LECTURE 2-1/2-2 REVIEW QUESTIONS

List 5 ways by which cancer cells differ from normal healthy cells

Cancer cells have multiple nuclei and large nucleoli; healthy cells have a single nucleus and nucleolus. Cancer cells grow and divide continuously; healthy cells stop dividing when space is limited (density-dependent inhibition). Cancer cells can invade neighboring tissues and metastasize; healthy cells grow locally. Cancer cells send signals to grow blood vessels (angiogenesis); healthy cells do not. Cancer cells have abnormal number and arrangement of chromosomes; healthy cells have organized chromosomes

Describe what the terms metastasis and angiogenesis refer to

Metastasis: Spread of cancer cells from the original tumor to other parts of the body via blood or lymph. Angiogenesis: Formation of new blood vessels to supply nutrients to tumors, promoting cancer growth.

Describe how proto-oncogenes and tumor-suppressor genes can be involved in cancer development.

Proto-oncogenes normally regulate cell growth; when mutated into oncogenes, they cause uncontrolled cell division. Tumor-suppressor genes normally inhibit cell growth; mutations that inactivate them remove growth control, leading to cancer.

List 4 external (environmental) factors that can enhance the occurrence of cancer.

UV radiation. Chemicals (e.g., tobacco, asbestos, hair dye). Viruses (e.g., HPV). X-rays and other radiation.

Can a virus cause cancer ? Give 2 examples of such viruses and the cancers they cause.

Yes. Human papillomavirus (HPV): cervical cancer. Hepatitis B virus: liver cancer.

How does chemotherapy work in the human body to reduce cancer growth ? What are the side-effects ?

Chemotherapy kills rapidly dividing cells by disrupting spindle formation during mitosis. Side-effects: damage to hair follicles, bone marrow, and intestinal cells (due to non-specific action).

Give an example of how immunotherapy can be used to fight cancer cells

Active immunotherapy: Adding cytokines like interferon or interleukin to boost the immune system to recognize and attack tumor cells. Radioimmunotherapy: Attaching radioactive isotopes or drugs to antibodies that target cancer cells specifically.

What are the various components that make up a cell membrane ? Provide details.

Phospholipid bilayer: Hydrophilic phosphate heads, hydrophobic fatty acid tails. Proteins: Integral (embedded) and peripheral (surface); functions include transport, enzyme activity, receptors. Cholesterol: Embedded in tails; maintains membrane fluidity and stability. Carbohydrates: Short-chain oligosaccharides on proteins/lipids; involved in cell recognition and signaling.

What does the term "amphipathic" mean ? Can you provide 2 examples ?

A molecule has both hydrophilic (water-loving) and hydrophobic (water-fearing) regions. Examples: Phospholipids, integral membrane proteins.

What functions do carbohydrates have in the cell membrane?

Cell-to-cell recognition. Cell signaling. Determining blood type (A, B, AB, O).

Describe 3 functions of membrane proteins.

Transport of molecules (channel and carrier proteins). Enzymatic activity. Signal transduction and cell recognition.

Describe 3 types of passive transport across the cell membrane.

Diffusion: Movement of molecules down a concentration gradient (e.g., oxygen). Osmosis: Movement of water from low solute to high solute concentration. Facilitated diffusion: Movement of molecules through channel or carrier proteins along a concentration gradient (e.g., glucose, ions).

Describe how a proton pump can be involved in co-transport.

Proton pumps move H⁺ ions out of the cell, creating a concentration gradient. This gradient drives the co-transport of other molecules (e.g., sucrose) into the cell via H⁺ symporters.

What is the purpose of a sodium-potassium pump and how does it work ?

Maintains negative charge inside the cell and proper ion balance. Pumps 3 Na⁺ out and 2 K⁺ in against their concentration gradients using ATP.

What is the difference between facilitated diffusion and co-transport?

Facilitated diffusion: Passive movement along a concentration gradient through a protein channel/carrier. Co-transport: Active transport where movement of one molecule against its gradient is coupled to the movement of another along its gradient.

Describe the 3 types of bulk transport that can occur in a cell.

Exocytosis: Large molecules exit the cell. Endocytosis: Large molecules enter the cell. Phagocytosis: “Cell eating” of large particles. Pinocytosis: “Cell drinking” of liquids. Receptor-mediated endocytosis: Specific molecules enter after binding to receptors.

Discuss how cystic fibrosis in humans is associated with membrane transport deficiency

Caused by mutation in CFTR gene, producing a faulty chloride transport protein. Chloride ions cannot move properly, leading to thick, sticky mucus. Results in respiratory and digestive problems; treated with physiotherapy, enzymes, bronchodilators, and antibiotics.