L3 Energ reacs in cells

Question 1

LO2: origins and fates of cell nutr.

Answer 1

• ori- diet, synth from precurs, rel from stor.
• transf in tiss- deg to rel energ in all tiss. synth cell compons excep mat erythroc. storage eg liver, adipose, skel musc. interconv to other nutr eg liver, adipose, kideny cortex. excretion eg liver, kidney, lung.

Question 2

LO3: rel btw catab and anab.

Answer 2

• catab paths- breakd larger molecs to small intermed metabols. rel lot free energ. break bonds. small step. pack energ. oxidative- rel H+-RP. forms co2, h2o.
  PRODS- build blocks eg sug, aa, fa. some need furth breakd to- organ precurs eg carb, fat, aa metab mink by aCoA. RP. ATP.
• anab- synth larger cell compons from intermediary metabols. use energ rel from catab as atp. reductive- use H+ from catab.

Question 3

LO4: expl why cells need contin energ supp.

Answer 3

• energ= capac do work. eg biosynth, transp x mem, spec func eg musc, nerve conduc, osmot.
• bal- av intake=expend. energ reqs:
  BMR- 1700/1400kcal req by awake indiv dur physic, dig, emot rest at 18 deg, sum of TOB.
  activity- 1000-3000kcal dep on type, intensity, durat. skel and heart musc.
  specif dynam action of food- 150kcal. ing, dig, abs food.
• excess stored adipose. need eg synth, rep, grow, preg.

Question 4

LO5: expl biol role ATP, creatine P and other molecs with high eenrg of hydrol of P grps.

Answer 4

• chem bond energ. eenrg change of chem reac ie bond break/form.
  exergonic rel eg catab, delta G less than 0=spont. P lower energ.
  endergonic req.
• ATP P bond hydrol rel energ. stand -31kJmol-1. energ used by coupling. must cyc, carrier NOT store. ATP stable w/o specif catalysts. energ flow contr, feedb. const t/o.
• some cells need incr metab activ v fast need high energ stores eg creatine P -43kJmol-1. creatine kinase to phosphocreatine uses ATP. Cr and PCr slow spont breakd to creatinine indic skel musc mass and kidney func. MI marker, CK-MM. use to estim urinary loss.
• phosphoenolpyruv to pyruv+Pi -62kJmol-1.
  1,3-BPG to 3-PG +Pi -49kjmol-1.

Question 5

LO6: role of redox reacs and H carriers in metab.

Answer 5

• redox reacs- bond energ of fuel molces rel by oxid reacs=rem e- or H atom (H+ and e-). accomp by reduc.
  -H atom transf to carrier, allow flexid use. NAD(P), FAD. cyc not store.
• carriers RP for: NADH for ATP prod, NADPH for biosynth. cont compons from B vits. reduced by add 2H+, one rel in sol.
• coupling- direc by use NADPH biosynth, indirec eg coup NADH to ATP prod.
  – carriers re-oxid by: cell resp, NADH and FAD2H from catab oxid in ETC, rel free eenrg for ATP synth. reused in catab.
  also reacs where S reduced eg lactic ac from pyruvic.
  reduction steps in biosynth.

Question 6

LO7: reoles of low and high energ sigs in metab reg.

Answer 6

• high energ sig activs biosynth eh high [ATP] and [NAD(P)H].
• low energ sig activs catab eg high [AM/DP] and oxidised NAD(P)+.

Question 7

LO1: define cell metabol and expl its funcs.

Answer 7

• metab=set of prcs that derive energ and raw mater from food and use to supp rep, growth, and activ of TOB to sust life.
• biol many small reacs few types. distinct but integ paths. some occ in all cells, some cert types or comparts. start pt, intermed metabols, end pts, interconnecs.
• FUNCS: energ for cell func and compjn synth, build blocks for growth, maint, rep, div. organ precursors allow interconv of blocks eg aCoA. biosynthet RP used in synth compons.