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ESA1 > ToB 5 Cell Ultrastructure > Flashcards

ToB 5 Cell Ultrastructure Flashcards

1
Q

What are the 2 types of electron microscopy?

A

1) Scanning

2) Transmission

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2
Q

What is the difference between the 2 types of electron microscopy?

A

Scanning microscopy fires electrons which bounce off the specimen, hitting a detector, creating an image. Transmission microscopy creates an image when the electrons pass through the specimen and reach the fluorescent screen beneath

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3
Q

What type of environment is found inside an electron microscope?

A

Vacuum

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4
Q

When looking at a cell nucleus via transmission electron microscopy, why are there 2 colours generated?

A

Nucleus contains DNA in 2 forms: heterochromatin which is in the solenoid form and very dense, and the euchromatin, which is in the beads-on-a-string form, which is much less dense so produces a lighter colour.

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5
Q

What type of filaments give microvilli their shape?

A

Actin microfilaments

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6
Q

Define ‘limit of resolution’:

A

The minimum distance at which 2 objects can be distinguished

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7
Q

What is the relationship between resolution and wavelength?

A

As wavelength decreases, resolution improves

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8
Q

Why are electron microscopes capable of much finer resolution than light microscopes?

A

Resolution is proportional to wavelength,

Electrons have a much smaller wavelength (0.004nm) compared to light microscopes (0.4um)

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9
Q

What extra process must a specimen go through to be seen via SEM, as opposed to TEM?

A

Specimen must be coated (with gold/platinum) to reflect electrons

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10
Q

Why must a specimen be coated with gold/platinum before being viewed via SEM?

A

To reflect the electrons to generate an image

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11
Q

List the membranes found in a bacterial/archaeal cell:

A

External membrane

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12
Q

List the membranes found in a eukaryotic cell

A 
External membrane
Membrane-bounded organelles ie:
-Nuclear envelope
-Outer/inner mitochondrial membranes
-ER
-Golgi
-Lysosomes etc
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13
Q

What is a phospholipid made up of?

A

Fatty acid(s)
Phosphate group
Glycerol
Choline

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14
Q

Define amphipathic:

A

Contains both hydrophobic and hydrophilic components

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15
Q

What main constituent of a cell is amphipathic?

A

Phospholipid within membranes

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16
Q

Why do transmembrane proteins often have a alpha helical structure?

A

Amino acids with hydrophobic side chains are the most compatible with alpha helix formation.

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17
Q

What is a glycocalyx?

A

Cell coating made of sugar residues on membrane proteins

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18
Q

Why is it possible to distinguish the glycocalyx from the plasma membrane?

A

The sugars can be stained

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19
Q

List 7 functions of the plasma membrane:

A

1) Endocytosis
2) Exocytosis
3) Selective permeability
4) Transport of materials along cell surface
5) Intercellular adhesion
6) Intercellular communication
7) Signal transduction

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20
Q

What is the name given to the space between the cisternae in the rER?

A

Intracisternal space

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21
Q

What is the main visual difference between the sER and rER?

A

rER appears rough due to presence of ribosomes, which are not present on sER

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22
Q

Name 5 places where sER is found in cells:

A

1) Testes
2) Ovaries
3) Mammary glands
4) Liver
5) Adrenal glands

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23
Q

What is the main function of the sER in an adrenal gland cell?

A

Steroidogenesis

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24
Q

What is the main function of the sER in a mammary gland cell?

A

Lipid biosynthesis

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25
Q

What is important to remember when looking at the endoplasmic reticulum via histology slides?

A

It is in fact contiguous, not made up of separate cisternae

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26
Q

Which face of the Golgi faces the rER?

A

Cis face

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27
Q

Which face of the Golgi faces the plasma membrane?

A

Trans face

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28
Q

From which face of the Golgi will the protein leave for exocytosis?

A

Trans face

29
Q

To which face of the Golgi will a protein enter the Golgi?

A

Cis face

30
Q

What are the 4 main functions of the Golgi, involving proteins?

A

1) Modify
2) Sort
3) Concentrate
4) Package

31
Q

What are the 3 possible paths that a modified protein may follow after going through the Golgi?

A

1) Stay in cell (lysosome)
2) Leave via signal-mediated exocytosis (regulated secretion)
3) Leave via constitutive secretion

32
Q

What is the difference between a primary and secondary lysosome?

A

A secondary lysosome is created when a primary lysosome fuses with a phagosome, and may release useful building block materials into the cytoplasm

33
Q

Describe the internal environment of a lysosome:

A

Acidic pH~5

Contains acid hydrolases

34
Q

Where are lysosomes created?

A

Golgi apparatus

35
Q

What stops the enzymes within a lysosome breaking down the lysosome membrane?

A

The glycocalyx

36
Q

What is an endosome?

A

A coated vesicle within a cell, which entered via endocytosis.

37
Q

What 3 things in a cell may a lysosome engulf and degrade?

A

1) Phagosome
2) Autophagosome
3) Late endosome

38
Q

Define autophagosome:

A

Vesicle containing part of the cells own cytoplasm (and organelles) which is destined for degradation via secondary lysosome formation

39
Q

In which 2 organs are peroxisomes abundant in cells?

A

1) Liver

2) Kidney

40
Q

Why is it important for liver and kidney cells to contain peroxisomes?

A

These detoxify substances such as alcohol, phenols, formic acid and formaldehyde

41
Q

What types of substances can peroxisomes detoxify?

A

Alcohol, formic acid, formaldehyde, phenols etc

42
Q

What is the function of a peroxisome?

A

Detoxification via oxidation

43
Q

What are the folds of the inner mitochondrial matrix named?

A

Cristae

44
Q

What is contained within the mitochondrial matrix?

A

Enzymes

Mitochondrial DNA

45
Q

Which mitochondrial membrane is impermeable to small ions?

A

Inner mitochondrial membrane

46
Q

What is the pH of the mitochondrial intermembrane space?

A

pH ~ 7

47
Q

What is the pH of the mitochondrial matrix?

A

pH ~ 8

48
Q

Why are mitochondria abundant in muscle cells?

A

They produce energy for the cell, so more mitochondria are needed in a muscle cell

49
Q

How are mitochondria different when in steroidogenic cells?

A

The cristae are tubulovesicular, rather than classically lamellar

50
Q

By what method do mitochondria replicate?

A

Binary fission

51
Q

What is the main function of mitochondria?

A

Generation of potential energy in the form of ATP via oxidative phosphorylation

52
Q

Name 3 parts/processes of the mitochondria which are similar to bacteria:

A

1) DNA
2) Ribosomes
3) Division

53
Q

Down which lineage is the mitochondrial DNA passed from one generation to the next?

A

Female lineage

54
Q

Which 3 filaments make up the cell cytoskeleton?

A

1) Actin microfilaments
2) Microtubules
3) Intermediate filaments

55
Q

What is the average diameter of an actin microfilament?

A

5-9 nm

56
Q

Describe the distribution of actin microfilaments in a cell:

A

Mainly cortical (around the edge) to maintain shape of cell

57
Q

Describe the strings of molecules make up the actin microfilament coil?

A

2 strings coil to form an actin microfilament

Polymers of one type of protein (actin)

58
Q

What is the average diameter of an intermediate filament?

A

10 nm

59
Q

What is the most common protein found in intermediate filaments?

A

Keratin

60
Q

Where are intermediate filaments found within a cell?

A 
Throughout cytoplasm (meshwork)
Forms nuclear lamina beneath the nuclear membrane
61
Q

What is the average diameter of a microtubule?

A

25 nm

62
Q

Describe a microtubule:

A

Long, hollow tube
Made of tubulin protein
25 nm diameter

63
Q

Where are microtubules found in a cell?

A

Nerve fibres
Mitotic spindle
Cilia
Flagella

64
Q

Where do microtubules originate from within a cell?

A

Centrosome

65
Q

What type of cytoskeleton tubules are mainly involved in motile cells?

A

Microtubules

66
Q

What is the function of microtubules within a nerve cell?

A

The neurotransmitters travel down the microtubules

67
Q

Describe the arrangement of microtubules within a cilium or flagellum:

A

9+2: 9 outer doublet microtubules form a ring around 2 central single microtubules

68
Q

Name the cytoskeleton tubules in order of diameter size, from smallest to largest:

A

1) Actin microfilaments (5-9nm)
2) Intermediate filaments (10nm)
3) Microtubules (25nm)

ESA1 (22 decks)

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