Cell Biology and Human Body Systems: Key Concepts and Structures

Cell Theory

All living things are made of cells.

Multicellular

Made of many cells.

Unicellular

Made of one cell.

Prokaryote

No nucleus, simple, bacteria.

Eukaryote

Has nucleus + organelles, animals/plants/fungi.

Organelle

Small structure inside a cell with a specific job.

Cytoplasm

Jelly-like substance that holds organelles in place.

Cell membrane

Controls what enters and leaves the cell.

Cell wall (plants only)

Rigid support layer around plant cells.

Nucleus

Holds DNA and controls cell activities.

Chloroplast (plants only)

Does photosynthesis (makes glucose).

DNA

Genetic instructions of the cell.

Gene

A section of DNA that controls a trait.

Chromosome

Tightly coiled DNA.

Chromatid

Half of a duplicated chromosome.

Centromere

Point where chromatids are held together.

Mutation

A change in DNA.

Diffusion

Particles move from high → low concentration.

Osmosis

Diffusion of water.

Cell division

Process of making new cells.

Cell cycle

Whole cycle of a cell growing, copying DNA, and dividing.

Mitosis

Division of the nucleus to form two identical cells.

Interphase

Longest stage; cell grows, copies DNA + organelles.

Prophase

Chromosomes thicken, nuclear membrane disappears, spindle forms.

Metaphase

Chromosomes line up in middle; spindle attaches to centromeres.

Anaphase

Sister chromatids pull apart to opposite sides.

Telophase

Nuclear membranes reform; chromosomes thin out.

Cytokinesis

Cell splits into two.

Tumour

A mass of cells dividing uncontrollably.

Benign tumour

Not cancerous, doesn't spread.

Malignant tumour

Cancerous, spreads (metastasis).

Cell specialization

Cells change to perform specific jobs.

Stem cell

Unspecialized cell that can become any cell.

Embryonic stem cell

From embryos; controversial for ethical reasons.

Hierarchy of the Body

Cell → Tissue → Organ → Organ system → Organism.

Epithelial tissue

Protective lining; ex. skin, lungs.

Muscle tissue

Contracts for movement.

Nervous tissue

Sends electrical signals.

Connective tissue

Supports body; ex. bone, blood.

Digestive System

Function: break down food, absorb nutrients, remove waste.

Villi & microvilli

Tiny folds in the small intestine that increase surface area for nutrient absorption.

Respiratory system

Takes in oxygen, releases carbon dioxide.

Alveoli

Air sacs where gas exchange happens.

Circulatory system

Moves blood around the body.

Arteries

Carry blood away from the heart.

Veins

Carry blood to the heart.

Capillaries

Very small vessels where gas exchange occurs.

Meristematic cell

Plant stem cell that divides to make new plant tissues.

Dermal tissue

Outer protective layer of plants.

Vascular tissue

Transports materials (xylem = water, phloem = sugar).

Ground tissue

Photosynthesis, storage, support.

Root tissue

Absorbs water/minerals.

Root system

All roots of a plant.

Shoot system

Stems + leaves + flowers (above ground).

Transpiration

Water evaporating from leaves → pulls more water up.