Biochemistry Flashcards
Who is the father of biochemistry?
Archibald Edward Garrod
What is biochemistry?
The branch of science is concerned with the chemical and physicochemical processes and substances that occur within living organisms.
Define metabolism.
All chemical reactions that maintain the living state of cells and organisms.
Define anabolism and does it require energy?
The synthesis of complex molecules in living organisms from simpler ones.
It requires energy.
Define catabolism and if it requires energy.
The breakdown of complex molecules in living organisms to form simpler ones.
It breaks down molecules to yield energy.
Where does all our energy come from?
Ultimately, all our energy comes from the sun
Define redox reactions
Redox reactions are reactions where both oxidation and reduction take place.
Sketch the anabolism redox reaction.
Check in notion
What are the two terms used in anabolic reactions?
Endergonic: Reaction that requires energy to proceed
Reductive: When a reactant accumulates electrons during a reaction.
What is the electron carrier in anabolism?
NADPH + H+
Sketch the catabolic reaction
Check notion
Sketch the catabolic reaction
Check notion
What are the two terms used in catabolism regarding the reactions?
Exergonic: It releases free energy.
Oxidative: A chemical reaction occurs when a substance comes into contact with oxygen or another oxidizing substance.
What is the electron carrier in catabolism?
NADH + H+
(FADH2)
Sketch the oxidative phosphorylation in redox reactions.
Check notion
What is the energy carrier in oxidative phosphorylation?
ATP (Adenosine Tri-phosphate)
Which is the most important carbohydrate?
Glucose
What three polysaccharides have more than half of all organic carbons? In what organism can you find them?
Starch and cellulose: Plants.
Glycogen: Animals.
What is our primary energy source?
Glucose, oxidised to CO2 and H2O
What five cells require glucose as an energy source?
-Erythrocytes
-Retina
-Renal Medulla
-Brain.
-All cancer cells
What are two polysaccharides?
Cellulose and glycogen
What are two polysaccharides?
Cellulose and glycogen
What are the four fates of glucose?
- Undergoes oxidation through aerobic glycolysis to become pyruvate.
- Fermentation by anaerobic glycolysis to become lactate
- Undergoes oxidation through the pentose phosphate pathway to become Ribose-5-phosphate.
- To become Glycogen, Starch and Sucrose, for conversion of lipids.
How do glucose transport into cells?
Via Na+/glucose symporters
Via passive facilitated diffusion glucose transporters.
What are all the glucose transporters?
GLUT 1
GLUT 2
GLUT 3
GLUT 4
GLUT 5
Where can each GLUT be found?
GLUT 1- Brain
GLUT 2- Liver and B-cells
GLUT 3- Brain
GLUT 4- Muscle and adipose tissue
GLUT 5- Gut
What do Beta cells do?
Cells that make insulin, a hormone that controls the level of glucose (a type of sugar) in the blood.
What does KM stand for in biochemistry?
The Michaelis constant (KM) is defined as the substrate concentration at which the reaction rate is half its maximum value.
What glucose transporters have high and low KM?
Low KM: GLUT 1 and GLUT 3
High KM: GLUT 2
What are glucose transporters and insulin-dependent/independent fructose transport?
Insulin independent: GLUT 2
Insulin-dependent: GLUT 4
Fructose transport: GLUT 5
What is GLUT 1, and how does it function?
GLUT 1 is a glucose transporter.
Glucose binds to the outside active site and triggers a conformational change. The binding site faces inwards. Glucose is released into the cytosol. Conformational change regenerates the binding site on the outside.
What is glycolysis?
A linear metabolic pathway of enzyme-catalyzed reactions that converts glucose into two molecules of pyruvate in the presence of oxygen or two molecules of lactate in the absence of oxygen.
What is the overall reaction of aerobic glycolysis?
glucose + 2 ADP + 2 Pi + 2 NAD+
(Arrow)
2 pyruvate + 4 ATP +2 H2O + 2 NADH + 2 H+
What do you need to do to glucose to break it down?
Destabilize it because glucose itself is a very stable molecule.
What is the overall design of the aerobic glycolysis pathway?
Check-in notion
What happens in the three stages of glycolysis?
Stage 1: glucose is trapped and destabilized
Stage 2: two interconvertible three-carbon molecules are formed
Stage 3: generation of ATP
What are the two major cellular needs?
-Production of ATP
-Provision of building blocks for synthetic reactions
What are the control points in glycolysis, their names, and their functions?
-These are enzymes catalyzing irreversible reactions
1. Hexokinase – Substrate entry
2. Phosphofructokinase – Rate of flow
3. Pyruvate Kinase – Product exit
What are the three Irreversible/controlled reactions in glycolysis?
Hexokinase
-glucose + ATP –> glucose 6-phosphate + ADP + H+
Phosphofructokinase
-fructose 6-phosphate + ATP –> fructose 1,6-bisphosphate + ADP + H+
-Pyruvate kinase
phosphoenolpyruvate + ADP + H+–> pyruvate + ATP
Why is phosphofructokinase so important?
Key enzyme controlling the rate of substrate movement along the glycolytic pathway.
What are the two activators of glycolysis and their effect?
AMP and fructose 2,6-biphosphate.
-Will increase glycolysis if energy is needed.
What are the three inhibitors of glycolysis and their effect?
- ATP- Will slow glycolysis if energy is abundant
- Citrate - TCA cycle intermediate. Slows down downstream pyruvate entry to the TCA cycle if energy is abundant.
- H+ - Slows glycolysis if too much lactic acid is being produced
What does PFK stand for?
Phosphofructokinase
What is the ATP/AMP ratio called?
The energy ratio
When is a cell fully charged?
When all adenylate nucleotides are in the shape of ATP
When is a cell discharged?
When the cell only contains AMP and Pi
Why is AMP and not ADP the positive regulator? Use the formulae.
Because if ADP is rapidly used up, adenylate kinase can salvage some of the energy in ADP.
The formulae:
-ATP —> ADP + Pi
-2 ADP –> ATP + AMP
What is the fate of pyruvate?
Carbon to fuel the Citric Acid Cycle in mitochondria.
What is the fate of 2 NAD+ and 2 NADH + 2 H+
Electron transport chain and ATP synthesis
What two things happen if mitochondria metabolism is inhibited by lack of oxygen?
Anaerobic (Lactic and fermentation).
-NADH is used to ferment pyruvate to lactic acid (lactate)
-NADH is re-generated at the beginning of stage 3
Draw the intracellular stages of metabolism involving Glucose, Fatty Acids, and Amino Acids.
Check-in notion.
What is the Warburg Effect?
Up-regulation of anaerobic glycolysis in cancer cells