compendium 5

Question 1

ways ions and molecules can pass through cells

Answer 1

1. diffusion through lipid bilayer
2. diffusion though ion channels
3. facilitated diffusion using carrier
4. active transport
5. exocytosis
6. endocytosis

Question 2

1. diffusion through lipid bilayer

Answer 2

Diffusion through lipid bilayer
lipid soluble substances
Moves from high concentration to low concentration

Question 3

2. diffusion through ion channels

Answer 3

water soluble substances
Need proteins to move across membrane
Moves from high concentration to low concentration

Question 4

3. facilitated diffusion using carrier

Answer 4

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

Question 5

4. active transport

Answer 5

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

Question 6

5. exocytosis

Answer 6

out of the cell
Secretary vesicles fuse with the plasma membrane and the secretory vesicles contents are released into the extracellular fluid

Question 7

endocytosis

Answer 7

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

Question 8

osmosis

Answer 8

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

Question 9

aquaporins

Answer 9

transmembrane proteins that function as water channels
= osmosis

Question 10

isotonic

Answer 10

no net movement of water, maintain normal shape

Question 11

hypotonic

Answer 11

cell gains water and swell / burst

Question 12

hypertonic

Answer 12

cell lose water and shrink

Question 13

3 destination for the nutrients we eat

Answer 13

Energy
Structural or functional molecules
Storage compounds

Question 14

Metabolism

Answer 14

all chemical reactions in the body

Question 15

Catabolism

Answer 15

chemical reactions that break down complex organic molecules

Question 16

Anabolism

Answer 16

chemical reactions that build up simple molecules into complex molecules

Question 17

atp

Answer 17

• molecule for temporary storage of energy
• used for muscle contraction, active transport, movement of structures within cells

Question 18

escribe the main stages of glycolysis and name its products

Answer 18

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

Question 19

Describe the main stages of the citric acid cycle (Krebs cycle) and name its products

Answer 19

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

Question 20

Briefly explain oxidative phosphorylation (electron transport chain) and how ATP is produced in the process

Answer 20

= 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

Question 21

5. How is glucose used to produce energy within cells? Describe the stages of cellular respiration.

Answer 21

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

Question 22

Integral proteins

Answer 22

width of whole membrane

Question 23

Peripheral proteins

Answer 23

inside or outside of membrane like floating icebergs

Question 24

Antiporters

Answer 24

moving in opposite direction

Question 25

Symporters

Answer 25

travelling in the same direction

Question 26

Formation of acetyl CoA

Answer 26

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

Question 27

Arrangements of phospholipid molecules

Answer 27

double layer
Polar heads (hydrophilic) facing the intracellular and extracellular fluid
Non-polar fatty tails (hydrophobic) facing the interior of the membrane

Question 28

Hydrophobic

Answer 28

not water loving

Question 29

Hydrophilic

Answer 29

water loving

Question 30

Fluid mosaic model

Answer 30

not rigid structure, can change its shape and composition over time

Question 31

cell membrane = Gate keeper of the cel

Answer 31

highly selective, controls what can pass in or out of the cell

Question 32

Water will move in a direction of a higher solute concentration

Answer 32

• 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

Question 33

osmolarity

Answer 33

= 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