ToB S3 - Cell Ultrastructure Flashcards Preview

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Flashcards in ToB S3 - Cell Ultrastructure Deck (15):
1

Determine the term limit of resolution

The minimum distance that two objects can be distinguished as separate

2

List two advantages and two disadvantages of light and electron microscopy

Light microscopy

+ Cheap

+ Can use live specimens

- Higher limit of resolution

- Lower magnification

Electron microscopy

+ Lower limit of resolution

+ Capable of higher magnification

- Expensive

- Uses dead tissue only

- Black and white images

3

What three components make up the cytoskeleton?

1) Microfilaments

2) Intermediate filaments

3) Microtubules

4

What are the functions of the plasma membrane?

Cell morphology and movement selectively permeability and transport of substances

5

What are the functions of the SER?

- Lipid and steroid synthesis

- Helps with protein folding

- Glycosylation 

- Disulphide bond formation

6

What is the difference between heterochromatin and euchromatin?

Heterochromatin - Chromosomes densely and coiled into solenoids, not being expressed

Euchromatin - Uncoiled DNA in form of 'Beads on a string', DNA is being expressed

7

What is the function of mitochondria?

ATP synthesis by oxidative phosphorylation

8

What is the function of lysosomes?

- Digestion of cell debris and waste material

- Produced by the golgi and fuse with material requiring digestion followed by the release of hydrolytic enzymes

9

What is the function of the nucleolus?

Ribosomes assembly and RNA modification

10

What are the functions of the nucleus?

- Stores the cells DNA

- It coordinates the cells activity; metabolism, growth, protein synthesis, mitosis

11

What is the function of peroxisomes?

a cell organelle containing catalase, peroxidase, and other oxidative enzymes and performing essential metabolic functions, as the decomposition of fatty acids and hydrogen peroxide

12

What are the three main types of cytoskeleton filaments?

1) Microfilaments

2) Intermediate filaments

3) Microtubules

13

Describe microfilament structure

- Two strings of actin twisted together

- Associated with ATP

- Can assemble and dissociate Eg a core of actin filaments allow intestinal microvilli to maintain their shape

14

Describe the intermediate filament structures

- Not dynamic

- Common in nerve and neurological cells

- Also common in epithelial cells made of cytokeratin.

They form tough supporting meshwork in the cytoplasm and are anchored to plasma membrane as strong intracellular junctions (desmosomes)

15

Describe the microtubule filament structure

- Thirteen α and β subunits polymerise to form the wall of the hollow microtubules

- They originate from the centrosome (tubular units added or subtracted)

- Found at sites where structures in cells are moved (Eg elongated cell processes such as nerve fibres, the mitotic spindle and the cores of cilia and flagella)