L. 15 Compartmentalisation of cells

Question 1

L.O.

Answer 1

• Explain the major functions of the plasma membrane
• Describe passive (diffusion and osmosis) and active processes which allow the flow of substances across a semi permeable cell membrane
• Define diffusion and osmosis and tonicity including hypo, iso and hypertonic solutions
• Describe how proteins are exported and imported out and into the cell via vesicular transport
• Compare and contrast between the three components of the cytoskeleton

Question 2

Prokaryotes movement

Answer 2

• Proteins act as the machinery to move the flagellum by pumping H+ ions
• Harnessing energy from reactions (ATP synthesis)

Question 3

Exergonic Vs Endergonic reactions

Answer 3

Exergonic:
- Energy from outside of organism to phosphorylate ATP.
- Food/ Photosynthesis

Endergonic:
- Energy from inside organism/ cell
- Hydrolysis of ATP into ADP+Pi

Question 4

Vesicles

Answer 4

• Carry proteins in and out from cell
• Golgi body modifies newly synthesized proteins

Question 5

Mitochondrion in Sperm

Answer 5

• Mitochondria come together to form 1 large mitochondrion, wrapping around the tail inside the ‘middle piece’
• The tail is similar to bacteria flagellum, it is made out of fibrous proteins and microtubules

Question 6

3 Major biological functions of mitochondria

Answer 6

1. Produce ATP via ATP synthesis
2. Production of steroid hormones (steroidogenesis) by removing the side chain from cholesterol
3. Apoptosis (causes “cell suicide”)

Question 7

Mitochondria attachment to cytoskeleton

Answer 7

• Often attached to microtubules of cytoskeleton and help in place by actin and myosin
• Adaptor proteins link the tubules and mitochondria
• Motor proteins link the adaptor protein to the microtubule and can move by hopping/ crawling.

Question 8

3 components of cytoskeleon

Answer 8

1. Microfilaments - Made of actin
2. Microtubules - Made of tubulin, thickest of 3
3. Intermediate filaments - Made of various proteins, often keratin

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Question 9

Microfilaments

Answer 9

• double helix made of actin molecules

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Question 10

Microtubules

Answer 10

• Spindle fibres of a cell are made from microtubules (mitosis)
• Made up of alpha and beta monomers/ tubulum
• Beta = positive end (fastest growing and shrinking end)
• Alpha = negative end

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Question 11

Intermediate filaments

Answer 11

• Create a very complex lattice that goes everywhere in cell
• Made up of strong peptide chains (small proteins)

Question 12

Movement across membranes

Answer 12

Passive diffusion:
- High to low grad. NO energy required

Controlled channels:
- Through alectrical attraction or diffusion
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Powered transport:
- Protein gets phosphorylated and undergoes conformational change to allow a molecule across
- Phosphotase enzyme removes Pi on protein and, protein undergoes conformational change again returning to its original state

Osmosis

Question 13

Osmosis

Answer 13

Spontaneous net movement of a solvent molecules across a semi-permiable membrane to create equilibrium
(water attracted to salt)

Question 14

Importing into the cell

Answer 14

Phagocytosis:
- Cell consuming large a molecule/ bacteria

Pinocytosis:
- Consuming smaller ions, “drinking”

Endocytosis:
- Cell interacts with specific molecule to consume it by binding with receptors.
- Proteins reinforce the vessicle containing molecules

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Question 15

Export from the cell

Answer 15

Exocytosis:
- Transporting vesicles and matter out of the cell