Lecture 2 - Why are cells organised into compartments?

Question 1

Describe the process of endosymbiosis

Answer 1

mitochondria are believed to have come from a bacteria that was engulfed by an archaea, creating eukaryotes

the same process is believed to happen with chloroplasts using cyanobacteria

Question 2

What are the benefits of compartmentalisation?

Answer 2

1) More complex and large cells - it space it too large, need a higher concentration of reactants. Smaller (organelles) need a smaller concentration of reactants (more efficient)

2) Each organelle will have a different function as different reactants

3) cytoskeleton can more molecules faster than diffusion alone.

Question 3

What is the role of the endoplasmic reticulum?

Answer 3

• network of membrane sacks and tubes
• rough or smooth
• involved in membrane synthesis and other pathways

Question 4

What it the role of the flagellum?

Answer 4

• motility structure
• made from microtubules

Question 5

What is the centrosome?

Answer 5

• region where the cells microtubules are initiated
• made from a pair of centrioles

Question 6

What is the function of the cytoskeleton?

Answer 6

• reinforces shape
• played a role in movement of the cell

Question 7

What are the 3 different parts of the cytoskeleton?

Answer 7

• microfilaments
• intermediate filaments
• microtubules

Question 8

What are microvilli?

Answer 8

membrane projections that increase the cells surface area

Question 9

What is the peroxisome?

Answer 9

organelle with various specialised metabolic functions
- produces hydrogen peroxide as a byproduct and then converts it to water

Question 10

What is the role of the mitochondria?

Answer 10

organelle where cell respiration happens and most ATP is produced

Question 11

What is the role of a lysosome?

Answer 11

digestive organelle where macromolecules are hydrolysed

Question 12

What is the role of the Golgi apparatus?

Answer 12

• organelle active in synthesis, modification, sorting and secretion of cell products

Question 13

What is the role of the plasma membrane?

Answer 13

membrane enclosing the cell

Question 14

What is the role of ribosomes?

Answer 14

• complexes that make proteins
• free in the cytosol or bound to rough ER or nuclear envelope

Question 15

What are the three elements that make up the nucleus?

Answer 15

• nuclear envelope
• nucleolus
• chromatin

Question 16

What is the role of the nuclear envelope?

Answer 16

• double membrane enclosing the nucleus with pores
• it is continuous with the ER

Question 17

What is the role of the nucleolus?

Answer 17

• nonmembranous
• involved in the production of ribosomes
• nucleus may have one or more

Question 18

What is the role of the chromatin?

Answer 18

• made of DNA and proteins
• can be seen in a dividing cell as condensed chromosomes

Question 19

What is the role of the central vacuole in plant cells?

Answer 19

• storage
• breakdown of waste products
• hydrolysis of macromolecules

enlarging vacuole is a major mechanism of plant growth

Question 20

What is the role of chloroplasts on plant cells?

Answer 20

• photosynthesis - light energy to chemical energy stored in sugar molecules

Question 21

What is the role of plasmodesmata in plant cells?

Answer 21

cytoplasmic channels through cell walls, connection the cytoplasms of cells next to each other

Question 22

What is the role of the cell wall in plant cells?

Answer 22

• maintains cell shape
• protects cell from damage
• made from cellulose, polysaccharides and protein