C1.2 Respiration SL Flashcards
what is ATP full name
ATP = adenosine triphosphate = the energy currency of the cell
adenosine is a base in DNA (altered version)
triphosphate = 3 phosphate
what is ATP?
- nucleotide
- contains the base adenine a 5-carbon sugar (ribose) and 3 phosphate groups
what is ATP made from?
- converted from adenosine diphosphate (ADP) and phosphate in condensation, catalysed by the enzyme ATP synthase using energy from organic compounds (e.g. glucose)
- this is done by aerobic and anaerobic respiration
- one glucose molecule creates 36ATP molecules in aerobic respiration and 2ATP molecules in anaerobic respiration
chemical properties of ATP
- table at neutral pH (as in the cytoplasm)
- will not pass through the phospholipid bilayer through simple diffusion, so a cell can control where the TP is located inside the cell or organelle
- when the 3rd phosphate is removed in hydrolysis (i.e. ATP → ADP + phosphate), a small amount of energy is released for the cell’s metabolic reactions
- a small amount is usually sufficient
- if too much energy is released, it would be wasted as heat
define cell respiration
the controlled release of energy from organic compounds to form ATP
how to control the release of energy in cell respiration?
end product inhibition
what life processes need ATP?
- active transport across membranes
- synthesis of macromolecules (anabolism)
- movement of the whole cell or cell components (e.g. chromosomes during anaphase)
- mitosis: sister chromatids; meiosis: bivalent
what are the organic compounds used in respiration?
- Usually glucose/carbohydrates
- Sometimes lipids/fatty acids, proteins
- Organic compounds contain carbon and hydrogen (hydrocarbons)
- exceptions: oxides, carbonates, hydrogencarbonate
Why store in glycogen form and not in glucose form?
- glycogen is insoluble
- glucose is soluble
- affects concentration gradient + water potential
- water potential inside cell decreases, water will enter the cell → cell will burst & die :(
what is pyruvate converted into?
lactic acid/lactate
INSERT CARDS ABOUT RESPIRATION PROCESS FROM DIAGRAM
describe aerobic respiration
- aerobic respiration occurs in the presence of oxygen
- reactions continue in the mitochondria
- a large yield of ATP
- water is waste product recycled in the cell
- CO2 is excreted through gas exchange
describe anaerobic respiration
- occurs in absence of oxygen
- reactions do not continue in the mitochondria
- carbon dioxide and ethanol are produced in yeast (fermentation) → bread, beer
- lactic acid/lactate produced in humans and other animals
- the overall yield of ATP is very low
what are the similarities between aerobic and anaerobic cell respiration
- both can start with glucose
- both produce pyruvate (by glycolysis)
- both produce ATP
- both produce CO2
what are the differences between aerobic and anaerobic cell respiration
Aerobic
- uses oxygen
- high yield of ATP
- waste products: CO2 and water
- pyruvate carried to mitochondria
- can metabolise other molecules
Anaerobic
- no oxygen
- low yield of ATP
- waste products: CO2 and ethanol (yeast), lactic acid (animals)
- occurs in cytoplasm only
- can only use glucose
what is the graduated syringe used for in respirometer experiment?
used to reset the experiment and repeat it for reliability
1) Explain the need for a base inside the respirometer [2]
absorb CO2
ensure that volume changes are due only to oxygen uptake
2) Deduce, giving a reason, the direction in which the fluid will move in the right-hand side of the capillary tube [2]
- the fluid will move upwards, towards the animal tissue in the tube
- volume of air inside tube reduces due to oxygen uptake
3) Predict, with a reason, the change in the amount of oxygen inside the tube during the experiment [2]
oxygen used by organism/tissue/cells
by aerobic respiration
4) Explain how the following changes would improve the reliability of results from the experiment: putting the test tube in a thermostatically controlled water bath [2]
- keep temp constant
- prevents volume changes due to temp changes
- heat produced by respiration
- external temp may change during an experiment
4) Explain how the following changes would improve the reliability of results from the experiment: attaching another test tube to the left-hand side of the capillary tube, that is identical to the right-hand tube but does not contain respiring tissue [2]
- seals the apparatus to prevent external pressure changes having an effect
- counteracts changes in external temperature both tubes affected equally so manometer fluid shouldn’t move
5) Discuss whether the repeats at each temperature are close enough to indicate that the results are reliable [1]
all close enough so results are reliable
8) Deduce (only state!!) the relationship between temperature and the respiration rate of the germinating pea seeds, using the graph [2]
non-linear/larger increase with each 5C rise in temp
- positive correlation (i.e. as temp increases, the volume of oxygen used = respiration rate also increases)
- sharpest increase from 25°C to 30°C, could indicate that the optimum temperature of enzymes used in respiration is between these values or above 30°C
ANAEROBIC RESPIRATION IN YEAST
9a calculate total loss of mass and mean daily loss
560-544g
15-16g total mass loss divided by 13 days
1.2 g per day
9b explain the loss of mass
anaerobic cell respiration / alcoholic fermentation
CO2 is a waste product
release of CO2 leads to loss of mass from the solution
10
population growth of yeast / more respiring
positive feedback / increasing co2 from higher pop leads to lower solubility
waste heat decreases co2 solubility
11 Suggest two reasons for the mass remaining constant from day 11 onwards [2]
substrate has run out
death of year (from high alcohol)
12 Suggest how the rate of respiration can be calculated from the data [2]
divide mass decrease values by time units
