Glucose Metabolism Flashcards
What is metabolism?
All chemical reactions in the body
What is catabolism?
breaking down complex molecules - exergonic as release energy
What is catabolic reactions important in?
Glycolysis , TCA cycle and electron transport chain
What is anabolism?
Endergonic, building complex molecules so requires energy
What are metabolic reactions controlled by?
enzymes
Do molecules have a infinite lifespan?
Nope, they all undergo catabolism
How do cells take up energy from their enviroment?
Through diet as provides a range of molecules needed as building blocks for key process
How do cells synthesize macromolecules?
energy generated from diet used
what are the 3 fates of nutrients?
Supply energy
Serve as building blocks
Stored for future use
what is the molecule used for energy transfer?
ATP - adenosine triphosphate
What bonds of ATP have high chemical potential energy?
Phosphoanhydride bonds of atp
is ATP an energy source?
No
What is lifespan of ATP molecule?
1 MIN
What does anabolic reactions transfer energy from - to?
From ATP to complex molecules
What does catabolic reactions transfer energy from-to?
from complex molecules to ATP
What is an e.g of complex molecules?
Glycogen
proteins
triglycerides
What are sources of carbohydrate?
Starch - glucose , plants
Glycogen - animals glucose
Lactose - glucose to galactose
Sucrose - glucose to fructose
What is the only mechanism in the body that can make energy without oxygen?
Glucose metabolism
What is glucose a major substrate for?
Cellular respirations
What does fate of glucose depend on?
ATP production
AA synthesis
Glycogen synthesis
Triglyceride synthesis
Where/To does glucose move in body?
Intestinal lumen to cytosol to blood
What is cellular uptake facilitated by?
Glucose transports
What transporters do most tissues use?
GLUT 2 - low km, and not affected by insulin
What does low km mean?
low concentration level to activate
What transporters do hepatocytes use?
GLUT 2 - regulated by insulin and high km
What happens to glucose upon entering a cell?
Phosphorylated
What uses GLUT 4?
Striated muscle and adipose tissue
Where is glut4 inserted?
PM in response to insulin
What is glycolysis?
10 reactions
splits 6 carbon glucose into 3 carbon molecules of pyruvic acid
Where is glycolysis carried out?
Cytosol to generate energy
What does fructose 1,6, biphosphate split into and uses what enzyme?
Aldolase - intro
dihydroxyacetone phosphate and glyceraldehyde 3-phosphate
How many ATP invested in glycolysis?
2 ATPS
What are 4 molecules of ATP generated for?
2 for each 3-carbon molecule
In step 6 what other 2 molecules generated?
NADH, H+
What is cellular respiration?
Oxidation of glucose to produce atp
What is biochemical reaction for glycolysis?
Glucose oxidised, 2 molecules of pyruvic acid are produced - production of 2 molecules of ATP and 2 molecules of NADH
What is biochemical reaction for acetyl coenzyme a?
Transition to prepare pyruvic acid for entry to tca cycle, produces NADH, H, CO2
What is biochemical pathways for tca krebs cycle?
oxidises acetyl coenzyme a and produced atp, co2, nadh, h, fadh2
What is biochemical for electron transport chain?
Oxidises nadh, h, fadh2 and transfers electrons through electrons carriers, atp produced by atpsynthase
What does fate of pyruvate depend on?
Oxygen availability
What happens to pyruvic acid with oxygen?
acetyl coenzyme a and enters tca cycle
What happens to pyruvic acid when no oxygen?
Reduced to lactic acid
What is galactose converted at?
Glucose - 6 - phosphate, multistep pathway
What is fructose converted at?
Phosphorylated by hexokinase in muscle and adipose to fructose-6-phosphate
What tissues have an absolute requirement for glucose?
Blood 120g
Erythrocytes 40g
What 3 steps in glycolysis irreversible due to atp ?
hexokinase
phosphofructokinase
pyruvate kinase
How are the key enzymes regulated?
Allosteric effects of metabolites - feedback due to build up of amp
Hormonal actions - enzyme modify ST, induction of enzyme LT
What does liver do?
Act as body sink for glucose
stores glucose
site for glucenogensis
What does pancreas to?
Pancreatic amylases and bicarbonate to aid carb digestions, produces insulin and glucagon
What is hexokinase?
Universal, unaffected by insulin, low km, inhibited by glucose-6-phosphate
what activates fructose-6-phosphate?
AMP
Insulin
What inhibits fructose-6-phosphate?
ATP, Citrate, glucagon
What activates phosphenolpyruvate?
Fruct,1,6,biph
insulin
What inhibits phosphonenolpyruvate?
ATP, Coenzyme a, glucagon
what are 2 peptide hormones for blood sugar?
Insulin - lowers blood glucose
Glucagon - increases blood glucose
what regulates level of peptide hormones?
Glucose concentrations
