Biological Fuel - Carbohydrates Flashcards
What is cellular respiration?
Most efficient way to obtain energy from carbohydrates
The breaking them down of carbs to generate energy
Carbs + Oxygen > CO2 + H2O + Energy
What is ATP?
Energy is produced in cells in the form of a molecular called Adenosine Triphosphate (ATP)
It is the currency and store of energy in cells and drives a variety of chemical reactions eg membrane pumps and the reproduction and movement of cells
What is ATP formed from?
ATP is formed from ADP in an energy consuming reaction
Energy is released from ATP when it is hydrolysed back to ADP
(Remember how G-protein receptors work)
What are the three types of carbohydrates / sugars?
- Monosaccharides
- Disaccharides
- Polysaccharides
What are monosaccharides?
Simplest carbohydrate containing a single sugar
Examples = ribose, fructose, and glucose
All sugars are made of the same chemical components but different spatial arrangements to create diversity. Because of this, suagrs can be described as isomers and / or optical isomers, what does this mean?
Isomer = same chemical formula but different orientations to form different sugars
Optical isomer = mirror image of a single sugar
What is the function of monosaccharides?
Priamrily used immediately as fuel, if this is not possible then they are stored as a di or polysaccharide
What are disaccharides?
Transport sugars made up of 2x monosaccharides joined with a glycosidic bond
Different types determined by which monosaccharides are joined:
Sucrose = Glucose + Fructose
Lactose = Galactose + Glucose
Maltose = Glucose + Glucose
What are polysaccharides?
Used for the storage of sugars and are polymers of 100s to 1000s of monosaccharides
Example = Glycogen, which is the major store of glucose in humans, tends to be short term storage that is depleted in a day
Metabolism is a process made up of two opposing chemical reactions, what are they and what do they do?
Catabolism = breakdown of foodstuffs into smaller molecules to generate energy
Anabolism = uses the energy from catabolims to drive the synthesis of other molecules
What is aerobic respiration?
The most efficient catabolic reaction used to generate energy (ATP), most commonly using glucose
The fundamental underlying processes of aerboic reactions are reduction and oxidation, also known as redox reactions. What are they?
Redox reactions decompose glucose to yield energy through the transfer of electrons (-ve charge)
Reduction = gain of electrons Oxidation = loss of electrons
Example:
Na and Cl
Na is oxidised, Cl is reduced
Result = Na+ and Cl-
How specifically does the respiration of glucose work via redox reactions?
- Glucose has an abundance hydrogens and therefore electrons
- The hydrogen from glucose will be transferred to oxygen via redox reactions
- Complete oxidation of glucose forms O2
- Complete reduction of oxygen forms H2O
C6 H12 O6 + 6(O2) > 6(CO2) + 6(H2O)
How do redox reactions work to extract energy?
Series of steps relying on active carriers as intermediaries
Carriers accept electrons and store temporarily
NAD+ is oxidised state, NADH is reduced state
The transfer of electrons from, NADH to oxygen leads to ATP generation
What are the stages of aerobic respiration?
- Glycolysis
- Citric Acid Cycle / Krebs Cycle
- Oxidative phosphorylation
What is glycolysis and how does it work?
The breakdown of glucose into pyruvate in cytosol
Glucose (6 carbons) is split into 2 pyruvate molecules (3 carbons)
There is an absence of oxygen and electrons are removed from glucose and transfered as part of redox reactions to form NADH
Glucose + 2x ATP = 2x NADH, 4x ATP, 2x Pyruvate
What is the citric acid cycle / krebs cycle?
The complete oxidisation of pyruvate within the mitochondria to produce lots of electron carriers
This requires oxygen and is broken down into 2 stages: oxidation of pyruvate and the krebs cycle
How does the citric acid cycle function?
- Pyruvate (3 carbons) becomes Acetyl CoA (2 carbons)
- Aceytl CoA is completely oxidised to form CO2
This process accoutns for 2/3 oxidation of carbon compounds in cells and produces LOTS of electron carriers (NADH and FADH2), generating ATP
What is oxidative phosphorylation?
The transport of electron chains within the mitochondria which establishes a H+ gradient
ATP is synthasised from this gradient generating the MOST ATP in aerobic respiration
What are the different fuels and their entry points for aerobic respiration?
- Carbohydrates (digetsed prior to entry and start at glycolysis)
- Proteins (Need to be broken down into amino acids before entering directly into citric acid cycle)
- Fats (Need to be broken down to glycerol or fatty acids before entering during glycolysis and citric acid cycle respectively)
