January Exam Flashcards
(181 cards)
0
Q
Compound
A
Molecule containing atoms joined together of more than one element
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Molecule
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Two or more atoms joined together
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6 main elements
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Oxygen, carbon, hydrogen, nitrogen, calcium and phosphate
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Weight (N)
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Mass x Force
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Subatomic particles of an atom
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Nucleus, neutrons, protons and electrons
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Atomic number
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Number of protons in the nucleus
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Mass number
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Sum of protons and neutrons
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Outer shell of electrons
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Valence shell
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Free radical
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A charged atom or group of atoms with an unpaired electron in the outermost shell
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Ionic bond
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Formed when atoms loose or gain and e- and a bond forms betwn oppositely charged ions
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Covalent bonds
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Weaker than ionic bonds and formed when atoms share electrons. Can be polar.
11
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Hydrogen bonds
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Form between water molecules due to the polar covalent bonding
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Energy
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The capacity to do work
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Bioenergetics refers to
A
The transformation and exchange of energy within a living system
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1st law of thermodynamics
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Energy cannot be created or destroyed but simply changed from one form to another without being depleted
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2nd law of thermodynamics
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All the potential energy in a system degrades to the unusable form of kinetic or heat energy
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Exergoinic reaction
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Releases energy to the environment (delta negative)
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Endergonic reactions
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Absorbs energy (delta positive)
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Synthesis
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Anabolic, endergonic e.g. Condensation
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Decomposition
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Catabolic, exergonic e.g. Hydrolysis
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Condensation
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Yields water (anabolic)
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Hydrolysis
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Uses water (catabolic)
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Oxidation
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Loss of electrons
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Reduction
A
gain of electrons
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Respiration redox
C is oxidised. O is reduced
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Dehydrogenase
Removes H
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Oxidases
Removes O
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Coenzymes
Temporary carriers of H and e-
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NAD+
Nicotinamide adenine dinucleotide (oxidised= NAD+, reduced= NADH)
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FAD
Flavin adenine dinucleotide (oxidised= FAD, reduced= FADH)
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Creatine kinase
Regulates energy metabolism via hydrolysis reaction
| ATP + Cr PCr + ADP + H+
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Mass action effect
The effect of the concentration of chemicals in solution on the occurrence of a particular chemical reaction
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Respiration
C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP
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Acids
Proton donors
| Acid --> proton (H+) + anion (-ve charge)
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Higher H+ conc
More acidic
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Hydrochloric acid
HCl
| Digestion
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Carbonic acid
H2CO3
| Chemical buffering
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Citric acid
C6H8O7
| Metabolic pathways
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Strong acids
Dissociate irreversibly in water
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Weak acids
Reach an equilibrium governed by the mass action effect
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Base
Proton acceptor, releases OH-, forms a hydroxyl ion and a cation (+I've charge)
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Bicarbonate
HCO3-
| Blood
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Ammonia
NH3
| Protein metabolism
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Concentration units
mmol.L-1 or mM
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pH
A quantitative measure of acidity or alkalinity
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pH of the body
7.4
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pH of blood
7.35 - 7.45
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pH of the CNS
>7.0
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pH of cytoplasm of active muscle
6.5
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Buffering in the body
Chemical and physiological mechanisms acting in an integrated system to moderate changes in the concentration of pH
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Chemical buffering
First line of defence
Occurs in the blood
Immediate response
Enzyme controlled
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Equation of chemical blood buffering
H+ + HCO3 H2CO3 CO2 + H2O
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Buffers in the body
Sodium bicarbonate in the blood, sodium phosphate in the cell, deoxygenated Haemoglobin in venous blood
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Examples of physiological buffering in the body
Renal buffering and ventilators buffering
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Renal buffering
Response is hours and days
Secretes NH3 and H+
Re absorbs alkali, chloride and bicarbonate
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Ventilatory buffering
Changes CO2 conc
| Faster than in kidneys and important in exercise
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The integrated buffering system
Occurs in the blood and uses the pulmonary, renal and bicarbonate buffering systems
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Alkalosis
Increases alkalinity occurring via hyperventilation, vomiting and overactive thyroid
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Acidosis
Increased acidity via hypoventilation, diarrhoea, lactic acidosis of muscles, ketosis
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Food
Chemical energy
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Fuel
A compound from which chemical energy can be transformed into other forms
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Glycogen
Stored in liver and muscles with H2O
| Enough for 12 hours
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Triacylglycerol
Stored in adipose tissues
| Enough for 15 days
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Energy uses in the body
Mechanical, chemical and transport
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Potential energy
Stored energy
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Kinetic energy
Energy of motion
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Exergonic energy
Energy released
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Endergonic energy
Energy absorbed
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Gram calorie
The energy required to increase the temp of 1g of water by 1 degree C
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kCal
Kilogram calorie
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SI unit of energy
Joules
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Joule J
The work done when 1N of force moves 1m
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1kCal= ?J
4.184
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Direct calorimetry
Measures the heat liberated as food burns
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Heat of combustion
The total energy value of food measured
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Coefficient of digestibility
The ability of the body's digestive process to extract the potential energy yield within food
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Atwater general factors
Values that estimate the net available energy to the body from food
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Dietary carbohydrate
4 kCal/g
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Dietary protein
4 kCal/g
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Dietary lipid
9 kCal/g
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Dietary alcohol
7 kCal/g
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Enzyme
A specific protein catalyst that accelerated the forward and reverse rates of chemical reactions without being consumed or changed in the reaction
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Fischer
Lock and key
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Koshland
Induced fit hypothesis
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Initial velocity
The rate of the initial forward substrate to product reaction
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Maximum velocity
The maximum rate at which substrate can be converted to product
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Michaelis constant (km)
Concentration of substrate required to produce 1/2 Vmax
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Coenzyme
Organic substances which assist with the work of enzymes e.g. Iron, zinc and b vitamins
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Alosteric enzymes
Positive and negative effectors of enzymes
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ATP
Adenosine triphosphate contains an adenine, a ribose and 3 phosphate chains
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Typical ATP:ADP ratio
50:1
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Reciever donor cycle
Cyclical process between ADP --> fuel oxidation --> ATP --> energy requiring process --> ADP
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Cells major energy transforming activities
Extracting potential energy from food
Extracting from ATP for biological work
ATP resynthesis via energy from food
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ATP hydrolysis
Releases energy as phosphate bonds are broken down using water
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ATP hydrolysis catalysed by
ATPase
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ATP hydrolysis releases
7.3 kCal.mol-1
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ATP hydrolysis equation
ATP + H2O --> ADP + Pi
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ATP resynthesis
2ADP AMP + ATP
| catalysed by adenylate kinase
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Store of ATP
80-100g
3mmol per kg muscle
2s worth
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ATP instant replenishment
Achieved by phosphocreatine PCr
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ATP resynthesis from PCr is catalysed by
Creatine kinase
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How much PCr cells store
6x more than ATP
| Theoretically gone in 8-12s but provides a buffer whilst the long term energy pathways are getting going
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Stimulus of creatine kinase
Increased conc of ADP
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Products from the CK reaction activate
Enzymes of glycolysis and oxidative phosphorylation
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PCr shuffle
The relationship between resynthesis inside the mitochondrial inner membrane and the myofibril where contraction is occurring
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ADP access to the mitochondrial matrix is
Restricted
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High energy phosphates are transferred between the mitochondrion and myofibrils by the exchange between
Cr and PCr to then resynthesis ATP
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Homeostasis
The tendency to regulate internal conditions by a system of feedback controls to stabilise health and functioning regardless of changing external conditions
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Negative feedback loop
Stimulator-->
| Receptor -> integrator -> effector -> response -> receptor
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Anti diuretic hormone
Vasopressin
| From the pituitary
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Passive transport
Simple and facilitated diffusion, osmosis, filtration
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Active transport
Sodium potassium pumps, endo cytosis, exocytosis, phagocytosis, secondary active transport
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Membrane potential
-70mV
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Depolarisation occurs when
Na+ in
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Repolarisation occurs when
K+ out
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Glucose symport
Electrochemical gradient is used to transport 1 glucose for every 2 Na+ e.g. By Glut-1 and -2 in the intestines
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Insulin release from pancreatic beta cell
```
Glucose in via glut-2
Glycolysis and respiration increase ATP:ADP ratio
K+ channel shuts
Depolarisation
Ca2+ channel opens and calcium moves in
Exocytosis of insulin occurs
```
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Motor neurone causing muscle contraction
Ach leaves neurone
Action potential moves down t tubules opening Ca2+ channels
Ca2+ move in and binds troponin
Actin binding occurs
Ca2+ channels shut and ATP used by Ca2+ pumps to restore conc
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Carbohydrate
CHO
| Cn(H2O)n
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Extraction of energy from CHO in3 steps
Glycolysis
TcA cycle
Oxidative phosphorylation
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Glycolysis
10 step oxidation of glucose in the cytoplasm
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Net result of glycolysis
2 pyruvate, 2 ATP, 2 NADH, 2H+
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Rate limiting steps of glycolysis
3 and 6.
3 is PFK
6 is NAD+
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Enzyme in step 1 of glycolysis
Hexokinase
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Enzyme in step 3 of glycolysis
Phosphofructokinase PFK
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In high oxygen and high NAD+ availability the pyruvate
Is used by pyruvate dehydrogenase and added to CoA to form acetylene coA which enters the TCA cycle.
NAD+ becomes NADH + H+ that goes to the ETC
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In low oxygen and low NAD+ avaibility the pyruvate
Lactate dehydrogenase turns it into lactate and NADH + H+ becomes NAD+ and goes to step 6 of glycolysis to maintain the glycolytic rate
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TCA cycle
Mitochondrial metric, occurs twice for 1 glucose molecule, 8 steps, cyclical
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TCA products per turn
3 NADH, 1 FADH2, 1ATP, 2CO2
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TCA cycle starts with
Oxaloacetate and acetyl coA
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The NADH from the TCA cycle
Goes to the ETC
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Maintain muscle ATP occurs using
PCr system, glycolysis and oxidative phosphorylation
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Types of fats
Neutral, compound, derived
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Neutral fat
Triaglycerides
134
Compound fat
Phospholipid
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Derived lipids
Cholesterol
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Triglycerides
1 glycerol and 3 hydrocarbon chains
| Sympathies isles in adipose via a condensation reaction
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Lipolysis
Breakdown of fats
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Lipoprotein lipase
Catalysed Lipolysis
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Hormone sensitive lipase
Regulated the release of fatty acids from adipose tissue by breaking off the first FA (HSL)
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Removal of glycerides is a
Hydrolysis reaction
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Glycerol diffuses...
Into the blood stream and is converted into glyceraldhyde 3-phosphate and enters step 6 of glycolysis
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Free fatty acids...
Bind to albumin which transports them for beta oxidatin
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Albumin
Transport protein that carries FFAs in LDL or HDL
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Bad density lipoproteins
LDL
145
Beta oxidation
Occurs in the mitochondrial matrix and removes carbon pairs from FFAs. FAD and NAD+ are reduced and take H to the ETC
Acyl coA becomes acetyl coA and enters the TCA
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1 glycerol yields
19 ATP
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18 C fatty acid yields
147 ATP
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16C fatty acid yields
130 ATP
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Entry of fatty acids into the TCA cycle
Can only occur if enough oxaloacetate is availed from step 1 of carb metabolism to combine with the acetyl co a from beta oxidation to form citrate and enter
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Gluconeogensis
Glycerol, lactate and certain a.a. --> glucose
| Via the liver
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Cori cycle
2 lactate --> 2 pyruvate --> 1 glucose
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Lipogenesis
Synthesis of lipids from glucose and a.a. By the liver and adipose cells
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Protein functions
Structural proteins, transport, enzyme function, hormones
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Number of a.a.
20
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Number of essential a.a.
8
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a.a. Composed of
Amino group, carboxyl group, alpha carbon, organic side chain
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Peptide bonds
Consideration reactions between the carboxyl group of one and the amino group of another amino acid
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Primary protein structure
Amino acid sequence
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Secondary structure
Hydrogen bonds between the amino acids within the chain form alpha helixes and beta pleated sheets
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Tertiary protein structure
The attractions between helixes or pleated sheets
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Quaternary protein structure
Two or more polypeptide chains joining together
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Proteindenaturation
Loss of structure and biological activity as tertiary and quaternary structure is lost
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Deamination
The removal of nitrogen from amino acid molecules that can then enter various stages of the TCA cycle
Releases ammonia
164
Ammonia is transported to the liver by
Alanine and glutamin and excreted by the urea cycle (ATP cost)
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Negative nitrogen balance
Net loss of muscle mass
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OILRIG
Oxidation is loss
Reduction is gain
Of electrons
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Components of cellular oxidation
Fuel, TCA cycle, coenzymes NAD/FAD, ETC and oxygen
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Cellular oxidation
Aimed at providing energy to resynthesis ATP in the presence of oxygen through the breakdown of CHO, lipid and protein
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Fuel broken down in
The mitochondrial matrix via TCA
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Coenzymes carry H to
The ETC where oxygen is the final electron acceptor
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Cells primary means of trapping chemical energy
Cellular oxidation >90% synth
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ETC
Inner mitochondrial matrix, 4 cytochromes
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NAD+ and FAD in the ETC
Carry 2 H each to the ETC from the TCA
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NADH + H+ reacts with cytochrome
1 and is oxidised as the cytochrome is reduced
| NAD+ returns to the TCA to get more.mprod uses 3 ATP
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FADH2 reacts with cytochrome
2 and is oxidised as the cytochrome is reduced. Gives 2 ATP
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Electrons pass along the cytochromes as
One is reduced by accepting an electron and the previous one is oxidised
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In 3 of the 4 cytochromes free energy release of the e- is associated with
Proton pumping of H+ from the matrix to the intermembranouse space
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Creation of the gradient in the ETC
H+ accumulates outside the matrix and then flows down a conc gradient back into the matrix and releases enough energy to phosphorylate ADP to ATP
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C4 is oxidised by
Oxygen, the final electron acceptor of the electron transport chain
180
Oxygen avaibility and the ETC
C4 cannot be oxidised and ETC backs up
NADH + H+ / FADH2 accumulates
Lack of NAD+ means reduced TCA cycle
