Combined Flashcards
1
Q
Iodine is an element commonly found in high abundance in which areas?
A
in the sea
2
Q
What is the RDI for iodine
A
150ug
3
Q
What is TRH? where is it released from?
A
Thyrotropin releasing hormone - released from the hypothalamus
4
Q
What is cretinism? what is it caused by?
A
A congenital condition caused by maternal iodine deficiency, worlds most common form of mental retardation and growth retardation
5
Q
Radiation from I (-131) can be used to what?
A
destroy the thyroid
6
Q
What kind of receptors do thyroid hormones operate via?
A
membrane receptors and cause direct activation of genes in DNA
7
Q
What is the atomic number of iodine?
A
53
8
Q
Where is cholesterol found in the body?
A
free in membranes and as esters in storage
9
Q
Where are human steroids derived from?
A
dietary steroids or are made from acetyl-coA in the liver
10
Q
Corticosteroids refers to which two groups of steroids?
A
Glucocorticoids (eg cortisol) and mineralocorticoids (aldosterone)
11
Q
Where are oestrogen and progesterone made primarily
A
ovary and also placenta during pregnancy
12
Q
Where is testosterone primarily produced?
A
testes
13
Q
Tamoxifen blocks what steroid action?
A
blocks oestrogen receptors and is used in the treatment of breast cancer
14
Q
What is the effect of leuprolide?
A
lowers testosterone - used in treatment of prostate cancers
15
Q
What are the actions of anabolic steroids?
A
interact with androgen receptors to increase muscle and bone synthesis
16
Q
Where does the name cholesterol originate from?
A
greek chole- (bile) and stereos (solid)
17
Q
What is cholesterol?
A
a waxy steroid metabolites
18
Q
What is cholesterols role in cell membranes?
A
required for proper membrane permeability and fluidity (makes membrane LESS fluid)
19
Q
What is a lipoprotein? What is their function?
A
biochemical assembly that contains proteins and lipids. Carry cholesterol in the blood
20
Q
What are some examples of lipoproteins?
A
chylomicrons, low density lipoprotein (LDL), very low density lipoprotein (VLDL) and high density lipoprotein (HDL)
21
Q
Arteriolosclerosis is promoted by excess levels of which lipoprotein?
A
LDL
22
Q
What did Goldstein and Brown win a nobel prize for?
A
Identifying the LDL receptor on the liver which carries LDL and VLDL into the liver via receptor mediated endocytosis - this process is essential for feedback inhibition of HMG-CoA Reductase, muatations in this receptor lead to familial hypercholesterolaemia
23
Q
Apart from its role in cell membranes what other roles (3) does cholesterol have?
A
- precursor to steroid hormones such as testosterone, cortisol, aldosterone, 2. component of bile salts 3. Vit D production
24
Q
how many carbons does cholesterol have?
A
27
25
How many more times energy does NADPH have compared to ATP
7 times more
26
Where are human steroids derived from?
Cholesterol -> dietary or made in the liver from Acetyl-CoA
27
What is the most abundant steroid in the body?
cholesterol
28
Where is oestrogen and progesterone made?
Ovary and placenta
29
How are steroids eliminated?
by CYP3A4 in the liver endoplasmic reticulum which adds a OH group
30
What is Cyproterone acetate? what is it used for?
Inhibitor of the andreogen receptor. Used to treat Hirsuitism in females, male-to female gender change, prostate cancer, benign prostatic hyperplasia, priapism and hypersexuality (chemical castration)
31
What protein does cortisol bind in the blood?
transcortin
32
Hb makes up what percentage of RBC dry content?
97%
33
carbon dioxide can bind to Hb and form what? what proportion of the total respiratory CO2 is in this form?
forms carbaminohaemoglobin15% of total
34
Hb carries nitric oxide bound to what molecule on globin?
thiol group of globin
35
Why does Hb carry nitric oxide?
releases it at the same time as oxygen to relax vascular walls and enhance gas diffusion
36
Kendrew and Perutz one a nobel price for doing what regarding Hb?
solving its protein structure (the first protein structure solved)
37
What is the structural difference between adult and foetal Hb?
Foetal: alpha2-gamma2Adult:alpha2-beta2
38
Mutations in amino acid sequences cause hundred of whats (in relation to Hb)?
haemaglobinopathies
39
What was Christian Bohrs contributed to our knowledge about Hb?
described the sigmoid binding character of Hb-O2
40
What is the structure of haemaglobin?
Tetramer of globin subunits (proteins) with 4 haem groups inserted into each
41
What colour is Hb-CO?
bright red
42
What colour is De-oxy Hb?
dark red
43
What colour is HbO2?
scarlet red
44
What binds better to Hb O2 of CO?
CO binds 200x better than O2
45
What is Met Hb?
Hb with Fe3+ in the haem due to oxidation = found in aged RBCs
46
Haem inserts into the globin via a locking mechanism involving binding of histidine residues F8 and E7. One is always bound whilst the other can be displaced - which is which?
F8 is always locked (think its FATE for globin and haem to be together)E7 can be displaced by O2, CO and cyanide
47
What is the role of Bisphosphoglycerate (BPG)
stabilises Deoxy-Hb via 8 salt bonds which makes this form rigid (tense) and stops Oxygen binding back to Hb in the tissues. It is displaced when O2 levels are high (in the lungs)
48
Oxygen binding to Hb shows cooperativity - what does this mean?
When the first Oxygen binds to Hb it induces a change in the quaternary structure of Hb which changes the affinity of the other Oxygen binding sites - this means with only small increases in the concentration of O2 it is much easier to saturate the rest of the Hb molecule
49
What happens to the Hb-Oxygen binding curve in the presence of acid (bohr effect)? What functionally is the relevance of this?
graph is shifted to the right- meaning Hb has LESS affinity for O2, the relevance of this is that working tissues produce lactic acid and they require more O2 so we want the DeOxy-Hb form to be more stabilized so more oxygen is given up in the tissues - this is achieved via bonding to histidine residues
50
How does altitude alter the Oxygen-Hb binding curve? how is this achieved?
shifts it to the right -> giving more O2 to the tissues compensates for less O2 being picked up in the lungs. At altitude RBCs produce more BPG
51
Why does foetal Hb have higher affinity for O2 than adult hb?
gamma subunits have 6 positive charges (not 8) so BPG is bound less avidly so deoxy-form is stabilised less
52
What was Archibald Garrods field of study?
inborn errors of metabolism
53
The major burden of pathology in australia from genetic diseases is due to what disease?
Cystic Fibrosis
54
________was the first disease to be routinely tested for at birth and treated as required
phenylketonuria (PKU)
55
Genetic testing is usually carried out using what technique?
PCR
56
What is the most common x-linked recessive disorder? give some other examples
red-green colour blindess is the most common, others are haemophilia Am duchenne muscular dystrophy, Lesch-Nyhan syndrome
57
What happens in children affected by PKU?
they lack phenylalanine hydroxylase leading to a build up of Phe which gets converted to phenylpyruvate (a ketone) which damages the brain and affects melanin synthesis
58
What is the incidence of CF in australia?
in in 2500 births
59
What is the carrier rate of the CF gene in Australia?
1 in 25
60
What is the most common CF mutation?
Delta F506 in the CFTR protein (chloride channel)
61
What is Ehlers Danlos syndrome?
Inherited connective tissue disoder - mostly autosomal dominant condition due to mutations in genes that encode the structure, production or processing of COLLAGEN or proteins that interact with collagen -> those affected have hypermobile joints, hyper-elasticity of the skin but also affects arteries.
62
What is Marfan Syndrome?
mutation in fibrillin gene leading to bone overgrowth and joint laxity, with disproportionately long extremities compared to the size of the trunk
63
What enzyme is important in melanin formation?
tyrosinase
64
Is the inheritance of skin colour mono or polygenetic?
polygenetic -> 40 genes influence skin colour
65
If you lack tyrosinase what colour is your skin?
NO melanin = albinism
66
How do dietary toxins get to the liver?
Directly, via the hepatic portal vein
67
Which molecules are oxidised by P450 system?
ALL foreign chemicals with MW < 5,000
68
Where in the cell are the P450 cytochromes located?
Endoplasmic reticulumMitochondria
69
What are microsomes?
Pink spherical vesicles with embedded cytochrome P450. They don't exist in cells - they're an artefact of centrifuging.
70
What sort of enzymes are the P450s?
Monoxygenases
71
What reaction do the P450s typically catalyse?
RH + NADPH + H+ + O2 --->ROH + H2O + NADP+(The key point is that RH becomes ROH)
72
What initiates the P450 cycle of reactions?
Binding of a substrate to the P450
73
What P450 is deficient in people who can't convert codeine to morphine?
CYP 2D6
74
What's the structure of bilirubin?
It's a a tetrapyrrole - an open chain of 4 pyrrole rings
75
Where is bilirubin usually produced?
In the spleen
76
What cells are responsible for the breakdown of senescent RBCs?
Macrophages
77
What haem breakdown product do macrophages make?
Biliverdin
78
What colour is bilirubin?
Yellow
79
What happens to bilirubin when exposed to light?
Some of the double-bonds isomerise
80
What isomer of bilirubin is more soluble?
The E,E-isomer
81
Which isomer of bilirubin is less soluble
The Z,Z-isomer
82
What's the clinical application of bilirubin isomerisation?
Phototherapy for jaundices newborns
83
What are the two chemical forms of bilirubin?
Conjugated and unconjugated
84
What's another name for conjugated bilirubin?
Direct
85
What's another name for unconjugated bilirubin?
Indirect
86
In which form is bilirubin excreted in bile?
Conjugated - as glucuronide
87
What toxicity does bilirubin have in high levels, and in which population?
Neurotoxicity in newborns
88
What's the name for bilirubin-induced neurotoxicity?
Kernicterus
89
What gives rise to jaundice?
Hyperbilirubinaemia
90
What things can cause elevated bilirubin?
Neonatal hyperbilirubinaemiaBile duct obstructionSevere liver failure w/ cirrhosisCriger-Najjar syndromeDubin-Johnson syndromeCholedocholithiasis
91
What is urobilinogen?
The colourless product of bilirubin reduction
92
How & where is urobilinogen formed?
In the intestines by bacterial action
93
What constitutes the normal enterohepatic urobilinogen cycle?
Some of the urobilinogen is reabsorbed from the gut and then excreted by the kidney
94
How many Australians have health problems related to risky alcohol consumption?
2-3 million
95
WHat proportion of Australians exhibit alcohol-induced Wernicke Korsakoff syndrome
2%
96
What is the primary organ of alcohol damage?
The liver
97
What stages of damage does the liver progress through?
Fatty infiltrationAlcoholic hepatitisCirrhosis
98
What is cirrhosis?
Irreversible fibrous degradation of the liver
99
What's the most significant pathway for alcohol breakdown?
Alcohol dehydrogenase
100
What's the inducible system of alcohol breakdown?
MEOS - Microsomal ethanol oxidising system
101
What is the enzyme involved in MEOS?
CYP2E1
102
What's the 3rd minor system of alcohol breakdown?
Oxidisation via catalase
103
What does aldehyde dehydrogenase do?
Converts acetaldehyde to acetate
104
What are the two fates of acetate?
Oxidisation for energy via the TCA cycleConverted to fat
105
At what rate do most humans clear alcohol?
10g per houror .015% BAC per hour
106
T/F: Addiction to alcohol is always due to inherited predispostition
False - there's multiple causes, but inherited predisposition is one of them
107
What are some ways to treat alcohol addiction?
Drugs that make alcohol less pleasurable to drink
108
T/F: Immense economic and social damage is caused by alcohol
TRUE
109
T/F: People who abstain from alcohol have better health and longevity
False - research suggests moderate drinkers are healthier
110
What two processes are linked by metabolism?
Catabolism & anabolism
111
What does catabolism refer to?
The breakdown of biomolecules (including food)
112
What does anabolism refer to?
The synthesis of biomolecules (including protein)
113
What are the two main "energy carrying" intermediates in metabolism
ATP & NADH
114
ATP vs NADH. Which is the low-energy intermediate?
ATP
115
ATP vs NADH. Which is the high-energy intermediate?
NADH
116
How many kJ/mol is ATP?
30.5
117
How many kJ/mol is NADH?
220
118
How many ATPs are produced in anaerobic metabolism?
2
119
How many ATPs are produced in aerobic metabolism?
32
120
In what form is the fasting reserve of glucose stored?
Glycogen
121
What are the two main families of sugars?
Aldose and ketose
122
What are some examples of aldose sugars (2)
GlucoseGalactose
123
What's an example of a ketose sugar?
Fructose
124
What proteins are the transporter of sugar into cells?
GLUTs
125
How many members of the GLUT family are there?
12
126
Which GLUT is universal?
GLUT1
127
Which GLUT is found on cells of the liver and pancreas?
GLUT2
128
Which GLUT is found on myocytes and adipocytes?
GLUT4
129
Which GLUT's translocation is dependent on insulin?
GLUT4
130
Problems with which GLUT plays a major role in diabetic hyperglycaemia?
GLUT4
131
What byproduct comes from anaerobic glycolysis?
Lactate
132
Which cells are obliged to perform anaerobic metabolism and why?
RBCs as they have no mitochondria
133
What is gluconeogenesis?
The generation of glucose from glycerol or AAs
134
Can fat be used for gluconeogenesis?
No
135
What sugar in processed food is correlated with increased obesity?
Fructose! ;)
136
How many mitochondria does a healthy cell have?
200-10,000
137
How many mitochondria do liver cells have?
~1,000
138
Define syncytium
A multinucleated cell formed by the fusion of many cells
139
What's are some examples of syncytium?
Skeletal muscleGiant cells
140
What's the evolutionary background of mitochondria?
They're endosymbiotic bacteria
141
How long ago was mitochondrial bacteria incorporated into eukaryotes?
2 billion years
142
What processes take place in the mitochondria?
Acetyl Coa productionKetone body synthesisTCAOxidative phosphorylation
143
Mitochondria can make Acetyl CoA from which substrates? (2)
PyruvateFatty acid oxidation
144
The TCA cycle is aka?
Krebs cycle
145
What are ketone bodies synthesised from?
Acetyl CoA via HMG-CoA
146
Which cells lack mitochondria?
RBCs and the retina
147
What happens when electrons leak from the electron transport chain?
They create ROSs
148
What process can explain many of the infirmities of age?
ROS damage - including loss of mitochondria
149
What causes mitochondrial diseases?
Mutations in mitochondria or nuclear DNA
150
What's the pathological appearance of many mitochondrial diseases?
Ragged red fibres
151
InfectionInherited abnormalities& ______ are major causes of disease?
Faulty nutrition (over & under)
152
What is macronutrition?
The study of obtaining energy to fuel normal activity
153
How many Joules does the typical adult need per day?
10MJ
154
In what form is the 10MJ of energy lost?
Heat
155
What is BMR?
The minimum energy required to sustain life
156
Can BMR be measured?
Yes
157
Exercise is usually less than __% of energy expenditure?
40%
158
What anatomical structures do humans have that define us as omnivores?
DentalGut
159
Archeological evidence shows healthy homonid skeletons from the hunter-gatherers of 30,000 years ago - what does Graham think this indicates?
That "caveman" diets may be our evolutionary optimum
160
Do different populations have different dietary needs?
Sort of - lactose intolerance is an example
161
What's out cheapest and most abundant fuel?
CHOs
162
What diseases does fibre protect us from (2)
DiverticulosisHaemorrhoids
163
What disease is fibre unlikely to protect us from (despite common belief?)
Cancer
164
Why are low GI diets recommended?
They avoid high glucose levels that can encourage insulin resistance
165
We need to eat protein for which two reasons?
For energyFor biosynthesis of all structural components and enzymes for metabolism
166
What molecule has the most complex digestive process?
Protein
167
What are the (basic) steps of protein digestion?
DenatureRender to AAsTransport AAs via gut transporters
168
What are the branched chain AAs?
ValineLeucineIsoleucine
169
Which AA's transaminate in muscles?
The branched chain ones
170
Is there any evidence that branched-chain AAs improve sports performance?
No
171
How many grams of protein do we make & breakdown daily?
300
172
What proportion of the protein we break down gets recycled?
200g
173
What is the major waste product that removed excess nitrogen?
Urea
174
Is there renal ammonia clearance?
Yes - some
175
Are proteins stored for fuel?
No
176
Can protein be used for fuel?
Yes
177
What are the products of protein breakdown? (2)
Glucose and ketone bodies
178
Define vitamin
An organic compound, not made by the body but with essential biochemical functions
179
Which are the fat soluble vitamins?
A, D, E, K
180
What are the water soluble vitamins?
Thiamin - B1Riboflavin - B2Niacin - B3Pyridoxine - B6Pantothenic acidBiotinFolateCobalamin (B12)Ascorbic acid (vit C)
181
In what situations should we consider vitamin deficiencies?
Unusual dietsPeriods of growthDiseaseDeveloping countries
182
What are the major minerals required by the body? (6)
SodiumPotassiumCalciumPhosphorusMagnesiumSulphate
183
What are the trace minerals required by the body? (7)
IronZincCopperManganeseFluorideChromiumMolybdenum
184
What things affect the trace mineral content of foods
Soil & water composition
185
What's the most common result of mineral deficiency in children?
Failure to grow & thrive
186
How is BMI calculated?
kg/m^2
187
What BMI is considered underweight?
<18.5
188
What BMI is considered normal weight?
18.5-25
189
What BMI is considered overweight?
25-30
