Cell Biology Basics

Cells

• All living things are made up of cells.
• Types of cells: unicellular (e.g., amoeba, paramecium, bacterium) and multicellular organisms.

Types of Human Cells

• Nerve cells
• Red blood cells: biconcave disc shape
• Muscle cells

Cell Structures and Functions

Animal Cell

• Cell membrane: controls the movement of substances into and out of the cell

Plant Cell

• Cell wall: protects, supports, and gives regular shape to the cell
• Large vacuole: contains mainly water and stores dissolved minerals
• Chloroplast: where photosynthesis takes place to make food

Common Cell Structures

• Nucleus: contains genetic materials (DNA)
• Cytoplasm: where chemical reactions (e.g., respiration) take place
• Cell membrane: controls the movement of substances into and out of the cell

Genetic Materials

• DNA (deoxyribonucleic acid): contains all instructions needed for the cell to carry out activities
• Function: determines features and characteristics inherited from parents

Cell Division

• Procedure:
  • Genetic materials make a copy of themselves
  • Nucleus divides into two
  • Cytoplasm divides into two
  • Two daughter cells are formed (with nucleus)
  • Daughter cells absorb nutrients and grow bigger

Abnormal Cell Division

• Cancer: cells divide abnormally

Microscope

• Purpose: to observe cells that are too small for the naked eye
• Types: light microscope (2D), electron microscope (3D)
• Structure:
  • Cover slip: to keep the specimen (e.g., onion skin) flat and prevent drying out
• Magnification:
  • Formula: Magnification = eyepiece x objective
  • Longer eyepiece: lower magnification
  • Longer objective: higher magnification

Microscope Usage Procedure

• Steps:
  1. Take the microscope on the arm and base
  2. Place near a light source
  3. Choose lower-power eyepiece and objective
  4. Adjust brightness
  5. Prepare specimen (e.g., onion skin, animal cell)
  6. Place specimen on slide, add solution, and cover with a cover slip
  7. Place slide on stage and hold in place with clips
  8. Observe with both eyes open
  9. Adjust coarse and fine adjustment knobs for a clear image
  10. Use higher magnification objective for further magnification
  11. Use fine adjustment knob only for focusing

Image Produced by Microscope

• Magnified and inverted
• Move left, see move right; move towards yourself, see move away from you

Sex Cells

• Sperms:
  • Have head and tail
  • Tail enables sperm to swim
  • 23 chromosomes with 1 sex chromosome (50% X, 50% Y)
• Ova (Egg):
  • Spherical shape
  • Surrounded by a jelly coat
  • Cannot move by itself