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Phase 1 > IMMS - Biochemistry > Flashcards

IMMS - Biochemistry Flashcards

1
Q

What are the proportions of water distribution in the body?
Base this on a 70kg male

A
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2
Q

How can water move between ICF and ECF?

A

-Water freely permeable through OCF and ECF through interstitium
-Determined by osmotic contents
-Any change causes water shift
-Always equal = isotonic

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3
Q

What is in the ECF?

A

-Sodium main contributor to ECF osmolality and volume
-Anions:
-Chloride
-Bicarbonate
-Glucose + urea
-Protein = colloid osmotic pressure (oncotic)

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4
Q

What is in the ICF?

A

Predominant cation id potassium

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5
Q

What are interstitial fluid and plasma?

A

-Interstitial fluid - surrounds the cells but dows not circulate
-Plasma - circulates as the fluid component of blood

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6
Q

What is osmalality?

A

Measures the concentration of all chemical particles found in the fluid or part of the blood

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7
Q

What affects plasma osmolality and how is it estimated?

A

-Largely determined by sodium and associated anions
-Estimated plasma osmalality = 2[NA] + 2[K] + urea + glucose mmol/L
-Ions are multiplied by 2 as they have a greater efect

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8
Q

What do changes in plasma osmolality do?

A

-Intra and extracellular osmolality are equal
-Change in plasma osmolality pulls or pushes water across cell membranes

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9
Q

Label the gains and losses of water within a day:

A
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10
Q

Label the diagram of the volumes of water gained or lost by each of these sources:

A
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11
Q

What should be the daily net gain of water?

A
  • 0
    -Under normal circumstances fluid intake = fluid loss
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12
Q

Why don’t we give water intravenously?

A

-Hypo-osmolar/hypotonic vs cell
-Water enters blood cells causing them to expand and burst - haemolysis
-Only occurs in vicinity of intravenous cannula

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13
Q

Describe changes of ECF osmolality:

A

-Very tightly regulated
-Changes in ECF osmolality lead to rapid response
-Normal plasma osmolality 275-295mmol/kg
-Water deprivation or loss leads to chain of events

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14
Q

What is the normal range of plasma osmolality?

A

275-295mmol/kg

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15
Q

Label this diagram:

A
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16
Q

What is the effect of ADH?

A

-Acts on distal convoluted tube
-Increases permeability of water
-More water moves from inside the tubule back into the medulla to be reabsorbed
-Lower volume of more concentrated urine

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17
Q

Describe the reaction to an increase in ECF volume:

A

-Cause a slower response compared to osmolality
-RAAS

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18
Q

Label the 5 effects of the RAAS:

A
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19
Q

Label the basic mechanism of RAAS:

A
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20
Q

What are the 5 main causes of water depletion?

A

-Reduced intake
-Sweating
-Vomiting
-Diarrhoea
-Diuresis/ diuretics

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21
Q

Name some common symptoms of dehydration:

A

-Thirst
-Dry mouth
-inelastic skin
-Sunken eyes
-Raised hamatocrit
-Weight loss
-Confusion - brain cells particularly vulnerable
-Hypotension

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22
Q

Label this diagram:

A
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23
Q

What are the risks of over-hydration?

A

-Hyponatraemia
-Cerebral overhydration:
-Headache
-Confusion
-Convulsions

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24
Q

What is hydrostatic pressure?

A

-Pressure difference between plasma and interstitial fluid
-Water moves from plasma into interstitial fluid

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25
Q

What is oncotic pressure?

A

-Pressure caused by the difference in protein concentration between the plasma and interstitial fluid
-Water moves from interstitial fluid into plasma
-Also called osmotic pressure

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26
Q

Label this diagram:
What does it show?

A

Normal water movement between the interstitium and plasma

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27
Q

Label this diagram:
What does it show

A

Normal movement of water between interstitium and plasma

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28
Q

What is oedema?

A

Excess accumulation of fluid in interstitial space

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29
Q

What can cause oedema?

A

-Disruption of the filtration and osmotic forces of circulating fluids:
-Obstruction of venous blood or lymphatic return
-Inflammation; increased capillary permeability
-Loss of plasma protein

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30
Q

What is serous effusion?

A

Excess water in a body cavity

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31
Q

What does this show?

A

Pitting oedema

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32
Q

Describe the pathogenesis and 4 things that can cause it:

A
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33
Q

What does this show?
Describe it:

A

-Inflammatory oedema
-Higher capillary permeability
-More water moving out into interstitial space than returning

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34
Q

What does this show?
-Describe it:

A

-Venous oedema
-Increased capillary hydrostatic pressure meaning increase water pushed out

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35
Q

What does this show?
Describe it:

A

-Lymphatic oedema
-Blockage of fluid movement into the lymphatic system

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36
Q

What does this show?

A

-Hypoalbuminaemic oedema
-Loss of osmotic gradient for movement of water back into vessels

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37
Q

Describe how pleural effusions occur:

A

-Normal pleural space has around 10mL fluid
-Balance between:
-Hydrostatic and oncotic forces in visceral and parietal pleural vessels
-Lymphatic drainage
-Pleural effusions result from disruption of this balance
-Different fluids can enter pleural cavity

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38
Q

What is transudate?

A

-Fluid pushed through capillary due to high pressure within capillary
-Low protein content
-In contect of pleural effusions

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39
Q

What is exudate?

A

-Fluid that leaks around cells of the capillaries
-Caused by inflammation and increased permeability of pleural capillaries to proteins
-High protein content
-In context of pleural effusions

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40
Q

What is measured to differentiate an exudative from a transudative pleural effusion?
What can each mean?

A

-Pleural fluid protein
-Exudative:
-Mailgnancy
-Pneumonia
-Transudative:
-LVF
-Cirrhosis
-Hypoalbuminaemia
-Peritoneal dialysis

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41
Q

What is the difference in protein levels between exudates and transudates?

A

-Exudates have a high protein level compared to transudates
-May also contain cells, bacteria and enzymes

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42
Q

What are the general principles of measuring plasma sodium?

A

-Normal range 135-145 mmol/L
-Concentration is a ratio, not total body content measurement
-High or low [Na] usually due to gain or loss of water rather than Na

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43
Q

What clinical effects usually show with plasma disorders?

A

-Clinical effects are on brain
-Due to constrained volume (skull)
-Rate of change more important than absolute levels

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44
Q

What two groups of things can cause hypernatremia and some examples?

A

-Water deficit:
-Poor intake
-Osmotic diuresis
-Diabetes insipidus
-Sodium excess:
-Mineralocorticoid (aldosterone) excess
-Salt poisoning

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45
Q

What 4 groups of things can cause hyponatremia and examples?

A

-Artefactual
-Sodium loss:
-Diuretics
-Addison’s disease
-Excess water:
-IV fluids (iatrogenic)
-SIADH
-Excess water ++ and sodium +:
-Oedema

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46
Q

What can hypernatremia cause?

A

-Cerebral intracellular dehydration (tremors)
-Irritability
-Confusion

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47
Q

What defined a living organism?

A

-One or more cell
-Capable of reproduction
-Responding to the environment
-Adapting and changing (inheritance)
-Require source of energy
-Growth and development

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48
Q

What is an organelle?

A

Aggregates of macromolecules used to carry out a specific function in the cell

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49
Q

Label this diagram:

A
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50
Q

What functions do macromolecules have?

A

-Osmotic
-Structural
-Optical
-Enzymatic
-Other complex functions

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51
Q

What are some examples of macromolecules?

A

-Haemoglobin
-DNA
-Glycogen
-Rhodopsin
-Collagen

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52
Q

Give 5 features of water:

A

-Universal solvent
-Polarity
-Hydrogen bonding
-Liquid over range 0-100o
-Max density at 4oC

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53
Q

What doesn’t water interact with?

A

-Non-polar substances
-Lipids
-Aromatic compounds

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53
Q

What doesn’t water interact with?

A

-Non-polar substances
-Lipids
-Aromatic compounds
-Hydrophobic compounds

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54
Q

What was probably the first step of life?

A

-First functional and structural definition of life
-Encapsulation of ‘self’ in a membrane of some kind (vesicle)

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55
Q

What are 4 groups of carbohydrates?

A

-Monosaccharides
-Disaccharides
-oligosaccharides
-Polysaccharides

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56
Q

Label the groups:

A
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57
Q

What groups are present on monosaccharides?

A

-Chain of carbons, hydroxyl groups, one carbonyl group
-An aldose has an aldehyde
-A ketose has a ketone

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58
Q

How do you name monosaccharides base on their carbons?

A

-Triose = 3C
-Tetrose = 4C
-Pentose = 5C
-Hexose = 6C

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59
Q

What do monosaccharides generally exist as and why?

A

-Ring structures
-Reaction of the aldehyde or ketone groups with a hydroxyl group of the same molecule

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60
Q

What are 4 sugar derivatives?

A

-Aminosugars - containing an amino group (often acetylated)
-Alcohol-sugars
-Phosphorylated - containing phosphate groups
-Sulphated - sulphate groups

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61
Q

What are glycosidic bonds and where are they found?

A

-Hydroxyl group of one monosaccharide react with OH or NH (to form glycosides)
-O glycosidic bonds form saccharides
-N glycosidic bonds found in nucleotides and DNA

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62
Q

What are oligosaccharides?

A

-Contain 3-12 monosaccharides
-Products of digestion of polysaccharides, or part of complex protein/lipids

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63
Q

What are polysaccharides?

A

Formed by thousands of monosaccharides joined by glycosidic bonds

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64
Q

What are proteoglycans?

A

Long unbranched polysaccharides radiating from a core protein

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65
Q

What are fatty acids?

A

-Straight C chains
-Mostly 16-20
-Methyl group and a carboxyl group at the ends
-Melting point decreases with degree of saturation

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66
Q

What are phosphoacylglycerols?

A

-Derive from phosphatidic acids
-Formed from fatty acids esterified to glycerol and phosphorylated at C3

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67
Q

What are sphingolipids?

A

Derive from ceramide (serine, palmitic acid and another fatty acid)

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68
Q

What are steroids derived from and what are their properties?

A

-Cholesterol
-Fat soluble
-Diffuse through cell membranes

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69
Q

What are eicosanoids?

A

-Synthesised from 20C atoms
-Eicosanoic acids with 3,4,5 double bonds
-Major biological functions

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70
Q

What are the components of nucleotides?

A

-Nitrogenous base
-Sugar
-Phosphate

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71
Q

What bonds form within a nucleotide?

A

-Ester bond between phosphate and sugar
-N-glycosidic between sugar and base

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72
Q

Describe amino acids:

A

-20 different
-Carbon with:
-Amino group
-Carboxyl group
-Side chain (R)
-charge determined by all 3
-Charge changes with pH of environment
-Side chain often determines polarity or nonpolarity

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73
Q

What id dissociation of amino groups?

A

-At different pH, carboxyl and amino groups are ionised (charged)
-Some aminoacids also have ionisable side side

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74
Q

Examples of non-polar amino acids:

A

All hydrophobic

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75
Q

Example of polar amino acids:

A

Usually contain sulphur

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76
Q

Example of charge amino acids:

A
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77
Q

What can some amino acids contain:

A

-Benzene ring
-Aromatic amino acids

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78
Q

What is folding in protein chains determined by?

A

-Charged interactions
-Flexibility
-Physical dimensions

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79
Q

What are 4 examples of protein structure-function relationships?

A

-Immunoglobulins
-Fibrous proteins - collagen
-Enzymes
-Channel and carrier proteins, receptors and neurotransmitters

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80
Q

What do amino acids form?

A

Linear chains - polypeptides

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81
Q

What are the properties of peptide bonds?

A

-Very stable
-Partial C-N bond
-Flexibility around C atoms not involved in bond - allows multiple conformations
-Usually one preferred native conformation determines mainly by type of side chain and their sequence in the polypeptide

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82
Q

What cleaves peptide bonds?

A

Proteolytic enzymes

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83
Q

What is a protein?

A

-Large polypeptide
-usually from a few 10s to 1000s amino acids
-Huge variety of functions arises from different number of 3D shapes
-Function is dependant on structure

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84
Q

What do these represent?

A

-Backbone - line following peptide bonds
-Cartoon - representation showing the fundamental secondary structures

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85
Q

Label the different protein structures:

A
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86
Q

What forces hold proteins together?

A

-Van der Waals forces
-Hydrogen bonds
-Hydrophobic forces
-Ionic bonds
-Disulphide bonds

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87
Q

What are hydrophobic forces?

A

-Uncharged and non-polar side chains poorly soluble in water
-Repelled
-Form tightly packed cores in interior of proteins excluding water molecules

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88
Q

What do disulphide bonds usually form between?

A

-Covalent bond between side chains of cysteine residues
-Extracellular domains of proteins
-Extra stability is needed in extreme conditions

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89
Q

Describe the primary structure of proteins:

A

-Linear sequence of amino acids linked by peptide bonds
-Functionally and evolutionary related proteins could have similarity
-Determines 3D conformation

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90
Q

Describe secondary structure of proteins:

A

-H bonds between each carbonyl group and H attached to N 4 amino acids along chain
-Side chains look outwards
-Proline breaks helix

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91
Q

What is this?
Describe it:

A

-Formed by H bonds between linear regions of polypeptide chains
-From two or same protein, parallel or unparallel

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92
Q

Describe the tertiary structure of a protein:

A

-Overall 3D conformation
-Forces:
-Electrostatic
-Hydrophobicity
-H-bonds
-Covalent bonds
-Conformations change with:
-pH
-Temperature

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93
Q

Describe quaternary structure of proteins:

A

-3D structure of protein composed of multiple subunites
-Same non-covalent interactions as tertiary structures

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94
Q

How do we determine protein structure?

A

-X-ray diffraction of protein crystals
-X-rays reflect off electrons within the protein

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95
Q

What is the function of enzymes?

A

-Powerful biological catalysts
-Bind substrates and convert them into products
-Release products to return to their original form
-Provide a way to regulate rate of reactions

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96
Q

What can enzymes be a marker for?

A

-Disease markers
-increased levels due to certain diseases

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97
Q

What can enzymes be a target for?

A

Can be drug targets for disease

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98
Q

What are these?

A
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99
Q

What is this?

A

-Porphyrin ring
-Core of each haem group
-Holds an iron atom

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100
Q

What is an iron-containing porphyrin called?

A

-Heme
-Iron atom is site of oxygen binding

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101
Q

Where does haemoglobin name come from?

A

Concatenation of heme and globin

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102
Q

What is carbonic acid effect on Hb and what reaction ocurrs?

A

.

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103
Q

What is effect on O2 binding to protonated Hb?

A
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104
Q

What does this show?

A
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105
Q

How does temperature affect haemoglobin oxygen dissociation?

A
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106
Q

How does carbon dioxide in the blood affect haemoglobin oxygen dissociation?

A
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107
Q

What factors affect haemoglobin saturation and why?

A

-Temperature
-H+
-PCO2
-Modify structure of haemoglobin and alter its affinity for oxygen

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108
Q

What do an increase and decrease of temperature, H+ and PCO2 cause on haemoglobin?

A

-Increase:
-Decrease haemoglobins affinity for oxygen
-Enhance oxygen’s unloading from blood
-Decrease acts in opposite manner
-All these parameters are high in peripheral capillaries where oxygen unloading is target

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109
Q

What is sickle cell anaemia?

A

-Genetic disorder
-Formation of hard, sticky, sickle-cell shaped red blood cells
-Contrasts to biconcave-shaped red blood cells
-Caused by mutation in haemoglobin

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110
Q

Where is malaria most prevalent?

A
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111
Q

What are immunoglobulins?

A

-Antibodies
-Produced to bind to antigens, typically toxins or proteins on the surface of microbial agents
-Targets labelled for destruction by cells in the immune system or by lysis through complement system

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112
Q

What is the structure of immunoglobulins?

A

-Supporting scaffold that serves to display highly variable loops of complementarity determining regions (CDRs)
-Diverse nature of CDR regions enables range of reversible bonding effects to act between antibody and antigens

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113
Q

Where are the antigen binding domains on immunoglobins?

A

-Top of supporting structural frameworks
-“arms” of antibody molecule can hinge to allow a degree of movement

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114
Q

What is the essence of antibody/antigen interaction?
What is the part of the antigen involved in this interaction called?

A

-Very close proximity of antibody CDR regions and antigen surface
-Innate contact allows combination of relatively weak interactions to produce strong binding surface
-CDR loops have sequence of amino acids that “complement” antigen surface
-This portion of antigen bound is known as epitope

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115
Q

What is the epitope?

A

Portion of the antigen recognised by the CDR loops

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116
Q

What are proteins a patchwork of?

A

-Charge - +ve or -ve -COO- -NH2+
-Hydrophobicity
-Polarity
-Bulk

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117
Q

What does this show?
Describe them:

A

-Vand der Waals forces
-Weak and short range
-Instantaneous dipole
-Only effective in short distances

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118
Q

What does this show?
Describe them:

A

-Hydrogen bonds
-Sharing of a proton between electronegative groups

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119
Q

What does this show?

A

Charged amino acids can be acidic or basic

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120
Q

What does this show?

A

Bulky amino acid groups can project from the amino acid surface

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121
Q

What does this show?

A

-Hydrophicity
-Hydrophobic groups resist exposure to surrounding aqueous solvent (H2O

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122
Q

What does this show?

A
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123
Q

Describe prokaryotic DNA:

A

-No nuclear membrane
-Single chromosome often
-Circular

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124
Q

Describe DNA in eukaryotes:

A

-Nucleus
-Bound to proteins to form chromatin
-Different appearance at different functional moment
-Mitosis - chromatin condenses into visible chromosomes
-Each made of 2 identical strands (chromatids) joined in centre at centromere
-Some DNA in mitochondria

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125
Q

What are the functions of DNA?

A

-Template and regulator for transcription and protein synthesis
-Genetic material, structural basis of hereditary and genetic diseases

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126
Q

What is the structure of nucleic acids?

A
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127
Q

How do the two strands of DNA run in relation to each other?

A

Antiparallel

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128
Q

What do DNA sequences act as and when is this useful?

A

-Templates
-DNA replication

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129
Q

What is the shape of DNA?

A

-Double helix
-Major and minor grooves within the backbone
-Allow proteins to enter for replication

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130
Q

Describe prokaryotic chromosomes:

A

-Supercoiled
-Circular
-2.5 x 106 kDa
-4 x 106 bases
-2mm linear

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131
Q

Describe human chromosomes:

A

-Complex packaging
-22 x2 + X, Y or X,X
-4 x 109 kDa
-3 x 109 bp
-2m linear (all)

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132
Q

What is heterochromatin and euchromatin?

A

-Heterochromatin:
-Tightly packed
-Inactive
-Euchromatin:
-Loosely packed
-Actively transcribed

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133
Q

What is a solenoid?

A

Compacted nucleosomes

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134
Q

Label this:
What does it show?

A

The cell cycle

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135
Q

Why is cell cycle control and DNA repair so important in medicine?

A

-Cancer
-Oncogenes
-Proto-oncogenes
-Cell cycle control
-DNA repair

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136
Q

Describe DNA replication:

A

-Prior to cell division DNA opens at replication fork
-Base sequence on each parent strand is copied into a complementary daughter strand
-Two parental strand separate in front of fork
-New DNA made behind fork, composed of a new and old strand: replication is semi-conservative
-Many proteins are involved in DNA replication, binding proteins and enzymes

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137
Q

How fast is DNA replication and how long?

A

-700-1000bp per second
-6 billion base pairs

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138
Q

What does O show?

A

-Origins of replication
-Multiple points of origin

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139
Q

What enzymes are involved in human DNA replication?

A

-Polymerases (5’ to 3’)
-Helicase
-Ligase
-Nuclease
-Primase
-Topoisomerase

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140
Q

In what direction is DNA replicated by DNA polymerase?

A

-Reads 3’ to 5’
-Prints 5’ to 3’
-Substrates are deoxyribonucleotides triphosphates
-Enzyme stays on the strand, at the same time extends and proof-reads

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141
Q

What opens the DNA strands during DNA replication?

A

-DNA helicase enzyme
-Single stranded binding proteins (SSB) keep it open
-Topoisomerase unwinds the supercoiling

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142
Q

Label this diagram:
What does it show?

A

DNA replication complex

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143
Q

What other function does DNA polymerase have?

A

-Editing function
-Detects incorrect insertion of base and will excise repeat

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144
Q

What can be used to amplify regions of DNA?

A

Polymerase Chain Reaction (PCR)

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145
Q

What are sources of constant genome damage?

A

-Chemical
-Radiation
-Spontaneous insertion of incorrect bases during replication

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146
Q

What is benzopyrene?

A

-Product of incomplete combustion of hydrocarbonds
-Barbecued food is good source
-DNA - adduct: Reacts with bases to form a bulky group that disrupts replication

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147
Q

Describe the effect of ionising radiation on DNA:

A

-Can damage bases
-Causes breaks in phosphate backbone
-UV forms thymine dimers

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148
Q

When can mutations occur?

A

-DNA damage:
-Chemicals
-UV
-Radiation
-Chance
-DNA repair:
-Base or nucleotide excision
-Mismatch repair

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149
Q

What do we have an elaborate system for?

A

-Detecting DNA damage
-Initiating repair
-Many are keyed in or linked to cell cycle control
-p53 as an example - tumour suppressor gene (sits on DNA and detects damage)

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150
Q

What can p53 do?

A
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151
Q

What does bp stand for?

A

Base pairs

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152
Q

What does kDa stand for?

A

-KiloDaltons
-1000 atomic mass units
-One dalton is mass of H atom

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153
Q

What does S stand for?

A

-Svedberg unit
-Refers to mass and shape of cellular organelles
-High S means larger mass
-Not additive
-Used in ultracentrifugation - how particles are separated

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154
Q

What are 3 differences between human DNA and RNA?

A

-DNA is double-stranded with a complementary chain / RNA is single-stranded and any double stranding is usually with itself
-Three types of RNA: mRNA, rRNA, tRNA with different functions
-DNA is present in cells at all time, many mRNA species only accumulate following cell stimulation and are short lived

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155
Q

Describe mRNA:

A

-Messenger RNA
-Printed as long linear transcript
-Processed to the mature form (in proximity of nuclear membrane)
-Has 5’CAP and 3’ Poly A tail

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156
Q

Describe rRNA:

A

-Ribosomal RNA
-Ribosomes are abundant in eukaryotic cytoplasm
-Four main types of rRNA combine with proteins to form 80S ribosomes

157
Q

What is the interaction between the 3 types of RNA?

A

rRNA prints mRNA with help from tRNA

158
Q

Describe tRNA:

A

-Transfer RNA
-Carry amino acids to ribosomes and check that they are incorporated in the right position
-Each tRNA only carries one amino acid so at least 20 different types
-Very small molecules
-Anticodon triplet sequence pairs with mRNA to ensure right amino acid for right triplet

159
Q

Label:

160
Q

What region sits before the target gene to be transcribed?

A

Promotor region

161
Q

What are 3 features of the genetic code?

A

-Degenerate, but unambiguous
-Many amino acids specified by more than one codon
-Each codon specifies only one amino acid
-Almost universal
-All organisms use same code
-Fewer than 10 exceptions
-Non-overlapping and without punctuation
-Codons not overlap
-Each nucleotide only read once

162
Q

What causes this?

A

-Lactate blocks repressor
-Complementary to active site deactivating it

163
Q

What initiates gene expression?

A

-Proteins called “transcription factors” find their way to specific sequences 5’ of 1st exon
-This is called promotor region
-“transcription complex” forms around TATA box 5’ of 1st codon
-Helix opens, DNA separates
-RNA pol II starts mRNA creation

164
Q

What is an enhancer?

A

Stretch of DNA far from gene which affects DNA expression

165
Q

What do these show?

166
Q

What 6 things can turn off gene expression?

A

-Activation of repressors (inhibit RNA polymerase binding)
-Each step of RNA transcription or processing finds no longer actively produced transcription and processing proteins
-Complexes do not form anymore - lack of phosphorylation
-Enzymes no longer activated
-DNA stability
-Other unknown mechanisms

167
Q

Label this diagram:

168
Q

Describe membrane permeability (3):

A

-Maintains internal environment
-Selectively permeable
-For membrane transport, impermeable substances may need: Transport proteins, energy

169
Q

Describe channel proteins and their functions

A

-Narrow aqueous pore
-Selective to: Size, charge
-Passive
-May be gated (voltage or ligand)
-Usually ions (e.g. Na+) or water (aquaporins)

170
Q

Describe carrier proteins and their function:

A

-Specific binding site
-Undergoes conformational change
-Different types
-Active (pumps) or passive

171
Q

What are the 3 different types of carrier proteins?

A

-Uniport - single substance
-Symport - two substances in the same direction
-Antiport - two substances in the opposite direction

172
Q

What are the 3 main driving forces of substances into/out of cells?

A

-Chemical
-Electrical
-Electrochemical

173
Q

What is the movement of substances based on?

A

-Presence of a gradient
-Either move with the gradient or can move against the gradient

174
Q

Describe the chemical driving force:

A

-Based on concentration differences across the membrane
-All substances have a concentration gradient
-Force directly proportional to concentration gradient

175
Q

Describe the electrical driving force:

A

-Also known as membrane potential
-Based on distribution of charges across the membrane
-Only charge substances
-Force depends on size of membrane potential and charge of ion

176
Q

Describe the electrochemical driving force:

A

-Combines chemical and electrical forces
-Net direction is equal to sum of chemical and electrical forces
-Only charged substances

177
Q

What are the two main types of membrane transport and 2 sub-types of each?

A

-Passive:
-Simple diffusion
-Facilitated diffusion
-Active:
-Primary
-Secondary

178
Q

Describe passive transport:

A

-Does not require an input of energy
-Substances move down its gradient
-Two type:
-Simple
-Facilitated

179
Q

What is an example of passive transport?

A

-Glucose
-GLUT4 carrier protein
-Skeletal muscle and adipose tissue
-Glucose uptake by facilitated diffusion
-Expression upregulated by insulin

180
Q

Describe too much glucose in pregnancy:

A

-Principal fetal nutrient - fetal gluconeogenic enzymes inactive + low arterial PO2
-From maternal circulation
-Fetal glucose level directly proportional to mother
-No mechanism to limit uptake
-Excess glucose can cause significant fetal harm

181
Q

Describe a condition that affects glucose uptake:

A

-GLUT1 deficiency syndrome
-Very rare
-Mutation in gene
-Reduces available glucose to brain cells
-Symptoms - seizures, microcephaly, developmental delay

182
Q

Describe active transport:

A

-Requires input of energy
-Substances move against its concentration gradient
-Primary and secondary

183
Q

Describe primary active transport:

A

-Directly uses a source of energy, commonly ATP
-Common example - Na+/K+ ATPase

184
Q

What’s an example of primary active transport going wrong?

A

-ATP7B protein is a Cu2+ ATPase in liver that transports copper into bile
-Wilsons disease - mutations in ATP7B gene
-Dispersion of copper in liver and other tissues - eyes, brain
-Symptoms - liver disease, tremor, Kayser-Fleischer rings

185
Q

Describe secondary active transport:

A

-Transport of a substance against its gradient COUPLED to transport of an ion (usually Na+ or H+) which moves it down its gradient
-Uses energy from generation of ions electrochemical gradient (usually primary AT)
-Na+/glucose cotransporter proteins (SGLT)
-Intestinal lumen
-Transports glucose from low to high
-Na+/K+ ATPase generates sodium gradient for co-transport

186
Q

Describe an example of when secondary active transport goes wrong:

A

-SGLT1 transports glucose and galactose from intestinal lumen
-Glucose-galactose malabsorption
-Very rare
-Mutation is SGLT1
-Inability to transport glucose and galactose resulting in malabsorption
-Symptoms - severe, chronic diarrhoea, dehydration, failure to thrive

187
Q

How does communication between cells take place?

A

-Signalling molecules
-E.g. hormones, neurotransmitters and growth factors

188
Q

What do signalling molecules bind to?

A

-Receptors
-Intracellular - steroid hormones
-Cell-surface - peptide hormones
-Second messengers - amplification
-Affect gene expression in the nucleus either directly or through signalling cascades

189
Q

Describe a disease that affects cell signalling:

A

-Cholera
-G-proteins integral part of G-protein-couples receptors on cell membrane surfaces
-Vibrio cholerae bacteria produce cholera toxin
-Crosses cell surface membrane
-Modifies subunit (intracellular action)
-Increased cAMP
-Stimulates transporters to surface membrane of intestinal cells
-Massive secretion of ions and water into gut
-Severe diarrhoea and dehydration

190
Q

Describe endocytosis:

A

-Large molecules require different methods of transport
-Transport into a cell by encapsulating it into a vesicle

191
Q

Describe exocytosis:

A

-Large molecules require a different method of transport
-Golgi vesicle fuses with membrane to release substance

192
Q

Describe cystic fibrosis in terms of transport:

A

-Mutation in CFTR protein
-Chloride channel
-Found in many tissues - gut, pancreas, lungs and skin
-“secretory epithelium”
-Abnormal function results in sticky, viscous mucus
-no osmotic drag

193
Q

What are some drugs that target membrane transporters?

A

-Cardiac glycosides
-Proton pump inhibitors
-Loop diuretics
-Thiazide diuretics

194
Q

What is metabolism and metabolic processes?

A

-Metabolism - sum of the chemical reactions that take place within each cell of a living organims
-Sequence of chemical reactions: particular molecule is converted into some other molecule or molecules in a defined fashion

195
Q

What 4 main pathways are dietary components metabolised?

A

-Biosynthetic
-Fuel storage
-Oxidative processes
-Waste disposal

196
Q

What does anabolic and catabolic mean?

A

-Anabolic - synthesise larger molecules from smaller components
-Catabolic - break down larger into smaller

197
Q

Are the 4 main metabolism pathways of dietary components anabolic or catabolic?

A

-Biosynthetic - anabolic
-Fuel storage - anabolic
-Oxidative - catabolic
-Waste disposal - either

198
Q

What type of reaction provides energy for cell processes from fuel molecules?

A

Catabolism

199
Q

What can catabolism provide energy for?

200
Q

What is the Kreb’s cycle and example of?

A

Catabolism

201
Q

What can Krebs cycle produce?

A

Some substrates for biosynthesis

202
Q

What do reactions often require?

203
Q

How is energy conserved in oxidative phosphorylation?

A

Via transfer of electrons in the inner mitochondrial membrane

204
Q

What does the electron transport chain consist of?

A

4 complexes and associated compounds like ubiquinone

205
Q

What does the electron transport chain do?

A

-Oxidises NADH and FADH2
-Thus releasing energy which is used to produce ATP

206
Q

What gradient drives ATP production?

A

Electrochemical proton gradient

207
Q

What tissue is this?
Describe it:

A

-Adipose
-85% fat
-Storage of energy-rich molecules

208
Q

What tissue is this?
Describe it:

A

-Liver
-Metabolically active

209
Q

What type of tissue is this and what is its function?

A

-Muscle
-Activity

210
Q

Label this diagram:
What does it show?

A

The Cori cycle

211
Q

What kind of molecule is insulin?

A

-Anabolic
-Aids the build up of molecules within cells

212
Q

What does this show?

A

The effects of insulin

213
Q

What does insulin do in adipocytes?

A

-Stimulates uptake of VLDL and glucose
-Stimulates conversion of fatty acids to triacyglycerols

214
Q

What does insulin do in skeletal muscles?

A

-Stimulates uptake of amino acids to be converted to protein
-Stimulates absorption of glucose

215
Q

What does insulin do in liver cells?

A

-Stimulates uptake of amino acids to be converted to protein
-Stops conversion of amino acids to glucose
-Stimulates conversion of glucose to glycogen
-Stimulates conversion of glucose to fatty acids and release of VLDL

216
Q

What are 7 dietary components?

A

-Fuels
-Essential amino acids
-Essential fatty acids
-Vitamins
-Minerals
-Water
-Xenobiotics

217
Q

How many main dietary energy sources are there and what are they?

A

-3
-Carbohydrates (recommended primary energy source)
-Lipids
-Proteins

218
Q

What is normal BMI?

A

-18.5 - 25: Normal/healthy
-25-30: Overweight
->30: Morbidly obese
-Measured in Kg/m2

219
Q

What do we do with dietary energy sources?

220
Q

What types of carbohydrates do we use?

A

Monosaccharides and disaccharides

221
Q

What are proteins made of?

A

-Amino acids in chains
-Carbon
-Oxygen
-Hydrogen
-Nitrogen (16% by weight)

222
Q

What lipids do we use?

A

-Triglycerides
-3 fatty acids esterified to one glycerol moeity
-More reduced than other energy sources

223
Q

How are dietary fuels stored in the body?

A

-Fat - Adipose tissue - 15% water
-Carbohydrate - glycogen in liver and muscles
-Protein - muscle - 80% water

224
Q

What happens to excess energy intake?

A

-Store as triglycerides in adipose (15kg)
-Store as glycogen (200g in liver, 150g in muscle, 80g in liver after overnight fast)
-Store as protein in muscle (6kg)

225
Q

Why is storage of glycogen limited compared to triglycerides?

A

-Hydrophilic whereas triglycerides are hydrophobic
-Attracts water

226
Q

How much energy per gram of carbohydrate?

227
Q

How much energy per gram of protein?

228
Q

How much energy per gram of alcohol?

229
Q

How much energy per gram of lipid?

230
Q

How much energy per gram of 4 molecules?

231
Q

What is the primary source of ATP supplied to the body at rest during low intensity activities?

A

-Oxidative system (aerobic)
-Primarily uses carbohydrates and fats

232
Q

Label the 4 things that energy can be utilized for:

233
Q

What is BMR?

A

-Basal Metabolic Rate (BMR)
-Energy needed to stay alive at rest
-Measure of the energy required to maintain non-exercise bodily fuctions

234
Q

What are 5 examples of non-exercise bodily functions?

A

-Respiration
-Contraction of heart muscle
-Biosynthetic processes
-Repairing and regenerating tissues
-Ion gradients across cell membranes

235
Q

What conditions are essential for measuring BMR (6)?

A

-Post absorptive (12 hour fast)
-Lying still at physical and mental rest
-Thermo-neutral environment (27-29)
-No tea/coffee/nicotine/alcohol in previous 12 hours
-No heavy physical activity previous day
-Establish steady state (30 min)

236
Q

What 5 factors can decrease BMR?

A

-Age
-Gender
-Dieting/starvation
-Hypothyroidism
-Decreases muscle mass

237
Q

Why do people with a higher muscle to fat ratio have higher BMR?

A

-Muscle cells require more energy to maintain than fat cells
-As we get older we tend to gain fat and lose muscle so BMR tends to decrease with age

238
Q

What factors increase BMR?

A

-Body weight (BMR)
-Hyperthyroidism
-Low ambient temp
-Fever-infection-chronic disease

239
Q

What is the rough estimate for BMR?

A

1kcal/kg body mass/hour

240
Q

What does NHS nutrition guidelines recommend as the daily energy intake for patients who are not severely ill or injured, nor at risk of re-feeding syndrome?

A

25-35 kcal/kg/day

241
Q

What happens metabolically during an overnight fast?

A

-Decrease in insulin
-Glycogenolysis

242
Q

How much glycogen does the liver have after an overnight fast and why?

A

-Brain requires about 150g of glucose a day
-After an overnight fast, the liver only has about 80g of glycogen

243
Q

What may happen during a longer period of fasting/starvation?

A

-Glucose must be formed from non-carbohydrate sources (amino acids, fatty acids)
-Gluconeogenesis

244
Q

What happens during 2-4 days of starvation?

A

Decreased insulin and increased cortisol = lipolysis and proteolysis
-Gluconeogenesis

245
Q

What does gluconeogenesis use?

A

-Lactate
-Amino acids:
-Muscle
-Intestine
-Skin
-Glycerol:
-Fat breakdown

246
Q

What happens during >4 days starvation?

A

-Liver -> ketones from fatty acids
-Brain adapts to using ketones
-Decreased BMR = accomodation

247
Q

What is malnutrition?

A

A state of nutrition with a deficiency, excess or imbalance of energy, protein or other nutrients, causing measurable adverse effects

248
Q

What are adverse effects of malnutrition?

A

Adverse effects are on:
-Tissue/body form (shape/ size/ composition)
-Body function
-Clinical outcome

249
Q

What are the dangers of re-feeding too quickly?

A

-Re-feeding syndrome
-Re-distribution of phosphate, potassium, magnesium etc. due to insulin
-Switch back to carbohydrates as the main fuel which requires phosphate and thiamine

250
Q

What are essential nutrients?

A

-Body can’t synthesise them
-Essential amino acids
-Essential fatty acids
-Vitamins
-Minerals

251
Q

What are micronutrients?
What are their uses in the body?

A

-Trace elements and vitamins
-Co-factors in metabolism
-Gene expression
-Structural components
-Antioxidants

252
Q

What are 3 uses of vitamin C (ascorbic acid)?

A

-Collagen synthesis
-Improve iron absorption
-Antioxidant

253
Q

Give 3 facts about vitamin C:

A

-Ascorbic acid
-Sourced from fruit and vegetables
-Heat labile

254
Q

What are 5 functions of vitamin B12?

A

-Protein synthesis
-DNA synthesis
-Regenerate folate
-Fatty acid synthesis
-Energy production
AND THEREFORE CELL DIVISION

255
Q

What is a function of vitamin B1?

A

-Thiamine
-Helps with energy production

256
Q

What is a function of vitamin B2?

A

-Riboflavin
-Energy production
-Helps body use other B vitamins

257
Q

What is a function of vitamin B3?

A

-Niacin
-Helps body use protein, fat and carbohydrate to make energy
-Helps enzymes work properly

258
Q

What is a function of biotin?

A

-Allows body to use protein, fat and carbohydrate

259
Q

What is a function of vitamin B6?

A

-Pyridoxin
-Helps body make and use protein and glycogen which is stored energy in muscle and liver
-Helps form haemoglobin

260
Q

what are some functions of folate (folic acid)?

A

-Helps produce and maintain DNA and cells
-Helps make red blood cells and prevent anaemia
-Getting enough folic acid lowers risk of having baby with birth defects like spina bifida

261
Q

What is the prudent diet (main 5)?

A

-5+ servings of fruit/veg
-Base meals around starchy carbohydrate foods
-No more than 5% energy should come from free sugars
-0.8g/kg/day protein
-No more than 30g for men and 20g for women of saturated fat

262
Q

What are the last 4 parts of prudent diet?

A

-Adults should have no more than 2.4g of sodium per day (6g salt)
-Advised to not regularly drink more than 14 units of alcohol a week (over >3 days)
-Avoid excess dietary supplementation
-Adequate calcium

263
Q

Label this diagram:

264
Q

Label this diagram:

265
Q

What can vesicles do?

266
Q

What does this show?

A

Phospholipid bilayer

267
Q

What makes up phospholipids and describe the components:

268
Q

Label the diagram:
What does it show?

269
Q

What modifies the fluidity of the phospholipid bilayer?

A

-Cholesterol
-Temperature

270
Q

What is the cell membrane freely permeable to?

A

-Water (aquaporins)
-Gases (CO2, N2, O2)
-Small uncharged polar molecules (urea, ethanol)

271
Q

What is the cell membrane impermeable to?

A

-Ions (Na+, K+, Cl-, Ca2+)
-Charged polar molecules (ATP, glucose-6-phosphate)
-Large uncharged polar molecules (glucose)

272
Q

What are the 6 ways substances can cross the cell membrane?

A

-Simple diffusion
-Facilitated diffusion
-Primary active transport
-Secondary active transport
-Ion channels
-Pino/phago-cytosis

273
Q

What do each of these show an example of?

274
Q

Why are membranes and membrane proteins needed?

A

-Cell polarisation
-Compartmentalisation
-Ionic gradients (diffusion, membrane potential)
-Tightly regulated
-Disease disrupts this

275
Q

What is the membrane potential (Em,/sub>)?

A

-Potential difference across the cell membrane generated by differential ion concentrations of key ions (K+, Na+, Ca2+, Cl-)
-Stable in most cells

276
Q

What is the major determinant of Em?

277
Q

What does convention dictate with membrane potential?

A

-Extracellular fluid potential = 0 mV (reference)
-Membrane potential is that on intra-cellular membrane

278
Q

Describe the various individual diffusion potentials that make up membrane potential:

A

+ve ion - -ve value if diffusing from IC to EC (K+)
+ve ion - +ve value if diffusing from EC to IC (Na+ or Ca2+)
-ve ion - -ve value if diffusing from EC to IC (Cl-)

279
Q

What equation relates to diffusion potential?
Recite it:

A

-Nernst equation

280
Q

What is a key determinant of Em and what is it dependant on?

A

-Ion conductance (permeability)
-Channel numbers
-Channel gating
-Change ion permeability -> change Em

281
Q

What plays a major role in K+ homeostasis and what can affect it?

A

-Kidneys and aldosterone
-Renal failure
-Conn’s syndrome (too much aldosterone)

282
Q

Describe increased concentration of K+:

A

-Hyperkalaemia
-Em less -ve (tending to depolarisation)
-Reaches threshold more easily
-Cell depolarisation more likely
-Heart - decreased SAN firing / bradycardia

283
Q

Describe decreased concentration of K+:

A

-Hypokalaemia
-Em more -ve (tending to hyperpolarisation)
-Disrupts various K+ channels
-Abnormal heart rhythms (arrhythmias)

284
Q

Describe ischaemia in terms of Em:

A

-Hypoxia = low ATP
-Opens KATP channel
-Em less -ve (~-55mV)
-Depolarises more easily
-Fast Na+ inhibited (~-55mV)

285
Q

What happens in terms of Ca2+ during ischaemia?

A

-Slow calcium mediated depolarisation:
-Early repolarisation
-Decreased plateau
-Decreased action potential time

286
Q

Describe:

287
Q

Describe 3 features of epithelia:

A

-Require polarisation of plasma membrane
-Permits cell-specific function (secretion/absorption)
-Strongly adhere to neighbours (tight junctions)

288
Q

What are ways in which cells communicate?

A

-Cell membrane receptors:
-Signal transduction
-Internalise extra-cellular signal

289
Q

What various receptors are involved in signal transduction?

A

-Ion channels
-Membrane-bound steroid receptors
-Neurotransmission
-Growth factors
-Nuclear steroid receptors

290
Q

Describe the six parts of GPCR:

A

-Receptor - give primary specificity
-Three G-proteins (alpha, beta, gamma) (gamma gives further specificity)
-Enzyme to modulate second messenger (e.g. cAMP)
-Enzyme to terminate signal

291
Q

What part of the G-protein determines second messenger?

A

Alpha G subunit

292
Q

How does pH affect membrane function?

A

-Both extremes damage protein
-Inhibits cell function

293
Q

What plays a critical role in acid:base homeostasis?

A

-Plasma Ca2+
-Cell membrane excitability/permeability

294
Q

What about calcium is measured clinically?

A

-Total serum calcium
-Ionised (Ca2+)
-Unionised (Ca)

295
Q

Describe serum calcium:

A

-45% free ionised Ca2+
-Biologically active
-Change Ca2+ (active) : Ca (inactive) with no change in total calcium

296
Q

Describe alkalosis and acidosis in terms of calcium:

A

-Acidosis - less Ca2+ bound to plasma proteins (H+ ions buffered by albumin)
-Alkalosis - more Ca2+ bound to plasma proteins (fewer H+ ions on protein)

297
Q

What are alkalotic patients more susceptible to?

A

-Hypocalcaemic tetany
-Due to increased neuronal Na+ permeability

298
Q

Describe the 55% of calcium that is not bound in serum:

A

-Not biologically active
-45% bound to albumin
-10% anions - phosphate; lactate active form

299
Q

Describe how temperature affects membrane function:

A

-Too cold - proteins slow down, membrane less fluid
-Too hot - proteins denature; increased membrane fluidity

300
Q

Describe the conditions associated with body temperatures:

A

-Heat exhaustion core temp >37 but <=40
-Heat stroke core temp >=40
-Dehydration

301
Q

What happens when core body temp decreases?

A

-Everything slows down
-Lowest survivable core temp 13.7

302
Q

What can affect regulation of SAN action potential (temp)?

A

-Hypothermia
-Decreased depolarisation rate of cardiac pacemaker cells
-Bradycardia
-Abnormal heart rhythms
-Fibrillation

303
Q

Describe hypokalaemia and the lethal triad:

304
Q

What is the currency of metabolic energy?
Whats its composition

A

-Adenosine-5-triphosphate
-High energy molecules composed of adenine (purine base), ribose and 3 phosphate groups

305
Q

What reaction of ATP is energetically favourable?

A

-Hydrolysis of ATP to ADP
-Releases inorganic phosphate, H+ and heat energy

306
Q

Label this diagram:
What does it show?

A

ATP-ADP cycle

307
Q

How do cells generate energy from nutrients?

A

-Glucose metabolism in a series of linked pathways:
-Glycolysis
-Krebs cycle
-Oxidative phosphorylation

308
Q

Describe the 3 stages of glucose metabolism:

A

-Glycolysis - anaerobic breakdown of glucose to pyruvate, small amount of ATP production from substrate level phosphorylation
-Krebs cycle - oxidation of AcetylCoA to CO, generates coenzymes NADH and FADH2
-Oxidative phosphorylation - transduction of energy derived from fuel oxidation to high energy phosphate, generates large amount of ATP

309
Q

Label this diagram:

310
Q

Where does glycolysis occur?

A

Cytosol under anaerobic conditions

311
Q

Why is glycolysis carried out?

A

-Emergency energy production pathway when oxygen limited (RBC, skeletal muscle)
-Generates precursor for biosynthesis
-G-6-P for nucleotides/glycogen
-Pyruvate for fatty acid synthesis
-Glycerol-3-P is backbone of triglycerides

312
Q

What is an overview of glycolysis?

A

-1 glucose converted into 2 pyruvate, 2 NADH + H+ + 2ATP
-Preparative phase
-ATP generating phase

313
Q

Describe the two phases of glycolysis:

314
Q

Label the preparatory phase of glycolysis:

315
Q

In what two stages of the preparatory phase of glycolysis is ATP used?

316
Q

Label this diagram of the ATP generating phase of glycolysis:

317
Q

In what 2 stages of the ATP generating phase of glycolysis is ATP generated?

318
Q

Label this diagram of glycolysis

319
Q

In what stages of glycolysis are ATP, NADH generated and used?

320
Q

What 3 things regulate gylcolysis?

A

-Hexokinase
-Pyruvate kinase
-Phosphofructose kinase - 1 (PFK-1) (MAIN ONE)

321
Q

What is the main regulator of glycolysis?

322
Q

What are the two types of regulation of glycolysis?

A

-Allosteric
-Binds to non-catalytic site
-Conformational change
-Increase or decrease affinity for substrate
-Hormonal
-Increase or decrease gene expression of enzyme
-Indirect route - regulatory molecules
-Increase or decrease enzyme activity

323
Q

What are activators and inhibitors of PFK-1?

A

-Activators:
-AMP
-Inhibitors:
-ATP
-Citrate
-F2, 6 BP

324
Q

Why is AMP a PFK-1 activator?

A

-ADP derivative
-When ATP is used up, ADP accumulates and converted to AMP by adenylate kinase reaction to generate ATP
-Increasing AMP relieves inhibition of PFK-1 by ATP

325
Q

What is the most important allosteric activator of PFK-1?

A

-Fructose-2,6-bisphosphate
-Mediates effect of insulin and glucagon

326
Q

What product of Krebs cycle can allosterically inhibit PFK-1?

A

-Citrate
-Increase signals that cycle doesn’t need more fuel

327
Q

What happens to pyruvate in anaerobic conditions?

A

-Lactate formation catalysed by lactate dehydrogenase
-Regeneration of NAD+

328
Q

What happens to pyruvate in aerobic conditions?

A

-Enters mitochondria and converted to Acetyl CoA and CO2 by pyruvate dehydrogenase
-Acetyl CoA can enter TCA cycle for more energy production

329
Q

What is the equation for what happens to glucose in anaerobic conditions?

330
Q

Label the diagram for what happens to pyruvate under anaerobic conditions:

331
Q

What is the equation for what happens to pyruvate under aerobic conditions?

332
Q

Describe the irreversible reaction of pyruvate under aerobic conditions:

A

-Catalysed by pyruvate dehydrogenase (multienzyme complex within mitochondrial matrix)
-Inhibited by high concentration of acetyl CoA and NADH
-inactivated by phosphorylation
-Activated by phosphate removal

333
Q

Where does Krebs cycle happen?

A

Mitochondrial matrix under aerobic conditions

334
Q

Why does the Krebs cycle occur?

A

-Generates LOTS of ATP
-Provides final common pathway for oxidation of carbohydrates, fat and protein via ACoA
-Produces intermediates for other metabolic pathways

335
Q

What is an overview of Krebs cycle and its products?

A

-Acetyl CoA condenses oxaloacetate with acetate
-Oxaloacetate regenerated in Krebs cycle

336
Q

Label the basic steps of Krebs cycle:

337
Q

Label the products of Krebs cycle:

338
Q

Label the enzymes of Krebs cycle:

339
Q

What is the net energy gain for Krebs cycle?

340
Q

What main enzymes regulate the Krebs cycle?

341
Q

What regulates citrate synthase?

A

Stimulates:
-ADP
Inhbits:
-ATP
-NADH
-citrate

342
Q

What regulates isocitrate dehydrogenase?

A

Stimulates:
-ADP
Inhibits:
-ATP
-NADH

343
Q

What regulates alpha-ketoglutarate dehydrogenase?

A

Stimulates:
-Ca2+
Inhibits:
-ATP
-NADH
-Succinyl CoA
-GTP

344
Q

What regulates pyruvate dehydrogenase?

A

Stimulates:
-Pyruvate
-ADP
Inhibits:
-ATP
-NADH
-Acetyl CoA

345
Q

Where does oxidative phosphorylation occur?

A

Inner mitochondrial membranes during aerobic conditions

346
Q

Why does oxidative phosphorylation occur?

A

-Releases majority of energy during cellular respiration
-Reduced NADH or FADH2 from glycolysis and krebs oxidised, electrons passed to ETC
-Energy released trapped in ATP

347
Q

Describe oxidative phosphorylation:

A

-ETC accept electrons (reduced) and pass them on (oxidised)
-Electrons transferred to final electron acceptor (oxygen)
-Free energy used to power movement of H+ across inner membrane creating proton motive gradient
-ATP produced as protons flux in through ATP synthase

348
Q

Describe oxidative phosphorylation:

A

-ETC accept electrons (reduced) and pass them on (oxidised)
-Electrons transferred to final electron acceptor (oxygen)
-Free energy used to power movement of H+ across inner membrane creating proton motive gradient
-ATP produced as protons flux in through ATP synthase

349
Q

Label this diagram of oxidative phosphorylation:

350
Q

What is the basic equation of oxidative phosphorylation?

351
Q

What sources of stored energy are in the body and for how long will they last?

A

-Glycogen - 12 hours
-Fats - 12 weeks
-Protein - used when muscle glycogen stores fall

352
Q

What makes up fatty acids?

A

-Carboxylic head
-Aliphatic tails
-Saturated and unsaturated

353
Q

Where are most fatty acids derived from?

A

-Triglycerides
-Phospholipids

354
Q

Describe fatty acid activation implications:

A

-Must be activated in cytoplasm before they can be oxidised in mitochondria
-If the Acyl-CoA has <12 carbons - it can diffuse through mitochondrial membrane
-Most dietary fatty acids have >14 carbons - taken through mitochondrial membrane using carnitine shuttle

355
Q

Describe fatty acid activation:

356
Q

Label this diagram of fatty acid b-oxidation:

A

Oxidation occurs at the beta carbon

357
Q

Under normal conditions, how is acetyl-CoA used?

A

-Most utilised via the TCA acid cycle to produce glucose
-Small proportion converted to ketones

358
Q

What are ketones?
three examples?

A

-Molecules produced by the liver from acetyl-CoA
-Characteristic fruity/nail polish remover smell

359
Q

What are three examples of ketones?

360
Q

What is produced during high rates of fatty acid oxidation?

A

-Large amounts of acetyl-CoA
-Exceeds the capacity of the TCA cycle which results in ketogenesis

361
Q

What can acetoacetate be converted into?

A

-Can undergo spontaneous decarboxylation to acetone
-Enzymatically converted to beta-hydroxybutyrate

362
Q

How are ketone bodies utilised?

A

-Utilised by extrahepatic tissues
-Conversion of beta-hydroxybutyrate and acetoacetate to acetoacetyl-CoA
-Requires enzyme acetoacetate:succinyl-CoA transferase which is found in all tissues but hepatic tissues

363
Q

What things regulate ketogenesis?

A

-Release of free fatty acids from adipose tissue
-High concentration of glycerol-3-phosphate in liver results in triglyceride production, low level results in ketone body formation
-When ATP demand is high, acetyl-coA is likely to be further oxidised via TCA to carbon dioxide
-Fat oxidation is dependant upon amount of glucagon (activation) or insulin (inhibition)

364
Q

Ketone production + usage during normal and low physiological conditions?

A

-Normal physiological conditions production of ketones occurs at low rate
-Carbohydrate shortages cause liver to increase ketone body production from acetyl-CoA
-Heart and skeletal muscles preferentially utilise ketone bodies for energy preserving glucose for brain

365
Q

What is ketoacidosis?

A

-Occurs in insulin-dependant diabetics when dose is inadequate or because of increased insulin requirement (infection, trauma, acute illness)
-Often presented by newly diagnosed type 1 diabetics
-Chronic alcohol abuse
-Present hyperventilation and vomiting

366
Q

Describe the flow chart of diabetic ketoacidosis:

367
Q

Describe the flow chart of alcoholic ketoacidosis:

368
Q

What are the consequences of ketoacidosis?

A

-Ketones relatively strong acids (pKa ~ 3.5)
-Excessive ketones lower blood pH
-Impairs ability of haemoglobin to bind to oxygen

369
Q

What are the blood values for ketoacidosis?

370
Q

What is the definition of homeostasis?

A

Maintenance of a constant internal environment

371
Q

What are 5 examples of homeostasis in the body?

A

-Temperature
-Glucose
-Potassium
-Blood oxygen
-Hydrogen ion

372
Q

What is the homeostasis model?

373
Q

What are the 2 communication systems in the body?

A

-Hormones
-Electrical

374
Q

What are the 3 categories of communication in the body?

A

-Autocrine
-Paracrine
-Endocrine

375
Q

What is autocrine communication?

A

Cells communicating to themselves

376
Q

What is paracrine communication?

A

-Cells communicating to neighbouring cells a short distance away
-Signal diffuses across gap between cells
-Inactivated locally so doesn’t enter blood stream

377
Q

What are 2 examples of paracrine communication?

A

-Interleukins:
-Immune system
-Mainly white blood cells
-PDGF
-Released from platelets
-Regulates cell growth

378
Q

What is endocrine communication?

A

-Cells communicating to other cells elsewhere in the body
-Hormones in the blood

379
Q

What are the main endocrine organs/glands?

A

-Hypothalamus
-Pituitary
-Thyroid
-Adrenals
-Pancreas
-Ovaries
-Testes

380
Q

What is a hormone and how are the classified?

A

-Molecule that acts as a chemical messenger
-Amino-acid derivatives
-Peptide
-Steroid

381
Q

What are amino acid hormones?
name and example:

A

-Derived from tyrosine
-Adrenaline

382
Q

What are peptide hormones?

A

-Made of amino acids
-Vary in size from few amino acids to small proteins
-Some have carbohydrate side chains (glycoproteins)
-Hydrophilic (like water)

383
Q

What types of hormone create a quick reaction in the body?

A

-Amino acid derivatives
-Peptide

384
Q

Describe the action of TSH:
What kind of hormone is it?

385
Q

Describe steroid hormones:

A

-All made from cholesterol
-Different enzymes modify molecule to produce a variety of hormones
-Can’t dissolve in water (hydrophobic)
-Can dissolve in lipids

386
Q

What kind of reactions produce a slow response?

A

-Steroid
-Example: testosterone

387
Q

Explain the role of testosterone:

388
Q

What is a positive feedback loop?

A

Signal is amplified

389
Q

What is a negative feedback loop?

A

-Slowing down/regulating process
-Maintains homeostasis

Phase 1 (23 decks)

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