Unit 9: Cell Processes

electron carriers = substances that are easily oxidised and reduced NAD = nicotinamide adenine dinucleotide REDOX occurs here

glycolysis = breaking apart a sugar - anaerobic within cytoplasm, enzyme catalysed steps PRODUCES - 2 ATP - 2 pyruvate molecules - 2 reduced NAD STEPS: (see diagram on iPad, C1.2.8)

ADP and NAD must be available for glycolysis to occur. If O2 available, reduced NAD is converted back to NAD. If no O2… pyruvate —–> lactate to convert reduced NAD to NAD by donating oxygen to make lactate Anaerobic respiration: - Glycolysis = 2 reduced NAD and 2 ATP - Lactate production uses 2 reduced NAD (oxidised to form NAD) - Net total = 2 ATP

Alcoholic fermentation = 2 steps to regenerate NAD if we want ethanol, no O2 allowed. BREAD 1. aerobically respires (producing water and co2) 2. switches to anaerobic, but still co2 produced 3. co2 bubbles get trapped in bread dough (fluffy bread) 4. ethanol burns off during baking ALCOHOL 1. sugar –> ethanol and co2 2. anaerobic 3. let off co2 4. alcohol content ↑ with sugar content 5. can be used for alcoholic drinks or bioethanol (renewable fuel)

See iPad C1.2.11

proteins embedded in the inner membrane of the mitochondria that are easily reduced and oxidised (gain and donate e-)

reduced NAD and reduced FAD donate e- to the chain

some energy from the e- is released at each pass along the chain the energy is used to pump protons from matrix to intermembrane space e- from reduced NAD = 10 e- from reduced FAD = 6 generates a high conc. gradient of protons in the intermembrane space

movement of protons from high conc. to low conc. through ATP SYNTHASE in order to convert ADP to ATP –> ATP synthase = channel protein for facilitated diffusion, catalyses the conversion of ADP to ATP through phosphorylation –> as protons move through, the part of the ATP synthase that extends into the matrix rotates. —-> causes conformational change in the protein, allowing ADP and a phosphate to bind conc. gradient –> kinetic energy –> bonds Reduced NAD: 2.5 ATP Reduced FAD: 1.5 ATP

reduction happens when 1 molecule has a higher affinity for electrons than the molecule getting oxidised oxygen has a high affinity for electrons –> acts as the final electron acceptor –> combines with H+ ions in the matrix to produce water w/o oxygen, there is nothing to accept the electron, then all of the electron carriers stop accepting electrons –> reduced NAD/FAD cannot donate electrons, so they remain reduced and then anaerobic respiration must take place to regenerate NAD –> yields less ATP

CARBS energy content: 4 cal/g reason: lots of O glycolysis?: yes anaerobic possible?: yes LIPIDS energy content: 9 cal/g reason: lots of C-H glycolysis?: no anaerobic possible?: no

= arrays of pigment molecules that can generate and emit excited electrons see iPad C1.3.9 photosystem II (wavelength 680) –> e- from photolysis of water –> produces ATP photosystem I (wavelength 700) –> e- from PS II –> produces reduced NADP

• lots of pigments = lots of photons can be absorbed • increases range of wavelengths • efficient energy transfer to the reaction center

splitting of water using energy from light

photon enters the photosystem and bounces around the pigment molecules then e- is lost (excitation) water is split to replace e- from photosystem II 2H2O –> O2 + 4H+ + 4e- this was what oxygenated the atmosphere and an increase in biodiversity after the evolution of early life forms

see C1.3.12 iPad

NAD = respiration NADP = photosynthesis see C1.3.12 iPad

systems for performing the light-dependent reaction of photosynthesis Bacterial thylakoids are part of the membrane Eukaryotic thylakoids are inside chloroplasts light independent reaction occur in the stroma (area around the thylakoids

carbon fixation reduction RUBP regeneration

RuBP = ribulose bisphosphate Rubisco = most abundant enzyme on earth but very inefficient, it is responsible for carbon fixation carbon fixation = attachment of a CO2 molecule on RuBP see C1.3.15 on iP ad

respiration substrate cellulose cell wall stored as starch

make amino acids, lipids using other metabolic pathways and the addition of other minerals

light dependent reactions PRODUCE ATP and reduced NADP light independent reactions REQUIRE ATP and reduced NADP PS II –> produces ATP PS I –> produces reduced NADP both are used in the calvin cycle