For my gribe

they need both if they are producing animal gametes

they need both if they are producing animal gametes

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?

92; two chromatids per chromosome

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?

they have uncoiled to form long, thin strands

Why is it difficult to observe individual chromosomes with a light microscope during interphase?

32

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

cytokinesis and mitosis; mitotic phase (M)

Which of these phases encompasses all of the stages of mitosis but no other events?

the mitotic phase

During _____ both the contents of the nucleus and the cytoplasm are divided.

interphase

During _____ the cell grows and replicates both its organelles and its chromosomes.

they are sites at which microtubules attach to chromosomes

Which of the following is true of kinetochores?

G1: follows cell division

Which of the following correctly matches a phase of the cell cycle with its description?

large cells containing many nuclei

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?

duplicated chromosomes attach to the plasma membrane

Which of the following is found in binary fission but not in mitosis?

cleavage

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?

centrosome

Where do the microtubules of the spindle originate during mitosis in animal cells?

the formation of the mitotic spindle

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____.

16; 16

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?

a groove in the plasma membrane between daughter nuclei

What is a cleavage furrow?

radioactive-labeled nucleotides

Using which of the following techniques would enable your lab group to distinguish between a cell in G2 and a cell from the same organism in G1?

E

What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?

formation of telophase nuclei

If the cell whose nuclear material is shown in the figure continues toward completion of mitosis, which of the following events would occur next?

gamma contains more DNA than beta

Of the following, the best conclusion concerning the difference between the S phases for beta and gamma is that _____.

are actually in the G0 phase

The best conclusion concerning delta is that the cells _____.

cell cycle checkpoints are not in place to stop cells with chromosome abnormalities

Cells from advanced malignant tumors often have very abnormal chromosomes as well as an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?

• cigarette smoke

• testosterone

• UV light

• fat

Are carcinogens

any substance capable of causing cancer in living tissue

Carcinogen

Fat

_____ is a carcinogen that promotes colon cancer.

G1

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell?

they remain confined to their original site

Which of the following is true of benign tumors, but not malignant tumors?

Cdk

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cycling to become catalytically active?

cyclin

Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?

activating a process that destroys cyclin components

The MPF protein complex turns itself off by _____.

Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins

Which of the following describe(s) cyclin-dependent kinase (Cdk)?

when they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture

Which of the following is true concerning cancer cells?

infection causes lymphocytes to divide more rapidly

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.

The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that _____.

suffering from cervical cancer

When cells were first taken from Henrietta Lacks, she was _____.

cells were taken while she was being treated for cancer many years ago, and these cells have been cultured in the lab ever since

How did doctors harvest and culture cells from Henrietta Lacks?

she was never told that her cells were being taken, and neither she nor her family has been compensated

Did doctors ask Henrietta Lacks' permission to take her cells, and was she paid for them?

they continue to divide and multiply after decades of culture

What property of Henrietta Lacks' cells was most unusual when they were grown in the laboratory?

• the development of a polio vaccine

• new treatments for cancer

• tests of the effects of atomic radiation on life

Cells taken from Henrietta Lacks have been used for experiments leading to _____.

III

MPF reaches its threshold concentration at the end of this stage.

it interferes with rapidly dividing cells

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?

separase enzyme cleaves cohesins and allows chromatids to separate

At the M phase checkpoint, the complex allows for what to occur?

Bacteria Only:

• chromosome separation begins at the origin of replication on DNA

Eukaryotes Only:

• before separation duplicated chromosomes condense

• nuclear envelope fragments permitting chromosome separation

• two copies of the duplicated chromosome are attached at their centromeres before separating

Both Bacteria and Eukaryotes:

• chromosomes replicate before cell division

• replicated chromosomes separate by attaching to some other structural feature of the cell

In all cells, separation of replicated chromosomes is a prerequisite for cell division. However, the mechanism of chromosome separation in bacteria is distinct from that in eukaryotes in several ways.

• the cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells

• vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate

Which of the following statements are true of cytokinesis in plant cells?

true; true; false

false; false; true

true; false; true

Plant and animal cells also require cytoskeletal proteins for cytokinesis, although the roles these proteins play differ among bacteria, plants, and animals.

For each space in the table, drag the appropriate label to indicate if the statement is true or false for each group of organisms.

cytokinesis when the cytoplasm divides forming two new cells

Select the part of the cell cycle where the cell actually produces two new identical cells.

as cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth

Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. This phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. A growth inhibiting signal is sent to both cells, preventing them from dividing. Certain external physical factors can affect this inhibition mechanism. Select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.

meiosis

Human gametes are produced by _____.

23

Normal human gametes carry _____ chromosomes.

16

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

produces offspring genetically identical to the parent

Asexual reproduction _____.

44 autosomes and 2 sex chromosomes

What number and types of chromosomes are found in a human somatic cell?

include genes that determine an individual's sex

The human X and Y chromosomes _____.

sporophyte

In alternation of generations, what is the diploid stage of a plant that follows fertilization called?

homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication

How are sister chromatids and homologous chromosomes different from each other?

each cell has eight homologous pairs

Which of the following is true of a species that has a chromosome number of 2n = 16?

63 chromosomes in 21 sets of 3

A triploid cell contains three sets of chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following?

a plantlike protist

Which of the following can utilize both mitosis and meiosis in the correct circumstances?

an error in either egg or sperm meiotic anaphase

Which of the following might result in a human zygote with 45 chromosomes?

two diploid cells ... four haploid cells

Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?

synapsis occurs

Which of the following occurs during meiosis but not during mitosis?

the exchange of homologous portions of nonsister chromatids

What is crossing over?

it has half the amount of DNA as the cell that began meiosis

If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents?

haploid, and the chromosomes are each composed of two chromatids

After telophase I of meiosis, the chromosomal makeup of each daughter cell is ______.

the statement is true for mitosis and meiosis II

Chromatids are separated from each other.

the statement is true for meiosis I and meiosis II

A cell divides to produce two daughter cells that are genetically different.

four sister chromatids

A pair of homologous chromosomes includes which of the following sets of DNA strands?

3

The following question refers to the essential steps in meiosis described below.

1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus

2. Alignment of tetrads at the metaphase plate

3. Separation of sister chromatids

4. Separation of the homologs; no uncoupling of the centromere

5. Synapsis; chromosomes moving to the middle of the cell in pairs

Which of the steps takes place in both mitosis and meiosis?

one chromosome 12 with one blue gene and one chromosome 19 with one long gene

A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene. As cells in her ovaries undergo meiosis, her resulting eggs (ova) may have which of the following?

one-half blue short and one-half orange short gene eggs

If a female of this species has one chromosome 12 with a blue gene and another chromosome 12 with an orange gene, and has both number 19 chromosomes with short genes, she will produce which of the following egg types?

-random fertilization

-independent assortment of chromosomes in meiosis

-crossing over

Which processes lead to most genetic variation in sexually reproducing organisms?

B and C

Which of these gametes contains one or more recombinant chromosomes?

meiosis

The shuffling of chromosomes that occurs during both fertilization and _____ can lead to genetic variation.