Cells and Organelles

Question 1

What is the function of the Plasma membrane?

Answer 1

• encloses cell contents
• provides barrier between outside and inside of the cell
• all signals into or out of the cell are mediated by this

Question 2

What is the function of the nucleus?

Answer 2

• stores genetic information

- DNA replication and gene expression occur here

Question 3

What is the function of mitochondria?

Answer 3

• Used for ATP production

- Contains cytochrome C for the ETC, if this leaks out apoptosis can occur

Question 4

What is the function of Rough endoplasmic reticulum?

Answer 4

Used for protein synthesis

Question 5

What is the function of smooth endoplasmic reticulum?

Answer 5

Used for lipid synthesis/calcium storage

Question 6

What is the function of the Golgi Apparatus?

Answer 6

Proteins sorted for final destination in the cell here

Question 7

What is the function of lysosomes?

Answer 7

Used to degrade unwanted molecules

Question 8

What is the function of Endosomes?

Answer 8

Vesicles that ensure delivery of molecules from plasma membrane to lysosomes.

Question 9

What is the function of peroxisomes?

Answer 9

Contain oxidases, catalase, and are involved in many processes such as detoxification and fatty acid metabolism.

Question 10

What is the function of integral plasma membrane proteins?

Answer 10

Allows transfer of small molecules across the membrane

Question 11

What are the types of integral plasma membrane proteins?

Answer 11

Channels, pumps, carriers

Question 12

Why do cells compartmentalize into organelles?

Answer 12

• To provide permissive environments for specific biochemical reactions.
• Localizes processes for specific functioning

Question 13

How does the phospholipid bilayer help the plasma membrane to carry out its function?

Answer 13

It has an antipatic nature to help provide a barrier

Question 14

How does cholesterol help the plasma membrane to function?

Answer 14

Allows the fluidity of the membrane

Question 15

How do lipid rafts help the plasma membrane function?

Answer 15

They concentrate proteins involved in signalling

Question 16

How do carbohydrates help the plasma membrane to function?

Answer 16

They are in the glycocalyx and allow the cell to be recognised

Question 17

What is the function of the cytoskeleton?

Answer 17

• Maintains the shape of the cell
• Supports plasma membrane
• Allows cell to adpot certain behaviours
• Facilitates movement of organelles

Question 18

What filaments make up the cytoskeleton?

Answer 18

• Microtubules
• Microfilaments
• Intermediate filaments

Question 19

What are microtubules composed of?

Answer 19

Composed of tubulin (accompanied by motor proteins dynein and kinesin)

Question 20

What is the function of microtubules?

Answer 20

• miotic/meiotic chromosomal movement
• intracellular vesicle transport (kinesins move cargo away, dynenins move cargo towards)
• Forms basis of motile structures
• Cilliary and flagellar motility (axonemes made of microtubules are cytoskeletal component of cilia and flagella)

Question 21

What are microfilaments composed of?

Answer 21

Composed of actin (accompanied by motor protein myosin)

Question 22

What is the function of microfilaments?

Answer 22

• Forms basis of cell projections
• Form network in cytoplasm
• Help push out membrane to facilitate movement (lamellipodia and filopodia)
• Forms contractile ring to seperate dividing cells during cytokinesis

Question 23

What are intermediate filaments composed of?

Answer 23

Composed of multiple protiens eg.(keratin, vimentin, desmin, lamins)

Question 24

What are the functions of intermediate filaments?

Answer 24

Gives structural integrity to cells that need alot of strength

Question 25

What are cellular junctions?

Answer 25

These are transmembrane protein complexes that interact with similar proteins on adjacent cells, lines the cell and their cytoskeleton together.

Question 26

What are the 3 types of cellular junctions?

Answer 26

Anchoring, tight, GAP

Question 27

What are the functions of GAP junctions?

Answer 27

• Cell-cell contact

- Allows passage of small molecule by linking cytoplasm of adjacent cells

Question 28

What do tight junctions do?

Answer 28

• Specialised cell-cell contact
• Forms barrier
• Prevents mixing of membrane proteins
• Prevents paracellular access

Question 29

Describe the gate and fence function of tight junctions?

Answer 29

‘gate’- regulates paracellular permeability
‘fence’- prevents membrane components on apical surface from mixing with membrane compartments in basolateral membrane. Results in cell polarity.

Question 30

What is the function of anchoring junctions?

Answer 30

Provides mechanical stability

Question 31

What are examples of cell-cell anchoring junctions?

Answer 31

Adherens(actin)

Desmosomes(Intermediate filaments)

Question 32

What are examples of cell-ecm anchoring junctions?

Answer 32

Focal adhesions(actin)
Hemidesmosomes(intermediate filaments)

Question 33

What can be a clinical consequence of defective lysosomes?

Answer 33

Tay-sachs disease: failure to degrade lipids, so they accumulate in neurons and thus cause progressive damage to nervous system.

Question 34

What can be a clinical consequence of microtubule dysfunction?

Answer 34

Kartagener’s syndrome; result of mutation in dynein, can lead to male infertility and recurrent respiratory infections

Question 35

What can be a clinical consequence of mitochondria dysfunction?

Answer 35

Can lead to many diseases , particularly in organs with high energy demands such as the brain and the muscles.
Cytochrome c can also leak ot from the mitochondria and cause apoptosis.