AP Biology Chapter 12 - The Cell Cycle

Questions and Answers

What are the three key roles of cell division? State each role and give an example.

Reproduction - binary fission of bacterium into two individual organisms. 2. Growth and Development - sand dollar embryo cell division and development. 3. Tissue Renewal - dividing bone marrow to create new RBCs.

What is meant by the cell cycle?

The cell cycle describes the life of a cell from the time it is first formed to its own division into two daughter cells.

What is the meaning of genome?

A cell's endowment of DNA.

How many chromosomes are in a human somatic cell?

46 chromosomes. Signup and view all the answers

Name two types of somatic cells in your body.

Skin cells and liver cells. Signup and view all the answers

What is a gamete?

Reproductive cell. Signup and view all the answers

Name two types of gametes.

Human spermatozoa and ovum. Signup and view all the answers

How many chromosomes are present in a human gamete?

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Define chromatin.

Chromatin is the entire complex of DNA and proteins that is the building material of chromosomes. Signup and view all the answers

How many DNA molecules are in each of your somatic cells?

<ol start="46"> <li></li> </ol> Signup and view all the answers

Define chromosome.

A package of DNA molecules. Signup and view all the answers

Define chromatid.

A copy of the original chromosome, joined with a sister chromatid. Signup and view all the answers

Define centromere.

The region containing specific DNA sequences where a chromatid is attached to its sister. Signup and view all the answers

What occurs in meiosis? How is the chromosome number of daughter cells different?

Meiosis yields nonidentical daughter cells that have only 1 set of chromosomes, half as many as the parent cell. Signup and view all the answers

What is mitosis? How is it different from cytokinesis?

Mitosis is the division of genetic information in the nucleus in the process of cell division, while cytokinesis is the division of the cytoplasm in the process of cell division. Signup and view all the answers

Give a brief explanation of what happens in each phase of the cell cycle.

G₁ - first gap, the cell grows; S - synthesis, the cell continues to grow and copies its chromosomes; G₂ - second gap, cell continues growing and completes preparation for cell division; M - mitosis and cytokinesis of the cell occur. Signup and view all the answers

What are growth factors? How does platelet-derived growth factor (PDGF) stimulate fibroblast division?

Growth factors are proteins released by certain cells that stimulate other cells to divide. PDGFs bind to fibroblast receptor tyrosine kinases that allows cells to pass G₁ checkpoint and divide. Signup and view all the answers

What is transformation? What is metastasis?

Transformation is the process that converts a normal cell to a cancer cell; metastasis is the spread of cancer cells distant from their original site. Signup and view all the answers

Distinguish between a benign tumor and a malignant tumor.

A benign tumor has too few genetic and cellular changes to survive at another site. A malignant tumor includes cells that can spread to new areas and impair organ function. Signup and view all the answers

Study Notes

Key Roles of Cell Division

Reproduction: Example includes binary fission of bacteria producing two independent organisms.
Growth and Development: Example is the cell division and development of a sand dollar embryo.
Tissue Renewal: Example involves division of bone marrow cells to produce new red blood cells (RBCs).

The Cell Cycle

Represents the lifecycle of a cell from formation to division into daughter cells.

Genome

Defined as the complete set of DNA within a cell.

Chromosome Count

Human somatic cells contain 46 chromosomes.
Human gametes are haploid, containing 23 chromosomes.

Types of Cells

Somatic cells examples: skin cells and liver cells.
Types of gametes: human spermatozoa and ovum.

Chromatin and Chromosomes

Chromatin: Complex of DNA and proteins forming chromosomes.
Each somatic cell contains 46 DNA molecules.
Chromosomes are packages of DNA; chromatids are copies joined at the centromere.

Mitosis vs. Cytokinesis

Mitosis refers to the division of genetic material in the nucleus.
Cytokinesis is the division of the cytoplasm following mitosis.

Meiosis

Produces non-identical daughter cells with half the chromosome number of the parent cell.

Cell Cycle Phases

G1 Phase: Initial growth phase of the cell.
S Phase: DNA synthesis occurs; chromosomes are duplicated.
G2 Phase: Further growth and preparation for division.
M Phase: Mitosis and cytokinesis occur.

Mitotic Spindle

Comprised of microtubules and proteins; originates from disassembled cytoskeletal microtubules.
The centrosome, also known as the microtubule organizing center, duplicates during interphase.

Cell Cycle Checkpoints

G1 Checkpoint: Assesses DNA integrity before DNA synthesis.
G2 Checkpoint: Ensures the cell is ready for mitosis.
M Phase Checkpoint: Checks if all kinetochores are attached to spindle microtubules.

Protein Kinase and Cyclins

Protein kinases activate/deactivate proteins via phosphorylation.
Activity of cyclin-dependent kinases (CDKs) fluctuates based on cyclin concentration.

Cancer Cell Behavior

Cancer cells ignore density-dependent inhibition and anchorage dependence leading to uncontrolled growth.
Transformation: Normal cells convert into cancer cells.
Metastasis: Spread of cancer cells to distant sites.

Cancer Treatments

High Energy Radiation: Targets localized tumors; more harmful to them due to compromised DNA repair.
Chemotherapy: Affects rapidly dividing metastatic tumors.

HeLa Cells

Derived from Henrietta Lacks, they are 66 years old and are immortal, used extensively in cancer research.

Tumor Types

Benign Tumor: Limited genetic changes, does not spread easily.
Malignant Tumor: Capable of metastasis, affects normal tissue function.

Summary of Cell Cycle Components and Functions

Kinetochore Microtubules: Shorten during anaphase to separate sister chromatids.
Nonkinetochore Microtubules: Help elongate the cell during anaphase.

Cytokinesis

In animal cells, it occurs via a contractile ring forming a cleavage furrow.
In plant cells, a cell plate forms from vesicles carrying cell wall materials, fusing with the membrane to create daughter cells.

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Description

Test your understanding of cell division with flashcards from Chapter 12 of the AP Biology Campbell Active Reading Guide. This chapter covers key roles of cell division, including reproduction, growth and development, and tissue renewal. Perfect for studying essential concepts in biology.