell?

Labeled tubular subunits appear in preexisting cytoskeleton microtubules

Which of the following statements about the function of the centrosomes is false?

Microtubules emanating from the centrosomes have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome.

Which of the following statements about a protein in the lumen of the ER is false?

Some of the proteins in the lumen of the ER can end up in the plasma membrane.

Microtubules are important for transporting cargo in nerve cell axons, as diagrammed in the figure. Notice that the two types of cargo are traveling in opposite directions. Which of the following statements is likely to be false?

The black cargo and the gray cargo are moving along microtubules of opposite polarity

You have inactivated the gene for a particular cytoplasms motor protein in mice. The mouse embryo begin development but do not survive past about 8 days of embryonic life. When cells from the embryo are examined, their Golgi complexes are seen to be fragmented and dispersal throughout the cytoplasm. What do you conclude from these data?

The motor protein encoded by the knocked out gene is responsible for positioning of the Golgi complex within the cell.

Which of the following is not tru regarding telomeres and telomerase?

The number of telomeres increases with every cell diversionary.

Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

The two types of tetramers associate to form an octamer.

Why are mitochondria so prevalent in skeletal muscle?

They are needed to provide energy for muscle contraction

The small intestine is the the site of digestion and absorption of nutrients. A single layer of epithelial cell lines the small intestine. In the duodenum (the first section of the small intestine), these epithelial cells secrete large quantities of digestive enzymes. Which of the following features would you expect to find in the these epithelial cells?

They would contain large quantities of rough endoplasmic reticulum.

You have grown a culture of bacterial cells and discover that it is heavily contaminated with yeast. Which of the following procedures will most likely eliminate the yeast cell without killing the bacteria?

Treating the culture with a drug that causes microtubules to fall apart

Which major class of cytoskeletal elements is abundant in filopodia?

actin filaments

What is thought to provide the motile force that leads to the protrusion of the leading edge of a lamellipodium?

actin polymerization in the absence of molecular motors

Elongation of the microtubule occurs by the

addition of tubular subunits to each end

Which of the following statements about the structure of microtubules is false?

alpha-tubulin and beta-tubulin are covalently bound to make the tubular dimer that then assembles into protofilaments

Lamellipodia

are thin sheets of cytoplasm use for cell movement

Which of the following structures is characteristics of both eukaryotic and prokaryotic cells?

cell membrane

The minus (-) ends of microtubules are often anchored at the _____, such that the dynamics associated with microtubules is at the plus (+) ends.

centrosome

Which of the following would most likely be associated with the surface of cells and provide a brushing motion, thereby moving materials over the surface of the cell?

cilia

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life?

copies of the herpesvirus genome permanently maintained in host nuclei

Kinetochore microtubules assist in the process of splitting centromeres by _______.

creating tension by pulling toward opposite poles

They type of reactions occurring in the chloroplast thylakoid are the same type of reactions occurring in the mitochondrial _____.

cristae

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

cytokinesis

The drawing shows two cells connected by cytoskeletal elements forming

desmosomes

Which of the following is not a function of plant cell vacuoles?

distributes toxic compounds to cytoplasm site of intracellular digestion in a plant cell

The microtubule molecular motor that moves cargo from the lysosome towards the centrosome is

dynein

_____ is the molecular motor used by transport vesicles carrying cargo from the plasma membrane to the early endosome.

dynein

A scientist is examining motile protozoa. He wishes to determine their direction of movement. Which of the following microscope techniques is least likely to be used to view these cells?

electron microscopy

Along which pathway do materials or the plasma membrane move into the cell from the outside to cytoplasmic compartments?

endocytic pathway

The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out. Which term describes the process by which external materials are captured inside vesicles and brought into the cell?

endocytosis

All of the following are moved by molecular motors except

glucose

Which of the following is the correct order of the levels of DNA packaging in eukaryotic chromosomes starting from the most compact structure to the least compact structure?

heterochromatin - looped domains - chromatin fiber - nucleosome

_____ resist shear forces and contain keratin to form the protective barrier fo the skin.

intermediate filaments

If a cell does not have a membrane-bound nucleus, it is also not likely to have:

membrane-bound organelles

The sum total of the chemical reactions in a cell is _____

metabolism

The contractile ring responsible for cytokinesis contains

microfilaments

Which of the following serve as tracks for molecular motors?

microtubules microfilaments

The major structural elements of the cytoskeleton are

microtubules, microfilaments, and intermediate filaments

Actin bundles give shape and support to the _____ found in cells of the small intestine.

microvilli

Muscle cells require more energy in order to function than most other cells. Therefore, muscle cells would be expected to have more _____ than most other cells.

mitochondria

Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely involved in this disease?

mitochondria

All of the following are roles of microfilaments except

mitotic spindle formation

Enzymes can be purified from the Golgi apparatus. The gene for the enzyme can be cloned and fused to the coding sequence of GFP to produce a GRP fusion protein. The GFP protein can then be expressed in cell culture. Antibodies to GFP are readily available. To determine which region of the Golgi apparatus the protein is located in the protein can be visualized by

none of the above methods are suitable

The _____ is made up of two concentric membranes and is concentric membranes is continuous with the membrane of the endoplasmic reticulum.

nuclear envelope

Which of the following represents the order of increasingly higher levels of organization of chromatin?

nucleosome, 30-nm chromatin fiber, looped domain

Gap junctions

permit passage of small molecules from one cell to its adjacent cell

Communication between animal cells is facilitated by

plasmodesmata

Which of the following are made on RER-bound ribosomes?

proteins associated with the inner cell membrane surface

The crawling displayed by many embryonic cells in animals involves distinct events. Which of the following sequences places these events in correct order?

protrusion at the cell's leading edge, attachment of protrusion, pulling the cell forward, release and retraction of trailing edge

The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect?

that the critical function of tellers must be maintained

Which part of the Golgi complex is closest to and sends material to the plasma membrane?

the trans-Golgi

Which part of the Golgi complex is thought to function primarily as a sorting station that distinguishes between proteins to be shipped back to the ER and those that are allowed to proceed to the next Golgi station?

the trans-Golgi

Which type of junction contributes the most to the polarization of epithelial cells?

tight junctions

What would happen to the movement of vesicles toward their eventual target if a drug that promotes the hydrolysis of GTP bound to tubular was added to cells?

vesicle movement would slow or stop

The products of the endoplasmic reticulum are transported to the Golgi apparatus by:

vesicles