Cell Biology Chapter 20-22 Questions

During which stage of the cell cycle is the chromosome content of a mammalian liver cell 1n (haploid)?

none of the above

Which of the following statements about the cell cycle is FALSE?

once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells (The DNA content is duplicated during S phase, A cell has more DNA during G2 than it did in G1, and An unfavorable environment can cause cells to arrest in G1 are true)

Cell cycle checkpoints

are critical points that determine whether or not the cell cycle proceeds to the next phase of cell division

levels of cyclin-dependent kinase (Cdk) activity change during the cell cycle as a result of 

the Cdks binding different cyclins to become active

A cell at the interphase of cell division does not undergo dramatic change morphologically as in the M phase, but it is biochemically active because it is actively engaged in

DNA synthesis 

Cells in the G₀ state

do not divide

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

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

the levels of cyclins change during the cycle

Mitotic cyclin (M cyclin)

falls in concentration at the end of the M phase as a result of degradation

Which of the following statements is FALSE concerning sister chromatids?

Sister chromatids separate during G2 phase.

How does a somatic cell that has just completed the S phase of its cell cycle compare in respect to its number of chromosomes and amount of DNA with a gamete of the same species?

it has twice the number of chromosomes and four times the amount of DNA

Which of the following statements about the cell cycle is correct?

when the S phase of the cell cycle is finished, a cell has twice as much DNA as it did during the G1 phase

Many growth factors are

extracellular signals that stimulate cell division

a cell that is terminally differentiated (at G0 phase) will

inactivate its cell-cycle control system

the process by which haploid cells are produced from diploid cells is called

meiosis

which of the following statements is TRUE?

the mitotic spindle helps segregate the chromosomes to the two daughter cells 

which of the following statements regrading the G1 phase of the eukaryotic cell cycle is NOT true?

most organells are duplicated at the G1 phase (If environmental conditions are favorable during the G1 phase, the cell will prepare to replicate its DNA, Most cells spend the majority of their lives in the G1 phase of the cell cycle, and Cells that are terminally differentiated may exit the G1 phase and enter the G0 phase are TRUE)

which of the following precede the cytokinesis in animals cells?

assembly of the contractile ring

a cell that lacks Cdk activity in M phase will be unable to

disassemble its nuclear lamina at prometaphase

which of the following is NOT an accurate description of a checkpoint that controls the progression of the cell cycle?

timing the cytokinesis to separate daughter cells

Programmed cell death occurs

by means of an intracellular suicide program

Apoptosis differs from necrosis in the necrosis

cause cells to swell and burst, whereas apoptotic cells shrink and condense

which protein is directly involved in apoptosis?

caspase

Which of the following statements about apoptosis is TRUE?

apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria

Apoptosis is

highly controlled: cells digest themselves by activating a caspase cascade without eliciting my immune response

The organelle participates actively in apoptosis

mitochondria

A 48-year-old woman has a malignant lymphoma involving lymph nodes in the para-aortic region. She is treated with a chemotherapeutic agent which results in the loss of individual neoplastic cells through fragmentation of individual cell nuclei and cytoplasm. Over the next 2 months, the lymphoma decreases in size, as documented on abdominal CT scans. By which of the following mechanisms has her neoplasm primarily responded to therapy?

Programmed cell death

What is the role of the caspases in apoptosis?

caspases are proteases that carry out the controlled destruction of the cell’s components during apoptosis

The hydrolytic enzymes involved in necrosis are likely released from

lysosomes

severe damage to the inner membrane of mitochondria can cause

A. apoptosis and B. malfunction of cellular respiration

Cancer cells are said to “break the rules” because they

lost anchorage-dependent growth property, lost contact-inhibition, and can evade apoptosis (all of the options)

Which of the following statements about cancer is FALSE?

all cancers involve genetic changes that are passed from parent to offspring (It is caused by an accumulation of mutations, Human cancers are related to exposure to carcinogens, and It is characterized by uncontrolled cell division are TRUE)

When cancer cells have the ability to migrate to other parts of the body, they are said to be

metastatic

Which of the following statements about cancer is false?

Even a single gene mutation is sufficient to convert a normal cell into cancer cell. (Chemical carcinogens cause cancer by changing the nucleotide sequence of DNA, Viruses cause some cancers, and Tobacco use is responsible for certain types of lung cancers are TRUE)

A mutated gene contributes to uncontrolled cell growth. Which term best describes this gene?

B. tumor suppressor gene and C. oncogeno

A malignant tumor is more dangerous than a benign tumor because

its cells invade other tissues

Which of the following statements about cancer is NOT accurate?

They always form a solid tumor. (defective in apoptosis, divide excessively even in the absence of growth factors, and escaped cell cycle control are TRUE)

A proto-oncogene is

a normal gene that helps cell grow

Which of the following genetic changes cannot convert a proto-oncogene into an oncogene?

A mutation that introduces a stop codon immediately after the codon for the initiator methionine

Which of the following statements about tumor suppressor genes is FALSE?

cells with a defective tumor suppressor gene will proliferate slower than normal cells (Inactivation of tumor suppressor genes leads to enhanced cell proliferation, Gene amplification of a tumor suppressor gene is likely less dangerous than gene amplification of an oncogene, and Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene are TRUE)

Stem cells are defined as

undifferentiated cells that reproduce themselves and can differentiate into other types of cells

What are the roles of stem cells in the growth and development of an organism?

B. to produce new specialized cells in the body to replace old cells or damaged cells and C. to produce new cells for tissue and organ formation in the fetus

What are adult stem cells?

undifferentiated cells found in different parts of the body that divide to replenish dying cells and regenerate damaged tissues

A somatic cell is

any cell of a living organism other than the reproductive cells

A germ cell or gamete is

the reproductive cells of an organism

What is the role of stem cells with regard to the function of adult tissues and organs?

They are undifferentiated cells that divide asymmetrically, giving rise to one daughter that remains a stem cell and one daughter that will differentiate to replace damaged and worn out cells in the adult tissue or organ

Where are the stem cells that renew the skin epithelium?

in the basal layer of the epidermis

Embryonic stem cells are isolated from

a blastocyst

Cells that are capable of developing into most, but not all, of the body’s cell types, are defined as ____. These cells are represented by _____.

pluripotent stem cells; embryonic stem cells

What does “self-renewal” mean?

the ability of stem cells to go through numerous cycles of cell division while maintaining the undifferentiated state; can only divide and make one cell type

What is a major difference between embryonic stem cells and adult stem cells?

embryonic stem cells can differentiate into more cell types than adult stem cells

Unipotent neural stem cells from the brain can differentiate into which types of cell

only specialized brain cells

what process best explains how muscle cells and nerve cells can develop from the same embryonic stem cells?

differentiation

which best explains why muscle cells are different from blood cells?

different genes are activated and expressed in muscle cells and blood cells

A blastocyst has a _____ which will become placenta and an _____ which will become the rest of the embryo

trophectoderm; inner cell mass

Induced pluripotent stem cells (iPSCs)

are created from differentiated somatic cells by forced expression of a set of key genes that control pluripotency

The artificial introduction of 4 ____ into an adult cell can convert the adult cell into a cell with the properties of embryonic stem cells.

transcription factors

Induced pluripotent stem cells (iPSCs) are

derived from adult cells that have been reprogrammed back into an embryonic-like cells

An hemopoietic stem cell found in the bone marrow

can differentiate into all types of blood cells

Name two defining features of stem cells

the capacity to differentiate into specialized cell types and self-renewal