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BIOLOGY > Cell structure and microscopes > Flashcards

Cell structure and microscopes Flashcards

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1
Q

how does a TEM work

A

stained by metal salts
beam of electrons passing through a specimen
darker the picture the more dense structure

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2
Q

What kind of images can you see from a TEM

A

2D black and white
organelles

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3
Q

how does an SEM work

A

beams of electrons are knocked off the cell surface

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4
Q

what image do you see from an SEM

A

3D images
black and white
surface

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5
Q

why do we stain cells

A

to distinguish between cells/organelles and recognise different cells/organelles
improving contrast
to see them more clearly

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6
Q

resolution and magnification of a light microscope

A

200x
200nm

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7
Q

magnification and resolution of a TEM

A

500,000
0.5nm

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8
Q

magnification and resolution of an SEM

A

100,00 x
10nm

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9
Q

how do you use an eyepiece graticule and stage micrometer to view a specimen

A

calibrate eye piece graticule by making the divisions align

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10
Q

Outline the functions of the cytoskeleton within a cell (3)

A

Cell support / stability / scaffold / maintain shape;

Movement of flagella / cilia / undulipodia;

Cytokinesis / change shape of cell / endo / exocytosis;

Holds organelles in place;

Moves vesicles;

Moves chromosomes / mRNA;

Forms spindle / centrioles

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11
Q

glucose + glucose =

A

maltose

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12
Q

what is the purpose of gram staining

A

To differentiate between gram positive and gram negative bacteria

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13
Q

What’s the stain and colour for gram positive bacteria

A

iodine/ crystal violet –> purple/blue

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14
Q

Whats the stain for gram negative bacteria

A

acetic orcein –> DNA red/pink
eosin –>cytoplasm /pink

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15
Q

Why do specimens have to be thin in microspcopy

A

to allow light to pass through

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16
Q

What are the advantages of light microscopes

A

Cheap
Portable
Easy to use - no training
living organisms

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17
Q

What are the disadvantages of light microscopes

A

low magnification and resolution

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18
Q

What type of staining is needed for electron microscopes

A

Metallic staining - lead

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19
Q

What can you see with a laser scanning confocal microscope

A

Depth of a cell

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20
Q

Evaluate the use of laser scanning confocal microscopes

A

Disadvantages - Lower mag an res then electron
Advantages - living cells , depth

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21
Q

Evaluate the use of electron microscopes

A

Disadvantages - Expensive ,training , non living organisms
Advantages - high mag and res

22
Q

What’s the difference between the images seen in TEM and SEM

A

SEM can have added colour while TEM cant
TEM has a greater mag and res

23
Q

What do samples have to be in an electron microscope before theyre viewed

A

dehydration

24
Q

Whats the purpose of differential staining

A

Identify different cellular components and cell types

25
Q

How are acid-fast staining techniques done

A

Cells are dyed and washed with acid

26
Q

What does mycobacterium stain via acid-fast technique

A

Bright red

27
Q

What stain and colour are bacteria

A

Methylene blue –> stain bacteria blue

28
Q

What’s the definition of magnification

A

Number of times larger the image is in comparison to the object

29
Q

Define resolution

A

ability to distinguish between the 2 smallest points

30
Q

How do you prepare a dry mount

A

thin specimen with a cover slip on top

31
Q

How do you prepare a wet mount

A

place water on a slip then cover with a specimen
Put the cover slip on at an angle to prevent nay air bubbles
place a stain next to it and a paper towel on the other end to soak the stain in

32
Q

What’s the size of the divisions on a stage micrometre

A

10 um
0.01 nm

33
Q

What’s the structure and function of the nuclear envelope

A

double membrane to protect the cytoplasm from damage

34
Q

What’s the function of the nucleolus

A

site of ribosome production –> stained dark

35
Q

What’s the function of the nuclear pore

A

allow molecules to move in and out

36
Q

What’s the structure and function of the RER

A

flattened membrane bound sacs (cisternae-> synthesis occurs)
covered with ribosomes
transport of proteins
Continuous folds with the nuclear membrane

37
Q

What’s the structure and function of the SER

A

fluid filled cavities
no ribosomes
lipid and hormone production

38
Q

What’s the structure and function of the gogi apparatus

A

Modifies and packages proteins into vesicles
flattened membrane sacs and has secretory vesicles

39
Q

What’s the function of the ribosomes

A

Site of protein synthesis

40
Q

What’s the structure and function of the mitochondria

A

Site of ATP production
double membrane - inner (cristae)
surrounded by the matrix

41
Q

What’s the structure and function of the lysosomes

A

Spherical sacs surrounded by a membrane
contains digestive enzymes - hydrolyse components and break them down

42
Q

What’s the structure and function of the chloroplast

A

Site of photosynthesis
2 separate membranes filled by a fluid space (stroma)
flattened sacs (thykloids - that contain chloroplasts)
inside chloroplasts there are granum which are joined by lamellae

43
Q

What’s the structure and function of the centrioles

A

Take part in mitosis to form spindle fibres
Made from microtubules

44
Q

What’s the structure and function of the cell wall

A

Provides tensile strength
insoluble
maintains strength

45
Q

What’s the structure and function of the flagella

A

Microtubules that contract to make it move

46
Q

What’s the structure and function of the cilia

A

Made from protein microtubules that help cilia to move

47
Q

How are proteins secreted

A
  1. mRNA is made in the nucleus which leaves through the nuclear pore
  2. moves to the ribosomes - where protein synthesis occurs
  3. gets pinched off into a vesicle and fuses with the Golgi apparatus
    4.protein becomes packaged and modified
  4. vesicle travels to the plasma membrane and fuses with it
  5. released by exocytosis - requires ATP
48
Q

What are the components of the cytoskeleton and their functions

A

Microfilaments - change the cell shape
Microtubules - move chromosomes and organelles
Intermediate filaments - whole cell support

49
Q

Compare the structure of prokaryotes vs eukaryotes

A

Ribosomes - 80 vs 70
Nucleus vs no nucleus
Membrane bound organelles vs no membrane organelles
Larger vs smaller
Circular DNA vs Liner DNA
Flagella in 9+2 formation vs Flagella in a helix structure

50
Q

Whats the formula to calculate magnification

A

I = AM

BIOLOGY (17 decks)

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