Energy and metabolism Flashcards
What main processes in the body require energy?
Contraction of muscle of all movement (skeletal, cardiac and smooth)
Accumulation of ions and other molecules against concentration gradient
Biosynthesis and hence building of tissues
Waste disposal and removal of end products
Generation of heat and maintnance of body temperature
What does gibs free energy show? What makes it positive or negative?
Difference between energy in substrate and product
If product contains more energy –> delta G = +
If product contains less energy –> delta G = -
What are exergonic and endergonic reations?
Exergonic reactions give out energy (catabolism = big broken into small)
Endergonic: requires energy
What is the structure of ATP?
Adenine joined to C1 of Ribose sugar, joined to 3 phosphate groups by C5
Phosphates joined together by phosphate anhydride bonds
How does ATP release energy?
Phosphate anhydride bonds broken in hydrolysis reaction which disapates a lot of energy
How is ATP regenerated?
Energy from catabolism causes the addition of inorganic phosphate and ADP to form ATP
Where in the cell does glycolysis, fatty acid oxidation, TCA cycle and oxidative phosphorylation occur?
Glycolysis: cytosol
Fatty acid oxidation: mitochondrial matrix
TCA cycle: matrix
Oxidative phosphorylation: across the inner mitochondrial membrane
Give an overview of glycolysis
Occurs in 2 phases: energy investement and energy generation
- Glucose -> fructose-6-phosphate –> fructose-1,6- biphosphate (uses 2 ATP)
- Glyceraldehyde-3-phosphate (x2) to pyruvate releases 1x NADH (x2) and 2x ATP (4 per glucose) and 1 H2O
Pyruvate converted to acetyl CoA (forms 1 NADH and 1 CO2)
Give an overview of fatty acid metabolism
Fatty acids transported in blood as a complex with albumin and taken up by cells
Modified to enter bacteria: modified by acyl-CoA synthetase to form fatty acyl CoA in endergonic reation
CoA replaced by carnitine to allow it to enter matrix through special transporter protein
Carnitine then replaced by CoA
Beta-oxidation cleaves carbon backbone between alpha and beta carbons proximal to carboxyterminal to form multiple acetyl-CoA
Give an overveiw of protein metabolism
Transamination:
- amine group transfered from amino acid to an alpha keto acid (forming a keto acid)
Deamination:
- amine group removed from keto acid to regenerate alpha-ketoacid
- ammonia enters urea cycle as otherwise toxic to body
Describe the TCA cycle
-Acetyl CoA combine with oxaloacetate to form citrate to forms citrate (6C)
- this is decarboxylated and dehydrogenated to form alpha-ketoglutarate (5C) - releases 1 NADH and 1 CO2
- Alpha-ketoglutaratre to succinyl CoA (4C) - release of 1 NADP and CO2
- Succinyl-CoA to succinate with release of GTP
- Succinate to Fumarate with release of FADH2
- Fumarate too Malate
- Malate to Oxaloacetate: release of NADH
Overall production of TCA cycle
- Per molecule of Acetyl CoA: 2x carbon dioxide, 3x NADH, 3x H+, 1x FADH2, 1x GTP
- Per molecule of Glucose: 4x carbon dioxide, 6x NADH, 6x H+, 2x FADH2, 2x GTP
Describe the process of oxidative phosphorylation
- Hydrogen carriers (NADH and FADH2) are oxidised → releases high energy electrons and protons
- NADH enters ETC at complex 1, donating a pair of electrons and protons
- Electrons passed along redox centres within complex one, each has one with a higher affinity for electrons
- This movement of electrons produces energy which enables protons to be pumped against conc. gradient into intermitochondrial space
- Co-enzyme Q passes electrons across complex 2, 3 and via cytochrome C to complex 4
- Complex 2 doesn’t pump protons across but is where FADH2 enters ETC and produces ATP from donated e-
- Proton pumping causes build up of electrochemical gradient
- Inner mitochondrial membrane impermeable to protons so they must pass through ATP synphase
- ATP synphase rotates as protons pass through it and ADP and inorganic phosphate are joined to form ATP
- Electrons at end of complex 4 are donated to oxygen to produce water (without oxygen ETC cannot occur)
What is BEE/ BMR
Basal energy expenditure/ basal metabolic rate represents energy required to maintain basic function whilst lying down
How can BMI be used to monitor energy balance?
Energy intake exceeding energy expenditure leads to weight gain –> increased BMI
Fatigue if more energy out than in
