Topic 5 - energy for biological processes Flashcards
draw and label the parts of a chloroplast, explaining their function
stroma (fluid)> where ATP is used, converting carbon dioxide to glucose
granum> stacks of thylakoids
thylakoids> where chlorophyll captures energy from light and uses it to produce ATP
inner and outer membrane (envelope)
lamellae > join together stack of membranes called grana
what are the two types of chlorophyll?
Which is the main pigment and which is an accessory?
chlorophyll A is the main pigment and chlorophyll B is the accessory pigment
what are the two stages of photosynthesis? where do these stages occur?
light dependent reactions (happens on thylakoid membranes)
light independent reactions (happens in stroma)
outline and explain the light dependent stage of photosynthesis
electrons hit chlorophyll in PSII , magnesium is reduced
Mg-> Mg2+ + 2e-
electrons are excited (go up energy levels)
can’t maintain this energy so they fall passively, releasing energy, and pumping H+ ions through thylakoid membrane
light energy absorbed by PSI - pair of electrons ‘excited again’
H+ ions turn ATP synthase (ADP->ATP) - this is chemiosmosis
These H+ join with NADP to form NADPH
photolysis is continually happening in the thylakoid
2H2O-> 2H++2e-+O2
electrons replace magnesium’s lost electrons
(ATP and NADP then used in light INDEPENDENT reaction.)
outline and explain the light independent stage of photosynthesis
calvin cycle
fixation:
RuBP (5 carbons) joins with CO2 to make 6 carbon compound, catalysed by RUBISCO
6 carbon splits into 2X 3 carbon molecules of GP
reduction:
each GP reduced into GALP
NADPH -> NADP (provides H for reduction)
ATP-> ADP + pi ( energy)
(some GALP removed from cycle and used to make glucose/lipids/AA)
regeneration:
regenerated back to RuBP
1 carbon taken to make glucose, other 5 taken back into cycle
ADP + Pi -> ATP
(takes 6 turns of the cycle to make glucose)
what molecule is produced by photophosphorylation?
ATP
where does carbon fixation take place in a chloroplast?
stroma
explain why the light-independent stage can’t happen without tight dependent stage.
light dependent stage produces products needed
ATP- provides energy
NADPH- used for reduction of carbon dioxide/GP
what are photoreceptors in plants used for and what are they affected by?
photoreceptors are used in plant growth and development.
they are affected by darkness.
when does cyclic phosphorylation take place?
when the chloroplast requires increased amount of ATP
what increases proton gradient?
H+ (protons) pumped from stroma through thylakoid membrane (can’t diffuse back)
NAD -> NADH (proton taken from stroma, decreasing amount of protons in stroma)
photolysis- protons are produced from water in thylakoid interior.
how is ATP generated in photosynthesis?
chemiosmosis during light dependent stage in electron transport chain
movement of H+ turns ATP synthase , turning ADP + Pi into ATP
what are the stages of aerobic respiration?
GLYCOLYSIS
glucose phosphorylated into 6c (ATP>ADP)
6c broken down to 2 x TP (ATP>ADP)
TP into pyruvate (NAD>NADH) (ADP>ATP)
LINK REACTION
pyruvate (3c) decarboxylated to form acetyl coenzyme A (2c)
NAD>NADH
KREBS CYCLE
acetyl coenzyme A joins with 2x oxalacetic acid
forms 6c citrate (enzyme returns to LINK)
6c citrate decarboxylated into 5c
NAD+>NADH
NAD>NADH2
5c is decarboxylated into 2x oxalacetic acid
FAD>FADH2
ADP>ATP
OXIDATIVE PHOSPHORYLATION
NADH and FADH2 now in ETC
carrier 1- NADH oxidised to NAD
carrier 2- FADH2 oxidised FAD
electrons fall between electron carriers in a series of redox reactions
what are the stages of anaerobic respiration?
mammals:
glycolysis : glucose,6c, 2xTp > pyruvate > lactate (by lactate dehydrogenase) NADto NADH
plants/yeast (fermentation) :
glycolysis : glucose,6c, 2xTp > pyruvate> 2x ethanal (2x co2 lost) > 2x ethanol (by alcohol dehydrogenase) (NADH to NAD)
how can a sprinter release sufficient energy without having enough oxygen available?
aerobic respiration with oxygen available
glycolysis produces ATP rapidly
some ATP already store din muscles
anaerobic respiration> produces lactate from pyruvate
body intolerant to lactate
needs to recycle NADH
