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OCR Biology Paper 1 > 2.1 - Cell Structure > Flashcards

2.1 - Cell Structure Flashcards

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1
Q

What does the objective lens do?

A

Focuses light and increases magnification.

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2
Q

What does the eyepiece lens do?

A

Increases magnification.

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3
Q

What does the light source do?

A

Shines light through a specimen so it can be seen clearer.

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4
Q

What is the role of an eyepiece graticule?

A
  • In eyepiece, used to measure the size of an object viewed under a microscope.
  • Has to be calibrated.
  • 100 divisions with no scale.
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5
Q

What is the role of a stage micrometer?

A
  • Used to calibrate eyepiece graticule.
  • 1mm with 100 divisions - each division = 10 micrometers.
  • Put in microscope as if it was slide.
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6
Q

Why is the cover slip lowered at an angle onto a slide?

A

To prevent bubbles.

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7
Q

What is differential staining?

A
  • Using multiple stains.
  • Each stain binds to different structures.
  • Allows separate structures to be identified.
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8
Q

Advantages of staining?

A
  • Increases contrast.
  • Can differentiate between different cells/parts of cell.
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9
Q

Advantages of light microscopes?

A
  • Cheap.
  • Easy to use.
  • Can observe living organisms.
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10
Q

Describe how a laser scanning confocal microscope works.

A
  • Specimen treated with fluorescent dye.
  • Laser causes components labelled with dye to reflect.
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11
Q

Advantages of laser scanning confocal microscope.

A
  • High resolution due to the fact laser beam has small wavelength.
  • Can view objects inside cells.
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12
Q

Structure of the nucleus

A
  • Has membrane with pores to allow molecules in and out of nucleus.
  • Stores cell’s DNA.
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13
Q

What is chromatin?

A

DNA + histones

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14
Q

Where are ribosomes produced?

A

Nucleolus

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15
Q

SER function

A

Synthesis of lipids

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16
Q

RER function

A

Protein synthesis for proteins to be outside of cell.

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17
Q

Golgi function

A

Stores, modifies and packages proteins.

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18
Q

Lysosome function

A

Contains hydrolysing enzymes

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19
Q

Mitochondria function

A

Site of aerobic respiration, where ATP production occurs.

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20
Q

Cytoplasm function

A

Site of chemical reactions in cell

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21
Q

Plasma membrane function

A

Controls what substances enter/exit cell

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22
Q

Centrioles function

A
  • Assemble microtubules in spindles for mitosis
  • Not in plant cells
23
Q

Components in plant cell, not animal

A

Chloroplasts
Permanent Vacuole
Cell wall

24
Q

Chloroplast function

A

Site of photosynthesis

25
Q

Vacuole function

A

Contains cell sap to help support the cell.

26
Q

Cell wall function

A
  • Made of cellulose.
  • Supports and maintains shape of cell.
27
Q

Microfilaments function

A
  • Cell movement
  • Contraction during cytokinesis
28
Q

Microtubules function

A
  • Provide tracks for movement of organelles.
  • Form spindle fibres.
29
Q

Intermediate fibres function

A

Give mechanical strength to cells

30
Q

What is prokaryote cell wall made of?

A

Peptidoglycan

31
Q

What is yeast cell wall made of?

A

Chitin

32
Q

Microtubules in flagella

A

Contract to make flagellum move.

In 9+2 formation (9 on outside, 2 in middle)

33
Q

What type of ribosomes are in bacteria vs eukaryotes?

A
  • 70S in bacteria
  • 80S in eukaryotes
34
Q

Which eukaryotic organelle is not membrane bound?

A

Ribosome

35
Q

How can microtubules be prevented from functioning?

A

Respiratory inhibitor

36
Q

Light microscope mag + resolution

A

x 1500

0.2 micrometers

37
Q

TEM mag + resolution

A
  • x 500,000
  • 0.2nm
38
Q

SEM mag + resolution

A

x 100,000

0.2nm

39
Q

Describe endosymbiotic theory

A
  • Mitochondria and chloroplasts found in eukaryotic cells represent formerly free-living
    bacteria that were absorbed into a larger cell.
40
Q

Evidence for endosymbiotic theory

A
  • Mitochondria contain ribosomes that are smaller
    than those found in the cell cytoplasm.
  • Mitochondria are a similar size to bacteria.
  • Chloroplasts have their own circular DNA.
41
Q

What is cristae?

A

Inner membrane of mitochondrion folded to form cristae.

42
Q

Describe the roles of the cytoskeleton.

A
  • Cell support and stability
  • Movement of flagella/cilia
  • Movement of ribosomes
43
Q

Define cell theory

A
  • All living organisms are composed of cells
  • Cells are the smallest components of life
  • Cells arise from pre-existing cells - they cannot spontaneously generate
44
Q

Define magnification

A

The number of times larger the image appears compared to the actual object

45
Q

Define resolution

A

The ability of a microscope to distinguish between two separate points

46
Q

Explain the difference between magnification and resolution

A
  • Magnification is the number of times larger the image is compared to the object
  • Resolution is ability to distinguish between two separate points
47
Q

How is magnification calculated?

A
48
Q

Why is the sample squashed before viewing?

A

Forces cells into single layer

49
Q

Why are shoot tip cells often used when preparing a plant cell sample?

A
  • Cells are continually replicating
  • Able to see different stages of mitosis
50
Q

Size of ribosome

A

10nm

51
Q

Distinguish between the chromosomes of eukaryotic cells and prokaryotic cells

A
  • DNA associated with histone proteins in eukaryotes, ‘naked’ in prokaryotes
  • DNA linear in eukaryotes, circular in prokaryotes
  • DNA within nucleus in eukaryotes, in cytoplasm in prokaryotes
52
Q

Explain the structure and function of the cytoskeleton

A

Microfilaments (actin)
- Cell movement and contraction during cytokinesis

Microtubules
- Determine shape of cell and provide ‘tracks’ for movement of organelles
- Form spindle fibres during cell division

Intermediate fibres
- Give mechanical strength to cells

53
Q

Define the function of the organelles found in prokaryotes

A
  • Cell wall - made from peptidoglycan, supports and protects the cell
  • Capsule - carbohydrate layer protecting cell from being engulfed
  • Pili - hair-like structures, enable exchange of information between cells
  • Flagella - whip-like structures that enable motility
  • Ribosomes (70S) - synthesise proteins
  • Nucleoid - region where single loop of DNA is found
  • Plasmid - additional circular DNA structures, often conferring antibiotic resistance

OCR Biology Paper 1 (20 decks)

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