BMB555 Exam 2

A diploid cell containing 32 chromosomes will make a haploid cell containing ___ chromosomes.

16

Kinetochores

Assemble onto chromosomes during late prophase.

Which of the following precede the reformation of the nuclear envelope during M phase in animal cells?

Assembly of the contractile ring

The Retinoblastoma (Rb) proteins blocks cells from entering the cell cycle by

Inhibiting the transcription of genes (e.g. cyclins) required for entry in S phase.

Which of the following statements about the round-seeded pea plants obtained in the F2 generation is FALSE?

C. We expect 25% of these plants to be homozygous for the seed-shape allele.

You create cells with a version of the origin recognition complex, ORC, that cannot be phosphorylated by S-Cdk and thus cannot be inactivated. Which of the following statements describes the likely consequence of this change in ORC?

Cells will replicate some regions of the genome more than once in a cell cycle.

The principal microtubule-organizing center in animal cells is the ____________. (a) centrosome. (b) centromere. (c) kinetochore. (d) cell cortex.

Centrosome

At the end of DNA replication, the sister chromatids are held together by the

Cohesins

How does S-Cdk help guarantee that replication occurs only once during each cell cycle?

It phosphorylated and inactivates Cdc6 and the ORC

Which of the following statements about genome-wide association studies (GWAS) is FALSE?

D. Studies using GWAS only examine SNPs that occur very rarely (<0.001%) in the population, as those SNPs are most likely to cause disease. FALSE because we examine all SNPs

During sexual reproduction, novel mixture of alleles are generated. This is because

During meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

Centrosomes are special regions of chromosomes that links a pair of sister chromatids. T/F?

FALSE

Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells. TRUE or FALSE?

FALSE

The anaphase promoting complex (APC) is continuously active throughout the cell cycle. T/F?

FALSE

The loading of the origin recognition complexes (ORCs0 is triggered by S-Cdk. T/F?

FALSE

An apoptotic animal cell is chemotactic and thus leading to massive cell and tissue death. T/F?

FALSE- If it was necrotic animal cells than true

All traits that Mendel studied were dominant

False

Mutations in somatic cells are passed on to individuals of the next generation. T/F?

False

Cdc25 dephosphorylation of Wee1 activates the kinase, promoting the G2/M transition.

False.

The cleavage furrow always forms in the middle of the cell. T/F

False.

The phenotype of an organism reflects all of the alleles carried by that individual. T/F?

False; Should be Genotype

Which of the following does not occur during M phase in animal cells?

Growth of the cell

Which is the order of the intrinsic pathway of apoptosis?

IN THIS ORDER: 1. Apoptotic stimuli (virus infection, radiation, etc) 2. Oligomerization of Bax/Bax on mitochondria 3. Mitochondrial membrane permeability increases 4. Release of Cytochrome C 5. Assembly of Apoptosome Complex 6. Recruitment and activation of Caspases 7. Caspase Cascade

Which of the following statements about the experiment diagrammed in Figure 19-24 is true?

If you crossed all the round-seeded pea plants from the F2 generation with true-breeding wrinkle-seeded pea plants, you would get more round-seeded pea plants from the F1 generation with true-breeding wrinkle-seeded pea plants.

If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of round-seeded plants (Fig. 19-24), how many wrinkle-seeded plants would you expect to obtain in the next generation?

None

Loss-of-function mutations

are usually recessive.

Condensins

assemble into complexes on the DNA when phosphorylated by M-Cdk

In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated?

at the end of G2

Mitogens are

extracellular signals that stimulate cell division.

The phosphorylated Retinoblastoma (Rb) proteins allows cells to enter the cell cycle by

Releasing the transcription of genes (e.g. cyclins) required for entry into S phase.

Sister chromatid separation occurs because_________ are destroyed by the APC/C

Securing

Conditional alleles are mutant gene versions encoding proteins that can function normally at the permissive condition but are defective at the restrictive condition. One commonly used condition is temperature. Conditional alleles are especially useful to geneticists because they permit the stodgy of essential genes. At the permissive temperature, the organism lives normally. When the organism is shifted to the non permissive temperature, the effect if inactivating the gene can be studied. Which of the three types if mutations shown in the following figure is most likely to lead to a conditional allele?

Single Nucleotide Substitution

Another name for fertilized egg cell is the zygote. T/F?

TRUE

Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria. T/F?

TRUE

During meiosis, the paternal chromosomes pair, with the maternal chromosomes before lining up at the metaphase plate. T/F?

TRUE

Meiosis involves a single round of DNA replication followed by two successive cell divisions. T/F?

TRUE

What would happen if a cell lacked a protein required for a checkpoint mechanism that operates in G2?

The cell would enter M phase under conditions when normal cells would not.

Mitochondrion actively participates in animal apoptosis. True or False?

True

Programmed cell death occurs by means of an intracellular suicide program. T/F

True

Somatic cells leave no proveny. T/F?

True

Levels of Cdk activity change during the cell cycle, in part because

cyclin concentrations change during the cycle (because of gene expression or cyclin degradation); Cdk can be phosphorylated or dephosphorylated; the levels of Cdk inhibitors change.

A cell that is terminally differentiated will

dismantle the cell-cycle control system.

Progression through the cell cycle requires a cyclin to bind to a Cdk because

the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

Imagine meiosis in a diploid organism that only has a single chromosome. Like most diploid organisms, it received one copy of this chromosome from each of its parents and the two homologs are genetically distinct. If only a single homologous recombination event occurs during meiosis, which of the following choices below correctly describes the four gametes formed. (a) None of the gametes will contain chromosomes identical to the chromosomes found in the original diploid cell. (b) All four of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell. (c) Three of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while one of the gametes will have chromosomes that are different. (d) Two of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while two of the gametes will have chromosomes that are different.

(D) Two of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while two of the gametes will have chromosomes that are different.

A cell with nuclear lamins that cannot be phosphorylated in M phase will be unable to ________________. (a) reassemble its nuclear envelope at telophase. (b) disassemble its nuclear lamina at prometaphase. (c) begin to assemble a mitotic spindle. (d) condense its chromosomes at prophase.

(b) disassemble its nuclear lamina at prometaphase.

Finding co-inheritance of a SNP variant and a disease tells scientists that ____________________. (a) everybody who carries this SNP will get the disease. (b) sequences within the SNP cause the disease. (c) a gene important for causing the disease is linked to the SNP. (d) SNPs on other chromosomes will not be co-inherited with the disease

(c) a gene important for causing the disease is linked to the SNP.

In the absence of recombination, how many genetically different types of gametes can an organism with six homologous chromosome pairs produce?

64

If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of round-seeded plants (Fig. 19-24), how many round-seeded plants would you expect to obtain in the next generation?

50%

The formation of ambivalent during meiosis ensures that

All four sister chromatids remain together until the cell is ready to divide.

Figure 19-24 diagrams one of Mendel's Experiments using the round and wrinkled seed traits. Which plants could be considered as a true-breeding strain for the seed-shape phenotype?

All of the wrinkle-seeded plants produced in the F2 generation

Which of the following reasons was essential for Mendel's law of independent assortment?

All the traits that Mendel examined involved genes that did not display linkage.

Which event does NOT usually occur during interphase?

The nuclear envelope breaks down; Duplicated chromosomes pull apart.

Which of the following reasons was essential for Mendel to disprove the theory of blended inheritance?

The traits that Mendel examined involved an allele that was dominant and an allele that was recessive.

A single no disjunction event during meiosis will result in the production of two normal gametes if it occurs during meiosis II.

True

After the first meiotic cell division, cells are produced that contain the same number of chromosomes as somatic cells. T/F?

True

Apoptosis differs from necrosis in that necrosis cause cells to swell and burst, whereas apoptotic cells shrink and condense. T/F

True

G2 phase is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis. It ends when a threshold level of active cyclin B/Cdk1 complex has been reached. T/F?

True

There are organisms that go through meiosis but do not undergo recombination when forming haploid gametes. Which of the following statements correctly describes the gametes produced by such an organism. (Assume that these organisms are diploid, that each of the two homologous chromosomes are genetically distinct as typically found in the wild, and that these organisms have more than one chromosome.) (a) All gametes formed during a single meiosis will be identical. (b) Due to the random assortment of homologs, each of the gametes formed during a single meiosis will be different. (c) This organism could potentially produce 2n genetically distinct gametes, where n is its haploid number of chromosomes. (d) The fusion of any two gametes produced by such an organism that does not undergo recombination during meiosis will create a cell that is genetically identical to that individual.

c) This organism could potentially produce 2n genetically distinct gametes, where n is its haploid number of chromosomes.

Cells in the G0 state ________________.

have entered this arrest state from G1 and do not divide, but they can reenter the cell cycle

The G1 DNA damage checkpoint

involves the stabilization of p53 and the inhibition of cyclin-Cdk complexes by p21

Disassembly of the nuclear envelope

must occur for kinetochore microtubules to form in animal cells

Cytokinesis in animal cells

requires ATP

The concentration of mitotic cyclin (M cyclin)

rises gradually during G2 and falls toward the end of M phase as a result of ubiquitylation and degradation.

Organisms that reproduce sexually

undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.