Deck 15: Gene Regulation in Prokaryotes

Question 1

The yeast Saccharomyces cerevisiae reproduces _______________,allowing easy determination of the cell-cycle stage in which a cell is found.

A) ambiguously
B) by fission
C) sexually
D) amorphously
E) by budding

Answer 1

E

Question 2

The yeast Saccharomyces cerevisiae is particularly useful for genetic analysis of cell-cycle control because

A) it is prokaryotic,allowing it to divide rapidly.
B) mutant yeast cells form cancerous tumours.
C) reproduction by budding allows easy identification of the cell-cycle stage.
D) all cells in a culture remain at the same stage of the cell cycle.
E) yeast cells lack G₁ and G₂ stages.

Answer 2

C

Question 3

The ____________ checkpoint is disrupted by mutations that alter p53 function.

A) G₀-to-G₁
B) G₁-to-S
C) S-to-G₂
D) G₂-to-M
E) M-to-G₁

Answer 3

B

Question 4

The cell-cycle checkpoint that occurs during mitosis causes nuclear division to pause until

A) DNA replication is complete.
B) sister chromatids have separated.
C) cytokinesis occurs.
D) telophase begins.
E) all chromosomes have attached to the mitotic spindle.

Question 5

Enzymes that covalently link phosphate groups to their substrates are termed

A) kinases.
B) phosphatases.
C) cyclins.
D) phosphatase inhibitors.
E) ligases.

Question 6

CDKs,such as CDC28,require the assistance of ____________ to carry out their enzymatic activity.

A) restriction enzymes
B) proteases
C) nucleases
D) growth factors
E) cyclins

Question 7

In the cell cycle of Saccharomyces cerevisiae,the appearance of a bud on the surface of a cell indicates that the cell

A) is entering M phase.
B) has a mutation in a gene regulating G₂M transition.
C) is haploid.
D) has a mutation in a gene regulating G₂S transition.
E) is reaching the end of G₁ phase.

Question 8

The temperature at which a cell with a temperature-sensitive mutation is unable to survive is considered the ___________ temperature.

A) restrictive
B) mutant
C) dissociative
D) permissive
E) alternative

Question 9

Which of the following does not occur during mitosis?

A) segregation of sister chromatids
B) duplication of chromosomal DNA
C) condensation of chromosomes
D) nuclear envelope breakdown
E) attachment of chromosomes to mitotic spindle

Question 10

Which of the following is not a common consequence of mutations that eliminate cell-cycle checkpoints?

A) increased DNA damage
B) decreased frequency of cell division
C) polyploidy
D) aneuploidy
E) increased chromosome loss

Question 11

Molecules that function to stimulate or inhibit cell division are collectively referred to as

A) transcription factors.
B) polymerases.
C) kinases.
D) growth factors.
E) checkpoints.

Question 12

Which of the following is not likely to result from the loss of functional p53?

A) the appearance of homogenously staining regions on chromosomes
B) increases propensity to arrest in G₁
C) alterations in the G₁ to S checkpoint
D) an increase in gene amplification in affected cells
E) generation of fragments of chromosomal DNA lacking telomeres and centromeres

Question 13

A programmed cell change that results in cell death is referred to as

A) apoptosis.
B) G₁ regulation.
C) post-translational control.
D) cancer.
E) metastasis.

Question 14

Damage to DNA that takes place during DNA replication results in arrest of normal cells at the _______________ checkpoint.

A) G₀-to-G₁
B) G₁-to-S
C) S-to-G₂
D) G₂-to-M
E) M-to-G₁

Question 15

CDKs associate with cyclins at specific stages of the cell cycle.The CDK subunit is responsible for phosphorylating a substrate protein,while the cyclin is responsible for

A) progression into G₀.
B) degradation of the CDK after phosphorylation.
C) ubiquitin function.
D) dephosphorylating Rb.
E) determining which specific proteins will be phosphorylated.

Question 16

________________ are proteins that form a structural scaffold on the inner surface of the nuclear membrane.

A) Mitotic tubules
B) Nuclear lamins
C) Chromatin fibrils
D) CDKs
E) Histones

Question 17

The solubility of nuclear lamins is regulated by the _____________ of lamin proteins.

A) length
B) phosphorylation state
C) kinase activity
D) molecular weight
E) condensation

Question 18

The retinoblastoma (Rb)protein regulates progression into S phase by regulating ___________ activity.

A) cyclin D
B) p53
C) CDK4
D) E2F
E) CDC28

Question 19

One characteristic of cancer is unregulated cell proliferation.A second characteristic of cancer cells is

A) the synthesis of additional copies of DNA polymerase.
B) arrest in G₀.
C) the failure to expand clonally.
D) apoptosis.
E) the ability to migrate to distant tissues.

Question 20

The cells in a population of yeast cells in which all members of the population have a temperature-sensitive mutation in the same gene involved in cell-cycle progression will appear _________ when shifted to the restrictive temperature.

A) to vary in morphology
B) as clumps of lysed cells
C) to adhere to each other
D) uniform in size and shape
E) arrested in all stages of the cell cycle

Question 21

In Saccharomyces cerevisiae,the _________________ protein inhibits progression of the cell cycle into mitosis in response to DNA damage.

A) p53
B) RAD9
C) Rb
D) E2F
E) CDK

Question 22

______________________ are mutant forms of normal genes that act dominantly to predispose a cell to a cancerous phenotype.

A) Polymerases
B) Oncogenes
C) Activators
D) Tumour suppressors
E) Proto-oncogenes

Question 23

Genes encoding which of the following protein types do not function as oncogenes when mutated?

A) transmembrane receptors
B) transcription factors
C) signal transmitters
D) growth factors
E) tumour suppressors

Question 24

Cyclin-dependent kinases require _______________________ to catalyze phosphorylation of appropriate substrate proteins.

A) cyclins
B) growth factors
C) mutagens
D) receptors
E) aneuploidy

Question 25

Cytoplasmic proteins that relay signals inside the cell are referred to as

A) growth factors.
B) signal transducers.
C) receptors.
D) transcription factors.
E) polymerases.

Question 26

Genetic testing for cancer can

A) identify individuals that are resistant to cancer.
B) indicate increased risk of certain cancers.
C) predict the age of cancer onset in an individual.
D) eliminate the possibility that an individual will develop cancer.
E) do none of the choices.

Question 27

______________________ are proteins that assist in regulating cell-cycle progression and are often rapidly degraded at specific times in the cell cycle.

A) Cyclins
B) Growth factors
C) Mutagens
D) Receptors
E) Cyclin-dependent kinases

Question 28

Genes whose mutant alleles can function in a recessive manner to predispose cells to cancerous growth are referred to as

A) polymerases.
B) oncogenes.
C) activators.
D) tumour suppressors.
E) proto-oncogenes.

Question 29

Cells that have migrated from a tumour and invaded a distant tissue are said to have

A) acclimated.
B) metastasized.
C) mutagenized.
D) carcinogenized.
E) capacitated.

Question 30

_____________________ are enzymes that function to promote or inhibit cell cycle progression by phosphorylating specific substrates.

A) Cyclins
B) Growth factors
C) Mutagens
D) Cyclic phosphatases
E) Cyclin-dependent kinases

Question 31

All cells in a cancerous tumour arise from a single mutant precursor cell,meaning that the cells in the tumour are

A) sporadic.
B) spastic.
C) benign.
D) divisionary.
E) clonal.

Question 32

_______________________ are proteins that span the plasma membrane and transmit signals from outside the cell into the cytoplasm.

A) Receptors
B) Transcription factors
C) Growth factors
D) Nucleosomes
E) Polymerases

Question 33

Which of the following statements regarding cancer is true?

A) All cancers are genetic diseases.
B) All cancers are sporadic.
C) All cancers run in families.
D) All cancers are caused by the same mutagen.
E) All cancers are caused by the same mutations.

Question 34

Alterations in the activity of cyclin-dependent kinases can affect the _____________ cell cycle checkpoint.

A) G₁-to-S
B) S-to-G₂
C) G₂-to-M
D) G₁-to-S or G₂-to-M
E) G₁-to-S,S-to-G₂,or G₂-to-M

Question 35

In its active form,the RAS protein is associated with

A) DNA.
B) ATP.
C) GTP.
D) RNA.
E) GDP.

Question 36

Which of the following does not function to reduce the likelihood of a cell becoming cancerous?

A) alternative splicing within the nucleus
B) mismatch repair enzymes
C) proofreading ability of DNA polymerases
D) cell-cycle checkpoints
E) tumour-suppressor genes

Question 37

The human papilloma virus (HPV)carries a gene that functions as an oncogene by inactivating the p53 protein.The fact that the loss of p53 function is oncogenic suggests that

A) p53 normally functions to prevent uncontrolled cell division.
B) the HPV protein is encoded by a tumour-suppressor gene.
C) p53 gene expression is upregulated by the HPV protein.
D) the HPV protein functions at origins of replication on DNA.
E) p53 is a proto-oncogene.

Question 38

Tumour cells removed from an individual with retinoblastoma are _________________ for a deletion of the RB gene.

A) homozygous
B) heterologous
C) hemizygous
D) heterozygous
E) endozygous

Question 39

The generation of a cancerous cell requires mutations in ____________ of that cell's genes.

A) none
B) one
C) two
D) six to ten
E) more than 100

Question 40

Normal alleles of tumour-suppressor genes function to encode proteins that

A) promote transition from G₁-to-S.
B) can slow the rate of cell division.
C) increase the rate of mutagenesis.
D) activate oncogenes.
E) associate with growth factors at the cell surface.

Question 41

Define: Signal transduction

Question 42

Of the approximately 300 cell types,some,once terminally differentiated,never divide again even if life continues for nearly a century.

Question 43

You wish to determine which genes are aberrantly expressed in a certain type of cancer.How would you measure a possible transcription difference on a genomic level between the cancer cells and normal cells?

Question 44

You have identified a mutation in Gene X that appears along with mutations in three other genes to cause an increased likelihood for a certain cancer.Develop an assay to test patients for the polymorphism in Gene X.

Question 45

An enzyme that removes a phosphate group from proteins is called a phosphatase.

Question 46

The cells in a cancerous tumour are described as being "clonal." What does this mean?

Question 47

DNA damage in normal cells only rarely leads to apoptosis.

Question 48

Oncogenes found in viral genome often cause _____________________ when incorporated into eukaryotic cells.

A) cell death
B) arrest in G₀
C) increased cell proliferation
D) arrest at the G₂-to-M checkpoint
E) apoptosis

Question 49

Name two mechanisms by which a retrovirus carrying a proto-oncogene can convert the proto-oncogene to an oncogene.

Question 50

Define: CDK

Question 51

Using yeast,you wish to test the hypothesis that two new temperature-sensitive mutations you have isolated are involved in different steps of the cell cycle.Describe the experimental setup necessary to do so.

Question 52

DNA damage activates the p53 transcription factor,which in turn induces expression of the p21 gene.

Question 53

The S phase is when sister chromosomes segregate into daughter cells.

Question 54

A temperature-sensitive screen is completed by treating cells with mutagen,replica plating,and then selecting for growth in permissive and restrictive temperatures.

Question 55

Cell-cycle check points are arrests to the cell cycle in which the integrity of the genome and cell-cycle machinery are "checked" prior to continuing to the next cell-cycle stage.

Question 56

Cyclin-dependent kinases together with cyclins control the timing of cell-cycle events.

Question 57

Define: Proto-oncogene

Question 58

Cell-surface receptors function to transmit signals from the outside of the cell into the cytoplasm.Name the three protein domains that are responsible for receptors to accomplish this signal transmission.

Question 59

Define: Apoptosis

Question 60

The cell cycle has four phases,G,S₁,S₂,and M.

Question 61

Define: Tumour-suppressor gene

Question 62

A patient presents with cancer tumours in several organs.You genotype for several genes often related to the causation of cancer and find that cells from each disparate tumour have the same genotype for all of the genes tested.How do you interpret this data?

Question 63

Define: RB

Question 64

Define: Growth factor

Question 65

Define: Oncogene