Adlington Bio 121 chapters 10 & 11 quiz

Which statement regarding the cell cycle is true?

-It is regulated by cyclins and CDKs. -Different levels of cyclins are observed at different cell cycle stages. -It can be "paused" by the action of p53. -It has many major cell cycle checkpoints.

The prokaryotic protein FtsZ is evolutionarily related to eukaryotic tubulin. What does this mean?

-The amino acid sequence for FtsZ is similar to tubulin. -The overall protein structure of FtsZ is similar to tubulin. -The two proteins evolved from a common ancestral protein. -The gene sequence for FtsZ is similar to tubulin.

What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores?

-The sister chromatids would not separate. -The chromosome would not line up properly at metaphase. -One of the daughter cells would have an extra copy of that chromosome.

Cilia:

-are used by epithelial cells to move substances along cell surfaces. can sometimes serve a sensory function -are specialized organelles found in some epithelial cells.

What would you expect to find within connective tissue?

-collagen -fibroblasts -elastin -polysaccharides

In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell?

46

Why don't plant cells use a contractile ring to divide their daughter cells?

A contractile ring can't "pinch" a cell wall.

Which statement is true regarding binary fission?

DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions.

A woman has her genome sequenced and finds that she carries a mutation in p53. Will she develop cancer?

Possibly; this mutation is likely to predispose her to developing certain types of cancer.

Replication of DNA in a eukaryote occurs during which phase of the cell cycle?

S phase

A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely:

S phase.

Suppose you analyze a time-lapse video of a cell under a microscope, and you observe what appears to be four chromatids tightly aligned along their lengths. Which of the answer choices is an interpretation of this observation?

The chromatids represent a bivalent and the cell is probably in Prophase I of meiosis.

What happens to CDKs in the absence of cyclins?

They are inactive.

To visualize chromosomes, a picture of each can be arranged such that homologous chromosomes are aligned with each other and arranged as pairs in order of decreasing size. What is this called?

a karyotype

The extracellular matrix is:

a network of proteins and polysaccharides outside the cell that play a role in structural support.

The protein p53 is an example of:

a tumor suppressor.

Which types of cell junctions are found in skin?

adherens junctions hemidesmosomes desmosomes tight junctions

In which phase of mitosis do sister chromatids separate?

anaphase

During what step in meiosis do homologous chromosomes separate?

anaphase I

What cellular process(es) is/are responsible for the increase in protein content associated with the gap phases of the cell cycle?

both transcription and translation

The natural loss of dead cells from the surface of your skin is a result of:

breakdown of adherens junctions.

Which answer choice correctly lists components of the extracellular matrix found in plants?

cellulose and lignin

What characteristics do you expect to observe with a microscope if you investigate the division of mitochondria and chloroplasts in eukaryotic cells?

circular DNA attached to the plasma membrane and binary fission

The basal lamina:

is a specialized extracellular matrix found beneath epithelial tissues.

The strength of collagen comes from:

its triple helical structure and bundling.

In which phase of mitosis do chromosomes line up at the middle of the cell?

metaphase

Dynein is a motor protein found attached to:

microtubules

Kinesin is a motor protein found attached to:

microtubules

The assembly of what cytoskeletal structures are initiated by the M cyclin-CDK complex?

microtubules

The division of genetic material in a eukaryotic cell is called:

mitosis

Which type of cellular junction(s) allow(s) for the movement of proteins and transfer RNA molecules?

plasmodesmata only

In which phase of mitosis does the nuclear envelope reform?

telophase

The centrosome is:

the microtubule organizing center for the mitotic spindle

What is the advantage of forcing materials to travel through cells instead of between cells?

- The exposure in internal tissues to the outside environment is limited -exposure to bacteria or viruses is limited. -Cells can control which materials are transported.

ecall the experiments of Peyton Rous and his colleagues. If he had found that filtered cancer cell extract could not cause cancer when injected into healthy animals, what could he have deduced?

-An intact cancer cell is necessary to cause cancer. -A large protein may cause cancer. -Cancer may be caused by bacteria.

What is the advantage of forcing materials to travel through cells instead of between cells?

-The exposure in internal tissues to the outside environment is limited. -Cells can control which materials are transported. -Exposure to bacteria or viruses is limited.

Intermediate filaments:

-play an important role in preventing skin from tearing by shear stress. -have a diameter that is larger than a microfilament, but smaller than a microtubule. -play an important role in maintaining cell shape. -undergo little change in length in comparison to microtubules and microfilaments

Tumor suppressors oppose oncogenes by:

-slowing cell division. -instructing defective cells to die. -repairing mutations. -blocking the action of an oncogene.

Suppose you analyze a time-lapse video of a cell under a microscope and you observe what appears to be crosslike structures within a bivalent. Which of the answer choices is an interpretation of this observation?

These structures represent crossing over between non-sister chromatids.

Gap junctions and plasmodesmata have what feature in common?

They both allow direct transport of materials between cells.

Which answer choice is true about the motor proteins myosin and kinesin?

They both use the energy of ATP.

How do CDKs promote cell division?

They phosphorylate proteins that allow passage through cell cycle checkpoints.

Microvilli are located on the ______ of an intestinal cell.

apical surface

Which answer choice correctly lists components found in the extracellular matrix of animals?

collagen, laminin, and elastin

A researcher is studying a population of mutant fibroblasts that fail to flatten and attach to extracellular matrix proteins on a flat surface. This is likely the result of mutations in genes encoding.

components of cell junctions.

A researcher is studying a population of mutant fibroblasts that fail to flatten and attach to extracellular matrix proteins on a flat surface. This is likely the result of mutations in genes encoding:

components of cell junctions.

The extracellular matrix is particularly important for which type of tissue?

connective

Where would you find a cell adhesion molecule?

in a cell junction

Structures known as microvilli are associated with:

increased surface area for nutrient absorption.

In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection.

intermediate filaments

Which type of cytoskeletal element is present in animal cells but absent from plant cells?

intermediate filaments

The internal cytoskeletal structure of cilia grows out from a structure called a basal body located near the base of the cilia. Based on this information, where would you predict the plus end of the microtubules to be located?

near the tip of the cilia (or flagella)

One of the important cell cycle checkpoints occurs during M phase. It inhibits progression to anaphase until all of the chromosome kinetochores are correctly attached to microtubules of the spindle apparatus. If anaphase of mitosis occurred when the kinetochore microtubule connected to only one of the two spindle poles but not the other, what could result?

nondisjunction

In nerve cells, the centrosome is located near the nucleus. Vesicles move from near the nucleus to the end of long extensions (axons) along microtubules. Based on these two facts, it is possible to conclude that these vesicles are moving in the _____ direction on the microtubule using the motor protein _____. What differentiates between the "plus" and "minus" ends of a cytoskeletal element (i.e., do these ends have specific locations in a cell)?

plus end; kinesin

What type of gene is c-src (cellular-src)?

proto-oncogene

If intermediate filaments were capable of dynamic instability, what outcome would be most likely?

Cell shape and support would be affected.

Which answer choice correctly describes the skin cell type it characterizes?

Fibroblasts are a cell type found in the dermis of the skin; its primary function is to secrete extracellular matrix.

What is the role of the protein FtsZ in prokaryotes?

It forms a ring at the site of constriction

Suppose you are observing some cells with a microscope, and you see a cell that appears to be dividing. You can see that as the cell starts to pinch in half, the DNA seems to be attached to the plasma membrane via a membrane protein. On further analysis, you find that this organism's DNA is circular - that is, it consists of a closed loop. What can you conclude about this organism and its mode of cell division?

It is a prokaryote that is dividing by binary fission.

Why would a compound that interferes with bacterial cell wall synthesis be useful for treating a bacterial infection?

It would limit growth of the bacterial population through cell division.

Which statement about intracellular transport is true?

Kinesin and dynein move substances along microtubules.

At which stage of the cell cycle could you see sister chromatids with a microscope?

M

__________ is not a cellular function of microfilaments.

Movement of motile cilia

How must spindle microtubules attach to chromosomes during prometaphase of meiosis I?

Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids.

Predict what would happen if an embryonic epidermal cell switched from expressing E-cadherin to N-cadherin.

The cell would leave the epidermis and adhere to neural cells.

Imagine that you are examining a mouse that does not produce basal lamina in the skin. How will this mouse be different from a normal, wild-type mouse?

The cells of the epidermis would not be properly connected to form a water-resistant barrier.

What would happen to the daughter cells if the G2 phase of the parent cell is shortened?

The cells would be smaller than normal.

There are laboratory techniques that allow researchers to determine the amount of DNA in cell nuclei. If you measure the amounts of DNA at the end of mitosis and at the end of meiosis, how do they compare to the starting cell (starting from prophase during mitosis and from prophase I during meiosis)?

The daughter cells at the end of mitosis have one-half the amount of DNA, and the daughter cells at the end of meiosis have one-fourth the amount of DNA.

Suppose a research team does a detailed analysis of the DNA sequence of all three copies of chromosomes 21 from an individual with trisomy 21 (Down syndrome). They discover that each of the three chromosomes has a unique DNA sequence. Which of the answer choices is consistent with this observation

The extra chromosome 21 resulted from first-division nondisjunction in one of the parents' gametes.

Which of the answer choices is true regarding CDKs?

The levels of CDKs change with the cell cycle.

A patient in a physician's office has a deep cut, and as it is being stitched up, a sample of tissue is taken for testing. Analysis of the tissue reveals it has few cells, surrounded by a large amount of extracellular matrix proteins with some blood vessels, sweat glands, and nerve cells. What kind of tissue is this?

The tissue is most likely dermis, and should also have some fibroblasts, but few keratinocytes and melanocytes.

First-division nondisjunction occurs when:

homologous pairs fail to separate during anaphase I.

The division of the cell's cytoplasm in a eukaryotic cell is known as:

cytokinesis

A zygote is:

diploid

A phragmoplast functions to:

form a new cell wall.

If a human has the genotype XXXY, they would:

have 2 inactivated X chromosomes and be male.

How do cells connect to the extracellular matrix?

through integrins

What is the function of histone proteins?

to package DNA in eukaryotic chromosomes

A proto-oncogene is a "normal" gene that, if mutated, can become an oncogene and lead to a cell becoming cancerous.

true

An example of second-division nondisjunction is when sister chromatids fail to separate during anaphase of meiotic cell division.

true

Construction of a karyotype from an image of stained chromosomes is a technique by which a researcher can see and count chromosomes.

true

Evidence exists (especially in dinoflagellates) that mitosis evolved from binary fission. For example, in certain eukaryotic cells during mitosis, DNA is attached to the membrane of the nucleus (much like a circular chromosome of a bacterium is attached to the plasma membrane).

true

Many scientists are working to generate organs in vitro. In some cases, cells are seeded onto a "scaffold" shaped like the desired target organ. Such scaffolds are likely composed of extracellular matrix proteins.

true

Nondisjunction can occur in both mitosis and meiosis.

true

Motor proteins cause movement by:

-undergoing a conformational change. -binding to the cytoskeleton -harnessing energy from ATP

It is estimated that a human cell in G1 phase of the cell cycle contains 6 picograms of DNA in its nucleus. If you measure the DNA content at various stages of mitosis and meiosis, what amounts of DNA can be expected in nuclei at the following stages? prophase mitosis: _____; prophase I meiosis: _____; prophase II meiosis: _____; telophase mitosis: _____; telophase meiosis II: _____. (All amounts are in picograms (10-12g.)

12; 12; 6; 6; 3

_________are components of the animal extracellular matrix

Collagen and elastin

Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of individual large cells. Predict what is different about the cell cycle in a muscle cell.

Cytokinesis does not occur.

Predict what would happen if crossing over between homologous chromosomes occurred as part of mitosis.

Daughter cells would not be genetically identical.

_________ is not a cellular function associated with microtubules.

Muscle contraction

Would genetic recombination result if crossing over occurred between sister chromatids?

No, because sister chromatids are genetically identical or nearly identical.

Could melanin granules be moved by dynein and kinesin along an actin microfilament?

No, these motor proteins are specific to microtubules and cannot move along microfilaments.

The epidermis contains several layers and receives its nutrients from the dermis by diffusion. What explains why the outermost layers of the epidermis consist of dead cells?

One of the major functions of the epidermis is forming a waterproof barrier. Once that barrier is formed, nutrients cannot pass through it and the cells beyond that layer die

The process of cell division in a prokaryotic cell is called:

binary fission.

Cadherins bind to which type of cytoskeletal element(s)?

both intermediate filaments and microfilaments

Which layer of the extracellular matrix of a plant provides the greatest strength?

the secondary cell wall

There are no discernible phenotypic effects for an individual with the genotype XYY

true