bio m&m homework #1-3

In organisms that result from sexual reproduction, the organism will have __1__ sets of chromosomes. One set comes from the ___2___ and the other comes from the ___3___.

1. 2 2. mother 3. father

There are two main reasons why cells divide rather than just continuing to grow larger and larger. State each of these reasons:

1. A larger cell places too many demands on the DNA of the cell. As the cell increases in size, the DNA cannot keep up with the demands of running the larger cell. 2. If the cell grows too large, it will have trouble transporting enough food and water into the cell, and getting rid of the wastes. As the cell grows, the volume of the cell increases much more rapidly than the surface area of the cell. There is not enough surface area to transport the larger amounts of food, wastes, etc.

What is true of interphase?

1. It consists of the G1, S, and G2 phases. 2. It composes a large part of the life cycle of a cell. 3. It is a time of cell growth and development. 4. A cell is preparing for division during this time

All of the cells of the human body have a chromosome number that is _____1_____, except for the gametes which have a chromosome number that is ______2______.

1. diploid 2. haploid

Prior to cell division, each chromosome must ________1_______. Each of these copies is called a __________2___________ and they are held together in an area called a ________3_________.

1. get copied 2. chromatid 3. centromere

Anaphase I splits apart _________1_______ and anaphase II splits apart _______2_________.

1. homologous pairs (tetrads) 2. sister chromatids

In general, when cells are in contact with other cells they respond by ________1_______. When an injury such as a cut occurs, the cells at the edge of the injury begin to ____________2__________

1. not growing 2. divide rapidly

advantages to asexual reproduction

1. parent doesn't have to find a mate 2. large numbers of offspring may result 3. the process is usually very fast

Prior to cell division, a cell has 14 chromosomes. How many chromosomes will each of the daughter cells have?

14

In a particular organism, 2N = 16. How many chromosomes will be found in each of the body cells of this organism?

16

A tetrad consists of...

4 chromatids

In a particular organism, 2N = 16. How many chromosomes will be found in each of the sex cells of this organism?

8

Distinguish these pairs of words: interphase and cell division

During interphase, the cell is not actually dividing. During interphase the cell is preparing itself for cell division by doubling the number of enzymes and organelles, replicating the chromosomes, and assembling the structures (centrioles, microtubules) that it will need for cell division. Cell division comes after all of these preparations have been made.

What are the five stages of the cell cycle?

G1, S, G2, mitosis and cytokinesis

Distinguish these pairs of words: haploid and diploid

Haploid means that a cell contains only a single set (one of each kind) of chromosomes. Diploid means that a cell contains both sets of homologous chromosomes (two of each kind of chromosome)

Distinguish these pairs of words: cleavage furrow and cell plate

In animal cells, a cleavage furrow is formed during cytokinesis. It is the "pinching in" of the cell membrane. The "pinching in" continues until the cell has been split into two cells. A cell plate forms in plant cells. Because of the rigid cell wall, the plant cell is not able to pinch into two cells like an animal cell. Structural polysaccharides are laid down along the middle of the cell, and a new cell wall is built, eventually dividing the cell into two new plant cells.

Distinguish these pairs of words: mitosis and meiosis

Mitosis is a type of cell division that results in 2 identical cells. Meiosis is reduction division. It results in 4 gametes that are different from one another

Distinguish these pairs of words: mitosis and cytokinesis

Mitosis is the division of the nucleus. Cytokinesis is the division of the cytoplasm

Distinguish these pairs of words: mitosis and cytokinesis

Mitosis is the division of the nucleus. Cytokinesis is the division of the cytoplasm.

What is the result of mitosis in a unicellular organism?

Mitosis results in new offspring by asexual reproduction

What is the result of mitosis in a multicellular organism?

Mitosis results in the growth and repair of the tissues of the organism.

What would happen if mitosis occurred, but cytokinesis did not occur?

One cell would have two nuclei.

What happens in S phase?

Replication of DNA occurs

Distinguish these pairs of words: asexual reproduction and sexual reproduction

Sexual reproduction requires 2 different parents, each of which pass half of their chromosomes to their offspring Asexual reproduction requires only one parent who passes all of their chromosomes to their offspring

Distinguish these pairs of words: sister chromatids and centromeres

Sister chromatids are the two identical parts of replicated chromosomes. The sister chromatids are held together in an area called the centromere.

What is the role of the DNA in a cell?

The DNA is the "information storehouse". It contains all of the instructions for making all of the proteins needed in a cell. These instructions are constantly being copied and sent out to the ribosomes in the form of RNA.

Distinguish these pairs of words: DNA and chromosome

The DNA is the carrier of genetic information. Chromosomes are composed of DNA with supporting proteins.

What happens in G2 phase?

The cell assembles the special structures needed for cell division such as centrioles and microtubules

Distinguish these pairs of words: telophase and cytokinesis

The cell has two complete nuclei in telophase. The remaining task is to divide the cytoplasm. Cytokinesis is the division of the cytoplasm. This occurs at the end of telophase.

What happens in G1 phase?

The cell increases its size. The cell doubles the number of enzymes and cytoplasmic organelles.

What might be the result if cytokinesis occurred before mitosis?

The cell would be divided into two cells. One cell would have a nucleus and chromosomes, and the other cell would not.

What problems might arise in a cell that did not complete its G1 phase prior to cell division?

The cell would not have an adequate supply of enzymes and cytoplasmic organelles. The cell would divide but the daughter cells would have too few organelles. It is not likely that the cell would survive.

What role does the spindle play in cell division?

The chromatids are attached to microtubules that compose the spindle. The shortening and lengthening of the microtubules will push the chromatids to the center during metaphase and will pull the chromatids apart during anaphase.

How does the number of chromosomes found in the two new daughter cells compare to the number of chromosomes found in the mother cell?

The daughter cells are exact copies of the mother cell. The daughter cells have the same number of chromosomes as the mother cell.

What is the end result of mitosis and cytokinesis? Why is this so important?

The end result is two new cells that are identical to the original mother cell. It is important that the new cells be able to carry out the same function as the mother cell.

Distinguish these pairs of words: mother cell and daughter cell

The mother cell is the original cell at the beginning of cell division. The mother cell will divide into two identical daughter cells that will be able to carry out the same function as the mother cell.

Distinguish these pairs of words: spindle and microtubules

The spindle is a fanlike structure that helps separate the chromosomes during mitosis. The spindle is composed of microtubules.

What role do centrioles play in cell division?

To organize the microtubules into the spindle.

All species have...

a number of chromosomes that is unique to that species

Name the stage in which the event occurs- The chromatids are pulled to opposite sides of the cell.

anaphase

Uncontrolled cell division results in...

cancer

Sister chromatids are attached to one another at an area called the...

centromere

The exchange of genes between segments of homologous chromosomes during meiosis

crossing over

true or false- As a cell grows larger, the surface area of the cell increases much more rapidly than the volume of the cell.

false

true or false- Each cell that is produced by mitosis has half the number of chromosomes as the mother cell.

false

true or false- If an organism has 12 chromosomes in each of its body cells, it would also have 12 chromosomes in its gametes.

false

true or false- The chromosomes are replicated during prophase.

false

true or false- The majority of the life of a cell is spent doing cell division.

false

the name given to sex cells; egg and sperm cells

gametes

advantage to sexual reproduction

genetic variation

Which of the following events occurs during prophase I of meiosis? (1) the DNA is replicated (2) homologous pairs of chromosomes are linked together (3) homologous pairs of chromosomes are pulled apart (4) 4 sex cells are produced.

homologous pairs of chromosomes are linked together

Name the stage in which the event occurs- The cell assembles the special structures needed for cell division.

interphase

Name the stage in which the event occurs- The cell increases its size as well as the number of enzymes and cytoplasmic organelles.

interphase

Name the stage in which the event occurs- The cell prepares for division by replicating the chromosomes.

interphase

What are G1, S, and G2 phase collectively known as?

interphase

Which of the following is not a stage of mitosis? (1) interphase (2) prophase (3) metaphase (4) anaphase (5) telophase

interphase

Which one of the following does not belong with the others? (1) cytokinesis (2) cell plate (3) cleavage furrow (4) interphase

interphase

What is the purpose of meiosis?

it is the process by which the numbers of chromosomes per cell is cut in half through separation of homologous chromosomes in a diploid cell

indicate if the statement is true of mitosis or meiosis- In this type of cell division tetrads are formed and crossing over may occur.

meiosis

indicate if the statement is true of mitosis or meiosis- This type of cell division occurs in the formation of sex cells.

meiosis

indicate if the statement is true of mitosis or meiosis- This type of cell division results in cells that are different from the mother cell.

meiosis

Crossing over occurs during?

meiosis I

Name the stage in which the event occurs- The pairs of sister chromatids are lined up at the center of the cell.

metaphase

indicate if the statement is true of mitosis or meiosis- One 2N cell --> Two 2N cells

mitosis

indicate if the statement is true of mitosis or meiosis- This type of cell division occurs in all cells of the body except for in the formation of sex cells.

mitosis

indicate if the statement is true of mitosis or meiosis- This type of cell division produces cells that are identical to each other.

mitosis

Name the stage in which the event occurs- Pairs of sister chromatids become attached to the spindle fibers.

prophase

Name the stage in which the event occurs- The centrioles first begin to move to opposite sides of the cell.

prophase

Name the stage in which the event occurs- The chromosomes condense and thicken and are now seen as separate, distinct structures.

prophase

Name the stage in which the event occurs- The nuclear membrane begins to break apart allowing the microtubules to reach the pairs of chromatids.

prophase

Name the stage in which the event occurs- The nucleolus disappears.

prophase

In which phase of meiosis are tetrads formed?

prophase I

What event occurs in prophase I of meiosis that did not occur in prophase of mitosis?

sister chromatids pair up with their homologous chromosome forming a tetrad

Name the stage in which the event occurs- A cleavage furrow or a cell plate forms to divide the cytoplasm into two parts.

telophase

Name the stage in which the event occurs- Cytokinesis occurs.

telophase

Name the stage in which the event occurs- The nuclear membrane reforms and the nucleolus returns

telophase

During the ___________ stage of meiosis, the diploid number of chromosomes is reduced to the haploid number of chromosomes.

telophase I

What are homologous chromosomes?

the 2 copies of each chromosome; one coming from the mother and the other from the father

The DNA is copied during which one of the following?

the S phase

What one thing do all cancers have in common?

the protein regulators that control the cell cycle have failed to do their job

What is the cell cycle?

the series of events that cells go through as they grow and divide. It is the life of the cell from the time it is first formed from a mother cell until its own cell division.

What is the most important in determining how quickly materials can move into and out of a cell?

the surface area of the cell

true or false- Chromatids form when DNA replicates prior to cell division.

true

true or false- DNA is replicated and chromatids are formed in both mitosis and meiosis.

true

true or false- If a cell doesn't have enough DNA to make all of the proteins it needs, it cannot survive.

true

true or false- The number of mitochondria are increased during interphase

true

Which of the following would be true at the completion of cell division?

two identical daughter cells will have been formed

As the cell grows larger, which increases more rapidly, the volume of the cell or the surface area of the cell?

volume