Cells

Prokaryote: Primitive cell type that does not possess a nucleus

Eukaryote: 'True Nucleus'. Type of cell found in multicellular organisms. 

Cell membrane: Provides cell shape, prevents contents from escaping and allows transport of molecules in and out of the cell. Made of a phospholipid bilayer (hydrophillic head and hydrophobic tail) and protein channels/transporters. 

Cytoskeleton: Provides support to the cell. Helps metabolic activities and anchors the organelles.

Microtubules - cables which the organelles are attached and may move. 

Intermediate fibres - tough, resists force to minimise cell damage.

Microfilaments- located near the cell membrane. Involved in cell division.

Cytoplasm: Fluid that fills the cell. Provides organelle support, nutrients and site for chemical reactions. 

Nucleus: Contains DNA in the form of chromosomes. Holds genetic material and manufactures ribosomes.

Ribosomes: Protein synthesis

Rough Endoplasmic Reticulum: Manufacture and transport of proteins.

Smooth Endoplasmic Reticulum: Manufacture and transport of steriod substances.

Lysosomes and Vacuoles: Lysosomes contain digestive enzymes for disposal of waste products. The remains are packed into vacuoles and excretes by exocytosis.

Golgi body: Modification of cell products. Involved in lysosome production.

Mitochondria: Responsible for producing ATP for energy for metabolic activities.

Centrosomes: 2 centrosomes located near the nucleus for cell division.

• 60 - 80% body made up of water
• Factors: 
  • Age (youger has higher proportion)
  • Hydration status
  • Diet
  • Fluid intake
• 66% Intracellular water: Water found within the cytoplasm
• 33% Extracellular water: Free fluid found within plasma of blood, lymphatic system, Cerebal spinal fluid, joint fluid, interstital fluid (surrounding cells)

Maintanance of homeostasis, cells must control transport and movement 

Passive transport: 

When a substance moves in and out of the cell in  the presence of ATP against the concentration gradient.

• Exocytosis: Mass movement of molecules out of the cell 
• Endocytosis: Mass movement of molecules into the cell
• Phagocytosis: When the cell membrane surrounds and engulfs material. Digested by lysosomes. Occurs in phagocytes
• Pinocytosis: Endocytosis of liquid

Movement of water molecules down the water potential gradient. (No ATP required)

• Tonicity: Defines relative concentration of 2 solutions separated by a semi permeable membrane.

• Hypotonic : Less solute molecules outside the cell than inside. Water moves into the cell

• Hypertonic: More solute molecules outside the cell than inside. Water moves out of the cell.

• Isotonic: Solute molecules equal inside and outside the cell.

• Solute molecules become charged when dissolved in water 

• Resting potential = -70mv 

• Sodium potassium pump imbedded in the membrane 3Na+ leave 2K+ enter

• requires ATP

• Occurs in all somatic cells
• For tissue growth and repair
• Binary Fission (identical daughter cells)

Interphase: DNA unravels

Prophase: DNA supercoils and replicates, Chromatids held together at centromere.

Metaphase: Chromosomes line up at equator, spindles attach to centromere.

Anaphase: Chromosomes are pulled apart to separate poles of the cell.

Telophase: Nuclear membrane reforms, pinches in center (cleavage furrow)

• Occures in gametes (sex cells)
• 4 genetically UNidentical daughter cells
• 1/2 chromosomes 

Interpase I: DNA unravels

Prophase I: Homologous pairs duplicate, crossing over and exchange genetic information

Metaphase I: Chromosomes line up at equator

Anaphase I: Chromosomes pulled to opposite poles

Telophase I: Cytoplasm divides

Metaphase II: Chromosomes line up at equator

Anaphase II: Chromatids pulled to opposite poles

Telophase II: Cytoplasm divides, nuclear membrane reforms

Cat - 38 - 19 pairs

Dog - 78 - 39 pairs

Human - 46 - 23 pairs