BIOLOGY WEEK 4

CELL TRANSPORT

It is the movement of substances into and out of cells through the cell membrane.

Obtain nutrients

Remove wastes

Maintain balance

Key Idea
The cell membrane controls what enters and leaves the cell.

CELLS TRANSPORT MATERIALS TO:

Passive

Does not require energy (ATP)

Moves substances from high to low concentration

Includes diffusion, facilitated diffusion, and osmosis

Active

Requires ATP (energy)

Moves substances from low to high concentration

Includes protein pumps, endocytosis, and exocytosis

PASSIVE

TRANSPORT

Substances naturally move down their concentration gradient.

DIFFUSION

Molecules move directly through the cell membrane.

Movement of small, nonpolar molecules such as oxygen (O₂) and carbon dioxide (CO₂).

Moves substances from high concentration to low concentration.

FACILITATED DIFFUSION

Requires transport proteins

Best for large or charged molecules such as glucose, amino acids, and ions (Na⁺, K⁺, Cl⁻).

Moves substances from high concentration to low concentration.

Solute

Any molecules that are dissolved in water.

Example: salt, sugar

Semipermeable Membrane

A barrier that allows water molecules to pass across, but not solute molecules.

HYPERTONIC

Hyper means above/more

A hypertonic solution has more solute

Shrink

HYPOTONIC

Hypo means below/less

A hypotonic solution has less solute

Swell, burst

ISOTONIC

Iso means same

Isotonic solutions have the same concentration of solute.

EQUILIBRIUM

When the concentration of water and solute is the same (isotonic) on both sides of a membrane.

Hypertonic solutions have more solute, so more water will always move towards the hypertonic side!

Towards the Hypertonic Side!

if water is attracted to solute...

where will most water molecules move across the membrane: towards the hyper or hypotonic side?

ACTIVE TRANSPORT

Requires ATP because substances move against the concentration gradient.

protein pumps

A membrane protein that uses ATP to pump molecules from low to high.

ENDOCYTOSIS

Cell takes materials into the cell.

Example:

Cells absorbing nutrients

EXOCYTOSIS

Cell releases materials outside the cell.

Example:

Release of hormones (e.g., insulin)

HOMEOSTASIS

• Stable internal environment

• Balances water, nutrients, ion and wastes

• Allows nutrients in.

• Removes wastes.

• Controls water and ion balance.

• Receives cell signals.

LOSS OF HOMEOSTASIS

• Cells may swell or shrink.

• Waste accumulates.

• Diseases may occur.

DISEASES

Diabetes

Cancer

Genetic disorders

CELLULAR ABNORMALITIES

Changes in cell structure or function.

May result from gene mutations, infections, toxins, or aging.

Can disrupt homeostasis.

Poor nutrient transport

Waste accumulation

Reduced communication between cells

Tissue damage

Organ dysfunction

HOW CELLULAR ABNORMALITIES AFFECT HOMEOSTASIS

CANCER

Cells divide uncontrollably.

Often caused by mutations in genes regulating the cell cycle.

Tumors may form and spread (metastasis).

Breast Cancer
Begins when abnormal cells in the breast grow and divide uncontrollably, forming a tumor.

Lung Cancer

Develops when abnormal cells in the lungs multiply rapidly and interfere with normal breathing.

Leukemia

A cancer of the blood in which abnormal white blood cells are produced, reducing the body's ability to fight infection.

Lung Cancer

Develops when abnormal cells in the lungs multiply rapidly and interfere with normal breathing.

Breast Cancer

Begins when abnormal cells in the breast grow and divide uncontrollably, forming a tumor

Leukemia

A cancer of the blood in which abnormal white blood cells are produced, reducing the body's ability to fight infection.

DIABETES

Glucose cannot efficiently enter cells because of insulin deficiency or insulin resistance.

High blood glucose damages tissues over time.

Glucose cannot enter cells efficiently because:

The pancreas produces little or no insulin (Type 1), or

Cells become resistant to insulin (Type 2).

GENETIC DISORDERS

Mutations in DNA affect proteins and cell function.

A mutation is a change in an organism's genetic material (DNA) that may affect the structure or function of cells.

Cystic Fibrosis

Inherited genetic disorder that affects the lungs, digestive system, and other organs.

Huntington's Disease

is an inherited disorder caused by a mutation in the HTT (Huntingtin) gene.

Down Syndrome

is a genetic disorder caused by an extra copy of chromosome 21 (Trisomy 21).

Cystic Fibrosis

Inherited genetic disorder that affects the lungs, digestive system, and other organs.

Huntington's Disease

is an inherited disorder caused by a mutation in the HTT (Huntingtin) gene.

down syndrome

is a genetic disorder caused by an extra copy of chromosome 21 (Trisomy 21).

key ways

✔ Cell transport is essential for cell survival.

✔ Passive transport moves substances without ATP.

✔ Active transport moves substances using ATP.

✔ The cell membrane maintains homeostasis by regulating the movement of substances.

✔ When transport mechanisms fail, cellular abnormalities occur and may lead to diseases such as cancer, diabetes, and genetic disorders.