compendium 5 Flashcards
ways ions and molecules can pass through cells
- diffusion through lipid bilayer
- diffusion though ion channels
- facilitated diffusion using carrier
- active transport
- exocytosis
- endocytosis
- diffusion through lipid bilayer
Diffusion through lipid bilayer
lipid soluble substances
Moves from high concentration to low concentration
- diffusion through ion channels
water soluble substances
Need proteins to move across membrane
Moves from high concentration to low concentration
- facilitated diffusion using carrier
a solute binds to a specific transporter on one side of the membrane and is released on the other side
Glucose - out of the cell
Fructose - into the cell
Rate of movement depends on steepness of concentration gradient and number of transporter proteins in membrane
Some are continuously open and some are gated
- active transport
requires ATP
Moves solutes against the concentration gradient
primary active transport: energy derived directly from ATP eg sodium potassium ion pump, maintains low concentration of Na+ and high concentration of K+
Secondary active transport: energy derived indirectly from ATP
- exocytosis
out of the cell
Secretary vesicles fuse with the plasma membrane and the secretory vesicles contents are released into the extracellular fluid
endocytosis
into the cell
Pinocytosis - engulfing small particles and fluids
Phagocytosis - engulfing large particles
Receptor mediated endocytosis - the movement of substances into the cell involving caveolae regions of the cell membrane
osmosis
Movement of water from a low solute concentration to a high solute concentration across a semi permeable membrane
Movement from low salt solution to high salt solution
Occurs when membrane is permeable to water but not certain solutes
aquaporins
transmembrane proteins that function as water channels
= osmosis
isotonic
no net movement of water, maintain normal shape
hypotonic
cell gains water and swell / burst
hypertonic
cell lose water and shrink
3 destination for the nutrients we eat
Energy
Structural or functional molecules
Storage compounds
Metabolism
all chemical reactions in the body
Catabolism
chemical reactions that break down complex organic molecules
Anabolism
chemical reactions that build up simple molecules into complex molecules
atp
- molecule for temporary storage of energy
- used for muscle contraction, active transport, movement of structures within cells
escribe the main stages of glycolysis and name its products
Breakdown of glucose
Glucose + 2NAD+ + 2ADP + 2iP - 2 pyruvic acid + 2NADH2 + 2ATP
- occurs in cytoplasm
Two ATP molecules are used to activate glucose
6C sugar is split into two 3C sugars
each sugar has a phosphate group
3. Phosphates are split from the sugar and captured by ADP to form 4 ATP molecules
remaining 3C sugars are pyruvic acid
Net gain of 2 ATP molecules
If O2 available pyruvic acid prepares to enter kreb cycle
If O2 not available pyruvic acid reduced to form lactic acid which diffused out of cell into blood which then convert it back to pyruvate
Describe the main stages of the citric acid cycle (Krebs cycle) and name its products
occur in matrix of mitochondria
Acetyl CoA (2C) enters the cycle and combines with a 4C compound to form citric acid = 6C
6C citric acid becomes 4C oxaloacetic acid through chemical transformations
Each acetyl CoA molecule produces
2 CO2
3 NADH2
1 ATP
1 FADH2
There are 2 CoA going into kreb cycle therefore x2
Briefly explain oxidative phosphorylation (electron transport chain) and how ATP is produced in the process
= pathway where energy is liberated by the movement of electrons through the electron transport chain
Glucose + 6O2 - 6CO2 + 6H2O + 36-38 ATP
occurs in inner membrane of mitochondria
Most energy produced here
Electron donors and acceptors
Movement of electrons from molecule to molecule release energy creating proton gradient
Proteins act as proton pumps which move H+ into the inner membrane space
H+ ions move through special channel used by ATP synthase to produce ATP
By product is water
Produces between 32-34 ATP
Total produced per molecule of glucose is 36-38 ATP
- How is glucose used to produce energy within cells? Describe the stages of cellular respiration.
glucose is catabolised in three ways
Glycolysis
Krebs cycle
Electron transport chain and oxidative phosphorylation
Anaerobic - ATP production in absence of O2 (glycolysis)
Aerobic - ATO production using O2 (oxidative phosphorylation)
4 steps of cellular respiration
Glycolysis
Formation of acetyl CoA as a transitional step
Krebs cycle
Electron transport chain
Integral proteins
width of whole membrane
Peripheral proteins
inside or outside of membrane like floating icebergs
Antiporters
moving in opposite direction
Symporters
travelling in the same direction
Formation of acetyl CoA
pyruvic acid enters the mitochondria and undergoes decarboxylation
2C acetyl group is attached to coenzyme A to form acetyl coenzyme A which enter the Krebs cycle
Coenzyme A is derived from vitamin B
Arrangements of phospholipid molecules
double layer
Polar heads (hydrophilic) facing the intracellular and extracellular fluid
Non-polar fatty tails (hydrophobic) facing the interior of the membrane
Hydrophobic
not water loving
Hydrophilic
water loving
Fluid mosaic model
not rigid structure, can change its shape and composition over time
cell membrane = Gate keeper of the cel
highly selective, controls what can pass in or out of the cell
Water will move in a direction of a higher solute concentration
- solution with higher solute concentration has a lower concentration of water molecules so the water moves towards the lower concentration of water molecules to even things up
osmolarity
= concentration
if a molecule has osmolarity of 290 and a solution has an osmolarity of 120
= hypotonic as the cell has less water molecules then the solution therefore the water moves into the cell
