Flashcards in Metabolism - Lynn Rogers Deck (100):
- Delta G
+ delta G
Gibbs free energy (difference between products and reactants)
What is ATP
Main form of energy (- delta G)
makes reaction its coupled with, occur
ATP when hydrolysed (eq.)
ATP -> ADP + Pi + energy
ATP -> AMP + 2Pi + energy
Draw the biological cycle
What are catabolic pathways?
release energy and produce ATP
What are anabolic pathways?
use energy and require ATP
What happens after you eat a meal?
increase blood glucose, which increases insulin (anabolic)
Glucose -> glycogen
AA -> Proteins
excess -> adipose fats
What happens a couple hours after the meal?
decrease blood glucose, thus decrease insulin
Glucagon is secreted and breaks down
glycogen -> glucose
Adipose fat -> fatty acids
so that fuel is available
What happens in a fight or flight response?
adrenaline is released (catabolic)
glyocgen -> glucose
Adipocytes -> fatty acids
Name 2 types of carbs, and their digestive enzyme
Lactose - digested by lactase
sucrose - digested by sucrase
Describe how and why Lactose intolerance occurs
People can't produce lactase, to hydrolyse lactose.
Lactose is a disach. and so is too large to be absorbed.
Lactose is broken down to carbolites and gas, then fermented by bacteria (gas) and absorbs water (bloating)
What breaks down fats/lipids?
bile salts (pancreatic lipase)
What are fats/lipids?
What are chylomicrons?
lipoprotein particles - consist of trigylcerides, phospholipids, cholesterol and protein
Does the OH group move in starch/cellulose? How does this affect the structure?
OH above the plane - alpha (starch)
OH below the plane - beta (cellulose)
What does amylase hydrolyse?
What is fiber?
carb which can't be absorbed by body
Name the 3 types of dietary fiber
1. Soluble - controls BGL, decreases chol (attracts water so softens poo)
2. insoluble - regulates bowel movements (hydrophobic so hardens poo)
3. Resistant - not digested, allows for growth of good bacteria
What is cholesterol?
lipid, NOT A FAT
insoluble so not a body fuel
accumulates in body (no enzymes to break it down) so blocks arteries
What is cholesterol essential for (3 reasons)
1. integrity of membrane
2. precursor for bile salts
3. precusors for Vitamine D and steroids
How is cholesterol added to body? What causes it to be high?
mostly from liver
some foods increase cholesterol
genes can increase cholesterol
diet and lifestyle
Name the 3 main types of lipoproteins
Where and it what form is glucose stored?
Liver and muscle in glycogen form
What is glucose used for in muscle?
What is glucose used for in liver?
broken down to control blood glucose levels
Where is fat stored, and in what form?
adipoctye as triglyceride or triacylglycerol
insoluble and neutral, so form fat conglomerates
Where are Amino acids stored? what are they used for?
used for proteins and enzymes
What does liver do
stores glucose as glycogen
makes fat from excess glucose
form glucose from AA (gluconeogenesis)
forms ketones from fat
What is gluconeogenesis?
formation of glucose from amino acids
What is glycolysis?
Form pyruvate from glucose, forming 1 ATP
What is glycogenolysis?
glycogen to glucose
What is glycogenesis?
glucose to glycogen
What is ketosis and where does it occur?
breakdown of fat to ketones in the liver
What does muscle store?
stores glycogen to be used for fuel
What does brain need, but can't store?
What does adipose tissue store?
glycogen and fat
What is Catabolism?
oxidation of food to supply ATP
What is anabolism?
conversion of simple to complex molecules (requires ATP)
List 2 electron and proton carriers
NAD+ (nicotinamide adenine dinucleotide) and FAD (flavine adenine dinucleotide)
What is NAD+ and FAD reduced to
NADH and FADH2
What are coenzymes
molecules which attach to enzymes (NAD+ and FAD are examples)
List the 3 stages of glucose oxidation
2. Krebs cycle
3. electron transport chain
What is hypoglycaemia?
low blood glucose levels
most common fuel
soluble and easily distributed
provides ATP aerobically and anaerobically
C6H12O6 + 6O2 -> 6CO2 + 6H20 + ATP
Is glycolysis an anabolic or catabolic proccess?
List the 3 steps in the process of Glycolysis
1. 6 carbon glucose, with the addition of 2 ATP, produces 6 carbon sugar diphosphate and 2 ADP
2. 6 carbon sugar diphosphate converts to 2 x 3 carbon sugar phosphate
3. 2 x (3 carbon sugar phosphate, with the addition of NAD+ and 2 ADP, produces 3 carbon pyruvate, NADH and 2 ATP)
How is ATP formed (Name the formal name)
substrate level phosphorylation
What is the rate determining enzyme (RDE)
What RDE is in glycolysis?
catalyses reaction which controls the whole pathway
PFK 1 - phosphfructokinase 1 (catalyses an irreversible reaction)
What does ATP inactive?
RDE - PFK 1
Under anaerobic conditions, what does Glucose produce?
2 x lactate molecules and a small amount of ATP very quickly
Describe what happens when Glucose is anaerobically oxidised
Glucose, with the input of NAD+ and 2 x ADP, converts to 2 x pyruvate, NADH and 2 x ATP. Then with the input of NADH, converts to 2 x lactate and NAD+ (NADH is oxidised in reaction)
What is substrate level phosphorylation?
enzyme transfers a P group from phosphorylated molecule to ADP to form ATP
Where does glycolysis occur?
Cytoplasm, however, under anaerobic conditions, pyruvate will go to Mitochondrial matrix to produce ATP.
What is lactase dehydrogenase?
present in all cells to catalyse anaerobic oxidation of glucose
What is lactic acid responsible for?
How can tumours be seen on a PET scan?
tumours, due to rapid growth, require easy access to energy.
blood vessels that surround the tumour, cannot meet demand, thus cells grow under hypoxia conditions (anaerobic) thus anaerobic glycolysis occurs (use glucose and produce lactate)
FDG (radioactive substance) shows where tumour is
When tumour removed, excess FDG in urine, shows in kidneys and bladder
Why are B vitamins important?
water soluble and not stored
precursors or coenzyme components
Importance of B3?
precursor for NAD+
thus a deficiency leads to fatigue, and CNS problems
What is the warburg effect?
Cancer cells undergo anaerobic glycolysis, and produce lactate, even in the presence of oxygen. Does this so that cells can produce ATP in short amount of time
Does the Krebs cycle occur after anaerobic or aerobic glycolysis?
Where does the Krebs cycle occur?
Explain how pyruvate converts to Acetyl CoA
Pyruvate travels into mitochondria and, with the addition of coenzyme A and NAD+, converts to Acetyl CoA, NADH and CO2
CH3COCOO-H+ + NAD+ + CoA-SH
-> CH3CO-SCoA + NADH +H+ +CO2
Why is thiamine important?
cofactor for pyruvate dehydrogenase, which converts pyruvate to Acetyl CoA
is found in meat, legumes, etc
reduced absorption in alcoholic and caffeine addicts
What is Coenzyme A? What does it need to be formed?
You need Pantothenate, which is from pantothenic acid
found in eggs, liver, veg
What happens if you have a deficiency Thiamine?
Can't convert pyruvate to Acetyl CoA, as can't produce pyruvate dehydrogenase, thus pyruvate converts to lactate in cytoplasm
Describe the Krebs cycle (Draw the cycle)
Where does electron transport chain occur?
inner mitochondrial matrix
Describe the electron transport chain
NADH and FADH2 gives up e- and H+ to a carrier molecule. These carrier molecules inner mitochondrial membrane) and reduced, then oxidised and give away their e- and H+ to another carrier molecule. Eventually oxygen takes up e- and converts to H20.
At the same time, H+ are translocated intermembrane space. These H+ become trapped, as membrane is impermeable, and so a proton gradient occurs.
How is ATP generated from proton gradient?
enzyme in membrane (F0F1 ATPase)
F0 - proton channel
F1 - enzyme
F0 allows protons to come back, which leads to a change. This leads to a change in F1 domain, and ADP phosphorylated with P to form ATP
Why does 02 need to be available in the e- transport chain?
So that it can accept e- in the chain
What is the rate of the chain determined by?
The sun is an exhaustible source of what?
Water is an exhaustible source of what?
Oxygen is an exhaustible sink of what?
Why is ATP transported to cytoplasm?
anabolism occurs here
When carrier molecules are reduced, then oxidised, where does the released energy go?
energy is used to transport H+ across to the transmembrane space
How does cyanide work?
inhibits protein in inner mitochondrial membrane
e- cant be absorbed
H20 cant be made from O2
not proton translocation, so no gradient
NO ATP = asphyxiation
What is an example of uncoupling poisons?
2, 4 DNP herbicides/fungicides
How do coupling poisons work?
allows protons to reenter MM without capturing energy
e- still absorbed, and H+ still translocate, but H+ are absorbed, thus dissipates gradient, so no ATP
increased fuel is consumed, and increased e- absorbed, but only heat is produced
What is fatty acid oxidation?
fatty acids are oxidised to Acetyl CoA in the MM
beta oxidation in presence of oxygen (aerobic)
Reaction in ETC
02 + 4e- + 4H+ -> 2H20
or if partial oxidation occurs
02 + e- -> 02'-
What is ROS?
reactant oxygen species (oxidant/free radical)
Formed from partial oxidation of ETC
e- escaped from ETC, and partially oxidised oxygen becomes highly reactive
Why is ROS bad?
as partiall oxidised oxygen has an extra e-, it becomes extremely reactive, and destroys all molecules it meets
What causes ROS?
alcohol, drugs, smoking, pollution, aerobic mtabolism
How do you decrease free radicals?
antioxidants - Vit C, E and A
vegetables contain phytochemicals - destroys carcinogens
What are iso enzymes?
enzymes which catalyse same chemical reaction, but have a slightly different structure
How are isoproteins released?
When the cell is injured or dies, cell membrane becomes highly permeable and cellular contents are released, releasing enzymes
Where is LDH found, and name the 3 different types
in all cells
LDH1 - myocardium (HHHH)
LDH3 - brain/kidneys (MMHH)
LDH5 - skel/muscle (MMMM)
Name the 8 hydrophobic AA
GALVIM (glysine, alanine, leusine, valine, isoleucine, methionine)
PTT (phenylalanine, tryptophan, tyrosine)
Name the 3 basic AA
LAH (lysine, arginine, histidine)
Name the 2 acidic AA
AG (aspartic, glutamic)
Name the 2 amide AA
AG (asparagine, glutamine)
Name the 2 hydroxylated AA
ST (serine, Threonine)
Name the 2 special AA
Cysteine - SH group
Proline - Imino group
What is creatine kinase?
An enzyme which phsoprylates ATP to ADP and creatine to creatine phosphate
Where is creatine made?
liver, but travels to skel. muscles, where it is converted to creatine phsophate