Cell Ultrastructure Flashcards Preview

Z OLD Tissues of the Body > Cell Ultrastructure > Flashcards

Flashcards in Cell Ultrastructure Deck (95):
1

How is the image viewed using a light microscope?

Directly

2

How is the image viewed using a transition electron microscope (TEM)?

On a fluorescent screen

3

What is the purpose of the heated filament in a TEM?

Source of electrons

4

What is used as the lenses in a TEM?

Electromagnets

5

Why is the specimen for a TEM not on glass?

Glass would disrupt the electrons

6

How is the image viewed using a scanning electron microscope (SEM)?

On a viewing screen

7

What is the specimen for a SEM treated with?

Gold or palladium

8

Why is the specimen for SEM treated with gold or palladium?

So it reflects electrons, giving a surface image

9

What is the limit of resolution?

The minimum distance at which two objects can be distinguished

10

What is the limit of resolution proportional too?

Wavelength

11

What happens to resolution as wavelength decreases?

It improves

12

What does the wavelength of electrons depend on?

Voltage

13

Is the theoretical limit of resolution ever reached?

No

14

What is the theoretical limit of resolution for light microscopes?

0.2µm

15

What is the theoretical limit of resolution for electron microscopes?

0.002nm

16

What membranes do prokaryotes have?

Have external membrane, but no internal membrane

17

Where do all biochemical processes of a prokaryotic cell occur?

All in same compartment

18

How are eukaryotic cells compartmentalised?

By internal membranes

19

Give 10 components of a eukaryotic cell

- Endosome
- Lysosome 
- Cytosol
- Golgi apparatus 
- Peroxisome
- Endoplasmic reticulum 
- Nucleus 
- Free polyribosomes
- Mitochondria
- Plasma membrane

20

How many proteins does a typical mammalian cell synthesise?

More than 100,000

21

What do phospholipids consist of?

#NAME?

22

What does the head group of phospholipids consist of?

Choline-Phosphate-Glycerol

23

What does the hydrophobic tail of a phospholipid consist of?

2 fatty acids

24

What kind of molecules are phospholipids?

Amphipathic

25

What do phospholipid molecules make up?

The cell membrane

26

What does the phospholipid bilayer form?

A relatively impermeable barrier to most water-soluble molecles

27

What mediates most other functions of the phospholipid bilayer?

Proteins ‘dissolved’ in the membrane

28

Are the proteins in the phospholipid bilayer free to move?

Some are attached to cytoskeletal elements, so can\t move as much, but some freely mobile

29

How can membrane proteins be associated with the bilayer?

#NAME?

30

What parts of proteins often sit in the membrane?

α-helical regions

31

What is the cell coat called?

Glycocalyx

32

What is the glycocalyx made up of?

Oligosaccaride and polysaccharide side chains on outside of plasma memebrane

33

What do sugars give to the cell membrane?

Specificity of action

34

What is the importance of the specificity of action of the glycocalyx?

It allows them to work as receptors or stimulators

35

What are the functions of the plasma membrane?

- Selective permeability 
- Transport of materials along cell surface
- Endocytosis 
- Exocytosis 
- Intercellular adhesion 
- Intercellular recognition 
- Signal transduction

36

What does the rough endoplasmic reticulum (RER) have?

Ribosomes

37

Do all cells have RER?

Yes

38

Where is RER more abundant?

In cells producing a lot of protein

39

Where are proteins made?

In the cisternae of RER

40

Does smooth endoplasmic reticulum (SER) have ribosomes?

No

41

Where is SER found?

#NAME?

42

What is the function of SER in the mammary glands?

Lipid biosynthesis

43

What is the function of SER in the adrenal glands?

Steriodogenesis

44

How does SER differ from RER?

More irregular

45

What is it thought of the ER membrane?

It is continuous and enclosed in a single lumen

46

What is the Golgi apparatus involved in?

Protein synthesis

47

What happens at the Golgi apparatus?

- Vesicles with proteins join at it’s cis face
- Proteins move through various sacs
- Vesicles pinch off

48

What are the functions of the Golgi apparatus?

Modify, sort, concentrate and package proteins synthesised in the ER

49

What modifications are made in the Golgi apparatus?

Glycocylation

50

What are lysosomes generated by?

Golgi apparatus

51

What do lysosomes contain?

Lots of acid hydrolytic enzymes

52

What hydrolytic enzymes do lysosomes contain?

#NAME?

53

What is the pH in lysosomes?

~5

54

What happens to anything defunct in a cell?

It can be wrapped in a membrane, fused with a lysosome and broken down

55

How is the membrane of a lysosome protected?

By a glycocalyx

56

What do lysosomes fuse with?

Any material requiring digestion

57

What material might require digestion?

- Bacterium 
- Other molecules taken up by endocytosis 
- Defunct cellular components

58

What happens when bacteria are taken up by phagocytosis?

They form phagosomes, which fuse with lysosomes

59

What happens to other molecules that are taken up by phagocytosis?

They form an early endosome, which changes to lysosome, which fuses with lysosome

60

What is the process of removal of defunct cellular components called?

Autophagy

61

What is formed in autophagy?

Autophagosome

62

Where are peroxisomes found?

#NAME?

63

What do peroxisomes do?

Detoxify a number of molecules

64

How do peroxisomes detoxify?

By oxidation

65

What molecules do peroxisomes detoxify?

- Alcohol
- Phenols 
- Formic acid
- Formaldehyde

66

Give the equations for detoxification that occurs by peroxisomes

- RH 2 + O 2 →  R + H 2 O 2
- R’H 2 + H 2 O 2 →  R’ + 2H 2 O

67

What do mitochondria consist of?

- Matrix 
- Inner matrix in folds in cristae 
- Outer membrane

68

What does the matrix contain?

100’s of enzymes and mitochondrial DNA genome

69

What does the inner membrane of mitochondria contain?

Enzymes for oxidation reactions of respiratory chain

70

What is an important feature of the inner mitochondrial membrane?

It is impermeable to small ions

71

Is the outer mitochondrial membrane permeable?

Yes, to molecules

72

What is the pH of the mitochondrial inner membrane space?

7

73

What is the pH of the matrix?

8

74

What are the mitochondria the site of?

A cells energy production

75

Where are the mitochondria cristae typically tubular?

In steriodogenic cells

76

Why are mitochondria unlike other organelles?

They contain their own genetic information and can divide

77

What is the primary function of mitochondria?

Generation of ATP by oxidative phosphorylation

78

What lineage to mitochondria have?

Female

79

What is meant by mitochondria having female lineage?

All mitochondria are inherited from mother

80

How big are actin filaments

5-9nm in diameter

81

How are actin filaments distributed?

Cortical

82

What are actin filaments made up of?

A coil of two strings

83

What are actin filaments able to do?

Get longer and shorter

84

What is the diameter of intermediate filaments?

~10nm

85

Where are intermediate filaments common?

In epithelial cells

86

What do intermediate filaments form?

A tough supporting meshwork in the cytoplasm.

87

Where are intermediate filaments found in the nucleus

Just beneath the inner nuclear membrane

88

What is formed by intermediate filaments beneath the inner nuclear membrane?

The nuclear lamina

89

What is the purpose of the nuclear lamina?

It helps bind cells together through plasmodesmata

90

What are microtubules?

Long hollow tubes

91

What are microtubules made of?

The protein tubulin

92

Where are microtubules found?

At sites where structures are moved

93

Give 4 places that microtubules are found

- Nerve fibres
- Mitotic spindle 
- Cilia 
- Flagella

94

Where do microtubules originate from?

Centrosome

95

Where do microtubules show the 9+2 arrangement?

- Cilium 
- Flagellum