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Biology AS > Cell Structure, 2.1 > Flashcards

Cell Structure, 2.1 Flashcards

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1
Q

Define magnification

A

Shows how much bigger an image is compared to the actual size of the object

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2
Q

Define resolution

A

Degree to which it’s possible to distinguish between two objects close together

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3
Q

What is the equation for magnification?

A

(Size of object) / (Real size of object)

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4
Q

What is the human eye resolution?

A

100 micrometres

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5
Q

What are the key facts about the Optical Microscope?

A

Max. magnification, x1500. Resolution, 200nm. Uses light - 400nm -700nm wavelength.

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6
Q

What are the advantages of using a Optical Microscope?

A

Quite cheap. Portable. Study whole living specimens.

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7
Q

What are the disadvantages of using a Optical Microscope?

A

Relatively low resolution and magnification. Specimens often need staining to show organelles.

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8
Q

What are the key facts about the Laser Scanning Microscope?

A

Max. magnification, x1500. Resolution 160nm. Uses laser beams to scan a sample point by point. Produce image on computer screen.

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9
Q

What are the advantages of using a Laser Scanning Microscope?

A

Images in a higher resolution than optical. Lasers can scan to different depths in living tissues.

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10
Q

What are the disadvantages of using a Laser Scanning Microscope?

A

Relatively low resolution and magnification. Expensive equipment. Requires training. Specimens require staining.

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11
Q

What are the key facts about the Transmission Electron Microscope?

A

Max. magnification, x2,000,000. Resolution, 0.1nm. Beam of electrons attracted by electromagnets through a sample. Produces a micrograph.

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12
Q

What are the advantages of using a Transmission Electron Microscope?

A

TEM has the highest resolution and magnification.

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13
Q

What are the disadvantages of using a Transmission Electron Microscope?

A

Large and expensive machinery. Specimen is dead - dehydrated and stains. Need training.

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14
Q

What are the key facts about the Scanning Electron Microscope?

A

Max. magnication x200,000. Resolution, 0.1nm. Beam of electrons bounce off the surface and are detected - produce a 3D scan.

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15
Q

What are the advantages of using a Scanning Electron Microscope?

A

Form complex 3D images. High magnification and resolution.

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16
Q

What are the disadvantages of using a Scanning Electron Microscope?

A

Large and expensive machinery. Need training. Specimen is dead - mounted in a vacuum in a metal film.

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17
Q

What do we do with unstained specimens?

A

Use a dark background. Observe living specimens.

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18
Q

Why do we use stains on specimens?

A

Can differentiate organelles or cell types by using specific stains. Bind to molecules. Provides a contrast.

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19
Q

When do we use acetic orcein?

A

DNA, Chromosomes (dark red)

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20
Q

When do we use eosin?

A

Cytoplasm

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21
Q

When do we use sudan red?

A

Lipids

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22
Q

Apart from stains how else might specimens be prepared?

A

Dehydrated. Embedded in wax. Thinly sliced in sections.

23
Q

What is an eyepiece graticule?

A

Measuring device, placed in the eyepiece of a microscope.

24
Q

What is a stage graticule?

A

Precise measuring device. Used to calibrate eyepiece divisions.

25
Q

How do you calibrate?

A

Align the eyepiece and the stage graticules, check the value of one eyepiece division. Divide the stage graticule by the eyepiece divisions.

26
Q

Describe the structure of a Lysosome.

A

Small spherical sacs bound by a membrane.

27
Q

Describe the function of a Lysosome.

A

Separates hydrolitic enzymes from the cell. Engulf old cell organelles and foreign substances. Digests
and recycles .

28
Q

Describe the structure of the Nucleus.

A

Largest organelle. Contains chromatin. Surrounded by nuclear envelope (double membrane with pores). Contains nucleolus.

29
Q

Describe the function of a Nucleus.

A

Genetic material. Control centre. Nuclear envelope - pores allow molecules through. Nucleolus - makes RNA and ribosomes.

30
Q

Describe the structure of a Ribosome.

A

Spherical. 2 sub-units. No outer membrane.

31
Q

Describe the function of a Ribosome.

A

Site of protein synthesis. mRNA used to assemble proteins.

32
Q

Describe the structure of Endoplasmic Reticulum (ER)

A

SMOOTH - flattened membrane sacs (cisternae). ROUGH - flattened membrane sacs (cisternae) Ribosomes on the outer surface.

33
Q

Describe the structure of Endoplasmic Reticulum (ER).

A

SMOOTH - lipid production (cholestrol, steroid hormones) and lipid absorption from the gut. ROUGH - modifies and transports proteins, large surface are for ribosomes.

34
Q

Describe the structure of mitochondria.

A

Spherical/rod shaped/branched. Highly folder inner membrane - cristae. Fluid filled matrix.

35
Q

Describe the function of mitochondria.

A

Responsible for aerobic respiration - produces ATP. Abundant in cells where lots of metabolic activity occurs.

36
Q

Describe the structure of Chloroplasts.

A

Double membrane separated by fluid filled space. Inner membrane continuous. Flattened sacs - thylakoids. A stack is a granum. Fluid filled matrix is the stroma.

37
Q

Describe the function of Chloroplasts.

A

Site of photosynthesis. Traps light energy. Abundant in leaf cells.

38
Q

Describe the structure of the Golgi Apparatus.

A

Stack of membrane bound flattened sacs. Secretory vesicles bring materials to and from.

39
Q

Describe the function of the Golgi Apparatus.

A

Post translation modification. Sugar - glycoproteins. Lipids - lipoproteins. Folded.

40
Q

Describe the structure of a centriole.

A

Bundles of mictrotubules. In a pair. Form a cylinder.

41
Q

Describe the function of a centriole.

A

Cell division - form spindle fibres which move chromosomes.

42
Q

Describe the structure of a vesicle.

A

Small membrane bound sacs which are fluid filled.

43
Q

Describe the function of a vesicle.

A

Store and transport substances. Fuse with plasma membrane.

44
Q

Describe the structure of a Vacuole.

A

Fluid filled sac with a membrane called a tonoplast.

45
Q

Describe the function of a Vacuole.

A

Plant cells - permanent vacuole with water, keeps the cell turgid.

46
Q

Describe the structure of the cellulose cell wall.

A

Outside of plasma membrane. Bundles of cellulose fibres.

47
Q

Describe the function of the cellulose cell wall.

A

Supports the cell, stops it from bursting. Maintains cell shape. Permeable.

48
Q

Describe the structure of the cilia.

A

Protrusions from the cell containing microtubules.

49
Q

Describe the function of the cilia.

A

Act as an antennae and moves material.

50
Q

What are the features of Eukaryotic cells?

A

Nucleus - DNA is organised, with a nuclear envelope. Nucleolus - containing RNA. Cytoplasm. Cytoskeleton. Plasma membrane. Ribosomes (80S). Membrane bound organelles. Complex.

51
Q

What are the features of Prokaryotic cells?

A

Cytoplasm. Plasma membrane. Ribosomes (70S). Have DNA and RNA. Under developed. No membrane organelles. Naked DNA - sometimes plasmid. Divide by binary fission.

52
Q

Describe the process of making and secreting a protein.

A
  1. Genes copied into mRNA, leaves the nucleus.
  2. At ribosomes instructions are translated and molecules assembled.
  3. Pass to RER
  4. Pass to golgi apparatus and the protein is modified
  5. Transported by a vesicle and secreted via exocytosis
53
Q

What are structures present in an animal cell but not a plant cell?

A

Centriole. Glycogen granule. Lysosomes. Flagella.

54
Q

What is the function of the cytoskeleton?

A
  1. Maintain cells shape/cell support/stability
  2. Movement of cilia
  3. Changing shape of cell
  4. Move organelles/hold them in place
  5. Move chromosomes

Biology AS (12 decks)

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