MCB exam 3

How do prokaryotic cells divide

binary fission

What one thing makes plant cytokinesis different?

Cell plate between two dividing cell. Similar structures as animals

What process is that of: the parental cell's DNA is divided and passed on to two daughter cells.

During mitosis and cytokinesis

What cell division process occurs in all cell division

binary fission: replication of DNA, segregation of replicated DNA to daughter cells, and division of one cell into two

g2

cell prepare to divide

g1

cell prepare to replicate

What are sister chromatids held together by?

centromere

Counting chromosomes is counting what?

centromeres

How many pairs are made up within humans

23 pairs, 22 homologous and 1 pair of sex chromosomes

Describe the first stage of interphase and then count how many sub stages of interphase there are (will ask question about the two other stages later)

3. first: g1 then s then g2 g1: between the end of M phase and the start of S phase,, The gap phase in which the size and protein content of the cell increase and specific regulatory proteins are made and activated in preparation for S-phase DNA synthesis. Once active, the regulatory proteins, many of which are kinases, then promote the activity of enzymes that synthesize DNA. s Phase: (S for synthesis), The phase of interphase in which the entire DNA content of the nucleus is replicated. G2 phase: between the end of S phase and the start of M phase,, The gap phase in which the size and protein content of the cell increase in preparation for M-phase mitosis and cytokinesis.

How many chromosomes does each human cell have except gametes

46

When the cell undergoes S Phase, how many chromosome pairs?

46 pairs but after mitosis we have our 23 pairs again. We are tetraploid after S Phase

At the beginning of mitosis, the nucleus of a human cell contains __ chromosomes, each of which is a pair of __

46, identical sister chromatids linked together at the centromere

How many stages in mitosis

5

What would be the consequence if a cell underwent mitosis but not cytokinesis?

A cell that undergoes mitosis but not cytokinesis will become a single cell with two nuclei (and therefore with twice the normal amount of DNA); this type of cell is called a multinucleate cell.

haploid

A cell with one complete set of chromosomes

centromere

A constriction that physically holds sister chromatids together; the site of the attachment of the spindle fibers that move the chromosome in cell division.

How is a new organism formed in sexual reproduction

A female gamete and a male gamete merge during fertilization to form a new organism

meiotic cell division

A form of cell division that includes only one round of DNA replication but two rounds of nuclear division; meiotic cell division makes sexual reproduction possible. Produces haploid gametes.

What do you predict would be the consequence of a mutation in FtsZ that disrupts the function of the protein it encodes?

A mutation that disrupts the function of the FtsZ protein will block cell division.

Karyotype

A standard arrangement of chromosomes, showing the number and shapes of the chromosomes representative of a species.

mitotic spindle & when is it formed

A structure in the cytosol made up predominantly of microtubules that pull the chromosomes into separate daughter cells. It is outside the nucleus within the cytosol. Formed during prophase.

sex chromosomes

Any of the chromosomes associated with sex. The sex chromosomes are the X and Y chromosomes. Individuals with two X chromosomes are female, and those with an X and a Y chromosome are male.

When can specific chromosomes be recognized

As G2 goes to mitosis, and the chromosomes start to condense and become visible in the nucleus ((The first stage of mitosis)) is known as ((prophase)) and is characterized by the appearance of visible chromosomes.

The process of cytokinesis involves components of the cytoskeleton. It is most similar to what other cytoskeletal function? Question 7 choices Choice A., vesicle transport on microtubules Choice B., muscle contraction Choice C., dynamic growth and depolymerization of tubulin Choice D., dynamic growth and depolymerization of actin

B

Under experimental conditions, we can delete the gene for the motor protein involved in contraction of the contractile ring during animal cell cytokinesis. Which of the following results might you predict? Question 6 choices Choice A., The cell cycle stops at the G1 phase and the cell eventually dies. Choice B., Additional rounds of the cell cycle continue producing a multinucleate cell. Choice C., The chromosomes do not separate at anaphase.

B

The contractile ring that leads to cytokinesis in animal cells has been shown to be made primarily of actin filaments (microfilaments). Which motor protein would you predict is involved in contraction of the ring? Question 5 choices Choice A., dynein Choice B., kinesin Choice C., myosin

C

What is needed for cell division?

Certain events that have to happen no matter what: we need replicated DNA they need to split from one another into two separate cells , divide membrane and cytosol. start with parent and end with daughter cells. replicate up dna, split up cell contents.

Metaphase

Chromosomes line up in the middle of the dividing cell when the MT of the mitotic spindles lengthen and shorten to allow them to get the middle. Very visibly distinctive. each pair of sister chromatids are connected to the MT of the mitotic spindle.

Why is division of eurkaryote material more complicated than the division of prokar?

Compared with the single, relatively small, circular DNA molecule that is the genome of prokaryotic cells, the genome of eukaryotic cells is typically much larger and is organized into one or more linear chromosomes, each of which must be replicated and separated into daughter cells. And whereas the DNA of prokaryotes is attached to the inside of the plasma membrane, allowing replicated DNA to be separated into daughter cells by cell growth, the DNA of eukaryotes is located in the nucleus.

Gamete

Eggs and sperm

How do eurkaroytic cells divide

First divide the nucleus by mitosis or meiosis (gametes) Division of cytoplasm by cytokinesis

What are the two requirements for a cell to divide

First, the two daughter cells must each receive the full complement of genetic material (DNA) present in the single parent cell. Second, the parent cell must be large enough to divide in two and still contribute sufficient cytoplasmic components such as proteins, lipids, and other macromolecules to each daughter cell.

What is a time of preparation for S-phase DNA synthesis

G1

What occurs after cytokinesis

G1 phase

What is a time of preparation to divide for M-phase mitosis and cytokinesis.

G2

Cytokinesis , animal

In animal: centrosome where MT form mitotic spindle. These are on far side of the two daughter cells, we have two separate nuclei. Between two cell, the contractile ring forms. The cytoplasm is split between two cells. Comes together and forms two separate cells.

phragmoplast

In dividing plant cells, during telophase: a structure formed by overlapping microtubules that guide vesicles containing cell wall components to the middle of the cell. Cell plate is formed when the vesicles fuse in the late ana/telophase in the middle of the cell

How is dna organized

In eukaryotic cells, DNA is organized with histones and other proteins into chromatin... which can be looped and packaged to form the structures we know as chromosomes

How does cell division proceed normally? Which stage does this occur in

In order for cell division to proceed normally, every chromosome in the parent cell must be duplicated so that each daughter cell receives a full set of chromosomes. S phase

During S phase, what occurs w/ the centrosomes and the MT spindles

In s Phase, prepping for mitosis: the centrosome duplicates and each one begins to migrate around the nucleus, the two ultimately halting at opposite poles in the cell at the start of prophase. The final locations of the centrosomes define the opposite ends of the cell that will eventually be separated into two daughter cells. As the centrosomes make their way to the poles of the cell, tubulin dimers assemble around them, forming microtubules that radiate from each centrosome. These radiating filaments form the mitotic spindle and later serve as the guide wires for chromosome movement.

What is cytokinesis, what happens and in which 2 distinct stage is categorized under?

In the M phase the division of the cell itself into two separate cells

what are the 2 distinct stages of the cell cycle which one is first, which one occurs second

M phase (1st) and interphase (2nd)

Prometaphase

MT form the mitotic spindle and attach to the chromosomes. Allow the chromosome to segregate to opposite poles. The nuclear envolope is also seperated.

FtsZ encodes what

Many copies of the protein it encodes assemble and form a ring at the site of constriction where the new cell wall forms between the two daughter cells. FtsZ is present in the genomes of diverse bacteria and archaeons, suggesting that it plays a fundamental role in prokaryotic cell division. Interestingly, it appears to be evolutionarily related to tubulin, which you will recall from Chapter 10 makes up the dynamic microtubules found in eukaryotic cells that are important in intracellular transport, cell movement, and cell division.

How is the DNA of eurk organized

as chromosomes

Differences between mitotic cell division and meiotic cell division

Mito: 2 daughter cells Mei: 4 daughter cells, each of the four daughter cells contains half the number of chromosomes as the parent cell, the four daughter cells are each genetically unique and they are genetically different from each other and from the parental cell.

Telophase

Nuclear membrane reforms around the chromsomes which makes two new nuclei, The MT of the mitotic spindle breaks down and then once the nuclei are more distinct, the chromosomes decondense are less visible. This is the end of mitosis. Now there are 46 chromosomes between the two new nuclei.

Successful division makes what

One nuclei in each of the two daughter cell

What is a homologous chromosome

Pairs of chromosomes, matching in size and appearance, that carry the same set of genes; one of each pair was received from the mother, the other from the father. Each pair of homologous chromosomes represents two of the same type of chromosome (both carrying the same set of genes), one of which was received from the mother and the other from the father.

M phase, what happens

Parent cell divides into two daughter cells The stage of the cell cycle consisting of mitosis and cytokinesis, in which the parent cell divides into two daughter cells.

Anaphase

Phase of mitosis in which the chromosomes that once were apart of sister chromatid separate at the centromere and then separate into now fully fledged chromosomes that will move to opposite ends (poles) of the cell. Spindle MT shorten to pull them to opposite ends. S phase makes 46 pairs and when anaphase occurs, there will be 46 chromosomes in the two daughter cells because 46 chromsomes (that were once apart of a sister chromotid, then chromotid, now a chromsome) are at both poles Centromere attached to sister chromosomes, release the chromosomes to individuals. Now, 46 individual chromosomes as they are pulled towards their poles.

When are sister chromatids produced?

S phase

What must occur before the two requirements for cells to divide occurs?

Satisfying these requirements means that key cellular components must be duplicated before cell division takes place. This duplication of material is achieved in a series of steps that constitutes the life cycle of every cell. When you think of a life cycle, you might think of various stages beginning with birth and ending with death. In the case of a single cell, the life cycle begins and ends with cell division.

Which DNA sequences are more alike: a pair of sister chromatids or a pair of homologous chromosomes?

Sister chromatids are the result of DNA replication during S phase, and so they have identical DNA sequences (with the exception of a few changes due to rare mutations). The two homologous chromosomes are inherited from two different parents. The DNA sequences of these chromosomes are therefore similar, but not identical.

Polyploid

Some organisms, such as plants, can have four or sometimes more complete sets of chromosomes. Such cells are polyploid.

Prophase I Name all the steps (5)

The beginning of meiosis I, marked by the visible manifestation of chromosome condensation. By this time, DNA replication has already taken place, so each chromosome has become two sister chromatids held together at the centromere. decondense synapsis occurs (gene by gene pairing) and a bivalent is formed. bivalent includes two copies of each the paternal homolog & two copies of each maternal homolog. look at pairs of sister chromatids here. These form gametes in meosis w/ starting of four copies to have four cells in the end. mitotic spindle is forming the bivalent line up and chiasma occurs (crossing over). Between non sister chromatids. The nuclear envelope is beginning to dissolve

What is the life cycle of a eurkaryotic cell known as

The cell cycle

cell cycle

The collective name for the steps that make up eukaryotic cell division.

What is long in eurka: the DNA in the nucleus or the cell diameter

The dna in nucleus

G0 phase

The gap phase in which cells pause in the cell cycle between M phase and S phase; may last for periods ranging from days to more than a year. It is distinguished from G1 by absence of preparations for DNA synthesis Cell not actively dividing

asexual reproduction What is it

The reproduction of cells or single-celled organisms by cell division; offspring are clones of the parent. May contain genetic mutations or differences compared to parent bc cell division is not error free

sister chromatids

The two copies of a chromosome produced by DNA replication.

kinetochore What is it and what is it important for

The two protein complexes on a chromatid where spindle fibers attach, located on each side. This arrangement ensures that each sister chromatid is attached to a spindle microtubule radiating from one of the poles of the cell. The symmetrical tethering of each chromosome to the two poles of the cell is essential for proper chromosome segregation.

What cells use mitotic cell division

Unicellular and regular, non sex cells. unicellular use this to do asexual reproduction eur: the means by which an organism's cells, tissues, and organs develop and are maintained in multicellular eukaryotes

How is a new generation formed in bacteria

When parent divides in two daughter cells The parent cell first makes identical copies of its genetic material so that each of the two daughter cells has the same genetic material as the parent cell.

When can chromosomes be seen

When they condense and do mitosis

Can cells in G0 still function

Yes, liver cells in g0 can metabolize and detox

Diploid

a cell with two complete sets of chromosomes is diploid.

centrosome

a compact structure that is the microtubule organizing center for animal cells. The centrosome is thus the structure from which the spindles radiate. Plant cells also have microtubule-based mitotic spindles, but they lack centrosomes.

When does the parent cell split into two

after mitosis, during cytokinesis. this is within M phase. Animal cells: a contractile ring forms in the middle of the cell made of actin filaments. The ring contracts, spliting the cytoplasm and turns the parent into two daughter cells.

Prophase

chromosomes condense. Centrosome radiate MT The MT migrate to opposite poles The nuclear envelope is still in tact.

What separates chromosomes into daughter cells

chromosomes of dividing eukaryotic cells attach to the mitotic spindle, which separates them into daughter cells.

What kind of shape does the prokaryote dna molecule have

circular

What are chromosomes before S phase?

diploid

When can specific chromosomes not be recognized?

during interphase because they are long and thin

What occurs during interphase (2)

during this stage the cell makes many preparations for division prep includes: 1. replication of the DNA in the nucleus so that each daughter cell receives a copy of the genome 2. an increase in cell size so that each daughter cell receives sufficient amounts of cytoplasmic and membrane components to allow it to survive on its own g1, g2 and s phase

What is a key challenge in dividing eurkayote cells

ensuring that both daughter cells receive an equal and complete set of chromosomes.

Bc the dna of eurkaroyte is located in the nucleus, what is the first step of cell division

eukaryotic cell division requires first the breakdown and then the re-formation of the nuclear envelope, as well as mechanisms other than cell growth to separate replicated DNA

What is cell division important for

growth, reproduction, replacing old WBC, skin cells, intestinal cells,

During meiosis I.. what happens

homologous chromosomes separate from each other, reducing the total number of chromosomes by half.

What is mitosis, what happens and in which 2 distinct stage is categorized under?

in M phase mitosis, the separation of the chromosomes into two nuclei

What is the second stage of the cell cycle When does it occur

interphase Between two successive M phases

What is the first step of mitosis (cell cycle)

is the condensing of chromosomes from long, thin, threadlike structures typical of interphase to short, dense forms that are identifiable under the microscope during M phase.

The genome of eurkaroytes is how?

larger, and organized into one or more linear chromosomes

Which cells stay in G0 forever?

lens and nerve cells

Centrosome

microtubule organizing center. The MT grow and shrink as apart of dynamic instability to explore the area where the nucleus once was.

Which process in continuous but split up by divided by dramatic changes in the cytoskeleton and in the packaging and movement of the chromosomes.

mitosis and cytokinesis

When does mitosis/ cytokinesis begin? Also, what distinct category is mitosis/ cytokinesis under?

mitosis first but cytokinesis starts before mitosis ends M phase

What is mitotic cell division

mitosis followed by cytokinesis

ploidy

number of sets of chromosomes in a cell.... The number of complete sets of chromosomes in a cell is known as

How many molecules of dna does a chromosome carry

one that carries genes

Where is the DNA of pro / eurka located?

pro: attached along the inside of a plasma membrane eur: in nucleus

Meiosis I begins with what

prophase I

Sexual reproduction

results in offspring that receive genetic material from two parents. Half the genetic material is supplied by the female parent and is present in the egg and the other half is supplied by the male parent and is contributed by the male's sperm.

How are dinoflagellates different/ similar from other eurk?

sim: they have linear chromosome and have a nucleus diff: the nuclear envelope does not break down but stays intact during cell division. Furthermore, the replicated DNA is attached to the nuclear envelope. The nucleus then grows and divides in a manner reminiscent of binary fission.

During meiosis II.. what happens

sister chromatids separate, as in mitosis.

Cell division

the process by which cells make more cells.

In prometaphase, what do the MT radiating from the centrosome do and where do they end up

they have dynamic instability, they explore the area where the nucleus was. then they come in contact with chromosomes and attach to chromosomes at their centromeres at their kinetochore.