Type of cells
Prokaryote: Primitive cell type that does not possess a nucleus
Eukaryote: 'True Nucleus'. Type of cell found in multicellular organisms.
Cell Structure - Eukaryotes
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
Cell Structure - Eukaryotes Continued
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
- Age (youger has higher proportion)
- Hydration status
- 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
- Diffusion: Movement of solute molecules from a high concentration to low concentration through a semi permeable membrane.
- Molecular size: Larger molecules do not pass through easily
- Lipid solubility: Lipid molecules pass more easily as membrane is lipid.
- Molecular charge : Charge reduce molecules ability to pass through membrane.
- Faciliated diffusion: Molecules assisted tho pass through the membrane. No ATP used.
- Carrier proteins
- Protein Channels
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
Chromosomes in animals
Cat - 38 - 19 pairs
Dog - 78 - 39 pairs
Human - 46 - 23 pairs