Biology: Chapter 9 - The Cell Cycle and Cellular Reproduction

What are the two major stages of the cell cycle?

Interphase and Mitotic stage

What occurs during Interphase?

Cells grow, organelles double, DNA replicates

What are the three phases of Interphase?

G1, S, G2

What happens in the G1 phase?

Cell growth and prep for DNA synthesis

What happens during the S phase?

DNA replication and chromosome duplication

What happens in the G2 phase?

Cell prepares proteins and microtubules for mitosis

What is the G0 phase?

Resting phase

What are chromosomes made of?

DNA and histone proteins forming chromatin

Define nucleosome

DNA wound around a core of eight histone proteins

Euchromatin vs Heterochromatin?

Euchromatin is loosely packed and active. Heterochromatin is tightly packed and inactive.

Define diploid

A cell with 2 sets (2n) of chromosomes

Define haploid

A cell containing one set (n) of chromosomes (e.g., sperm and egg cells).

Phases of Mitosis

Prophase, Prometaphase, Metaphase, Anaphase, Telophase

What is the purpose of centrosomes?

They organize microtubules into the mitotic spindle

What are kinetochores?

Protein complexes that attach chromosomes to spindle fibers.

When do sister chromatids separate?

Anaphase

Define cytokinesis

Division of the cytoplasm into two daughter cells

Cytokinesis in animal cells involves:

Formation of a cleavage by a ring of actin microfilaments

Cytokinesis in plant cells involves:

Formation of a cell plate from Golgi-derived vesicles

Function of mitosis

Growth, repair, and development

Define benign tumors

Non-cancerous, encapsulated tumors that do not spread.

Define malignant tumors

Cancerous tumors

Three characteristics of cancer cells

1) Grow and divide abnormally

2) Abnormal plasma membrane, cytoskeleton, chromosome number, and metabolism

3) Cells do not stay anchored properly in tissues because plasma membrane adhesion proteins are defective or missing

What is angiogenesis?

Formation of new blood vessels to nourish tumors.

What is a proto-oncogene?

A normal gene promoting cell cycle progression that can mutate into an oncogene.

Role of tumor suppressor genes?

They inhibit the cell cycle and promote apoptosis.

What is the p53 gene?

A tumor suppressor gene involved in halting the cell cycle and triggering apoptosis.

Why do telomeres shorten?

They shorten with each cell division, eventually stopping cell division.

How do cancer cells avoid telomere shortening?

Mutations activate telomerase enzyme, continually lengthening telomeres.

How do prokaryotes reproduce?

By binary fission.

Describe binary fission.

DNA replicates, chromosomes attach to the cell membrane, cell elongates, and divides into two cells.

Difference between binary fission and mitosis?

Binary fission involves a simple split without spindle formation; mitosis involves a complex division process with spindle fibers.

Functions of cell division in prokaryotes and single-celled eukaryotes?

Asexual reproduction.

Functions of cell division in multicellular eukaryotes?

Growth, tissue renewal, and repair.

Define apoptosis.

Programmed cell death involving caspases.

What are cyclins?

Proteins regulating progression through the cell cycle checkpoints.

Define metastasis.

Spread of cancer cells from original tumor site to distant organs.

Define chromatid.

One half of a duplicated chromosome.

What is a cleavage furrow?

The indentation during cytokinesis in animal cells.

What are stem cells?

Cells capable of continuously dividing and differentiating into specialized cell types.