Cellular Processes (91156)

Cell Organelles
1. Plant Cells
  1. Chloroplasts - oval shaped, found in leaf cells (particularly palisade cells), and are the site of photosynthesis
    1. Chloroplast Structures
      1. Double Membrane - Outer is simple and permeable allows for great rate of transport of materials needed for photosynthesis -Inner is semi-permeable, only allowing for the entry and exit of reactants/products of photosynthesis
      2. Stroma - Clear fluid substance (so that sunlight can get through) - Where light independent reactions take place (CO2 and H2 join)
      3. Lamellae - tubes connecting Grana to each other
      4. Thylakoids + Grana - Thylakoids are individual flattened membranes arranged into disc shapes, light-dependent reactions occur here - Grana are stacks of thylakoids -Embedded in these membranes is chlorophyll, the light-absorbing pignment
    2. Chloroplasts are more abundant in regions of the plant that are exposed to sunlight, such as those close to the top of the leaf (but beneath the epidermal layer)
  2. Cell Wall - Made of cellulose bundled together, provide strength and structure for the cell
2. Animal Cells
  1. Centrioles - involved in cell division,, composed of microtubules which extend to form spindles moving chromosomes apart
  2. Cilia and Flagella - cellular projections, associated with movement in unicellular organisms and small animals
3. Both Cells
  1. Mitochondria - oval shaped, found in most cells (particularly those with high-energy demands), and are the site of aerobic respiration
    1. Mitochondria Structures
      1. Matrix - the space between cristae which contains many enzymes
      2. Cristae - inner membrane is folded into these to greatly increase the surface area for where Hydrogen Transfer chain reactions will occur
      3. Double Membrane
    2. Mitochondria are more abundant in animal cells, particularly those with high energy demands, eg. Muscle cells
  2. Vacuoles - membrane-bound sacs filled with fluid
    1. Lysosome - vacuole containing digestive enzymes, their job is to break down old organelles, digest bacteria engulfed by phagocytes/white-blood cells
  3. Golgi Body - After proteins have been synthesized in the ER, they are sent here to be modified
  4. Endoplasmic Reticulum (ER) - A network of membranes spanning across the cell that has multiple functions including being a transport system, carrying materials from one side of the cell to the other
    1. Smooth - no ribosomes attached and is instead responsible for the production of lipids and steroids
    2. Rough ER - ribosomes are attached, involved in protein production therefore, are common in cells that make/secrete proteins
  5. Nucleus - contains DNA in the form of chromatin, which organises all cell processes
    1. Nucleolus - inside the nucleus, produces the RNA components of ribosomes
  6. Ribosomes - site of protein synthesis/ production
  7. Plasma/Cell Membrane - A phospholipid layer with proteins embedded, and is semi-permeable (only allows some substances to enter/exit)
Cell Processes
1. Cell Division
  1. DNA Replication
    1. Happens before a cell divides
    2. 1. DNA unwinds
    3. 2. Nucleotides match up to exposed bases
    4. 3. Enzymes check and correct errors
    5. After replication 2 DNA molecules form a chromosomes, each identical half is called a chromatid, and are joined by a centromere
  2. Mitosis - Cell division that produces two identical cells for growth, repair and maintenance.
    1. 1. DNA replicates, nuclear membrane breaks down and spindles form
    2. 2. Chromosomes line up at equator (cell centre)
    3. .3 .Fibres contract, pulling chromatids to opposite ends of the cell
    4. 4. Nuclear membranes form. Cell Divides
  3. DNA Structure -
2. Respiration
  1. Anaerobic Respiration
    1. Occurs in the cell cytoplasm, not in Mitochondria
    2. Oxygen is not involved in this reaction
    3. Pyruvates formed in Glycolysis are broken down into lactic acid - this build up creates muscle fatigue
    4. Only Glycolysis takes place
    5. Substrates = Water + Glucose
    6. Products = Lactic Acid + 2 ATP
  2. Aerobic Respiration
    1. Substrates = Oxygen + Water + Glucose
    2. Products = Carbon Dioxide + Water + ATP + (heat energy)
    3. Symbol Equation = C6H12O6 + 6O2 --> 6H20 + 6CO2 + 38ATP + (heat energy)
    4. Three main chemical ENZYME-CONTROLLED pathways
      1. 1. Glycolysis - Occurs in Cytoplasm of cell (not Mitochondria), Glucose broken down into 2 pyruvate molecules, 2 ATP molecules produced
      2. 2. Krebs Cycle - occurs in matrix of Mitochondria, C02 (waste) and H atoms (used in next stage) are produced
      3. 3. Electron Transfer Chain - occurs in Cristae of Mitochondria, H atoms from Krebs cycle are ionised and their electrons are 'bounced' through electron transfer chain, the energy released is used to form ATP from ADP, electrons are then returned to H atoms to combine with O2 and form H20 (product)
        To become ATP (Adenosine Triphosphate), ADP (Adenosine Diphosphate) gains a phosphate
  3. How organisms get energy to fuel life processes
3. Photosynthesis
  1. Occurs only in Plants
  2. Products = Glucose + Water + Oxygen
  3. Substrates = Carbon Dioxide + Water
  4. Symbol Equation: 12H2O + 6CO2 -- (Sunlight +Chlorophyll) --> 6H2O + C6H12O6 + 6O2 OR 6H2O + 6CO2 -- (Sunlight +Chlorophyll) --> C6H12O6 + 6O2
  5. Two main chemical ENZYME-CONTROLLED pathways
    1. 1. Light-Dependent Reacton - takes places in grana of chloroplasts, sunlight is absorbed in thylakoid membrane, water is splt into Hydrogen H (used in next stage) and Oxygen 02 (Waste)
    2. 2. Light-Independent (Calvin Cycle) - Occur in stroma of chloroplast, CO2 and H enter the cycle and after extensive arrangement, Glucose (C6H12O6) is formed as the final product
  6. Rate of Photosynthesis Influences
    1. Temperature
    2. Light Intensity + Wavelength
    3. Substrate Concentration (CO2)
Enzyme Activity
1. Factors that infleunce Enzyme Activity
  1. Temperature
  2. pH
  3. Substrate Concentration
Transport of Materials
1. Active Transport
  1. Cytosis
    1. Endocytosis
      1. Pinocytosis
      2. Phagocytosis
    2. Exocytosis
2. Passive Transport
  1. Diffusion
    1. Facillitated Diffusion
    2. Osmosis

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Cellular Processes (91156)

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	Created by Demelza Robinson over 8 years ago