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Paper 1 Important topics > 1 Cells and microscopy > Flashcards

1 Cells and microscopy Flashcards

1
Q

how is magnification calculated?

A

image size / actual size

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2
Q

how is total magnification calculated?

A

eye piece magnification x objective magnification

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3
Q

what are the differences between light and electron microscopes?

A

light v electrons

light uses living; electron has vacuum ∴ dead samples

light can distinguish colour; electron can’t

light has low mag. and res.; electron has high mag. and res.

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4
Q

what does an electron microscope use to focus?

A

an electromagnet

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5
Q

what is the maximum resolution for a

  • light microscope
  • electron microscope?
A
  • 200nm

- 0.1nm

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6
Q

what is the maximum magnification for a

  • light microscope
  • scanning electron microscope (SEM)
  • transmission electron microscope (TEM)?
A
  • 1500x
  • 100,000x
  • 500,000x
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7
Q

what is the definition of magnification?

A

the degree of enlargement of an image to reveal further detail

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8
Q

what is the definition of resolution?

A

the ability to distinguish between two different points and to see detail

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9
Q

what is the use of a microtome?

A

to cut extremely thin non-living specimens

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10
Q

how does a TEM produce an image?

A

e- passed through specimen and scattered

magnetic lenses focus image on fluorescent screen/photographic plate

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11
Q

how does an SEM produce an image?

A

e- knock other e- from surface of specimen

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12
Q

what is added to TEM specimens?

A

heavy metal impregnation

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13
Q

what is added to SEM specimens?

A

coated with carbon/gold

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14
Q

outline the process of temporary staining

A

fixation

staining

mounting

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15
Q

outline the process of permanent staining

A

fixation (immersion in gluteraldehyde)

dehydration (incr. alcohol content)

clearing (xylol removes alcohol)

embedding (in epoxy/resin)

sectioning

staining

mounting

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16
Q

what is cryosectioning?

A

tissue embedded in gel medium is rapidly frozen to -20/-30.C

cut with cryostat into 5-10 um sections, then stained

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17
Q

what is the purpose of differential staining?

A

to make certain structures appear darker or different in colour from other structures

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18
Q

how is Leishman’s stain applied?

A

blood smear prepared

fixed with methanol for 2 mins

distilled with water for 6 mins

slide washed until pink to naked eye

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19
Q

how is Wright’s stain applied?

A

blood smear prepared

dipped in stain for 15-30s

dipped in water for 15-45s

dipped in fresh water for 25s

dried vertically

oil applied

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20
Q

what is the purpose of a blood smear?

A

to observe the appearance of the blood:

  • presence/absence of cells
  • cell morphology
  • cell health
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21
Q

how is a blood smear achieved?

A

place a small drop of blood at the end of a clean, sterile, dry slide

another slide used to spread blood at 30. angle

immediately labelled

slide left to dry

fixative used to preserve cells

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22
Q

what are the functions of the blood?

A

delivery of O(2) and nutrients to tissue

removal of waste products from tissues

immunological protection

clotting

transport of cell-signalling molecules

buffer to regulate body pH and temperature

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23
Q

what is the function of erythrocytes?

A

{red blood cells, RBCs}

to deliver oxygen to tissues as oxyhaemoglobin

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24
Q

how are erythrocytes produced?

A

produced from erythropoietic stem cells in bone marrow following stimulation from erythropoietin

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25
how is the structure of an erythrocyte related to its function?
no nucleus; few organelles (incl. mitochondria) biconcave (incr. SA) production of haemoglobin (for oxygen transportation)
26
how is the structure of a neutrophil related to its function?
lobed nucleus granular cytoplasm many lysosomes containing hydrolytic enzymes (phagocytosis)
27
what are the requirements of a haemocytometery sample?
mixed (representative) known dilution (accurate counting)
28
how is a cell count performed using a haemocytometer?
count number of cells in 3-line square using NW rule = ___ find volume (0.2 x 0.2 x 0.1 = 0.004 mm3) in 1 mm3 = 1/0.004 x ___ = ~~~ cells account for dilution = ~~~ x dilution factor = ........ cells
29
what is flow cytometery used for?
analysis of physical and chemical characteristics of cells in heterogenous cell populations
30
what are the components of flow cytometery?
flow cell (liquid stream carrying single file cells) measuring system detector amplification system computer + relevant analysis software
31
how can cell size and volume be analysed by flow cytometery?
specific antibodies can be tagged to different fluorochromes --> recognise and target specific antigens inside cells/on CSM fluorochromes can be attached to a chemical that binds to a specific of DNA/cell membrane/cells structure each fluorochrome has its own peak of excitation and emission wavelengths laser causes tagged cell to fluoresce so it can be counted scattering based on size and density
32
what are the 7 principles of cell theory?
cell = basic unit of all life forms organisms can be uni- or multi-cellular metabolic processes take place inside the cell new cells are derived from existing cells cells process genetic material which is passed to daughter cells cell = smallest unit of an organism capable of surviving independently
33
what are the structural components of the cell surface membrane (CSM)?
phospholipid bilayer - selective permeability cholesterol - strength and consistency proteins - integral (channels) and peripheral (recognition) carbohydrates - glycoproteins (recognition)
34
what is the function of the CSM?
maintains physical integrity maintains a chemical environment selective permeability marks and signals cell
35
what is the structure of the nucleus?
double membrane pores in nuclear envelope (allows exchange of molecules) contains at least one nucleolus
36
what is the function of the nucleus?
control of hereditary characteristics replication of DNA for mitosis control of gene expression
37
what is the structure of the nucleolus?
granular and fibrillar components ill-defined matrix
38
what is the function of the nucleolus?
ribosome assembly pre tRNA transcription, processing and assembly
39
what is the structure of the mitochondria?
double-membrane bound matrix containing proteins, lipids, DNA, ribosomes
40
what is the function of the mitochondria?
ATP production through aerobic respiration
41
what is the structure of the endoplasmic reticulum?
folding network of cisternae held together by cytoskeleton RER also has attached ribosomes
42
what is the function of the endoplasmic reticulum?
RER: protein production SER: production, metabolism and storage of fats and steroid hormones sarcoplasmic reticulum: storage and release of Ca2+ ions for muscle contraction
43
what is the structure of a lysosome?
membrane sacs containing hydrolytic enzymes
44
what is the function of a lysosome?
breaking down macromolecules in hydrolysis
45
what is the structure of the golgi apparatus?
fluid-filled flattened sacs of cisternae held together by matrix proteins and cytoplasmic microtubules
46
what is the function of the golgi apparatus?
processing and packaging lipids and proteins made by the endoplasmic reticulum making vesicles for transportation of molecules for exocytosis (i.e. lysosomes)
47
what is the structure of a ribosome?
cytoplasmic granules made from rRNA proteins in clusters called polysomes two subunits: - small (40 Svedberg units) - large (60 Svedberg units)
48
what is the function of a ribosome?
protein synthesis through translation of mRNA to polypeptides
49
what is the structure of a centriole?
short lengths of microtubules lying parallel around cavity
50
what is the function of a centriole?
increasing effectiveness of mitosis movement of cilia and flagella
51
what is the structure of a vacuole?
membrane-bound sacs tonoplast (selectively permeable membrane)
52
what is the function of a vacuole?
cell rigidity storage
53
how do organelles work together to produce a protein?
nucleus contains gene for transcription of protein ribosomes = site of translation of proteins vesicles transport protein to golgi apparatus, which processes it (e.g. quaternary structure by adding prosthetic groups) vesicles transport protein to CSM
54
what are the features of a prokaryotic cell?
no nucleus/membrane-bound organelles 70Svedberg ribosomes peptidoglycan cell wall flagella polysaccharide capsule plasmid DNA
55
what are the three main types of eukaryotic cells?
amoeba chlamydomonas paramecium
56
what is the role of the cytoskeleton?
cell stability/support movement of cilia and flagella changing shape of cell during cytokinesis/phagocytosis/exocytosis movement of organelles/vesicles
57
what are the three components of the cytoskeleton?
microfilaments intermediate filaments (10nm) microtubules (23nm)
58
outline the process by which motor proteins move along the cytoskeleton
binding conformational change filament release conformational relaxation filament rebinding
59
what is the purpose of colourimetery?
quantitative analysis of a solution to determine its quantity/quality
60
what is simple diffusion?
the passive movement of particles from an area of high concentration to an area of low concentration
61
what are the factors affecting the rate of diffusion?
concentration gradient SA diffusion distance composition of cell membrane temperature
62
what is facilitated diffusion?
the movement of particles across a membrane using specialised proteins
63
what is function of - channel proteins - carrier proteins?
- water-soluble molecule transmembrane transportation | - specific to transported molecules (e.g. mineral ions)
64
what is active transport?
the movement of molecules against their concentration gradient, requiring ATP requires a carrier protein: - with a specific binding site - to undergo a conformational change - have a binding site for ATP - ∴ can carry out hydrolysis
65
outline the process of active transport across a membrane
carrier protein takes up molecule from outside molecule binds to carrier protein ATP attaches to membrane protein on inside molecule causes conformational change to structure --> access for molecule opened molecules released to inside of membrane using E from hydrolysis of ATP release of molecule causes carrier protein to revert to binding configuration
66
what are the two forms of endocytosis?
pinocytosis (liquid material) phagocytosis (solid material)
67
what is the function of endocytosis?
uptake of nutrients engulfing bacteria
68
what is the function of exocytosis?
insoluble waste material excreted from cell
69
what is the test for lipids?
add ethanol and shake add to water mixture turns cloudy/milky
70
what are the similarities between a triglyceride and a phospholipid?
contain glycerol contain fatty acids contain ester bonds contain C, H and O
71
what are the differences between a triglyceride and a phospholipid?
T: 3 fatty acids; P: 2 fatty acids T: 3 ester bonds; P: 2 ester bonds T: absence of phosphorous; P: presence of phosphorours

Paper 1 Important topics (8 decks)

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