Topic 1: Cell Biology

Overview

• Eukaryotic vs Prokaryotic Cells
  • All living things are made of cells: prokaryotic (bacteria) or eukaryotic (animals and plants).
  • Eukaryotic cells have a cell membrane, cytoplasm, and nucleus containing DNA.
  • Prokaryotic cells are smaller, with a cell wall, cell membrane, cytoplasm, single circular strand of DNA, and plasmids.
  • Organelles are structures within cells that perform different functions.

Orders of Magnitude

• Used to compare sizes, e.g., 10 times bigger is 10^1.
• Prefix multipliers: centi (0.01), milli (0.001), micro (0.000001), nano (0.000000001).

Animal and Plant Cell Structures and Functions

• Nucleus: Contains DNA coding for proteins; enclosed by a nuclear membrane.
• Cytoplasm: Site of chemical reactions; contains enzymes and organelles.
• Cell Membrane: Controls entry and exit of substances.
• Mitochondria: Site of aerobic respiration.
• Ribosomes: Site of protein synthesis, located on rough ER.

Plant Cells (Additional Structures)

• Chloroplasts: Site of photosynthesis, contains chlorophyll.
• Permanent Vacuole: Contains cell sap, provides rigidity.
• Cell Wall: Made of cellulose, provides strength.

Bacterial Cells

• Different cell walls made of peptidoglycan.
• Single circular DNA and plasmids in the cytoplasm.

Cell Specialisation

• Cells specialize through differentiation.
• Animal Cells: Differentiate once; examples include sperm, nerve, and muscle cells.
• Plant Cells: Retain ability to differentiate; examples include root hair and xylem cells.
• Stem Cells: Undifferentiated cells that can form specialized cells.

Microscopy

• Light Microscope: Uses light, max magnification x2000, resolving power 200nm.
• Electron Microscope: Uses electrons, max magnification x2,000,000.
• Calculations include magnification and object size.

Culturing Microorganisms (Biology Only)

• Grow microorganisms using nutrient broth or agar plates.
• Steps must be sterile to avoid contamination.
• Bacteria multiply by binary fission.

Cell Division

• Chromosomes: DNA coils, 23 pairs in each cell.
• Mitosis: Cell division cycle includes interphase, mitosis, and cytokinesis.
• Stem Cells: Types include embryonic, adult, and meristems.

Transport in Cells

• Diffusion: Movement from high to low concentration; passive.
• Osmosis: Water movement across membranes; passive.
• Active Transport: Movement against concentration gradient; requires energy.

Factors Affecting Diffusion

• Concentration gradient, surface area to volume ratio, temperature.

Adaptations for Efficient Exchange

• Large surface area, thin membranes, efficient blood supply.

Additional Topics

• Osmosis in Cells:
  • Effects on plant and animal cells in different solutions.
• Active Transport in Plants and Animals:
  • Needed for uptake of nutrients in root hairs and gut.