False
True or False: The process of binary fisson produces two genetically identical cells in a process that requires prophase, metaphase, anaphase, telophase and cytokinesis.
synthesis of ATP
What body/cellular functions does not typically involve some type of cell division?
binary fission
Bacteria divide by:
DNA replication
The first step of bacterial replication is
the amount of DNA present, whether the DNA is housed in a nucleus or not, whether the DNA is linear or circular
What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?
False. M phase is shorter than interphase; cells spend most of their time in interphase.
True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase.
24. Each chromosome (12) is replicated, there are 24 DNA molecules in the nucleus during G2 phase.
A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?
A check that growth factors are present
A check that the cell is large enough for division
A check that nutrients are sufficient
*A check that chromosome replication has been successfully completed (Chromosome replication does not occur until after G1; this checkpoint is a G2 checkpoint.)
A check that the cell is large enough for division
A check that nutrients are sufficient
*A check that chromosome replication has been successfully completed (Chromosome replication does not occur until after G1; this checkpoint is a G2 checkpoint.)
Which of the following checkpoints does not occur late in G1?
44
If a cell had 22 chromosomes at the end of mitosis, how many will it have at the end of the next S Phase?
The chromosomes must be duplicated, which occurs during interphase.
What must happen before a cell can begin mitosis?
Prophase
The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
Metaphase (Occurs in the MIDDLE of mitosis)
The chromosomes line up in the center of the cell during which phase of mitosis?
Anaphase
The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
Telophase, the final phase of mitosis.
The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?
Cytokinesis
At the end of the mitotic (M) phase, the cytoplasm divides in a process called
interphase
Nucleoli are present during
Telophase
Cytokinesis often, but not always, accompanies
Prophase, the chromatin fibers become discrete chromosomes
Chromosomes become visible during
Anaphase, sister chromatids separate and migrate to opposite poles
Centromeres divide and sister chromosomes become full-fledged chromosomes during
Prometaphase
Spindle fibers attach to kinetochores during
two chromosomes and four chromatids
During prophase a homologous pair of chromosomes consists of
Interphase
Which of the following phases does the average cell spend the most time in?
two, genetically identical
Mitosis produces _______(how many) cell(s) that are that are _________(genetically identical/different).
92
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. There are _____ chromatids.
they have uncoiled to form long, thin strands
Individual chromosomes are usually observed with a light microscope during mitosis, even though cells spend more time in interphase. This is because _____.
100 units. G2 follows S, and that during the S phase, DNA is replicated. Then, chromatids are separated during mitosis to form daughter cells.
A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA in one of the grasshopper daughter cells?
G1
Cells will usually divide if they receive the proper signal at a checkpoint in the _____ phase of the cell cycle.
stimulates angiogenesis
ignores cell cycle checkpoints
*is considered totipotent
is immortal
has lost density dependence
ignores cell cycle checkpoints
*is considered totipotent
is immortal
has lost density dependence
Which of the following is not a property of a malignant cancer cell?
Anaphase
The M-phase checkpoint in mitosis determines whether sister chromatids have divided properly and there is the proper amount of DNA on each side of the dividing cell. Specifically, we would predict that this checkpoint occurs in
Cancer cells continuously secrete growth factors into the cell culture medium.
In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell culture. What is one explanation that could account for this?
density-dependent inhibition.
As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of
large cells containing many nuclei
“multinucleated”
“multinucleated”
In some organisms such as certain fungi and algae, cells undergo mitosis repeatedly without subsequently undergoing cytokinesis. What would be the consequence of this?
Benign tumors do not metastasize; malignant tumors do.
What is the difference between a benign tumor and a malignant tumor?
Prophase
In the telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in
Anaphase
The phase of mitosis during which the chromosomes move toward separate poles of the cell is
Metaphase
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?
four haploid cells
Meiosis starts with a single diploid cell and produces
interphase
A cell preparing to undergo meiosis duplicates its chromosomes during what phase?
homologous chromosomes stick together in pairs.
During prophase I of meiosis,
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.
The correct order of events during meiosis is
prophase I.
During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?
are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes
In many organisms, including humans, chromosomes are found in homologous pairs. Homologous chromosomes
homologous chromosomes.
Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are
-They have one member of each pair of homologous chromosomes
-They are haploid
-They function in sexual reproduction
-They have one half of the genetic material
-They are haploid
-They function in sexual reproduction
-They have one half of the genetic material
Gametes differ from somatic cells in what ways?
The pairing up of homologous chromosomes and crossing over only occur during meiosis.
The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two processes differ in the arrangement and behavior of their chromosomes. How?
False
True or False: Cytokinesis always occurs immediately following the events of mitosis to produce two cells and meiosis to produce four cells.
-Genetic diversity is enhanced by random fertilization of gametes.
-Genetic diversity is enhanced by random alignment of homologous pairs at Metaphase I.
-Genetic diversity is enhanced by crossing over (recombination) during Prophase I.
****-Genetic diversity is enhanced by mitosis in somatic cells.
-Genetic diversity is enhanced by random alignment of homologous pairs at Metaphase I.
-Genetic diversity is enhanced by crossing over (recombination) during Prophase I.
****-Genetic diversity is enhanced by mitosis in somatic cells.
Which of the following statements regarding genetic diversity is false?
-Diploid daughter cells are produced.
-Chromosomes without sister chromatid arrangement line up along the metaphase plate.
-Centromeres divide.
****-Crossing over (recombination) occurs.
-The spindle apparatus (centrosomes + microtubules) forms.
-Chromosomes without sister chromatid arrangement line up along the metaphase plate.
-Centromeres divide.
****-Crossing over (recombination) occurs.
-The spindle apparatus (centrosomes + microtubules) forms.
Which of the following occurs in meiosis I but not meiosis II?
two … haploid
Meiosis I produces _____ cells, each of which is _____.
four … haploid
Meiosis II typically produces _____ cells, each of which is _____.
anaphase II
During _____ sister chromatids separate.
telophase I
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
prophase I
Synapsis occurs during _____.
anaphase I
Homologous chromosomes migrate to opposite poles during _____.
metaphase II
During _____ chromosomes align single file along the equator of a haploid cell.
telophase II
At the end of _____ and cytokinesis there are four haploid cells.
prophase II
During _____ a spindle forms in a haploid cell.
This brings the chromosomes into alignment so that crossing over can create new combinations of genes present on a single chromosome.
During meiosis I, homologous chromosomes form a tetrad. What does this accomplish?
Two. Only two of the four chromatids present in a tetrad cross over at the chiasma. The other two chromatids do not exchange parts and are unaltered
In a cell with eight chromosomes, one chiasma develops during meiosis I in only one particular pair of homologs. How many recombinant chromosomes will there be at the completion of meiosis II?
The chromosome number in both cases would be normal, but in trisomy there would be three chromatids on one chromosome and in a duplication there would be two chromatids on one chromosome. (Trisomy means three copies of a chromosome)
You suspect that a serious developmental disorder is due to a chromosome abnormality and prepare a karyotype from an affected individual. In analyzing the karyotype, how could you distinguish trisomy from a chromosome structural defect such as a duplication?
Somatic (referring to the body). These cells are diploid and have **two homologous copies of each chromosome.
An example of a cell that is 2n is a ______ cell?
Mitosis. Zygotes are somatic cells.
After fertilization, the resulting zygote begins to divide by what process?
Telophase I and prophase II. (If DNA were to replicate at this phase, then the cell would still be haploid, but it would contain an abnormal number of chromosomes.)
At a critical point in meiosis, the chromosomes do not replicate. This occurs between what two phases?
Four. (Because of the synapsis of homologous chromosomes, the number of tetrads in meiosis will be the same as the haploid number of chromosomes.)
An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis?
Synapsis (the pairing of homologous chromosomes) occurs only in meiosis (prophase I).
What is a key difference between meiosis and mitosis?
It allows the exchange of genes between homologous chromosomes. (combining DNA from two parents into a single chromosome allows for genetic variation.)
Why is crossing over important?
Reciprocal translocation (the exchange of genetic material between nonhomologous chromosomes)
The exchange of parts between nonhomologous chromosomes is called
Sexual reproduction can produce great variation among the offspring, whereas asexual cannot.
How do asexual and sexual reproduction differ?
92. When the cell prepared to divide, the chromosomes were replicated, and the chromosome number went from 46 to 92. Because these were not separated into daughter cells during cytokinesis, the cell still has 92 chromosomes.
Imagine that a human skin cell went through mitosis but did not undergo cytokinesis. How many chromosomes would be in the cell?
