PCS 1 Flashcards
What is an amphiobolic reaction?
A catabolic and anabolic reaction together e.g. Krebs
What is mean by the term ‘Accommodation’?
Slow and prolonged depolarization due to inactive sodium channels.
Sodium cannot be transported into the cell therefore depolarization occurs slowly.
What is the function of a tight junction? What are the proteins that make them up called?
They link epithelial cells together. Claudins are transmembrane proteins present in tight junctions .
What is the main regulatory point in glycolysis? What steps does it catalyse?
PFK.
Fructose-6-Phosphate –> Fructose-1,6-Bisphosphate
What are the three most commonly fractured carpal bones?
- Scaphoid 2. Triquetrum 3. Lunate
What is the function of the Biceps Brachii?
FLEXES and SUPINATES the forearm at the elbow joint.
In which muscle type(s) are the contractile filaments organized into sarcomeres?
Cardiac and Skeletal muscles.
Which cell type gives rise to osteoblasts?
Osteoprogenitor cell
What is the definition of a motor unit?
One lower motor neurone and all the skeletal muscle fibers that it innervates.
What makes up ground substance?
GAGs and Proteoglycans.
In which muscle type(s) are satellite cells present?
Skeletal. Satellite cells are stem cells.
Go through the steps of muscle contraction with actin and myosin including the power stroke.
- ATP bind to myosin.
- Binding of ATP to myosin causes the myosin to dissociate from actin.
- ATP hydrolysis into ADP and Pi. This causes myosin to change the angle of its head.
- With ADP and Pi still present, myosin binds to actin at a new angle.
- When Pi leaves, myosin pulls against actin, causing the power stroke (contraction!)
What is calculated using the Nernst Equation?
Equilibrium Potenital
What is the resisting membrane potential for sodium and potassium?
Sodium +60mV
Potassium -90mV
Name the FOUR major classes of simple epithelia.
Squamous, cuboidal, columnar, pseudostratified
What enzyme catalyses the link reaction? Steps involved?
Pyruvate dehydrogenase.
Pyruvate –> Acetyl CoA.
Irreversible reaction.
What is the function of the carnitine shuttle?
Transporting fatty acids from the intermembranous space of the mitochondria to the mitochondrial matrix.
Without this shuttle, the fatty acids would not be able to be transported into the matrix, meaning fatty acids would not be available to be metabolised, making it the rate limiting factor.
What reaction does Hexokinase catalyse?
Glucose –> Glucose-6-Phosphate (via the transfer of a phosphate molecule from ATP to glucose)
1st step in glycolysis
What are the three main controls in glycolysis?
Phosphofructokinase
Hexokinase
Pyruvate Kinase
What determines the contraction speed of skeletal muscle fibers?
ATPase activity of myosin
What is the action of Myosin Light chain kinase?
Phosphorylates myosin, allowing it to bind to actin for contraction to occur.
What is the action of Myosin Light chain phosphotase?
Dephosphorylates myosin light chain / detatches cross bridges. Inhibits muscle contraction.
Name the epithelium lining the tongue.
Non-keratinised stratified squamous epithelium.
What proteins form gap junctions?
Connexons. They require 6 connexins to form one connexon.
What proteins are involved in Adhering Junctions?
Cadherin molecules bound to actin.
What proteins are involved in Gap Junctions?
Connexons
What proteins are involved in Hemidesmosomes?
Integrins
What proteins are involved in Desmosome junctions?
Cadherin to Keratin filaments
In glycolysis, what does Phosphoglucose Isomerase catalyse?
The second step!
Glucose 6-phosphate - Fructose 6-phosphate
What are the products in TCA cycle?
3 NADH
1 FADH
2 Co2
1 GTP
What is the function of complex 1-4 in the ETC?
Complex 1 -> NADH- CoQ reductase (transfers electrons from NADH to CoQH2)
Complex 2 –> Succinate CoQ reductase (uses FADH2 and is part of kreb cycle too)
Complex 3 –> CoQ Cytochrom c reductase (transfers electrons from COQH2 to Cyt c)
Complex 4 –> Cytochrome C Oxidase (final complex in ETC)
What are Islets of Langerhans?
Endocrine tissue found in the pancreas which releases glucagon and insulin.
Which complex in the electron transport chain does carbon monoxide inhibit?
Complex IV
What is the problem in Mcardle’s disease?
The inability to produce glycogen phosphorylase. (required to break down glycogen to glucose)
Fill in the table for Insulin.
a) origin
b) metabolic effects
c) effect on blood glucose levels
Fill in the table for Glucagon.
a) origin
b) metabolic effects
c) effect on blood glucose levels
Fill in the table for Adrenaline.
a) origin
b) metabolic effects
c) effect on blood glucose levels
Fill in the table for Cortisol.
a) origin
b) metabolic effects
c) effect on blood glucose levels
Fill in the table for Growth Hormone
a) origin
b) metabolic effects
c) effect on blood glucose levels
If you ran a 100m sprint, what would be your main energy source?
A 100m sprint requires a short burst of energy.
In most cases, pre-synthesised ATP, creatine phosphate and anaerobic glycolysis are the main processes that provide ATP to make you sprint.
Oxidative phosphorylation would be too slow to activate.
What would be he main energy source for running between 100m - 1km?
Oxidative Phosphorylation is usually sufficient enough to provide energy to one going from over 100m to 1km.
Glycogen may begin to be used towards the end of this time but it would not be the ‘main’ energy resource.
What energy sources would be used when running a half marathon?
Would it be the same source throughout or would it change?
Oxidative phosphorylation is used for the first part of the half-marathon and may be used throughout the race.
After about 1km, your body will begin to use glycogen reserves and Beta-oxidation of fatty acids to primarily provide your ATP needs over a long period of time.
Is the brain insulin sensitive or resistant?
It is considered an insulin resistant organ
The main places where insulin acts are hepatocytes, adipocytes and myocytes.
What is the main energy source for a red blood cell?
RBCs have no nucleus or mitochondria.
oxidative phosphorylation and beta oxidation cannot take place so …
GLUCOSE can be the only molecule used by the cell to generate ATP.
What does a 2% NaCl solution mean?
0.02 x 100 =
2g/100ml
What does 0.9% NaCl solution mean?
0.9g/100ml
Convert the units of
2% NaCl solution into
mg/ml units
2% = 2g/100ml
2000mg/100ml
i.e. 20mg/ml
What is the liver isoform of hexokinase called?
Glucokinase
Requires a much higher glucose concentration for maximal activity. It has a high Km - requires more substrate to work.
Most active after the consumption of a carbohydrate rich meal.
How does DNP (2,4-dintirophenol) disrupt ATP synthesis?
It disrupts the proton gradient in the electron transport chain.
DNP is a hydrophobic molecule, so can freely diffuse across the inner mitochondrial membrane.
It can carry protons across the inner mitochondrial membrane, which is normally impermeable to them.
This means that they don’t go down the usual route, through ATP synthase.
This means that normal ATP synthesis stops. It is said to be an ‘uncoupler’ of oxidative phosphorylation.
How many molecules of NADH are produced for each pyruvate –> acetyl CoA?
1
Which electron carrier is produced by Vitamin B3?
NADH
What 2 components make up the nicotinamide ring of NAD+?
Niacin (vitamin B3)
Tryptophan
What occurs when NAD+ accepts electrons?
A hydride ion covalently binds to it, reducing NAD+ to NADH, and oxidizing the substrate.
What occurs when FAD accepts electrons?
It gets reduced as it accepts 2 hydride ions, and the substrate is oxidized.
What do the reduced cofactors FADH2 and NADH do with their electrons?
Transfer them to the ETC
What do the electrons from reduced CoQ get passed on to?
Cytochrome c
(consist of a Heme group & Protein)
How is a cytochrome changed when it accepts an electron?
The IRON of the heme group is reduced from Fe3+ to Fe2+
What is Thiamine pyrophosphate (TPP)? What is it made from?
Derivative of Thiamine (B1)
Formed from ATP and thiamine
Deficiency = beri beri
What is the pentose phosphate pathway?
Products?
Rate limting enzyme?
2 pathways
Oxidative phase - begins with glucose-6-phosphate
**Gl-6-Phos –> Rib-5-Phos generates 2 NADPH from 2NADP+**
Non oxidative - begins with ribulose-5-phosphate
RLE: Glucose-6-Phosphate Dehydrogenase
Number of NADH, FADH per molecule of glucose in the TCA cycle?
Number of enzymes involved?
What two things start the cycle?
one glucose, 2 turns of the cycle.
6 NADH, 2 FADH, 8 enzymes
Acetyl CoA & oxaloacetate
What happens to GTP produced from the Krebs cycle?
GTP –> ATP
by the enzyme Nucleoside Diphosphokinase
It is always converted afterwards because GTP cannot be used as an energy source for many cell functions (GTP is specific to protein synthesis and gluconeogenesis)
What is temporal summation?
Temporal summation occurs when a single neuron fires many excitatory post synaptic potentials (EPSPs). If the summation crosses the threshold potential, then the post-synaptic cell will depolarise and generate and action potential.
What is spatial summation?
Spatial summation occurs when different neurons synapse with the cell body of a neuron and they each fire EPSPs.
When does an Inhibitory postynpatic potential occur?
It occurs when a presynaptic membrane release a neurotransmitter that causes the opening of Cl- channels in the postsynaptic membrane and hyperpolarisation.
What does Frequency potentiation mean?
It occurs when many action potentials arrive at the presynaptic membrane, leading to a larger release of neurotransmitter from the presynaptic cell. The postsynaptic membrane is therefore more likely to depolarise.
Under what conditions will a reaction occur spontaneously?
if delta G = -ve (exothermic)
A reaction will only proceed if there is an increase in disorder (delta S) within the system
Name the types of proper connective tissue.
Name the types of special connective tissue.
proper = Loose, Dense regular, Dense irregular
special = adipose, blood, cartilage, bone
Fibro blasts are the active cells in connective tissue. They secrete ECM including fibres such as __, __, __, __?
collagen, elastin, reticulin, ground substance
Sickle Cell Anaemia = change of __ to __ ?
(amino acids)
Glutamic acid –> Valine
Location and function of:
GLUT1
GLUT2
GLUT3
GLUT4
GLUT5
GLUT1 - all cells - basal uptake
GLUT2 - liver & pancreas - glucose uptake (from blood)
GLUT3 - all cells - basal uptake
GLUT4 - muscle & adipose - *insulin sensitive*
GLUT5 - S.intestine - fructose (F.diff)
What is the action of ‘Enolase’ enzyme?
Takes water out
i.e. dehydration
What makes up ATP?
Adenine, Ribose, 3 x Phosphate
What is the nernst equation? units?
Simplified version? (under what conditions?) units?
Normal: ** -ve **, Temp in K, z = charge of ion
units: v –> x 1000 = mv
Simplified - at 37oC. units: mv
Convert oC –> Kelvin.
+273.15
How would you calculate a 95% reference range using a given mean and SD?
Exclude top and bottom 2.5%
Range = (mean-1.96SD) to (mean+1.96SD)
Two pathways for glucose?
2 x (pyruvate –> acetyl CoA)
2 x (pyruvate –> lactate)
Link reaction.
How many are made per glucose molecule?
NADH
ATP
CO2
(1 x glucose –> 2 x pyruvate)
2 NADH
0 ATP
2 CO2
TCA cycle
How many are made per glucose molecule?
NADH
FADH2
ATP
CO2
6 NADH
2 FADH2
0 ATP (2 GTP –> converted to ATP)
4 CO2
What is ketogenesis?
The production of ketone bodies (highly acidic) from acetyl coa.
What is the ‘committed’ step in glycolysis?
How is it regulated in skeletal muscle?
PFK
Inhibited by low pH (as a result of increased lactic acid). This will denature the enzyme, preventing more lactic acid from being produced.
ATP allosterically inhibits at high concentrations but this will be removed by the high AMP present.
What is the final end product of beta oxidation?
How does it enter the TCA cycle?
Beta oxidation creates acetyl CoA & acyl CoA until all carbons of acyl CoA are gone.
There will be a three carbon end product Propinyl CoA produced if the fatty caid chain contains an odd number of carbons.
Propinyl CoA is converted to Succinyl CoA which enters the TCA cycle.
Place in order (excitation contraction):
1) Depolarisation spreads to the T tubules
2) Ca2+ is released from the sarcoplasmic reticulum
3) ACh released from alpha motor neurons
4) Signal is passed to the terminal cisternae
5) Binding of ACh to receptors on the sarcolemma
5) Binding of ACh to receptors on the sarcolemma
3) ACh released from alpha motor neurons
1) Depolarisation spreads to the T tubules
4) Signal is passed to the terminal cisternae
2) Ca2+ is released from the sarcoplasmic reticulum
**T tubules are imaginations of the sarcolemma (cell membrane) into the muscle fiber
**Terminal Cisternea are expanded portions of the sarcoplasmic reticulum that come in close proximity to the T tubules.
