CELLULAR TRANSPORT
CELL TRANSPORT TERMS
Concentration: amount of material per unit volume, or as a percentage
Solution: one substance (solute) dissolved in another (solvent)
eg. saltwater has salt (solute) dissolved in water (solvent)
Diffusion: movement in a solution from an area of high concentration to an area of low
concentration (different regions of concentration = concentration gradient)
-material diffuses naturally by KMT
Brownian movement: movement in straight line until collision, then movement in new straight line
Osmosis: diffusion of solvent (usually water) through a membrane
Dialysis: diffusion of solute (eg. salt, water) through a membrane
Hypotonic solution: concentration of solute is lower in solution than in cell
(eg. cell in fresh water: water will enter cell, salt will leave cell, cell gets bigger)
Hypertonic solution: concentration of solute is higher in solution than in cell
(eg. cell in salt water: water will leave cell, salt will enter cell, cell shrinks)
Isotonic solution: concentration of solute inside the cell is equal to outside
-diffusion will stop, as there is no concentration gradient
Turgid:
- describes a swollen cell filled with solvent (in hypotonic solution)
-if a plant cell is turgid, the large vacuole remains filled, and the cell wall holds shape
-if an animal cell is turgid, the cell swells, then explodes (lyses) due to lack of cell wall
Turgor pressure: pressure of water pushing out on the cell membrane
Osmotic pressure: pressure of water through the cell membrane
Plasmolysis: cell membrane shrinking (in hypertonic solution)
Passive Transport: movement through a membrane by diffusion, without use of cellular energy
1. Simple diffusion: some substances can diffuse through imperfections in the cell membranes
phospholipid bilayer
-this occurs to small uncharged (eg. oxygen) as well as polar compounds (eg. water)
2. Facilitated diffusion: diffusion of larger particles (eg. glucose) or charged atoms (eg. sodium ions)
-this occurs through proteins in the phospholipid bilayer
Active Transport:
-movement through a membrane via proteins using the cells energy (ATP provides this energy)
-this occurs against a concentration gradient (low to high conc.) or with gradient but quicker
eg. sodium/potassium pump needs ATP to move sodium against a concentration gradient
Large Scale Transport:
-bulk movement of particles into vacuoles using ATP
Endocytosis:
-bulk movement into cells
a) Phagocytosis: “cell eating”
-cell reaches out with pseudopods (cell arms)
-food is surrounded in a vacuole this way
-lysosomes add digestive enzymes to vacuole
(eg. white blood cells)
b) Pinocytosis: “cell drinking”
-liquid is ingested as cell membrane pinches in with small vacuoles
c) Receptor Mediated Endocytosis:
-particles land on receptors on cell membrane
-the receptors clump together and are engulfed in a vacuole
Exocytosis:
-bulk movement out of cells
-vacuole (or vesicle) merges with cell membrane, releasing contents
PHOTOSYNTHESIS
Photosynthesis:
-chemical reactions which make sunlight energy into stored chemical energy (sugar)
-occurs in green chlorophyll in chloroplasts of plants
Chloroplast structure: -have double membrane
-fluid stroma
-stacks of chlorophyll containing lamella called grana
-space called intergrana in between grana
two reactions occur:
light-dependent reactions:(occurs in thylakoid membranes)
-water (with red and blue light) is turned into oxygen and hydrogen
light-independent reactions:(occurs in stroma)
-hydrogen and carbon dioxide make glucose (sugar)
word equation:
red and blue light + carbon dioxide + water ---chlorophyll---> oxygen + glucose
symbol equation:
red and blue light + 6CO2 + 6H2O ---chlorophyll---> 6O2 + C6H12O6 (stored chemical energy)
REACTANTS
PRODUCTS
Autotrophs:
-organisms that produce their own food (eg. plants ---> with chloroplasts, algae, some bacteria)
chemosynthesis:
-some bacteria make ATP from sulphur and iron containing compounds
AEROBIC CELLULAR RESPIRATION
Aerobic Cellular Respiration:
-stored chemical energy (sugar) is broken into useful stored chemical energy (ATP) using oxygen
ATP = adenosine triphosphate
-ATP is an easy to use chemical energy, used for life functions
ADP + energy + phosphate <----> ATP (energy now stored in bonds)
-energy is released as ATP breaks into ADP and P (exergonic reaction – energy is lost)
-building ATP is an endergonic reaction as energy is stored
-partially occurs in mitochondria
mitochondria structure: - outer and inner membranes
-a folded inner membrane(called a cristae)
-a fluid called matrix in the middle
-three reactions occur:
1. Glycolysis (in cytoplasm): 1 glucose makes 2 ATP
2. Kreb’s cycle (in matrix of mitochondria): oxygen is used, 2 ATP and carbon dioxide are made
3. ETC (in inner membrane of mitochondria): water is made, as well as 32 ATP
word equation:
36 ADP + 36 P + glucose + oxygen ---enzymes-> water + carbon dioxide + 36 ATP
symbol equation:
36 ADP + 36 P + C6H12O6 + 6 O2 ---enzymes->6 H2O + 6 CO2 + 36 ATP
ENZYMES
Enzymes are “organic catalysts”
Catalyst:
-chemical that reduces energy needed to start reactions (activation energy)
eg. now reaction will occur at room temperature
Organic:
-from living things, containing C, H
ANAEROBIC CELLULAR RESPIRATION
Fermentation is also called anaerobic cellular respiration
-stored chemical energy in glucose is converted into 2 ATP without the use of oxygen
Comparison
Point
organisms
first reaction
formula
Alcoholic Fermentation
Lactic Acid Fermentation
-bacteria, yeast
-bacteria, animals
-glycolysis
-glycolysis
glucose ---enzymes-> 2ATP +
ethyl alcohol + CO2
glucose –enzymes-> 2ATP +
lactic acid