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As-Level Biology - Cell Structure And Division - Baxter > Analysis Of Cell Componenets > Flashcards

Analysis Of Cell Componenets Flashcards

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1
Q

What is magnification?

A

How much bigger the image is than the specimen

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2
Q

What is the formula for magnification?

A

Size of image ÷ size of real object

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3
Q

How do you convert nanometres into micrometers?

A

÷1000

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4
Q

How do you convert micrometres into millimetres?

A

÷1000

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5
Q

What is the resolution?

A

How well a microscope distinguishes between 2 points that are close together

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6
Q

What are the 2 types of microscope?

A

Optical

Electron

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7
Q

What are optical microscopes?

A

Use light to form an image

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8
Q

What is the maximum resolution of an optical microscope?

A

0.2 micrometers

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9
Q

What is the maximum useful magnification of an optical microscope?

A

x1500

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10
Q

What can you see with an optical microscope?

A

Mitochondria

Nucleus

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11
Q

What are electron microscopes?

A

Use electrons to form an image

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12
Q

What is the maximum resolution of an optical microscope?

A

0.0002 micrometers

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13
Q

What is the maximum useful magnification of an electron microscope?

A

x1 500 000

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14
Q

What are the 2 types of electron microscope?

A

Transmission

Scanning

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15
Q

What are transmission electron microscopes?

A

Use electromagnets to focus a beam of electrons which is then transmitted through the specimen

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16
Q

Why do denser parts of the specimen look darker on the image?

A

Absorb more electrons

17
Q

What are the advantages of TEMs?

A

Give high resolution images so can see internal structures of organelles

18
Q

What is are the disadvantages of TEMs?

A

Have to view specimen in a vacuum so cannot look at living specimens

Only used on thin specimens

19
Q

What are scanning electron microscopes?

A

Scan a beam of electrons across a specimen which knocks of electrons from specimen which are gathered in a cathode ray tube to form an image

20
Q

What are the images like in SEMs?

A

Show surface of specimen

Can be 3D

21
Q

What is an advantage of SEMs?

A

Can be used on thick specimens

22
Q

What is a disadvantage of SEMs?

A

Give lower resolution images than TEMs

23
Q

What is cell fractionation?

A

Separating organelles from the rest of the cell

24
Q

What are the 3 steps of cell fractionation?

A

Homogenisation

Filtration

Ultracentrifugation

25
Q

What does homogenisation do?

A

Breaks up plasma membrane and releases organelles into solution

26
Q

2 ways of homogenisation?

A

Vibrating cells

Grinding cells in a blender

27
Q

What are the 3 conditions for homogenisation?

A

Ice cold

Isotonic solution

Buffer solution

28
Q

Why must the solution be kept ice cold in homogenisation?

A

To reduce enzyme activity

29
Q

Why must the solution be isotonic?

A

Prevents damage to organelles though osmosis

30
Q

What does an isotonic solution mean?

A

Same concentration of chemicals as the cells being broken down

31
Q

What does the buffer solution do?

A

Maintains the pH

32
Q

What happens after the cell solution is homogenised?

A

Filtered through gauze to separate any large cell debris or tissue debris

33
Q

What is left after filtration?

A

A solution containing a mixture of organelles

34
Q

How can you separate a particular organelle from all the others?

A

Ultracentrifugation

35
Q

What is the process of ultracentrifugation?

A

Cell fragments poured into tube

Tube put in centrifuge and spun at low speed

Supernatant reined off into another tube and spun at a higher speed in centrifuge

Process repeated at higher speeds until all organelles are separated out

36
Q

Why is the solution spun in a centrifuge?

A

To separate heavies organelles from lightest

37
Q

What happens to the heaviest organelles in ultracentrifugation?

A

Form a thick sediment called a pellet at bottom of tube

As-Level Biology - Cell Structure And Division - Baxter (3 decks)

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