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