TLC Flashcards
1
Q
What are the 2 types of electron microscope?
A
> Scanning.
> Transmission.
2
Q
How does a Transmission electron microscope work?
A
> Fires electrons through a thin sample.
> Electrons are seen by the detector.
3
Q
What is an electron lense?
A
An electromagnet used to focus electrons
4
Q
How does a Scanning electron microscope work?
A
Detects electrons reflected of the samples surface.
5
Q
What are the disadvantages of electron microscopy?
A
> Samples must be sliced extremely thin. > Sample prep requires the use of toxic chemicals (heavey metals). > Sample prep can alter tissues. > Expensive. > Requires specialist knowledge.
6
Q
How is it possible to detect specific proteins using light microscopy?
A
> Linking antibodies to florescent labels.
> Linking antibodies to gold beads.
7
Q
Cytology is the study of what?
A
Structure and function of cells.
8
Q
Histology is the study of what?
A
Microscopic structure of tissues and organs.
9
Q
Pathology is the study of what?
A
Abnormal structure and function.
10
Q
What is the function of the cytoskeleton?
A
Controlling the shape and mobility of the cell.
11
Q
What are 3 ways it is possible to see parts of cells?
A
> Cut the tissues into slices.
Remove individual cells.
Use specialised imaging techniques (staining).
12
Q
How do you prepare slides (bright field microscope) ?
A
> Fixation (preserves). > Embedding in wax (makes more rigid). > Cut into sections. > Mounting. > Staining. > Covering.
13
Q
What colour do Haematoxylin and Eosin stain?
A
> Haematoxylin - DNA blue
> Eosin - proteins pink
14
Q
What are the 5 main parts of a light microscope?
A
> Eyepiece. > Objective. > Sample. > Condensor. > Collector lense.
15
Q
What are some advantages of bright field microscopy?
A
> Sample prep simple.
Clear images of overall tissue morphology.
Quick imaging.
16
Q
What are some disadvantages of bright field microscopy?
A
> Images low contrast. > low sensitivity. > Samples must be stained. > Can not image living cells! > Colour resolution poor.
17
Q
What is phase contrast microscopy?
A
Microscope designed by Fritz Zernike where 2 rings are inserted into the light path; one before the sample, one in the objective.
18
Q
What are some advantages of phase contrast microscopy?
A
> Quick to set up.
> Can be done on living samples.
19
Q
What are some disadvantages of Phase contrast microscopy?
A
> Produces poor spatial resolution.
“halo” produced hiding detail.
Not sharp.
20
Q
What is Differential interferance contrast microscopy?
A
Light microscopy wher components are added; 2 polorizers and 2 prizms.
21
Q
What are advantages of Differential interference contrast microscopy?
A
> Very good resolution.
Sharp.
Can be done on live samples.
22
Q
What are disadvantages of Differential interference contrast microscopy?
A
> Complex to carry out.
Sensitive configurations.
Can not be done with samples in plastic dishes.
23
Q
How other than by using stains can parts of a cell be labelled?
A
Using fluorophores.
24
Q
How does Fluorescence work?
A
> Bright light shone through filter.
Light reflected on to sample by a dichroic mirror.
Light given off collected through filter.
25
What is "pseudocolouring"?
Adding a false colour to make image clearer.
26
What are the advantages of Fluorescence microscopy?
> Increased sensitivity.
> Used to distinguish 4 or more different stains.
> Used for live cells.
> Non-toxic.
27
What are the disadvantages of Fluorescence microscopy?
Dyes bleach as light is shone on them.
28
What is Immunostaining?
Binding a coloured antibody to a selected protein.
29
What is the Cytoskeleton made of?
> Actin - filaments.
| > Tubulin - microtubules.
30
How are proteins made?
> Proteins destined to live inside the cell are made by ribosomes.
> Proteins destined to live within membranes or be transported out of the cell follow a more complex path.
31
How are intracellular membranes distinguished between under microscope?
> Proteins they contain.
| > How they move.
32
How are lysosomes recognised?
Using a red stain activated under acidic conditions.
33
What are the main components of a (eukaryotic) cell?
```
> Plasma Membrane.
> Cytoskeleton.
> Nucleus.
> Mitochondria.
> Endoplasmic reticulum.
> Golgi.
> Secretory vesicles.
> Endosomes.
> Lysosomes.
```
34
What is hyperplasia?
Cell division.
35
What is hypertrophy?
Increase in cell size.
36
How are exact copies of DNA made in cells?
Semi-conservative replication.
37
When does mitosis occur normally?
During early embryogenesis.
38
When does mitosis occur pathologically?
> Benign hyperplasia of the prostate.
| > Development of mammary tumours.
39
What happens during hypertrophy?
Extensive biosynthesis.
40
When does hypertrophy occur naturally?
In structures such as endochondral bone formation.
41
When does hypertrophy occur pathologically?
> Obesity - adipocytes enlarge.
| > Hypertrophic heart disease - cardiomyocytes enlarge.
42
What are the 3 inter-dependant cell cycles?
CYTOPLASMIC cycle.
CHROMOSOME cycle.
CENTROSOME cycle.
43
What happens during the cytoplasmic cycle?
Growth and biosynthesis fuels:
> Chromosome and centrosome cycles.
> Organelle replication.
> Seperation of daughter cells.
44
What happens during the chromosome cycle (mitosis) ?
> DNA replication.
| > Segragation.
45
When does the centrosome cycle happen and what happens?
> Prior to mitosis.
| > Formation of the mitotic spindle fibres.
46
Whats the difference between a centrosome and centriol?
Centrosome consists of 2 centrioles.
47
What happens during cell cycle arrest?
Halt in progression through cell cycle, hypertrophy still occurs.
48
When during the cell cycle do the checkpoints take place?
> Between G1 and S phase (restriction).
> Between G2 and prophase.
> During metaphase of mitosis (spindle)
49
What's the point of a checkpoint 1 (restriction)?
> Ensuring DNA is not damaged.
| > Ensuring cell is large enough.
50
What's the point of checkpoint 2?
> Ensuring DNA is not damaged.
| > Ensuring DNA replication is complete.
51
What's the point of checkpoint 3?
> Ensuring mitotic spindle is assembled.
| > Ensuring chromosomes are properly aligned?
52
When does the double check occur?
During checkpoint 2, it ensures that there is no error in duplication of chromosomes.
53
What happens during the G1 phase?
Normal cell activity (biosynthesis) production of organelles.
54
What happens during the S phase and how long is it?
> Cell content doubles (DNA + cytoplasm).
> Chromosome forms 2 sister chromatids.
> S phase is 3-6 hours.
55
What happens during the G2 phase?
> Normal cell activity (biosynthesis).
> 2-4 hour delay.
> Cell cycle checkpoint.
56
What happen if cells become locked in G1 phase?
HYPERTROPHY
57
What happens if cells have unrestricted acces to the mitotic phase?
HYPERPLASIA
58
Which is the longest phase?
G1
59
What happens during the M phase and how long is it?
> Protein synthesis ceases.
> Chromosomes condense.
> 1 hour.
60
What sort of cells spend time in a resting state G0 phase?
Cells dividing less frequently than once a day.
61
What happens in the G0 phase?
Cells either become QUIESCENT or undergo HYPERTROPHY.
62
What part of the cell cycle can be transient or permanent?
G0 phase
63
how do cells reduce the length of their cycle e.g. during the rapid growth of embryonic cells?
Through virtual ELIMINATION of G1 and G2.
64
How can cells in each steps of the cell cycle be quantified?
> Estimated by microscopy.
> Labelled with radiolabelled niwcleotides.
> Using flow cytometry.
65
How is control of the cell cycle maintained?
Decision points and Checkpoints.
66
What are features of the cell cycle?
> Time limited (has a clock)
> Invariable order.
> Phases are irreversible.
> Robust - works even after malfunction.
67
What do cyclins and CDK's do?
Regulate cell cycle activity.
68
What happens when CDK's are active?
PHOSPHORYLATION - progression of the cell cycle.
69
What happens when CDK's are inactive?
No phosphorylation - cell cycle is halted.
70
What must happen in order for an EXPLOSIVE RISE in CDK binding and formation of the ACTIVE COMPLEX?
Cyclin concentration must reach a THRESHOLD
71
What does the mitotic CDK-cyclin stimulate?
> Nuclear breakdown.
> Chromosome condensation.
> Mitotic spindle formation.
> Targeted protein degradation.
72
What controlls ACTIVATION of cell replication?
Cyclin-CDK and phosphorylation.
73
What controlls INACTIVATION of cell replication?
Inhibitory phosphorylation of the KINASE SUBUNIT.
74
What happens to cyclins onced they have served their function?
The protein ubiquitin degrades it
75
The formation of what complex triggers DNA synthesis?
S-CDK
76
What is a kinase?
Enzymes that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.
77
Which 2 cyclins are START CYCLINS?
D and E
78
Checkpoint protein act when?
When they receive negative intracellular signals.
79
What is a mitogen?
An extra-cellular signalling molecule that changes cell cycle activity.
80
What does a mitogen do?
> Triggers cell-division and SIGNALLING CASCADE.
> Overcomes intracellular mechanisms that blocks the cell cycle.
> Increases transcription of genes for G1-CDK, S-CDK and G2-CDK.
81
What is a growth factor?
A protein that stimulates cell divisin and differentiation.
82
What does a growth factor do?
> Bind to cell surface receptors.
> induce expression of G1 cyclins.
> They are supressed by tumour supressors.
83
What is the purpose of the cell membrane?
> Allow passage of nutrients, minerals and water into the cell.
> Excrete waste out of the cell.
> Cell signalling.
84
What is the purpose of proteins in the cell membrane?
Communicating with the external enviroment e.g. receptors, channels and pumps.
85
What is the purpose of carbohydrates in the cell membrane?
Signalling e.g. glycoproteins and glycolipids.
86
What does AMPHIPATHIC mean?
Has a polar (hydrophilic) and a non-polar (hydrophobic) part.
87
Where in the membrane do you find cholestral?
Between phospholipids.
88
When does the amount of cholestral vary and why?
With temperature - colder cells more cholesterol - helps maintain fluidity of membrane (stop from freezing).
89
What is the structure of cholestral like?
> Polar (hydrophilic) hydroxyl group.
> Rigid ring system.
> Flexible non polar (hydrophobic) side chain.
90
What molecules can travel across the membrane unfacilitated?
> SMALL uncharged, polar (hydrophilic) molecules e.g. water.
| > Non-polar (hydrophobic) molecules.
91
What different kind of proteins can you find within the membrane?
> Peripheral.
> Lipid-anchored.
> Integral (transmembrane).
92
What properties must a protein have in order to be Integral?
Must be AMPHIPATHIC > contains a hydrophobic alpha helix in the middle part.
93
What are the different kind of integral (transmembrane) proteins?
```
> Transporter.
> Anchor.
> Receptor.
> Enzyme.
> Monotopic.
```
94
What percentage of the membrane mass is carbohydrate?
10%
95
What are the 3 different type of filament?
> Microtubules
> Microfilaments
> Intermediate filaments
96
What is the function of intermediate filaments?
To provide (non-cotractile) mechanical strength.
97
What is the basic subunit of the microtubule?
> α-tubulin.
> β-tubulin.
Monomers which combine to form an αβ-dimer
98
Explain the role of kinesin and dynein in vesicle transport?
> Kinesin transports cargo from negative to positive anterograde.
> Dynein transports cargo from positive to negative retrograde.
99
Outline the structure of cilia and flagella and explain how they are motile?
> Axoneme structure.
> Including a 9+2 arrangement of microtubules.
> Each doublet microtubule has a dynein arm- this is a motor protein.
> Dynein uses a sliding tubule mechanism this helps the structure to move.
100
What is the energy source for actin?
Treadmilling - ATP being hydrolysed at both positive and negative end of ffilament.
101
What is cytoscaffold?
Complex network of filamentous proteins extending throughout the cytoplasm.
102
What's the function of the filaments that make up the cytoscaffold?
```
> Shape the cell.
> Anchoring of organelles.
> Organelle development.
> Tensile strength.
> Chromosome movement.
> Cell polarity.
> Motility.
```
103
What sub-units make up the intermediate filaments polymer?
> Keratins.
> Desmins.
> Neurofilaments.
> Nuclear lamins.
104
How does the intermediate filaments polymer appear?
> 8-stranded (rope-like).
| > Forms a hollow tube.
105
How does the microtubule polymer appear?
> 13-strands.
| > Forms hollow tubes.
106
What is the diameter of a microfilament?
7 nanometres
107
What sub-units make up a microfilament?
Globular- actin monomers.
108
How does the microfilament polymer appear?
> Single filaments.
| > Interacts with proteins to create complex arrangements.
109
What is the function of actin microfilaments?
> Structural support - is contractile.
> Cell movement.
> Interacts with molecular motor myosin.
110
What are the 2 forms of the actin cytoskeleton?
> Parallel bundles of filaments.
| > Criss-crossed bundles that form a network.
111
How can the actin cytoskeleton be modified?
> Cross-linking.
> Cutting.
> Binding of proteins.
112
What are the 4 Key processes microfilaments perform for cell motility?
> Gel-Sol transition within cytoplasm.
> Lamellipodial transition.
> Actin-myosin interactions.
> Focal adhesions.
113
What connects the pairs of dublet tubules to one another?
Nexin Links
114
What forms F-actin?
Lots of G-actin.
115
What happens during prophase?
> Chromosomes begins to condense.
| > Mitotic spindle begins to assemble.
116
What happens during pro-metaphase?
> Nuclear membrane breaks down.
> Cell cycle checkpoint.
> Spindle fibres attach to chromosomes via the kinetichore.
117
What happens during metaphase?
> Sister chromatids align on the cell equator.
> Cell cycle checkpoint.
> Kinesin motor protein walks to the end of polar microtubules connected to a microtubule from the oposite pole - this pushes poles apart.
118
What happens during anaphase A?
> Enzyme seperase brakes down a protein called cohesin which holds the 2 sister chromatids together.
> The motor protein dynein carries the sister chromosomes along the kinetichore microtubules to their polar ends.
119
What happens during telophase?
> Chromosomes arrive at poles.
> Chromosomes decondense (unwind).
> Nuclear envelope reforms.
120
Where do the microtubules form?
MICROTUBULE ORGANISING CENTRES (MTOC)
121
Give 2 examples of a Microtubule organising centre (MTOC)?
> Kinetichore.
| > Centrosome.
122
What surrounds the centrioles to make up the centrosomes?
The PERICENTRIOLAR MATRIX
123
What are 3 the differnt type of microtubule present in mitosis?
> Kinetichore microtubule.
> Polar microtubule.
> Astral microtubule.
124
What is the contractile ring?
Ring made of actin.
125
How does the contractile ring work?
The actin ring pinches the cells apart through the action of myosin motors.
126
What is the "metaphase plate"?
The equator of the cell.
127
What happens during anaphase B?
> Overlapping polar microtubules slide against one another, pushing the spindle poles apart.
> A pulling force acts on the poles (centrosomes) to move them apart.
128
What roles do kinesin and dynein play in anaphase B ?
> Kinesin pushes spindles apart.
| > Dynein pulls polls apart.
129
What did Claude Bernard quote about homeostasis?
"The constancy of the internal enviroment is the condition of the free life"
130
Who came up with the phrase 'homeostasis'?
Walter Cannon
131
What is cybernetics?
Science of control mechanisms.
132
What are the basic concepts of a control system?
What are the basic concepts of a control system?
133
What are the 3 interdependant components of homeostatic control?
> Receptor
> Control center
> Effector
134
What does the receptor do?
> Monitors the environment.
| > Responds to change (stimuli), by sending input to the control centre, via the afferent pathways.
135
What does afferent mean?
Movement towards something.
136
What does the control centre do?
> Determines set point at which level is to be maintained.
| > Analyses the input and determines the appropriate response.
137
What does the effector do?
Provides the control centres response (output) via the efferent pathways
138
What diseases are caused due to homeostatic disturbance?
> Renal failure.
> Diabetes.
> Respiratory failure.
> Fluid overload.
139
How does negative feedback work?
It causes a change in direction opposite to that of the initial change.
140
How does positive feedback work?
It enhances or exaggerates the original stimulus so activity (output) is accelerated.
141
How is blood pressure autoregulated?
> By the sympathetic nervous system - fast (contraction of vessels)
> And renal systems - slow (siving)
142
How are respirotory gases controlled in the blood?
> Chemoreceptors sense levels of pH / CO2.
> Information is sent to the brain.
> Phrenic nerve causes breathing reflex.
143
Outline briefly the positive feedback mechanism of childbirth?
> Stretch receptors in uterus are stimulated.
> Hypothalamic release of oxytocin into bloodstream.
> Uterus contracts more forcively.
> Ferguson reflex - contraction of uterus after cervix.
144
What's another word for childbirth?
Parturition
145
How can blood clotting problems be caused?
> Damage to the cells lining the blood vessels (endothelial cells)
> Reduced blood flow.
> Platelet activation.
146
What is the innate immune system?
Cells and proteins that are always present and ready to mobilize and fight microbes at the site of infection.
147
What is autoimmunity?
Disorder in which the bodies immune system fights it's own tissues.
148
Define homeostasis?
The ability to maintain a steady state within a constantly changing environment
149
Name some causes of excessive bleeding?
> Vitamin K deficiency.
> Haemophilia.
> Thrombocytopaenia- low platelet count.
150
What is the adaptive immune system?
Cells and proteins that adapt against pathogens that are able to overcome innate immune defenses.
151
Give some examples of negative feedback systems?
```
> Control of blood sugar.
> Regulation of temperature.
> Blood pressure.
> Respiration.
> Fluid and electrolyte balance.
> pH balance.
```
152
Give some examples of positive feedback systems?
> Blood clotting cascade.
> Labour contractions.
> Breast feeding.
> Urination.
153
What is a baroreceptor?
They are sensors located in the blood vessels that sense blood pressure.
154
What is extracellular?
Outside the cell
155
What does extracellular fluid consist of?
```
> Ions such as: Sodium, chloride, bicarbonate.
> Glucose.
> Fatty acids.
> Oxygen and Carbon dioxide.
> Cellular waste products.
```
156
What does intracellular fluid consist of?
Ions such as: potassium, magnesium, phosphate.
157
How much of the body's fluid is extracellular?
1/3
158
What is transcellular fluid?
Fluid within epithelial lined spaces (smallest component of extracellular).
159
What are the 3 mechanisms of cell transport?
> Simple diffusion.
> Facilitated diffusion (using proteins).
> Active transport.
160
What is a hypertonic solution?
A solution where the outside of the cell has a higher concentration of solutes than the inside.
161
What is a hypotonic solution?
A solution where the outside of the cell has a lower concentration of solutes than the inside
162
What is an isotonic solution?
A solution where the inside and outside of a cell has the same concentration of solutes.
163
What are the buffering systems in blood?
> Bicarbonate.
> Proteins.
> Phosphates.
> Haemoglobin.
164
What is the role of the carbonic anhydrous enzyme?
Combining carbon dioxide and water to make carbonic acid - this acts as a buffer.
165
How do capillaries maintain water?
Using sodium potassium pumps, Na+ is actively transported into capillary > followed by water.
166
What are the buffering systems in extra cellular fluid (ECF) and cellular spinal fluid (CSF)?
> Bicarbonate.
> Proteins.
> Phosphates
167
What are the buffering system of Intracellular fluid?
> Bicarbonates.
> Proteins.
> Phosphates.
168
What is hypernatremia?
Electrolyte imbalance - high level of sodium in the blood
169
How is hypernatremia caused?
> Excess Sodium (overproduction of aldosterone - Cushings syndrome)
> Loss of water (diabetes insipidus)
170
Ideal pH for mammalian tissues?
7.4
171
What is hyponatremia?
Electrolyte (ion) imbalance - low level of sodium in the blood.
172
What are the 2 different types of Acid-base disturbances?
> Respiratory.
| > Non-respiratory.
173
How does the body compensate when plasma CO2 levels are increased due to chronic respiratory disease?
More bicarbonate is produced - this acts as a base and increases the pH.
174
Where is the enzyme carbonic anhydrase found?
In the lumen of the proximal tubules of the kidney
175
How is hyponatremia caused?
> Excess water (overproduction of ADH)
| > Loss of water (decreased aldosterone production - Addisons disease)
176
How do capillaries maintain water?
> Using sodium potassium pumps.
> Na+ is actively transported into capillary
> Followed by water.
