Cell Biology

Question 1

What is the difference between a prokaryotic and eukaryotic cell?

Answer 1

Prokaryotic cell has a nucleoid and no membranes

Eukaryotic cell has a nucleus and membrane-bound organelles

Question 2

What is the function of slime layer/capsule?

Answer 2

1. Protect the cell against immune system of host cell
2. Prevents dehydration
3. Sticky to adhere to substrate or other individuals in colony

Question 3

What is the difference between the slime layer and the capsule?

Answer 3

Slime layer = not well-organised

Capsule = dense

Question 4

What is the function of the cell wall?

Answer 4

1. Provide protection
2. Give cell shape
3. Prevents cell from bursting in a hypotonic environment (low salt)

Question 5

What is the cell wall made of?

Answer 5

Peptidoglycan which are modified sugars and polypeptides

Question 6

What are pili (sing. pilum)?

Answer 6

Appendages that bring two cells together prior to DNA transfer from one cell to another

Question 7

What is a plasmid?

Answer 7

A circular DNA found in prokaryotic cells and is released into the environment upon cell death

Question 8

What is resolution?

Answer 8

Measure of clarity of an image

Question 9

What is magnification?

Answer 9

The ratio of an object’s image size to real size

Question 10

What is contrast?

Answer 10

The difference between the brightness and darkness in an image

Question 11

What are the 3 basic principles of a cell confirmed by microscopy?

Answer 11

1. All living things are composed of cells and cell products
2. A single cell is the smallest unit of life
3. All cells come from pre-existing cells

Question 12

Explain the Gram Stain Technique

Answer 12

1. Culture bacteria

Question 13

Explain the Gram Stain Technique

Answer 13

1. Culture bacteria

Question 14

Explain the Gram Stain Technique

Answer 14

1. Culture bacteria

Question 15

Explain the Gram Stain Technique

Answer 15

1. Culture bacteria

Question 16

Explain the Gram Stain Technique

Answer 16

1. Culture bacteria

Question 17

What is the use of SEM?

Answer 17

Useful for detailed study of topography of a specimen

Question 18

What does SEM stand for?

Answer 18

Scanning Electron Microscope

Question 19

What does TEM stand for?

Answer 19

Transmission Electron Microscope

Question 20

What is the TEM used for?

Answer 20

Obtaining a detailed internal structure of cells

Question 21

How does the SEM work?

Answer 21

1. Directs a beam of electrons at a specimen

2. Creates an image based on electrons that are reflected

Question 22

How does the TEM work?

Answer 22

1. Directs a beam of electrons at the specimen

2. Creates an image based on electrons absorbed

Question 23

What is Cell Fractionation?

Answer 23

The disruptions of the cell and the separation of its parts by centrifugation at successively increasing speeds

Question 24

Centrifugation

Answer 24

The piece of equipment used for this task is the centrifuge, which spins test tubes holding mixtures of disrupted cells at a series of increasing speeds, a process called differential centrifugation

Question 25

Process of Cell Fractionation

Answer 25

1. Tissue cells are homogenized
2. Homogenate goes through centrifugation and becomes known as supernatant
3. At lower speeds, pellets consist of larger components
4. At higher speeds, pellets consist of smaller components
5. It is differential because at increasing speeds, the supernatant is poured into another tube