carbohydrates Flashcards
(53 cards)
1
Q
what are carbohydrates
A
organic molecules
gwnweral formula ch2o
2
Q
function of carbohydrates
A
- store enrgy in form of starch or glycoges
- energy source, through metabolism pathways and cycles
- supply carbon for synthesis of other compounds
- structural components
- dna/rna and atp
3
Q
groups of carbohydrates
A
- sugars: monosaccharides or disaccharides
- polysaccharides
4
Q
classification of monosaccharides
A
- number of c
- triose, tetrose, pentose, hexose
5
Q
classification of monosaccharides based on functional group
A
- aldoses: contain aldehyde group CHO
- ketoses: contain ketone group CO
6
Q
how are D and L designations made?
A
- assymetric C furthest away from aldehyde or ketone in monosaccharide related to the assymetric C of D-glyceraldehyde
- assymetric C = C thet has 4 diff entities
7
Q
what are anomers?
A
- special type of epimer
- occur avter cyclization
- reflect change in configuration at hemiacetal or hemiketal carbon C1
- alpha configuratin C1 = C2
- beta C1 is opposite of C2
8
Q
sugar derivates
A
- sugar acids
- amino sugars
- sugar alcohols
9
Q
disaccharides
A
2 monosaccharides bound with glycosydic bond
- maltose
- cellobiose
- lactose
- sucrose
10
Q
olygosaccharides
A
3-10 monosaccharides
11
Q
homopolysaccharides
A
- starch and glycogen
- cellulose
- hyaluronic acid
12
Q
starch
A
- common plant polysaccharide
- many alpha d glucoses
- amylose - watersoluable
- amylopectin - non water soluable
13
Q
glycogen
A
- animal storage product
- accumulate in liver and muscle
- non.water souable
14
Q
cellulose
A
- polysaccharide in plant cell wall
- degraded by microbila cellulase
non water soluable
15
Q
hyaluronic acid
A
- glucosaminoglycan
- repeating disaccharide
- degradation: hyaluronidase
16
Q
chondroitin sulphate
A
- vit A has role in suphate group binding
- structural component of cartilage and bone formation
17
Q
heparin
A
- soluable glucosaminoglycan in granules of mast cells
- highly sulphated
- repeating disaccharides
- extended helical conformation
- clearing factor bc of liberation of lipoprotein lipase in blood
18
Q
heteropolysaccharides
A
glycoproteins
19
Q
glycoproteins
A
- carbohydrate portion is shorter and often brnched
- serve as structural proteins, constituent of cell membrane, antigenic determinants of blood groups
20
Q
carbohydrate metabolism
cori cycle
A
- carbohydrates turn into glucose 6 p
- glucse 6 p can turn into glycogen via glycogenesis and back via glycogenolysis
- glucose 6 p to pyruvic acid via glycolysis, back via gluconeogenesis
- pyruvic acid lactic acid
- glucose 6 p glucose
21
Q
cori cycle
A
- sophisticated cycle of secretion and uptak of glucose
- between liver and muscle
22
Q
glycogenesis - GG
A
- synthesis of glycogen from glucose
- liver, muscle, cytoplasm
- storage of glucose as consequence of high blood glucose
23
Q
glycogenolysis - GGL
A
- degradation of glycogen to blood glucose
- to elavate blood sugar
24
Q
glycogen synthase
A
regulatory enzyme
25
glucosynthase in liver
active only at high gucose conc
26
compare hexokinase and glucokinase
- km of hexokinase is lower than glucosekinase of liver
27
glycogenolysis
| where, steps, endproduct
- first step is called phosphorolyse
- bc degradation start with addition of one Pin
- endproduct of degraation is glucose in liver
- glucose 6 P in other organs - enter glycolysis
- localization: liver, muscle, kidney cytoplasm
28
energy balance of glycogenesis and glycogenolysis
```
glycogenesis:
- hexokinase: -1 ATP
- UDP-glucose phosphorylase: - 1UDP (=-1 ATP)
- total: -2ATP
glycogenolysis
- no energy gain or utilization
```
29
regulation of glycogenesis and glycogenolysis
- both can happen in same cell at same time
- opposite effect
- regulation by cascade mechanism
- two types of reg: slow hormonal, fast allosteric
30
```
cascade mechanism
(reg of GG and GGL)
```
- first messenger molecules (ex: hormones)
- induce intensive cellular answer by second messenger molecules
(intensity of cell reac can be 1000-10.000)
31
hormonal regulation
- transmembrane glucagon or adrenalin binding receptors bind hormones = first messengers
- after binding of receptor - Gprotein process
- activated alpha subunit dissociates (from g protein) activates adenylate cyclase
- atp->PPin+AMP-> cyclic AMP (cAMP)
32
hormonal reg - cAMP
- activates intracellular protein kinase A
- PKA activates glycogen phosphorylase kinase
- GPK activates glycogen phosphorylase
- glycogenolysis begin
33
protein kinase A
- inactive ave 4 sub units
- 2 catalytic, 2 regulatory
- after cAMP binding, regulatory subunits dissociate
- active PKA formed
34
Example: regulation of glycogenesis-glycogenolysis
– Glycogen phosphorylase active - first enzyme of glycogenolysis
– Glycogen synthase active is the last enzyme of glycogenesis
–after phosphorylation of both enzymes will be induced
glycogenolysis and after dephosphorylation of both enzymes will be induced
glycogenesis in the organism
(hva i helvete)
35
hormonal reg - insulin
- gg and ggl also regulated by insulin
| - insulin receptor belongs to tyrosine kinase - PIP3
36
receptor tyrosine kinase activation by insulin
- insuling bound to receptor
- inactive PI3-k is phosphorylated to PI3-K
PIP2 phosphorylated to PIP3
-protein kinase B inactive to active
- phosphodiesterase inactive to active
-cAMP broken down to AMP
- protein kinase A active to inactive
- glycogen synthase and glycogen phosphorylase dephosphorylated
- GS active and GP inactive formed
37
allosteric regulation liver
- allosteric inhibitor of GP is glucose
38
allosteric regulation muscle
allosteric activator of GP is ca2+
39
glycolysis
- degradation of glucose to pyruvate
- aerobe in cardiac muscle, brain, liver
- energy gained from oxidation of FA
- further degradation to acetyl-CoA
- or anaerobically to lactate
40
gluconeogenesis
- prod of glucose from non-carbohydrate sources in liver
| - glucogenic AAs, glycerol, lactate, propionate
41
role of lactate in meat quality
PSE
DFD
- PSE= pale, soft, exudative
| - DFD= dark, firm and dry
42
pasteur effect
- in presence of O2, NADH+H+ has bigger affinity to respiratory chain and glycerol shuttle
- absence of O2 NADH+H+ is used for lactate production from pyruvate
43
gluconeogenesis
| used where
- nessecary for use as fuel source by brain, testes, erythrocytes, adrenal medulla
44
what will activate/inhibit phosphofructokinase
- fructose-2,6-biphosphate +
- AMP +
- ATP -
- citrate-
- H -
45
what inhibit/activates fructose-1,6-biphosphatase
- Fructose-2,6-biphosphate -
- AMP -
- citrate +
46
what inhibit/activate pyruvate kinase
- fructose-1,6-biphosphate +
- ATP -
- Alanine -
47
what inhibit/activate pyruvate carboxylase
- acetyl CoA +
| - ADP -
48
what inhibit/ activate phosphoenolpyruvate carboxykinase
- ADP-
49
what inhibit/activate glycolysis?
- insulin +
| - glucagon -
50
what inhibit /activate gluconeogenesis
- glucagon +
| - insulin -
51
AcCoA synthesis from pyruvate
- pyruvate into mitochondria
- pyruvate dehydrogenase, need five factors:
- TPP, Lipoic acid, HSCoA, NAD+, FAD
52
steps of AcCoA synthesis
1. co2 is removed -TPP
2. oxidation, h removed - NAD+, FAD
3. HSCoA - acetyl CoA - lipoic acid
53
energy gain of oxidation of one glucose molecule
36 ATP
