glucose and carbohydrate Flashcards
how much energy is released from one NADH
220 kJ/mol
what is the amount of energy released from one ATP
30.5 kJ/mol
how many ATP is produced through the anaerobic and aerobic metabolism of 1 glucose
anaerobic - 2 ATP
aerobic - 32 ATP
what kind of sugars are glucose, galactose and fructose
glucose and galactose - aldose
fructose - ketose
which GLUT transporter is in muscle and adipose tissue
GLUT4
which GLUT transporter is in the liver and pancreas
GLUT 2
which GLUT transporter is universal for all cells of the body
GLUT 1
what substrates are used for gluconeogenesis
glycerol or amino acids (NEVER FROM FATS)
which ion is bound to free ATP
Mg
how does hyperglycaemia cause blindness and gangrene
covalent reaction of free glucose in the blood with amines of the blood vessel walls –> brittle –> prone to clots –> blindness or gangrene
fasting level of glucose
4-5mM
what is the blood test to test for uncontrolled diabetes other than fasting glucose
Hb A1C
in which places of the body is anaerobic metabolism essential
in RBCs, lens and retina (lack mitochondria)
equation for glycolysis
glucose +2NAD+ + 2ADP + 2Pi –>
2pyruvate + 2NADH + 2ATP + 2H20
why is it that anaerobes need to consume more glucose that aerobes
because aerobes get 32ATP per molecule, while anaerobes only get 2
function of hexokinase in glycolysis
combines glucose and ATP –> glucose 6-P
function of phosphohexose isomerase in glycolysis
conversion between glucose6-P and fructose 6-P
what is the function of phosphofructokinase-1 in glycolysis
converts fructose 6-P to fructose 1,6bisP
then commited to make pyruvate
what is the feedback mechanism for glycolysis
phosphofructokinase is only active when cells have low ATP
which substrate can be used for short bursts of anaerobic metabolism
creatine
how much glucose does the brain need per day
120g
what is galactosaemia
enzyme defect so the body cannot metabolise galactose
what is fructose
the ketose form of glucose
what is bad about fructose
- does not elicit insulin release from the pancreas
- fails to increase the production of leptin from fat cells
- does not appear to suppress the production of ghrelin
- is broken down mostly into the backbone of triacyglycerols
which sugar can FAs be metabolised to
fructose (not glucose)
what are the physical signs that humans are omnivores
dentition - incisors and canines for tearing, and molars for chewing plants
gut structures - short - for meat and plant digestion
why are low Gycaemic index diets recommended
because it avoids the high peak glucose levels that can lead to insulin resistance
what happens to the extra glucose that we dont need for glycogen synthesis in the fed state
The NADPH drives cholesterol synthesis and fat synthesis
- cholesterol synthesis through oxidation via pentose phosphate pathway
- fat synthesis via oxidation via glucolysis –> pyruvate –> fat
is alpha or beta isomers of glucose present in the body
alpha
beta in plants - eg cellulose
which GLUT receptor is in muscle
GLUT 4
why is that muscles dont “share” their glucose stored as glycogen
because they dont have glucose-6-phosphatase to release free glucose into the blood
in what form do muscles use their stored glycogen and how is it made
glucose-1-P
broken down by glycogen phosphase
what is the process called when the liver breaks down its glycogen and releases glucose into the blood
gluconeogenesis
what kind of receptor is the insulin receptor
tyrosine kinase
why do elite athletes benefit from carbo loading
it maximises the glycogen load in the muscles prior to exercise so they can use this during exercise and not rely on other substrates for a longer period
how is glycogen formed (from what precursor)
glucose-6-phosphate crosslinked between Cs 6 and 1
what is the noticable sign that your muscles have switched from using glycogen to fatty acids
you “hit the wall”
explain the chemical and osmotic properties of glycogen
chemically inert (due to ester linkages) osmotically equivalent to 1 glucose molecule
what causes Pompes disease
lack of alpha-1,4-glucosidase
causes accumulation of glycogen in the lysosomes (as this enzyme isnt there to break it down
when is glycogen broken down
- in the fasting state
- in response to adrenaline (exercise
how does adrenaline cause glycogen breakdown in the muscle
activation of a cyclase –> cAMP –> cascade –> 1000s of molecules of glucose-1-P –> glucose for muscle
effect on blood sugar of free sugars (mono and disaccharides)
- cause a rapid rise in blood sugar
- stimulates insulin release
effect on blood glucose of short chain carbohydrats
- may be unabsorbed and fermented by gut bacteria
effect on blood glucose of starch
most starch is rapidly digested and absorbed giving a response much like free sugar
what were the constituents of the typical cave man diet
high protein, more polyunsaturated fats, fibre, calcium and vitamin C and low sodium
4 parts of the wheat husk and what is in each
bran - rich in nutrients and fibre
endosperm - starch and proteins
germ - rich in vitamins and minerals
husk - inedible part of the grain
what causes Beriberi
thiamine deficiency
what food is beriberi associated with?
corn - people whose diets were primarily corn did not have enough thiamine –> beriberi
what is the effect of fibre in the GIT
delays stomach emptying and increases the speed through the GIT
how does fibre have a protective effect against diverticulitis and haemorrhoids
fibre is highly hydrophilic –> keeps water with it –> faeces is not hard and therefore less risk of irritation of the intestine or anal sphincter
what is the glycaemic index
ranking of carbohydrates based on their immediate effect on blood glucose
