BIO 1110 chapter 11

Meiosis _____ is sometimes called reductional division because _____.

I; the number of chromosomes is reduced by half

Meiosis _____ is similar to mitosis in that _____ separate.

II; sister chromatids

What is the role of the protein FtsZ in prokaryotes?

It forms a ring at the site of constriction.

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

proto-oncogene

Synapsis is best described as:

the pairing of homologous chromosomes in prophase I

A couple has a baby that only has one X chromosome and no Y chromosome. This could have occurred because: there was nondisjunction of the sister chromatids in meiosis II in the mother. Meiosis in the father was normal. there was nondisjunction of homologous chromosomes in meiosis I in the mother. Meiosis in the father was normal. there was nondisjunction of sister chromatids in meiosis II of the father. Meiosis in the mother was normal. there was nondisjunction of the paired X and Y chromosomes in meiosis I in the father. Meiosis in the mother was normal. All of the above

All of the above

How would the loss of p53 activity affect a cell? DNA damage could accumulate. CDK activity would not be appropriately regulated. The G1 /S checkpoint would not be functional. All of the above

All of the above

Recall 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. All of the above

All of the above

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. All of the above

All of the above

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

The cells would be smaller than normal.

Suppose a research team does a detailed analysis of the DNA sequence of all three copies of chromosome 21 from an individual with trisomy 21 (Down syndrome). They discover that two of the three chromosomes are essentially identical in sequence, whereas the third chromosome has a significant number of sequence differences. Which of the answer choices is consistent with this observation?

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

A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells?

These cells likely contain damaged DNA

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 phenotype a genotype a prototype a karyotype

a karyotype

In a person with the genotype XXY, we can tell that nondisjunction must have taken place in the mother and not the father. T/F

false

In mammals, females have two copies of the X chromosome, whereas males have only one copy. Dosage compensation (equalization of the numbers of each gene) is accomplished in mammals by:

females randomly inactivating one of the X chromosome in all cells.

Which of the answer choices is part of the process of binary fission in prokaryotes? condensation of chromosomes separation of sister chromatids rearrangement of the microtubule cytoskeleton formation of a new cell wall

formation of a new cell wall

A human cell with a total of 23 chromosomes is:

haploid

If a human has the genotype XXXY, they would:

have 2 inactivated X chromosomes and be male.

A malignant cancer differs from a benign tumor in that:

malignant cancers invade surrounding tissue and benign cancers do not.

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

microtubules

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

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. Yes, she will certainly develop cancer given the role of p53 in the cell cycle. No, mutations in p53 do not contribute to cancer.

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

The development of cancer requires both the _____ of an oncogene and the _____ of a tumor suppressor.

activation; inhibition

Which cellular conditions promote progression of the cell cycle? the accumulation of cyclins the expression and synthesis of cyclin proteins binding of cyclins to CDKs the activation of CDKs all of the above

all of the above

When do sister chromatids separate in meiosis?

anaphase II

Genes that participate in cell growth and division, but do not cause cancer, are:

proto-oncogenes.

Several years ago, a man noticed a small mole on his wrist. Years later, the mole grew in size and the man was diagnosed as having metastatic melanoma. This was likely the result of:

several mutations affecting proto-oncogenes and/or tumor suppressor genes

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

true

Nondisjunction can occur in both mitosis and meiosis. T/F

true

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^-12 g.)

12; 12; 6; 6; 3

At the start of mitosis, how many sister chromatids are present in a human 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.

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.

Mitotic cell division is considered asexual because:

the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical.

Which of the answer choices is true regarding CDKs? Loss of CDK activity would lead to cancer. CDKs are active in cells that enter G0 phase of the cell cycle. CDKs are active except when they bind to cyclins. The levels of CDKs change with the cell cycle.

the levels of CDKs change with the cell cycle