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AS Biology > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

Source of radiation of Light/Electron Microscopes

A

Light

Electrons

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2
Q

Wavelength of radiation of Light/Electron microscopes

A

400-700nm

0.005nm

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3
Q

Max. resolution of Light/Electron microscopes

A

200nm

0.1-0.5nm

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4
Q

Lens of Light/Electron Microscopes

A

Glass

Electromagnet

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5
Q

Specimen of Light/Electron Microscopes

A

Alive

Dead

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6
Q

Image of Light/Electron Microscopes

A

Coloured photomicrograph

B/W electron micrograph

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7
Q

View of Light/Electron microscopes

A

Eye piece

Fluorescent Screen

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8
Q

Magnification formula

A

Magnification=Image/Actual

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9
Q

What is resolution, and what is electron resolution?

A

Ability to distinguish 2 points. Electrons have smaller wavelength so have better resolution (0.5nm).

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10
Q

SEM vs TEM

A

SEM=Observe reflected electrons - 3D-like structure

TEM=Observe transmitted electrons - those that pass through the specimen

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11
Q

Electron Microscopy - Points of method

A

Must dehydrate specimen

Must cover specimen in heavy metal

Must be placed in a vacuum

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12
Q

Eyepiece graticule

A

Ruler for cells. Transparent scale placed in eyepiece.

Divisions = arbitrary units called “eyepiece units”

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13
Q

Stage micrometer

A

Essential to calibrate graticule. Divisions often 0.1 and 0.01mm.

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14
Q

Graticule calibration

A

1) Find value of each eyepiece unit
- Value=mm/units
OR
- Convert mm to um:
- Value=(mm x 1000)/units

2) Multiply no. units by value of each unit
- 20units x 2.5um = 50um

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15
Q

Cell surface membrane size

A

7nm

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16
Q

Appearance of surface membrane under 100,000x magnification

A

Trilaminar appearance

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17
Q

Job of surface membrane

A

Partially permeable - controls exchange of particles between inside/outside of cell

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18
Q

8 Functions of surface membrane

A
  • Barrier between inside/outside of cell
  • Cell signalling
  • Cell recognition
  • Cell-to-cell adhesion
  • Site for enzyme catalyzed reactions
  • Anchoring for cytoskeleton
  • Selection of substances that enter/exit
  • Formation of H bonds w/ water for stability
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19
Q

Diameter of Nucleus

A

10um

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20
Q

Outer membrane of Nuclear envelope continuous with…?

A

Rough ER

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21
Q

Nuclear pores: 4 things that enter, 2 things that exit

A

Enter: Proteins (for ribosomes), Nucleotides, ATP, Hormones (Thyroid T3)

Exit: mRNA, ribosomes

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22
Q

Purpose of chromosomes

A

Contain DNA organised into genes

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23
Q

Purpose of Genes in cells

A

Control activity of cell and heredity

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24
Q

Diameter of Nucleolus

A

0.2-0.5um

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25
Q

Job and contents of Nucleolus

A

Contains DNA and RNA. Functions to make ribosomes

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26
Q

Rough ER: 80s or 70s?

A

80s. Eukaryotes = 80s.

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27
Q

Role of Rough ER

A

Protein synthesis.

Provide pathway for transport of materials through cell.

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28
Q

Transport vesicles bud off from the Rough ER to join and form…?

A

Golgi Body

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29
Q

What is the structure of Rough ER?

A

Flattened 2D stacks of sacs, which are membrane-enclosed structures

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30
Q

Diameter of ribosomes

A

25nm

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31
Q

Ribosomes are made of

A

RNA and Protein

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32
Q

Proteins can be exported from the cell via…?

A

The Golgi vesicles

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33
Q

Role of Smooth ER

A
  • Site for lipid synthesis
  • Site for steroid synthesis
    (Cholesterol)
  • Site for Hormone production (Testosterone + oestrogen)
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34
Q

Role of Golgi Body

A

Collects, processes and sorts molecules ready for transport to other parts of cell, or out of cell through Golgi vesicles

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35
Q

Give 2 examples of protein processing in the Golgi Body

A

Addition of sugars to form Glycoproteins

Removal of the first amino acid Methionine forming Functional Proteins

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36
Q

How does Secretion/Exocytosis occur via the Golgi body?

A

Fusion of vesicles with plasma membrane to release content

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37
Q

What does the Golgi Body produce?

A

Lysosomes, Glycoproteins, Functioning proteins

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38
Q

Diameter of Mitochondria

A

1um

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39
Q

Is mitochondrion membrane double or single layered?

A

Double layered envelope.

40
Q

Name the space between mitochondrion membrane layers

A

Intermembrane space

41
Q

Name of proteins in outer membrane of mitochondria

A

Porin

42
Q

Role of proteins in outer membrane of mitochondria

A

Form wide aqueous channels to allow easy access for water-soluble molecules to enter from cytoplasm into intermembrane space

43
Q

How selective is the inner membrane of mitochondria

A

Very!

44
Q

What does the inner membrane of mitochondria allow into the organism?

A

Specific ions and molecules.

45
Q

What determines the amount of mitochondria in any given cell?

A

The amount of aerobic respiration undergone by the cell. Increases in muscle cells

46
Q

Name the folding inner membrane that projects into the interior matrix of mitochondria

A

Christae

47
Q

What are Christae

A

Folding inner membrane that projects into the interior matrix of mitochondria

48
Q

Type of ribosomes in mitochondria

A

70s - Prokaryotes have 70s ribosomes. Supports the endosymbiont theory.

49
Q

What is made up of 3 phosphate groups, a nitrogenous base and a ribose sugar?

A

ATP.

50
Q

ATP is produced in the _______?

A

Mitochondria.

51
Q

Energy is released by breaking ATP into ADP, a reversible _______ reaction?

A

Hydrolysis.

52
Q

What is the Endosymbiont theory?

A

Mitochondria + Chloroplasts wer bacteria now living in plants/animals.

It’s why they have circular DNA.

53
Q

Where is mRNA translated into polypeptides? With the help of what?

A

In Ribosomes, with help of tRNA (transferRNA).

54
Q

How does mRNA get to the Ribosomes?

A

Transcribed from the Nucleus.

55
Q

Where are 80S ribosomes found?

A

Cytoplasm, Rough ER.

56
Q

Where are 70S ribosomes found?

A

Chloroplasts, Mitochondria.

57
Q

Size of Lysosomes?

A

0.1-0.5um.

58
Q

Number of membranes in Lysosomes?

A

Single membrane.

59
Q

What is in Lysosomes?

A

Contain hydrolytic (digestive) enzymes.

Kept separate from cell to prevent damage.

60
Q

What is responsible for the breakdown of unwanted structures in a cell?

A

Lysosomes.

Eg: Old organelles
In WBC to digest bacteria

61
Q

Name for what makes up the cytoskeleton?

A

Microtubules.

62
Q

Size of cell wall?

A

10 nm.

63
Q

Why is the cell wall rigid?

A

Contains fibres of cellulose (polysaccharide).

64
Q

Purpose of the cell wall?

A

Maintain rigidity and shape.

Prevents cell from bursting (by osmosis) - allows turgidity.

65
Q

Permeability of the cell wall?

A

Freely permeable.

Allows anything in.

66
Q

What sometimes strengthens the cell wall?

A

Lignin.

67
Q

Plasmodesmata are __________?

A

“Pore”-like structures.

68
Q

Where are plasmodesmata found?

A

In the cell wall.

69
Q

What links cells through plasmodesmata?

A

Fine threads of cytoplasm.

70
Q

ATP is also known as the _____________ carrier?

A

Universal energy carrier

71
Q

Diameter of Microtubules

A

25nm

72
Q

What does MTOC stand for

A

Microtubule organising centres

73
Q

Name one structure that is part of the cytoskeleton

A

Microtubules

74
Q

What is tubulin and what is it for?

A

A protein

Used to make Microtubules

75
Q

What are dimers and what are they made up of?

A

Dimers are double molecules, made up of alpha-tubulin and beta-tubulin molecules.

76
Q

How are dimers organised together and what do they form?

A

Joined end to end to form protofilaments

77
Q

Dimers forming from end to end to form protofilaments is an example of what?

A

Polymerisation

78
Q

How many protofilaments line up to form a microtubule?

A

13

79
Q

Name the special location that is used to assemble microtubules

A

MTOCs (Microtubule organising centres)

80
Q

Give an example of lysosomes depositing enzymes outside of the cell

A

When the body replaces cartilage with bone during growth

81
Q

When do lysosomes break down whole cells?

A

In mammary glands after lactation

82
Q

What is the lysosome at the head of a sperm cell called, and what is its function?

A

Acrosome, to break down a pathway to the ovum.

83
Q

Provide 2 benefits of electron microscopes

A

Very small particles can be observed - electrons easily absorbed

Electron micrographs show the most organelles - due to higher resolution

84
Q

Define the term “Ultrastructure”

A

The structure revealed by the electron microscope

85
Q

Order the following organelles in order from smallest to largest, and provide their sizes:

Surface membrane
Nucleus
Nucleolus
Mitochondria
Ribosomes
Lysosomes
Chloroplasts
Cell wall
A 
Surface membrane (7nm)
Cell wall (10nm)
Ribosomes (25nm)
Lysosomes (0.1-0.5um)
Nucleolus (0.2-0.5um)
Mitochondria (1um)
Chloroplasts (5-10um)
Nucleus (10um)
86
Q

What is the job of ribosomes

A

Translates mRNA into polypeptides with the help or tRNA. Helps with protein synthesis.

87
Q

What is the structure of microtubules?

A

They are long hollow tubes that make up the cytoskeleton which helps determine cell shape.

88
Q

What two proteins make up microtubules and how are they differentiated?

A

Alpha-tubulin and Beta-tubulin

89
Q

What two things combine to form dimers

A

Alpha and Beta-Tubulin

90
Q

What process is involved when joining Dimers end to end?

A

Polymerisation

91
Q

How are protofilaments formed?

A

Dimers joining end to end

92
Q

How are protofilaments arranged to form the microtubule, and how many are used?

A

13 protofilaments are lined up in a cylinder with a hollow center

93
Q

What is the purpose of microtubules?

A

To form an intracellular transport system moving along secretary vesicles, organelles and cell components on its outer surface.

94
Q

Name the transport system within the cell that moves along secretary vesicles, organelles and cell components.

A

Microtubules

95
Q

What is the centrosome?

A

A pair of centrioles at right anhgles that are involved in nuclear division and act as MTOCs.

96
Q

What is a centriole?

A

9 Triplets of microtubules organised in a cylinder.

97
Q

How are centrioles involved in nuclear division

A
  1. Microtubules extend from centriole and attach to kinetochore of chromosomes, forming spindle fibres
  2. Centrioles duplicate, and a pair of centrioles then move to opposite poles of the cell (2 centrosome regions), This separates sister chromatids during nuclear division.

AS Biology (1 decks)

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