L8 energ stor: glycogen and fat

Question 1

LO2: desc reacs in glycog synth and breakd.

Answer 1

SYNTH: reqs energ.
gluc to G6P (by HK in liv) to G1P and UDP (P glucomutase) to UDP gluc (uridyl transferase) to glycogen(n+1) by glycogen synthase.
GLYCOGENOLYSIS: stress
glycog to gluc1P and glycog(n-1) (glycog Pase) to G6P (P glucomutase) ent musc for glycol or liver for gluc rel to blood.

Question 2

LO3: comp funcs of liv and musc stores.

Answer 2

-glycog polar so lim amnt can store, attr water. no spec stor tiss. liver store up to 100g, musc 300g.
-liver- gluconeogen- G6P to glucose by G6 Pase. glycog buff of blood gluc.
-musc- lack gluc6Pase so G6P to glycol to lactate or CO2 and atp.
-gluc1P to glycogen by gycog synthase and br enz.
rev by glycog Pase and de br enz.
-GLUT4 insulin sensit in musc and other periph. GLUT? in liver, not modul by insulin.
-REGUL:
glycog synthase INHIB by glucagon by P. ACTIV by insulin by deP.
glycog Pase INHIB by insulin by deP. ACTIV by adren by P.
in musc glucagon no eff. amp allost activ musc glycog Pase but not liver form.

Question 3

LO4: expl clinic conseqs glycog stor dis.

Answer 3

-inher err metab. defic/dysfunc enz. glycog Pase encod diff genes in musc/liver. glycog struc may be abnorm.
11 types, incid vary. sev deps on tiss/enz aff. liver and/or musc aff. excess glycog can= tiss dam. hypog and exerc intol. eg von Gierkes gluc 6Pase defic, liver. mcArdle dis musc glycog Pase defic.

Question 4

LO5: expl why and how gluc prod from non C source.

Answer 4

-8-10 hr fast glycog decr. 3 maj precurs gluconeogen:
lactate from anaer glycol in musc/RBC. cori cyc.
glycerol from adip breakd TAG.
aa mainly alanine. any whos emetab invs pyruv or or TCA intermeds can be conv to gluc.
-3 reacs NOT rev glycol:
in mito oxaloacetate to PEP by PEPCK.
F16bP to F6P by F16bPase. these 2 are maj contr sites. glucag and cortisol ACTIV. insulin INHIB.
gluc6P to gluc by gluc6Pase. all neg delta G.

Question 5

LO6: expl why TAG used as effic energ stor in adip.

Answer 5

• excess energ conv to TAG. phob, stor anhyd. 2x energ per g carb/prot. used in exerc, stress, starvat, preg. stor and mob horm contr.
• adipocytes- large lip drop TAG and chol esther. 0.1mm. av ad 30bn weigh 15kg. can incr size 4x bef div.

Question 6

LO7: desc how diet TAG proc for stor.

Answer 6

• small int TAG to glycerol and FA by panc lipase. int epith pack to chylomicron to LN to blood. to adip TAG lipop lipase high Km (ACTIV by insulin) so pref use diet chylom to stor. horm sensit lipase mobils FA (INHIB by insulin) to FA albumin in blood to consum tiss. can go straight to consum tiss from blood init by low Km lipop lipase. to FA oxid for energ.

Question 7

LO8: disc how FA deg diff from synth.

Answer 7

diff= flexib, contr, thermod irrev bypass.
-OXID:
cyc reacs rem 2C. 2C rem as aCoA. prod aCoA. MITO. sep enzs, mito ma. oxidative, prod FADH2 and NADH. req atp activ FA. intermeds linked to coA. reg indirec by FA av mito. STIM by glucag and adren. INHIB by insulin.
- SYNTH:
cyc reacs adds 2C. 2C added as malonyl CoA. cons aCoA. CYTOP. multi enz complex cytop. reductive req NADPH. req lot atp. intermeds linked to FA synthase by carr. reg direc by activ aCoA carbox. ACTIV by insulin. INHIB by glucag and adren.

Question 8

LO1: desc maj energ stores.

Answer 8

-gluc pref fuel. absol req eg R+WBC, testis, kidney medulla, lens and cornea. brain pref and always need some. glycogen store allows const BG. too much insulin= hypog, galactosaemia, chronic alc. BM 2.8 mM confus, 1.7 weak, 1.1 musc cramps, 0.6 brain dam and death.
-glycogen stored as grans-
musc- intra and inter myofib glycogen grans.
liver- grans in hepatocs.
glycog br origin from dimer glycogenin-primer at core. a1-6 ev 8-10 resids. 10-100kDa= min osomot eff. br= rap synth and deg.