A2.2 Cell structure

Question 1

What are the cell theories?

Answer 1

1. organisms are made up of 1 or more cells
2. cells are the smallest unit of life
3. all cells come from pre-existing cells

Question 2

What are the 2 types of microscopes?

Answer 2

Light & electron microscopes

Question 3

What are the characteristics of a light microscope?

Answer 3

• magnifies up to x200
• can be used for both living and non living organisms
• black & white

Question 4

What are some characteristics of an electron microscope?

Answer 4

• Magnifies up to x500,000
• can be viewed in 3D
• uses electron beams
• for non living organisms
• black & white

Question 5

How is total magnification calculated?

Answer 5

ocular x objective

Question 6

How is magnification calculated?

Answer 6

image size / actual size

Question 7

What are artefacts?

Answer 7

Structures that are produced due to perpetration processes, inevitable

Question 8

What is freeze fracture for?

Answer 8

study of the layers of the membrane

Question 9

How is freeze fracture prepared for electron microscopy?

Answer 9

1. specimen frozen
2. physically broken apart (fracture)

Question 10

What are the functions of life?

Answer 10

(MR SHENG)
Metabolism
Reproduction
Sensitivity
Homeostasis
Excretion
Nutrition
Growth

Question 11

What are features common to all cells?

Answer 11

Plasma membrane
DNA
Cytoplasm

Question 12

What are some characteristics of prokaryotic cells?

Answer 12

• 1st life forms on earth
• Uni-cellular
• “naked” - not associated with histone proteins, mostly found in nucleoid

Question 13

What is the flagella for?

Answer 13

Movement

Question 14

What is the pili for?

Answer 14

Attachment & communication, can also exchange genetic material

Question 15

What is the naked DNA (Nucleoid) for?

Answer 15

DNA and chromosomes, genetic code
- no nuclear envelope
- not associated with histones

Question 16

What is the 70S ribosome for?

Answer 16

Protein production

Question 17

What is the plasmid for?

Answer 17

Extra DNA, replicates independently

Question 18

What is the plasma membrane for?

Answer 18

allowing and restricting movement of substances in & out of the cell (also used for binary fission)

Question 19

What is the cell wall for?

Answer 19

Helps maintain the cell structure, prevent bursting

Question 20

What is the capsule for?

Answer 20

Survival of the cell, adherence, extra layer (only some have this)

Question 21

What are the steps in binary fission and which cell does it occur in?

Answer 21

Prokaryotic cells
1. chromosome is semi replicated semi conversely
2. 2 copies of DNA move to opposite ends of the cell
3. Cell elongates
4. Plasma membrane grows inward & pinches off
5. Creates 2 separate genetically identical cells

Question 22

What is binary fission for?

Answer 22

reproduction of prokaryotic cells

Question 23

What are the advantages of compartmentalisation?

Answer 23

1. Create higher concentrations of certain substances within organelles
2. Separate toxins & potentially damaging substances from the rest of the cell
3. Control conditions inside organelles to maintain optimal conditions (for enzymes)