[MOD16A - BIOCHEM] Cell Cycle, Apoptosis, and Cancer_2028

What happens in the G1 phase of the cell cycle?

Cell grows and prepares for DNA synthesis

What happens in the S phase of the cell cycle?

DNA replication occurs, forming two identical copies of the genome

What happens in the G2 phase of the cell cycle?

Cell prepares for mitosis

What happens in the M phase of the cell cycle?

Cell divides into two daughter cells

[T/F] The cell cycle is loosely regulated to allow rapid growth.

FALSE. The cell cycle is tightly regulated to ensure proper growth and prevent uncontrolled division.

What is the role of cyclins in the cell cycle?

They bind to and activate CDKs at specific points in the cycle

What is the function of CDKs?

They regulate cell cycle progression when activated by cyclins

What regulates the activity of cyclins and CDKs?

DNA damage and checkpoint pathways

[T/F] Dysregulation of cyclins and CDKs may lead to cancer.

TRUE

What is the function of cell cycle checkpoints?

They monitor the integrity of each phase and can pause the cycle for DNA repair

[T/F] Damaged cells are allowed to proceed through the cycle by checkpoints.

FALSE. Checkpoints halt the cycle to prevent propagation of damaged cells.

A disease marked by uncontrolled cell growth and division due to disrupted cell cycle regulation.

Cancer

How do gene mutations contribute to cancer?

They disrupt normal cell cycle control, allowing uncontrolled proliferation.

What can happen when cell growth becomes uncontrolled?

They form tumors that may invade nearby tissues or spread.

Promote cell growth when mutated or activated.

Oncogenes

Restrain cell division, repair DNA, or trigger apoptosis when mutated.

Tumor suppressor genes

What is the role of p53?

It halts the cycle or initiates apoptosis in response to DNA damage

Where is BRCA1 located?

Chromosome 17

Where is BRCA2 located?

Chromosome 13

How do checkpoint abnormalities lead to cancer?

They disable the brakes on division, allowing damaged cells to keep dividing

[T/F] Checkpoint failure can cause accumulation of mutations.

TRUE

How do cell cycle-targeting drugs treat cancer?

They disrupt specific stages to prevent division or trigger cell death

Why is combination therapy used in cancer treatment?

It improves outcomes by targeting multiple cell cycle stages

The process by which normal cells transform into cancer cells.

Carcinogenesis

What happens in initiation?

A mutation or DNA damage makes a cell susceptible to malignancy

What happens in promotion?

The initiated cell is stimulated to proliferate by growth factors, hormones, or chronic inflammation

What happens in progression?

The cell gains more mutations and becomes aggressive and invasive

What happens in metastasis?

Cancer cells spread to distant sites via blood or lymph

A condition where cancer appears more frequently in a family due to inherited or shared lifestyle factors.

Familial cancer syndrome

[T/F] All familial cancers are caused solely by inherited mutations.

FALSE. Both hereditary and lifestyle factors may contribute.

A tightly regulated process of programmed cell death essential for homeostasis and removing damaged cells.

Apoptosis

[T/F] Apoptosis is an unregulated process.

FALSE. Apoptosis is highly regulated and controlled.

What is the final executioner caspase of both apoptosis pathways?

Caspase-3

What regulates the intrinsic apoptosis pathway?

Bcl-2 family proteins (e.g., Bax, Bak)

[T/F] Both intrinsic and extrinsic pathways converge at caspase-3.

TRUE

What happens if p53 is mutated in breast cancer?

It disables the intrinsic pathway, making cancer cells resistant to chemotherapy

What is the effect of HER2 overexpression in breast cancer?

It promotes abnormal proliferation and contributes to treatment resistance

Which of the following is a characteristic of cancer cells?

Dysregulation of growth and division

What is the primary cause of cancer development?

Inherited genetic mutations

What is the role of apoptosis in normal and malignant cells?

Eliminating damaged or unwanted cells

What is the main difference between the extrinsic and intrinsic pathways of apoptosis?

Source of the signal that initiates apoptosis

What are oncogenes and tumor suppressor genes?

Genes that regulate cell growth and division

Enumerate the main phases of the cell cycle

G1

S

G2

M

Enumerate the proteins that regulate the cell cycle

Cyclins

Cyclin-dependent kinases (CDKs)

Enumerate the causes of cell cycle dysregulation

Loss of checkpoint control (e.g., TP53 mutation)

Activation of oncogenes

Inactivation of tumor suppressor genes

Enumerate the four steps of carcinogenesis

Initiation

Promotion

Progression

Metastasis

Enumerate the causes of DNA mutations in carcinogenesis

Carcinogen exposure (e.g., UV, tobacco)

DNA replication errors

Faulty DNA repair

Enumerate the three stages of apoptosis

Initiation

Execution

Phagocytosis

Enumerate key proteins in apoptosis

Bcl-2 family proteins (chromosome 18)

Caspases

Enumerate the two main pathways of apoptosis

Extrinsic (death receptor pathway)

Intrinsic (mitochondrial pathway)

Enumerate the differences between extrinsic and intrinsic apoptosis pathways

Extrinsic: Triggered by extracellular signals (e.g., FasL, TNF); activates caspase-8; no mitochondria involved

Intrinsic: Triggered by intracellular stress; involves cytochrome C and caspase-9; mitochondria involved

Enumerate examples of extrinsic apoptosis

Immune cells (via FasL, TNF)

Virus-infected cells (via perforin/granzyme)

Cancer cells (via therapeutic activation of death receptors)

Enumerate examples of intrinsic apoptosis

Damaged neurons (e.g., Alzheimer's)

Cancer cells exposed to chemotherapy/radiation

Embryonic cells during tissue remodeling

Enumerate therapeutic strategies that target apoptosis

Chemotherapy

Targeted therapies

Immunotherapy

Combination therapies