2B4 Cellular Growth and Reproduction

Question 1

What are the two major stages involved in the cell cycle phases for eukaryotic somatic cells?

Answer 1

1. Interphase
2. M-Phase

Interphase = cell growth

M-Phase = cell division

Question 2

What is interphase?

Answer 2

The non-dividing part of the cell cycle.

The cell spends most of its life in this stage.

Question 3

What are the three subphases of interphase?

Answer 3

• First Gap (G1) phase
• Synthesis (S) phase
• Second Gap (G2) phase

Question 4

What happens during the G1 phase of interphase?

Answer 4

Cell grows and replicates organelles but does not replicate chromosomes.

Question 5

What occurs during the S phase of interphase?

Answer 5

Cell chromosomes duplicate, creating sister chromatids.

Question 6

What is the function of the centromere in mitosis?

Answer 6

It serves as the attachment point for the two sister chromatids, ensuring they are connected until they are pulled apart during anaphase.

It also acts as the site where spindle fibers attach to separate the chromatids during cell division.

The number of centromeres determines the chromosome count in a cell, not the number of arms or chromatids.

Question 7

What are chromatids?

Answer 7

One of the two copies of the chromosome.

Question 8

What are sister chromatids?

Answer 8

Duplicated chromosomes containing identical DNA molecules.

Question 9

What is the purpose of the G2 phase in interphase?

Answer 9

Cell continues to grow and undergoes protein synthesis in preparation for cell division.

Question 10

What is cell division?

Answer 10

A process in which a mother cell divides and gives rise to two new cells.

Question 11

What is the purpose of the M phase in the cell cycle?

Answer 11

To separate sister chromatids and form two identical cells from a single cell.

M phase is also known as mitosis.

Question 12

What are the five stages of mitosis?

Answer 12

• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase

Question 13

What is the importance of mitosis?

Answer 13

It is essential for organism growth and the replacement of damaged and worn out cells.

Question 14

What occurs during prophase in cellular division?

Answer 14

1. The nucleolus disappears.
2. Uncoiled DNA called chromatin condenses into chromosomes.
3. A mitotic spindle made out of microtubules form.

Question 15

What is the function of the mitotic spindle?

Answer 15

To help equally divide the chromosomes in the parent cell to ensure equal, identical copies in both daughter cells after mitosis.

Mitotic spindle is composed of fibers made from microtubules and proteins, and it forms in the cytoplasm during prophase.

Question 16

What is the composition of the mitotic spindle?

Answer 16

Fibers made from microtubules and proteins.

Question 17

What is the function of the centrosome in mitosis?

Answer 17

Organizes the cell’s microtubules.

Question 18

What are microtubules made of?

Answer 18

Long polymers of tubulin.

Question 19

What occurs during prometaphase of mitosis?

Answer 19

1. The nuclear envelope disappears.
2. Centrosomes begin to move to opposite poles.
3. Spindle fibers connect to kinetochores.

Kinetochores are protein structures near the center of the chromosomes.

Question 20

Where does the kinetochore assemble?

Answer 20

On each side of the chromosome or essentially on the outermost side of each of the sister chromatids.

Question 21

What are kinetochore microtubules responsible for during mitosis?

Answer 21

Attaching the chromosome to the poles of the cell and separating the chromosomes to ensure each daughter cell gets the same number of chromosomes and identical genetic information.

Question 22

What is the role of astral microtubules during mitosis?

Answer 22

Anchoring the spindle poles to the cell membrane and helping the spindle to position correctly to control the plane of cell division.

Question 23

What happens during metaphase in cellular division?

Answer 23

Sister chromatids align along the central plane of the cell.

Question 24

What is the metaphase plate?

Answer 24

An imaginary line in the middle of the cell halfway between the spindle poles where the chromosomes align during mitosis.

Question 25

What takes place during **anaphase** in cellular division?

Answer 25

Sister chromatids separate into individual chromosomes and the cell elongates.

Question 26

What occurs during **telophase** in cellular division?

Answer 26

1. Individual chromosomes are pulled to opposite ends. 2. Nuclear envelope forms. 3. Chromosomes begin to unravel and turn into chromatin. 4. Cell prepares for cytokinesis.

Question 27

What happens to the mitotic spindle after the chromosomes *arrive at the opposite poles* of the cell?

Answer 27

It *disassembles*, and its work is complete.

Question 28

What is **cytokinesis**?

Answer 28

The process in which the cytoplasmic contents of the cell are *divided*. ## Footnote The name cytokinesis comes from the Greek words cyto-, which means compartment or cell, and -kinesis, meaning movement.

Question 29

How do *animal cells* perform cytokinesis?

Answer 29

'From the outside in' by forming a **cleavage furrow**.

Question 30

What is a **cleavage furrow** in animal cells?

Answer 30

An indentation on the cell surface that continuously deepens until the animal cell is 'pinched' into two separate halves.

Question 31

What is responsible for *constricting* the cleavage furrow in animal cells?

Answer 31

* A contractile ring of actin filaments. * Movement of myosin motor proteins.

Question 32

How do **plant cells** complete cytokinesis?

Answer 32

By using a network of microtubules and vesicles called the *phragmoplast* to transport macromolecules to the center of the cell, creating a **cell plate.**

Question 33

What is the direction of division in plant cells during cytokinesis?

Answer 33

'From the inside out" by forming a **cell plate** made of microtubules.

Question 34

Why can't plant cells make cleavage furrows?

Answer 34

Because their rigid outer cell walls do not bend like the cell membrane.

Question 35

How does cytokinesis *differ* in animal and plant cells?

Answer 35

* In **animal cells**, cytokinesis is accomplished via a cleavage furrow. * In **plant cells**, it involves the formation of a cell plate.

Question 36

Why is *chromosome movement* important in mitosis?

Answer 36

To move the chromosomal copies to opposite sides of the cell *to ensure each daughter cell gets a full set of chromosomes*.

Question 37

What is the main difference between mitosis and meiosis?

Answer 37

* **Mitosis** is involved in cell division of body cells or somatic cells that are *genetically identical.* Results in 2 cells. * **Meiosis** is the process that creates *genetically different* gametes (sperm and egg cells). Results in 4 cells.

Question 38

What is **ploidy**?

Answer 38

Refers to the number of chromosomes that are found in the nucleus of a cell. ## Footnote Varies from organism to organism.

Question 39

What is the *ploidy* of cells produced through mitosis and meiosis?

Answer 39

* Mitosis: **Diploid** (full set of genetic information) * Meiosis: **Haploid** (half of the genetic information) ## Footnote Diploid: 2 sets of chromosomes. 1 from each parent in sexually producing organisms. Haploid: 1 set of chromosomes. 2 haploid cells combine to produce a diploid cell in sexually reproducing organisms.

Question 40

What is **cancer**?

Answer 40

The *uncontrolled reproduction of cells* caused by **mutations** in the DNA within cells, jeopardizing the function of body systems.

Question 41

What can cause abnormal cell proliferation and lead to cancer?

Answer 41

Factors like *radiation* and *environmental toxins*.

Question 42

What are the **cell checkpoints** in the cell cycle?

Answer 42

* The G1/S checkpoint * The G2/M checkpoint * The metaphase/anaphase checkpoint

Question 43

What are **positive regulators** in the cell cycle?

Answer 43

Are molecules that **promote the progression and continuation of the cell cycle**. ## Footnote Examples: Cyclins and CDKs.

Question 44

What are **cyclins** and their role in the cell cycle?

Answer 44

These are special **proteins** that affect each phase of the cell cycle. ## Footnote There are four main types: G1 cyclins, G1/S cyclins, S cyclins, and M cyclins.

Question 45

What are **cyclin-dependent kinases (CDKs)** and their role in the cell cycle?

Answer 45

CDKs are *enzymes that attach phosphate groups* to target proteins, allowing them to perform their functions in the cell cycle.

Question 46

What are positive regulators in the cell cycle?

Answer 46

* Cyclins * CDKs ## Footnote Positive regulators cause the cycle to progress and continue forward.

Question 47

What are **oncogenes**?

Answer 47

Damaged positive regulators that become overactive and cause excessive cell proliferation.

Question 48

What are **negative regulators** in the cell cycle?

Answer 48

Regulators that **halt** the cell cycle from progressing. ## Footnote Especially when cell DNA is damaged.

Question 49

What are **tumor suppressors** in the cell cycle?

Answer 49

Negative regulators that effectively halt the progression of the cycle when DNA is damaged, such as p53 and Rb.