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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
Q

how is the structure of an erythrocyte related to its function?

A

no nucleus; few organelles (incl. mitochondria)

biconcave (incr. SA)

production of haemoglobin (for oxygen transportation)

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26
Q

how is the structure of a neutrophil related to its function?

A

lobed nucleus

granular cytoplasm

many lysosomes containing hydrolytic enzymes (phagocytosis)

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27
Q

what are the requirements of a haemocytometery sample?

A

mixed (representative)

known dilution (accurate counting)

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28
Q

how is a cell count performed using a haemocytometer?

A

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

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29
Q

what is flow cytometery used for?

A

analysis of physical and chemical characteristics of cells in heterogenous cell populations

30
Q

what are the components of flow cytometery?

A

flow cell (liquid stream carrying single file cells)

measuring system

detector

amplification system

computer + relevant analysis software

31
Q

how can cell size and volume be analysed by flow cytometery?

A

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
Q

what are the 7 principles of cell theory?

A

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
Q

what are the structural components of the cell surface membrane (CSM)?

A

phospholipid bilayer - selective permeability

cholesterol - strength and consistency

proteins - integral (channels) and peripheral (recognition)

carbohydrates - glycoproteins (recognition)

34
Q

what is the function of the CSM?

A

maintains physical integrity

maintains a chemical environment

selective permeability

marks and signals cell

35
Q

what is the structure of the nucleus?

A

double membrane

pores in nuclear envelope (allows exchange of molecules)

contains at least one nucleolus

36
Q

what is the function of the nucleus?

A

control of hereditary characteristics

replication of DNA for mitosis

control of gene expression

37
Q

what is the structure of the nucleolus?

A

granular and fibrillar components

ill-defined matrix

38
Q

what is the function of the nucleolus?

A

ribosome assembly

pre tRNA transcription, processing and assembly

39
Q

what is the structure of the mitochondria?

A

double-membrane bound

matrix containing proteins, lipids, DNA, ribosomes

40
Q

what is the function of the mitochondria?

A

ATP production through aerobic respiration

41
Q

what is the structure of the endoplasmic reticulum?

A

folding network of cisternae held together by cytoskeleton

RER also has attached ribosomes

42
Q

what is the function of the endoplasmic reticulum?

A

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
Q

what is the structure of a lysosome?

A

membrane sacs containing hydrolytic enzymes

44
Q

what is the function of a lysosome?

A

breaking down macromolecules in hydrolysis

45
Q

what is the structure of the golgi apparatus?

A

fluid-filled flattened sacs of cisternae held together by matrix proteins and cytoplasmic microtubules

46
Q

what is the function of the golgi apparatus?

A

processing and packaging lipids and proteins made by the endoplasmic reticulum

making vesicles for transportation of molecules for exocytosis (i.e. lysosomes)

47
Q

what is the structure of a ribosome?

A

cytoplasmic granules made from rRNA proteins in clusters called polysomes

two subunits:

  • small (40 Svedberg units)
  • large (60 Svedberg units)
48
Q

what is the function of a ribosome?

A

protein synthesis through translation of mRNA to polypeptides

49
Q

what is the structure of a centriole?

A

short lengths of microtubules lying parallel around cavity

50
Q

what is the function of a centriole?

A

increasing effectiveness of mitosis

movement of cilia and flagella

51
Q

what is the structure of a vacuole?

A

membrane-bound sacs

tonoplast (selectively permeable membrane)

52
Q

what is the function of a vacuole?

A

cell rigidity

storage

53
Q

how do organelles work together to produce a protein?

A

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
Q

what are the features of a prokaryotic cell?

A

no nucleus/membrane-bound organelles

70Svedberg ribosomes

peptidoglycan cell wall

flagella

polysaccharide capsule

plasmid DNA

55
Q

what are the three main types of eukaryotic cells?

A

amoeba

chlamydomonas

paramecium

56
Q

what is the role of the cytoskeleton?

A

cell stability/support

movement of cilia and flagella

changing shape of cell during cytokinesis/phagocytosis/exocytosis

movement of organelles/vesicles

57
Q

what are the three components of the cytoskeleton?

A

microfilaments

intermediate filaments (10nm)

microtubules (23nm)

58
Q

outline the process by which motor proteins move along the cytoskeleton

A

binding

conformational change

filament release

conformational relaxation

filament rebinding

59
Q

what is the purpose of colourimetery?

A

quantitative analysis of a solution to determine its quantity/quality

60
Q

what is simple diffusion?

A

the passive movement of particles from an area of high concentration to an area of low concentration

61
Q

what are the factors affecting the rate of diffusion?

A

concentration gradient

SA

diffusion distance

composition of cell membrane

temperature

62
Q

what is facilitated diffusion?

A

the movement of particles across a membrane using specialised proteins

63
Q

what is function of

  • channel proteins
  • carrier proteins?
A
  • water-soluble molecule transmembrane transportation

- specific to transported molecules (e.g. mineral ions)

64
Q

what is active transport?

A

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
Q

outline the process of active transport across a membrane

A

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
Q

what are the two forms of endocytosis?

A

pinocytosis (liquid material)

phagocytosis (solid material)

67
Q

what is the function of endocytosis?

A

uptake of nutrients

engulfing bacteria

68
Q

what is the function of exocytosis?

A

insoluble waste material excreted from cell

69
Q

what is the test for lipids?

A

add ethanol and shake

add to water

mixture turns cloudy/milky

70
Q

what are the similarities between a triglyceride and a phospholipid?

A

contain glycerol

contain fatty acids

contain ester bonds

contain C, H and O

71
Q

what are the differences between a triglyceride and a phospholipid?

A

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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