ToB 5 Cell Ultrastructure Flashcards Preview

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Flashcards in ToB 5 Cell Ultrastructure Deck (68)
1

What are the 2 types of electron microscopy?

1) Scanning
2) Transmission

2

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

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

3

What type of environment is found inside an electron microscope?

Vacuum

4

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

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.

5

What type of filaments give microvilli their shape?

Actin microfilaments

6

Define 'limit of resolution':

The minimum distance at which 2 objects can be distinguished

7

What is the relationship between resolution and wavelength?

As wavelength decreases, resolution improves

8

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

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

9

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

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

10

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

To reflect the electrons to generate an image

11

List the membranes found in a bacterial/archaeal cell:

External membrane

12

List the membranes found in a eukaryotic cell

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

13

What is a phospholipid made up of?

Fatty acid(s)
Phosphate group
Glycerol
Choline

14

Define amphipathic:

Contains both hydrophobic and hydrophilic components

15

What main constituent of a cell is amphipathic?

Phospholipid within membranes

16

Why do transmembrane proteins often have a alpha helical structure?

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

17

What is a glycocalyx?

Cell coating made of sugar residues on membrane proteins

18

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

The sugars can be stained

19

List 7 functions of the plasma membrane:

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

20

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

Intracisternal space

21

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

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

22

Name 5 places where sER is found in cells:

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

23

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

Steroidogenesis

24

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

Lipid biosynthesis

25

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

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

26

Which face of the Golgi faces the rER?

Cis face

27

Which face of the Golgi faces the plasma membrane?

Trans face

28

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

Trans face

29

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

Cis face

30

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

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

31

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

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

32

What is the difference between a primary and secondary lysosome?

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

33

Describe the internal environment of a lysosome:

Acidic pH~5
Contains acid hydrolases

34

Where are lysosomes created?

Golgi apparatus

35

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

The glycocalyx

36

What is an endosome?

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

37

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

1) Phagosome
2) Autophagosome
3) Late endosome

38

Define autophagosome:

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

39

In which 2 organs are peroxisomes abundant in cells?

1) Liver
2) Kidney

40

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

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

41

What types of substances can peroxisomes detoxify?

Alcohol, formic acid, formaldehyde, phenols etc

42

What is the function of a peroxisome?

Detoxification via oxidation

43

What are the folds of the inner mitochondrial matrix named?

Cristae

44

What is contained within the mitochondrial matrix?

Enzymes
Mitochondrial DNA

45

Which mitochondrial membrane is impermeable to small ions?

Inner mitochondrial membrane

46

What is the pH of the mitochondrial intermembrane space?

pH ~ 7

47

What is the pH of the mitochondrial matrix?

pH ~ 8

48

Why are mitochondria abundant in muscle cells?

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

49

How are mitochondria different when in steroidogenic cells?

The cristae are tubulovesicular, rather than classically lamellar

50

By what method do mitochondria replicate?

Binary fission

51

What is the main function of mitochondria?

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

52

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

1) DNA
2) Ribosomes
3) Division

53

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

Female lineage

54

Which 3 filaments make up the cell cytoskeleton?

1) Actin microfilaments
2) Microtubules
3) Intermediate filaments

55

What is the average diameter of an actin microfilament?

5-9 nm

56

Describe the distribution of actin microfilaments in a cell:

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

57

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

2 strings coil to form an actin microfilament
Polymers of one type of protein (actin)

58

What is the average diameter of an intermediate filament?

10 nm

59

What is the most common protein found in intermediate filaments?

Keratin

60

Where are intermediate filaments found within a cell?

Throughout cytoplasm (meshwork)
Forms nuclear lamina beneath the nuclear membrane

61

What is the average diameter of a microtubule?

25 nm

62

Describe a microtubule:

Long, hollow tube
Made of tubulin protein
25 nm diameter

63

Where are microtubules found in a cell?

Nerve fibres
Mitotic spindle
Cilia
Flagella

64

Where do microtubules originate from within a cell?

Centrosome

65

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

Microtubules

66

What is the function of microtubules within a nerve cell?

The neurotransmitters travel down the microtubules

67

Describe the arrangement of microtubules within a cilium or flagellum:

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

68

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

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