IMMS Flashcards
(286 cards)
1
Q
Water distribution: how much water is there in:
a) the ECF?
b) the ICF?
A
a) 14L (35%)
b) 28L (65%)
2
Q
Water distribution: how much water is there in the (ECF)in 70kg man:
a) interstitial fluid
b) plasma
A
a) interstitial - 11L
b) plasma 3L
3
Q
What is the predominant electrolyte(s) in the ICF?
A
K+
4
Q
What is the predominant electrolyte(s) in the ECF?
A
Na+, Cl-, HCO3-
5
Q
What is the definition of osmosis?
A
Movement of H2O across a partially permeable membrane from an area of high water potential to an area of low water potential.
6
Q
What is the definition of osmolarity?
what about osmolality
A
The number of solute particles per L of solution. (A high osmolarity has more solute particles per L).
osmolality = Concentration of solutes in plasma per kg of solvent
7
Q
What is the definition of oncotic pressure?
A
Oncotic pressure is a form of osmotic pressure exerted by proteins in a blood vessels plasma (albumin) that tends to pull fluid back into the capillary
8
Q
What is the definition of osmotic pressure?
A
The pressure that must be applied to a solution to prevent inward osmosis through a partially permeable membrane.
9
Q
define hydrostatic pressure
A
Pressure difference between plasma and interstitial fluid
10
Q
Electrolyte homeostasis: what is the cause(s) of hypernatremia? And what are the risks?
A
Cause - water deficit (poor intake, diabetes insipidus etc).
Risks - Dehydration.
(High sodium = low H2O which dehydrates the brain).
11
Q
Electrolyte homeostasis: What is the cause(s) of hyponatremia and what are its risks?
A
Causes: Excess water due to IV fluids, diuretics.
Risks: Over hydration - headache, confusion.
12
Q
Electrolyte homeostasis: What is the cause(s) of hyperkalemia and what are its risks?
A
Causes: renal failure, acidosis, diuretic inhibitors.
Risks: Cardiac arrest.
13
Q
Electrolyte homeostasis: What is the cause(s) of hypokalemia and what are its risks?
A
Causes: D+V, alkalosis, diuretics.
Risks: weakness and dysrhythmia.
14
Q
Electrolyte homeostasis: What is the cause(s) of hypercalcemia and what are its risks?
A
Causes: hyperparathyroidism, Vit D toxicity, malignancy.
Risks: renal stones and metastatic calcification.
15
Q
Electrolyte homeostasis: What is the cause(s) of hypocalcemia and what are its risks?
A
Causes: renal disease, Vit D deficiency, intestinal malabsorption.
Risks: tetany (spasms).
16
Q
What is the function of rough ER?
A
Protein synthesis
17
Q
What is the function of smooth ER?
A
Lipid synthesis
18
Q
What is the function of the golgi apparatus?
A
Processes and modifies ER products.
19
Q
What is the cis face of the golgi apparatus?
A
The cis face is nearest the nucleus and receives ER vesicles.
20
Q
What does the medial Golgi do?
A
It modifies products by adding sugars forming oligosaccharides
21
Q
What does the trans face of the golgi do?
A
It sorts molecules into vesicles.
22
Q
What are the functions of vesicles?
A
Transports and stores materials. These are membrane bound organelles.
23
Q
What are desmosomes?
A
Attach cells together via the cytoskeletons
24
Q
What are tight junctions?
A
Binds cells together to prevent leakage of molecules in between them.
25
What is the function of gap junctions?
allow passage of molecules between cells.
eg myocytes, smooth muscle: Conduct electrical signals.
26
List 4 functions of a plasma membrane.
1. Physical boundary for the cell.
2. Regulates the movement of substances.
3. Has receptors for cell to cell signalling.
4. Attaches the cell to the external environment.
27
Name 4 molecules you'd find in a plasma membrane.
1. Cholesterol
2. Glycoproteins
3. Glycolipids
4. Integral proteins
28
Define genotype.
The genetic constitution of an individual.
29
Define phenotype.
The appearance of an individual due to the environment and genetics.
30
Water distribution: How much water is there in the ICF?
28L
31
What is an example of type 1 collagen?
Bone, skin and teeth.
32
What is an example of type 2 collagen?
Cartilage.
33
What is an example of type 3 collagen?
Arteries, liver, kidneys, spleen, uterus
34
What is an example of type 4 collagen?
Basement membranes
35
What is an example of type 5 collagen?
Placenta
36
Define allele.
An alternative form of a gene at a specific locus.
37
Give an example of an autosomal dominant condition.
Huntingtons disease.
38
Give an example of an autosomal recessive condition.
Cystic fibrosis.
39
Summarise autosomal dominant inheritance.
- Manifests in the heterozygous state.
- Male to Male transmission is seen.
- Both males and females are affected equally.
- The disease is present in several generations.
- There is a 50% chance of offspring having the disease.
| eg huntingtons
40
Summarise autosomal recessive inheritance.
- Manifests in the homozygous state.
- The disease is often not seen in every generation.
- 25% chance of offspring having the disease.
- 50% chance of offspring being carriers.
- Healthy siblings have a 2/3 chance of being carriers.
41
Give an example of an X linked recessive condition.
Duchenne muscular dystrophy
42
What is a mis-sense mutation?
A point mutation in which a single nucleotide change results in a codon that codes for a different amino acid (substitution). This can have a varied affect and can result in a silent mutation and a non functional protein E.g Sickle cell disease where CAG was replaced with CTG
43
What is a non-sense mutation?
A single nucleotide change that produces a premature stop codon. This results in an incomplete/non-functional protein.
eg Duchenne muscular dystrophy
44
What are the products of glycolysis?
2 ATP, 2 NADH, 2 Pyruvate
45
What is the rate limiting enzyme in glycolysis?
Phosphofructokinase-1
46
Where in a cell does glycolysis take place?
Cytoplasm
47
Where in a cell does the Krebs cycle take place?
The matrix of the mitochondria
48
Define metabolism.
Chemical reactions that occur in a living organism.
49
Define BMR.
The energy needed to stay at live rest. (1kcal/Kg/hour)
50
How much energy do carbohydrates provide?
4kcal/g
51
How much energy do proteins provide?
4kcal/g
52
How much energy do lipids provide?
9kcal/g
53
How much energy does alcohol provide?
7kcal/g
54
How much energy is stored as triglycerides?
15kg
55
How much energy is stored as glycogen? And where is it stored?
350g
- 200g in the liver
- 150g in muscle
56
How much energy is stored as protein?
6kg
57
What factors increase/decreaseBMR?
58
Name an endogenous source of ROS?
Produced as a by product of O2 metabolism
59
Name 3 ketone bodies
- acetoacetate
- acetone
- beta hydroxybutyrate
60
Where does ketogenesis usually occur?
In the liver
61
When would ketogenesis occur?
During high rates of fatty acid oxidation too much acetyl CoA is produced; this overwhelms the Krebs cycle and so you get ketone body formation
62
What molecules make up ATP?
1 adenine, 1 ribose, 3 phosphate
63
Define buffer.
A solution that resists changes in pH when small amounts of acid/base are added.
64
What is the equation to demonstrate the mechanism of a bicarbonate buffer?
H2O + CO2 -> H2CO3 -> HCO3- + H+
| Arrows are reversible
65
How do protein buffers work?
If the pH falls H+ binds to the amino group of the protein.
If the pH rises H+ can be released from the carboxyl group of the protein.
66
What can cause respiratory acidosis?
Inadequate ventilation due to airway obstruction (COPD, asthma).
67
What happens to the PaCO2 levels in respiratory acidosis?
PaCO2 increases leading to an increase in H+ ions and so pH decreases.
CO2 production is greater than CO2 elimination
68
What can cause respiratory alkalosis?
Hyperventilation in response to hypoxia.
| CO2 elimination exceeds O2 reabsorption.
69
List 3 causes of metabolic acidosis?
Renal failure, loss of HCO3-, excess H+ production.
70
List 2 causes of metabolic alkalosis.
Vomiting (loss of H+), increased reabsorption of HCO3-.
71
What do fatty acids produce.
| Where is this product used?
Acetyl CoA
| Used in the Krebs cycle
72
Name 4 ways in which ATP can be produced?
- Krebs cycle.
- Glycolysis.
- Oxidative phosphorylation.
- Substrate level phosphorylation.
73
What is gonadal mosaicism?
When there are 2 different populations of cells in the gonads. One population is normal and the other is mutated. All gametes from the mutated line are effected.
74
What type of cells are produced in mitosis?
2 diploid daughter cells which are genetically identical to the parent cells.
75
What is mitosis used for?
Growth and repair.
76
What are the 4 phases of the cell cycle?
G1, S, G2 and M
77
What phases of the cell cycle make up interphase?
G1, S and G2
78
what happens during interphase?
cell growth, DNA replication , normal cell processes
79
What happens in prophase?
80
What happens in prometaphase?
81
What happens in metaphase?
82
What happens in anaphase?
83
What happens in telophase?
84
What happens in cytokinesis?
The cytoplasm divides producing 2 genetically identical daughter cells.
85
What type of cells are produced in meiosis?
4 haploid daughter cells that are genetically different to the parent cell.
86
what happens during meiosis 1 and meiosis II
During meiosis I, homologous chromosomes (pairs of chromosomes with the same genes) are separated, while during meiosis II, the chromatids (each half of a duplicated chromosome) are separated.
87
What is meiosis used for?
The production of gametes.
88
How is genetic diversity introduced in meiosis?
-- Prophase 1 = crossing occurs between non-sister chromatids
- Metaphase 1 = random assortment.
- Meiosis II – sister chromatids separate. Haploid cells are produced
| - Prophase 1 = crossover.
89
Name 3 molecules that make a nucleotide.
1. Pentose sugar.
2. Phosphate.
3. Nitrogenous base.
90
What is splicing?
The removal of introns from pre-mRNA
DNA mutations cann affect accuracy
91
List 3 features of the genetic code.
1. Non-overlapping
2. Universal
3. Degenerate
92
What condition is trisomy 21?
Down's syndrome
93
Define lyonisation.
One of the female X chromosomes becomes inactivated early in embryogenesis.
94
What is a triglyceride?
A glycerol backbone with 3 fatty acids.
95
What 2 carbohydrates form sucrose?
Glucose and fructose
96
What 2 carbohydrates form maltose?
Glucose and Glucose
97
What 2 carbohydrates form lactose?
Glucose and galactose
98
What is the respiratory burst?
WBC's using ROS in phagocytosis to damage the membrane of invading cells.
99
Name 2 equations that form hydroxyl radicals.
1. Fenton's
| 2. Haber-Weiss
100
What is Fenton's equation?
Fe2+ + H2O2 -> Fe3+ + OH• + OH-
101
What is the Haber Weiss equation?
O2- + H2O2 -> O2 + OH• + OH-
102
Give 3 examples of endocytosis.
1. Phagocytosis.
2. Pinocytosis.
3. Receptor mediated.
103
Name 3 mechanisms by which a molecule can move across a plasma membrane.
1. Diffusion - movement down a concentration gradient.
2. Facilitated diffusion.
3. Active transport - uses ATP, against concentration gradient.
104
Name 3 types of cell receptors.
1. Ion channel receptors.
2. G-protein coupled receptors.
3. Enzyme linked receptors.
105
Name 3 ways in which we intake fluids.
1. Drink.
2. Food.
3. IV Fluids.
106
Define insensible losses.
Water loss that we are unaware of. It is comprised only of solvent and can not be measured.
eg - sweat, breath, vomiting, faeces
107
Name 3 hormones involved in water homeostasis.
1. Aldosterone.
2. ADH - antidiuretic hormone.
3. ANP - atrial natriuretic peptide.
108
What is oedema?
Excess H2O in the interstitial fluid.
109
Name the 4 types of oedema.
1. Lymphatic.
2. Venous.
3. Hypoalbuminaemic.
4. Inflammatory.
110
What is serous effusion?
Excess H2O in a body cavity.
111
Name 2 places DNA can be found.
1. Nucleus of a cell.
| 2. Mitochondria (purely maternal DNA).
112
What is the function of topoisomerase?
It unwinds the DNA double helix by relieving the supercoils.
113
In what direction does RNA polymerase build a new strand?
3' to 5' - antiparellel to the DNA template
MOVES 3' to 5'
BUILDS 5' to 3'
114
What is the product of transcription?
mRNA
115
Where does translation occur?
At a ribosome.
116
Briefly describe translation.
A tRNA with a complementary anticodon to the codon on mRNA binds. Peptide bonds from between amino acids = polypeptide chain.
117
What are the 4 bases in RNA?
Adenine, Cytosine, Guanine, Uracil.
118
What is non-disjunction?
The failure of chromatids to separate.
| For example; Down's syndrome - trisomy 21. Turner's syndrome - Monosomy of X chromosome.
119
What enzyme of glycolysis is inhibited in acidosis?
Phosphofructosekinase-1 (PFK-1 is pH dependent).
120
Which phase of mitosis is this: The chromosomes are moving towards opposite poles of the cell and there are no nuclear membranes.
Anaphase.
121
What enzyme catalyses the formation of 3-phosphoglycerate from 1,3-bisphosphoglycerate?
Phosphoglyceratekinase.
122
What enzyme catalyses the formation of glyceraldehyde-3-phosphate from dihydroxyacetone phosphate?
Triose phosphate isomerase.
123
Oxidative phosphorylation: What enzyme transports protons into the mitochondrial matrix?
ATP synthase.
124
Is the mitochondrial membrane permeable or impermeable to ions?
Impermeable.
125
What are steroid hormones synthesised from?
Cholesterol.
126
What will epiblasts in a 3-week embryo become?
Ectoderm.
127
How many days after fertilisation does implantation occur?
7-8 days.
128
How long is pregnancy?
40 weeks.
129
What does the blastocyst divide into?
Embryoblast (inner cell mass) and Trophoblast (outer cell mass).
130
What does the embryoblast divide into?
Epiblast and Hypoblast = bi-laminar disc.
131
What does the trophoblast divide into?
Cytotrophoblast (inner) and Syncytiotrophoblast (outer).
132
How is the primary utero-placental circulation established?
Lacunae form in the syncytiotropohoblast and maternal blood enters.
133
What happens in the third week of embryonic life?
Gastrulation - formation of a tri-laminar embryonic disc.
134
What is the function of chorionic villi?
Allows the transfer of nutrients from maternal blood to foetal blood.
135
What part of the tri-laminar disc are somites formed from?
Paraxial plate mesoderm.
136
What part of the tri-laminar disc is the circulatory system formed from?
Lateral plate mesoderm.
137
What does the ectoderm form?
CNS, PNS, skin, posterior pituitary and sweat glands.
138
What does the endoderm form?
Respiratory tract, GI tract, urinary tract, auditory tube, liver, pancreas, thyroid and parathyroid glands.
139
What happens in the 4th week of embryonic life?
The flat tri-laminar disc folds into a cylindrical embryo.
140
What are the 3 layers of the walls of arteries and veins called?
Intima, Media, Adventitia
141
What causes trisomy 21?
Failure of the chromatids to separate; non-dysjunction.
142
Name 2 electron accepting coenzymes.
1. NAD.
| 2. FAD.
143
what is the precursor of ATP?
ADP
144
Approximately how many ATP molecules are produced from oxidation of NADH?
2.5.
145
Approximately how many ATP molecules are produced from oxidation of FADH2?
1.5.
146
how much ATP is produced per gluocse molecule in the electron tranport chain?
approx 26-34 ATP per glucose moelcule
| + krebs + glycolysis = 30-38. but depends on where NADH and FADH2 end up
147
Briefly describe what happens in anaerobic respiration.
NAD is regenerated from NADH. Pyruvate, from glycolysis, forms lactate. Lactate dehydrogenase catalyses this reaction. NAD goes back to glycolysis so ATP can be produced.
148
What is the normal pH range of the human body?
7.35-7.45
149
What is the importance of acylcarnitine?
It is required to transport fatty acids into the mitochondria for beta oxidation.
150
What are the products of fatty acid beta oxidation?
4 ATP equivalents per round of oxidation in the form of one FAD(2H) molecule and one NADH molecule, as well as one acetyl CoA molecule.
151
Where does the acetyl CoA from beta oxidation go?
To the krebs cycle.
152
What are removed in splicing of pre-mRNA?
Introns.
153
What is gametogenesis?
Precursor cells undergo cell division and differentiation to form haploid gametes.
154
Gametogenesis: when do meiotic divisions occur in a male?
At puberty.
155
Gametogenesis: when is meiosis 1 complete in a female?
At ovulation.
156
Gametogenesis: when is meiosis 2 complete in a female?
If fertilisation occurs.
157
What is Mendel's second law?
The law of independent assortment. The alleles of one gene sort into gametes independently of the alleles of another gene.
158
Why can X linked genes not be passed from father to son?
Because the dad is XY and gives only the Y chromosome to his son and the X to his daughter.
159
what type in inheritance does this show?
x-linked
* no male to male
* mother carrier disproprtionately affect male offspring (on 1 x chromosone, daughter has two and would need both to be mutated)
* male carrier will always pass to daughter to make carrier.
(daughter can be affected through skewed x-inactivation)
| eg rec - duchenne
dom - alports
160
Can males ever be carriers of X linked conditions?
No. They are either affected or they do not carry the gene. (doesnt have another X to compensate affected chromatid)
161
Would an X linked dominant condition be more common in males or females?
X linked dominant conditions occur twice as frequently in females as they do in males.
162
Would an X linked recessive condition be more common in males or females?
More common in males.
## Footnote
no other X to compensate
163
Would an affected male of an x-linked recessive condition and an unaffected female have any affected children?
No affected children but all the daughters would be carriers.
164
What is multifactorial disease?
A disease due to genetic and environmental factors e.g. diabetes or schizophrenia.
165
Define karyotype.
The number and appearance of chromosomes in the nucleus of a eukaryotic cell.
166
Define penetrance.
The proportion of people with a gene who show the expected phenotype.
167
Define sex limitation.
Both sexes have a gene but its expression is limited to only one of the sexes and it is turned off in the other.
168
Define variable expression.
Variation in clinical features of a genetic disorder between individuals with the same gene alteration.
169
Name 2 allosteric activators of PFK-1.
1. AMP.
| 2. Fructose-6-bisphosphate.
170
Name 3 allosteric inhibitors of PFK-1.
1. Acidosis.
2. ATP.
3. Citrate.
171
Lipids have hydrophobic and hydrophillic parts. What is this called?
Amphipathic.
172
What layer of the tri-laminar disc does the epiblast form?
Ectoderm.
173
What cells does the epiblast give rise to?
Amnioblasts that line the amniotic cavity.
174
What cells does the hypoblast give rise to?
Cells that line the blastocyst cavity.
175
What is the chorion composed of?
The extra-embryonic mesoderm and the 2 layers of trophoblast.
176
What is the role of ATP synthase in oxidative phosphorylation?
It transports H+ into the mitochondrial matrix.
177
What is the role of cytochrome-C oxidase complex in oxidative phosphorylation?
It transports H+ out of the mitochondrial matrix.
178
What generates the energy needed to phosphorylate ADP -> ATP?
The movement of H+ in and out of the mitochondrial matrix.
179
Where does oxidative phosphorylation occur?
In the inner mitochondrial membrane.
180
What transports H+ out of the mitochondrial matrix?
Cytochrome-C oxidase complex.
181
A gene sequence is coded in ...
Single strand DNA.
182
A promoter sequence is coded in ...
Single strand DNA.
183
What is a promoter sequence?
The promoter region controls when and where the RNA polymerase will attach to DNA so transcription can commence.
184
What is a transcriptome?
All the messenger RNA molecules in a cell.
185
Which protein structure is created by covalent bonds?
Primary structure (peptide bonds between amino acids are covalent).
186
What type of bond is a peptide bond?
A covalent bond.
187
What is a single nucleotide polymorphism?
A single nucleotide substitution in DNA resulting in variation amongst a population.
188
What type of inheritance pattern is seen with sickle cell disease?
Autosomal recessive.
189
What is the mechanism by which sickle cell RBC's block capillaries?
They activate endothelial cells and cause inflammation, this results in blockage of the capillaries.
190
What are the sub-units of haemoglobin?
2 alpha and 2 beta subunits.
191
A mutation in what gene results in HbS production?
HBB gene.
192
How do HbS sub-units cause sickling?
They bind to the cytoskeleton which causes sickling.
193
What is the affect on HbS in hypoxia?
The HbS sub-units polymerise.
194
What is the affect on insensible losses if temperature increases by 1 degree?
Insensible losses will increase by 10%.
195
Why is sodium doubled in the plasma osmolality equation?
To account for negatively charged ions.
196
If a patient has diabetes insipidus and is not producing any ADH what is her blood and urine osmolality after 3 hours of water deprivation going to look like?
Blood osmolality would be high.
| Urine osmolality would be low - very dilute urine.
197
What are Mendel's 3 laws?
1. Law of dominance.
2. Law of independent assortment.
3. Law of segregation.
198
How many hydrogen bonds form between adenine and thymine?
2.
199
How many hydrogen bonds form between cytosine and guanine?
3.
200
How many genes are there in the human genome?
20,000.
201
What enzyme, expressed normally in embryonic cells and abnormally in neoplastic cells, lengthens telomeres?
Telomerase.
202
Give 2 reasons why cancers are more commonly in the elderly.
1. The elderly are more likely to have accumulated mutations.
2. Their immune system is weaker and so they're more vulnerable.
203
What is Knudson's two hit hypothesis?
The idea that a sporadic cancer requires 2 acquired mutations whereas an inherited cancer requires only 1 acquired mutation and 1 inherited. Therefore you are more likely to develop an inherited cancer as the chance of one mutation is greater than the chance of 2.
204
What is it called when a child shows a phenotype for a disease younger than their father/mother does? e.g. in huntington's disease.
Anticipation.
205
Give 4 functions of tight junctions.
1. Holds cells together.
2. Generates a concentration gradient across the epithelium.
3. Allows the passage of water and glucose.
4. Prevents the passage of large molecules.
206
What enzyme does high insulin levels stimulate?
PFK-1
## Footnote
insulin promotes anything that will decrease blood glucose levels. This can happen in two ways: either converting glucose--> pyruvate (glycolysis) or by converting glucose-->glycogen (glucogenesis). Glucagon does the opposite, it promotes any pathway that will increase blood glucose levels.
207
How does insulin increase the breakdown of glucose to pyruvate?
It stimulates PFK-1 indirectly through increasing fructose-2,6-bisphosphate levels and so increases the rate of glycolysis.
208
Name 3 biological buffers.
1. Protein
2. Haemoglobin
3. Bicarbonate
209
what factors decrease BMR
being female, starvation
210
label this cell!
211
what is the function of nucleus?
Nucleus: Storage and transcription of DNA
212
function of mitochondria?
Mitochondria: Respiration and ATP formation
213
function of ribsomes?
Ribosomes: translation - Protein synthesis
214
function of Rough ER?
Rough ER: Synthesis and processing proteins
215
function of smooth ER?
Lipid synthesis
216
function of lysosomes?
Lysosomes: Contain digestive enzymes, waste disposal system
217
function of nucleolus?
makes ribosomes
218
what is the purpose of the ouer membrane of mitochondria?
Separates organelle from rest of cell + regulates molecule/ion movement
219
what is the purpose of the intermembranous space of mitochondria?
Intermembranous space: Storage of H+ to maintain an electrochemical gradient
220
what is the purpose of inner membrane of mitochondria?
Inner membrane: Folded into cristae, contains proteins for Electron Transport Chain and ATP synthesis
221
where in the mitochnodria does the krebs cycle take place?
Matrix: Enzymes for Krebs
222
decribe the structre of the cell membrane
Double layer of phospholipids (bilayer)
Phospholipids: Hydrophobic head (out), hydrophilic tails (in) (creates barrier between in and out of cell - repell charged ions)
Cholesterol: Integrity
Proteins, glycoproteins, lipoproteins: Signalling, cell-cell adhesion, receptors, recognition
223
name 4 functions of cell membrane
224
what percentage of the mass of a cell membrane is made from proteins?
what are the two types of proteins?
50%.
peripheral (one side of membrane, eg receptor) and integral (goes all the way through)
225
what feature do transport proteins in the phospholipid bilayer of a cell membrane have that allow it to maintain an intracellular environment?
Transport proteins in the phospholipid bilayer are **selectively permeable **to maintain an intracellular environment
226
What is simple diffusion?
Simple diffusion: The passive movement of substances across a selectively permeable membrane from an area of higher to lower concentration directly through the bilayer.
small, non charged, lipophillic proteins - no energy required.
227
what is facilitated diffusion?
Facilitated diffusion: The passive movement of substances from an area of higher to lower concentration with the assistance of specific transport proteins or channel protein.
no energy required, might be small and charged.
228
what is active transport?
Active transport: An energy-requiring process that moves molecules or ions against their concentration gradient from an area of lower to higher concentration via specific transport proteins, utilising energy from ATP.
229
name the three types of cellular signalling
autocrine, paracrine, endocrine
230
describe autocrine signalling
Autocrine: Messenger molecules bind with receptors in the cell where they are produced
ege part of positive feedback loop
231
what is paracrine signalling?
Paracrine: Messenger molecules between cells in close-proximity through the ECF (same tissue)
232
describe endocrine signalling?
Endocrine: Secretions of messenger molecules into the blood to act on cells in other parts of the body
233
describe how a simple feedback works
234
what is a positive feedback loop?
235
what is a negative feedback loop?
236
which type of hormones are stored for quick response? How do they work? Give an example
Peptide hormones
-quick response via secondary messanger cascade
-binds to membrane receptor
e.g. Insulin, Growth Hormone, ADH
237
what type of hormone is testosterone, oestrogen and cortisol?
how do they work?
are they soluble insoluble?
Steroid.
Made by cell and diffuses out when made - not stored, slower release.
requires transport proteins in blood
Directly affects Transcription DNA
Intracellular receptor target.
Made from Cholesterol - water insoluble, lipid soluble
238
what are amino-acid derivative hormones synthesised from?
give an example
tyrosine.
act same way as peptide hormones
e.g adrenaline, thyroid
239
on a whiteboard, draw out the RAAS system
240
how does water homeostasis work when dehydrated?
241
describe homeostasis of sodium
Sodium:
Filtered out glomerulus in kidney
80-90% reabsorbed at proximal convoluted tubule (PCT) and loop of Henle
Absence of aldosterone = sodium remains in filtrate and ends up in urine
242
decribe how potassium levels are maintained
Potassium:
Filtered out glomerulus in kidney
90% reabsorbed in PCT and loop of Henle
Presence of aldosterone = higher potassium excretion
243
describe calcium levels are maintained
Calcium:
Calcitonin decreases blood calcium
PTH and calcitriol increase blood calcium
244
what happens to pyruvate in anaerobic conditions?
how much ATP formed?
Pyruvate is converted to lactate which undergoes fermentation
2ATP formed
245
what happens to pyruvate in aerobic conditions?
how much energy is formed?
Pyruvate enters citric acid cycle for oxidative phosphorylation
38 ATP
246
what does a Kinase enzyme usually involve?
movement of phosphate group
247
draw out the steps of glycolysis
248
what does the krebs cycle depend on, and what is it inhibited by?
Depends on the availability of NAD+ and FAD
Inhibited by high concentrations of NADH
249
what happens to pyruvate after glycolysis before enetering krebs
Prior to the cycle, pyruvate is converted into Acetyl Coenzyme A
250
draw out the krebs cycle on a whiteboard
251
what are the product of the krebs cycle?
1 ATP, 3 NADH, 1 FADH2, 2 CO2
252
what is the purpose of the krebs cycle?
to produce NADH and FADH which can donate their H to the electron transport chain in oxid. phosop.
253
what is the rate limiting step of krebs cycle?
isocitrate dehydrogenase.
254
where does oxidative phosphorolation occur?
membrane of mitochondira
255
what are the regulators of the krebs cycle?
256
describe beta oxidation
## Footnote
iftoo much fatty acid ox, too much Acetyl CoA for Krebs, so Acetyl CoA diverted to form Ketones
257
what happens when Large amounts of acetyl-CoA are generated from high rates of fatty acid oxidation, this exceeds Krebs cycle capacity
Ketogenesis – Biochemical process by which ketone bodies are produced in the liver from fatty acids, occurs when the supply of glucose is limited.
Skeletal muscles can use ketones for fuel
258
what is a glycosidic bond?
bonds between monosaccharides (carbohydrates)
hydroxyl of monosaccharide with OH or NH group
259
What do O-glycosidic bonds form?
disaccharides, oligosaccharides and polysaccarides
260
what is an ester bond?
bond between glycerol and fatty acids in lipids.
formed via condensation reaction
261
where are N-glycosidic bonds found?
nucleotides in DNA
262
whate are peptide bonds?
bonds between amino acids, formed by condensation
263
how many amino acids are there?
describe their structre
20
264
describe the primary structure of proteins
sequence of a chain of AAs
265
describe secondary protein structure of proteins
local folding of polypeptide chain into a-helix or B-pleated sheets
266
describe tertiary protein structure of proteins
3D shape of a protein due to side chain interactions.
porpertied begin to be influenced.
267
describe quaternary protein structure
multiple poly peptide chains interacting
268
what is an enzyme?
biological catalysts - provide an alternative reaction pathway with a lower activation energy.
bind to reactants, convert them, release them and return to their original form.
tertiary or quaternary proteins
269
what are the nucleotide bases of DNA? which nucleotides pair with which?
Adenine - Thymine
Cytosine - Guanine
270
decribe how Chromosones are formed from DNA
DNA coils around histone proteins to form nucleosomes. Nucleosomes supercoils to make chromosones
271
how many chromosones in a human genome?
46 (22 autosome pairs and 1 pair sex chromosones)
XX male
XY female
272
what is a karyotype?
Karyotype: number and appearance of chromosomes in a cell
273
name three functions of DNA
Functions:
-Storage and transfer of genetic information
-Template and regulator for transcription and protein synthesis
-Structural basic of hereditary and genetic diseases
274
what is a duplictation mutation?
Duplications - sections repeating, incorrect protein generated
275
name the two types of deletion mutations
Out of frame – sequence shifts meaning the reading frame of the gene is changed (reading frame completely disrupted)
In frame – whereby one codon is removed thus only one amino acid is lost. Reading frame is not changed
276
explain how mutations in DNA can lead to Huntington's Disease
CAG repeated = Expansion of tri-nucleotide repeat
Anticipation: in diseases such as Huntington’s, repeats get bigger when they are transmitted to the next generation resulting in earlier symptoms of greater severity (anticipation)
277
name these types of mutations
278
What protein unwinds the double helix by reveiling supercoils?
what proteins sperates the DNA exposing nucleotides?
and what prevents the DNA re-annealing?
* **Topoisomerase** unwinds the double helix by relieving the supercoils.
* 1. DNA **helicase** then separates the DNA apart exposing the nucleotides.
* 1. Single stranded binding proteins (**SSBP**’s) coat the single DNA strands to prevent DNA re-annealing.
279
what is the start codon?
AUG - codes for methionine
280
which way do codoing strands run and which way to template stands run in DNA Transcription?
Coding strand runs 5’ to 3’, template strand runs 3’ to 5’
281
# initiation, elongation, termination
Explain how Transcription occurs.
| DNA --> RNA --> Proteins
282
what is the orientation of the mRNA strand that is made by RNA polymerase?
a 5’CAP head and a 3’Poly A tail - starting at a promoter
283
Transcription i stopped by what codons?
Stop Codon
UAG UGA UAA
| RNA has no T
284
explain how translation works
285
what is aneuploidy?
what is polyploidy?
Aneuploidy: the condition of having an abnormal number of chromosomes in a haploid set
Polyploidy: Polyploidy is the heritable condition of possessing more than two complete sets of chromosomes
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