Plasma Membrane and Organelles

Question 1

what must a cell do

Answer 1

• Manufacture cellular materials
• Obtain raw material
• Remove waste
• Generate the required energy

Question 2

What must they (cells) do

Answer 2

• Many different processes
• Require different conditions
• Need separate compartments; Organelles

Question 3

describe what Organelles do

Answer 3

• provide special conditions for specific processes
• keep incompatible processes apart
• allow specific substances to be concentrated
• form concentrations gradients
• package substances for transport or export

Question 4

what organelles do plants and animals cells have in common and not

Answer 4

in common:

• nucleus
• plasma membrane
• Golgi apparatus
• mitochondria
• ER (endoplasmic reticular)

not in common:

• Lysosome
• chloroplasts
• central vacuole
• cell wall

Question 5

what are cells bounded by

describe it

Answer 5

• bounded by the plasma membrane
• is a semi-permeable barrier
• controls movement of substances in and out of the cell
• this interaction with the environment limits the maximum size of the cell
• a small cell has a greater surface area to volume ratio than a larger cell

Question 6

describe the phospholipid bilayer

Answer 6

• is made up of lipids that have a hydrophilic head and a hydrophobic tail
• the head likes water, the tails dont
• the temperature will affect how fluid the phospholipid bilayer

Question 7

how does different temperatures affect the phospholipid bilayer

Answer 7

• the higher the temperature the more connected energy they have so they move around resulting in unsaturated tails that prevent packing
• low temperatures mean there’s less movement so the saturated tails pack together

Question 8

how does cholesterol help with the phospholipid bilayer

Answer 8

• the cholesterol stabilizes the membrane fluidity as it packs itself in the hydrophobic tails

Question 9

what is passive transport and the 2 subtypes of it

Answer 9

• is movement across the semi-permeable plasma membrane that requires no energy
• diffusion
• facilitated diffusion

Question 10

describe diffusion

Answer 10

• membranes are permeable to lipid soluble (hydrophobic) molecules such as steroid hormones and gases
• they move down their concentration gradient and therefore require no energy
• it restricts movement of water soluble and charged molecules such as glucose, ions and water

Question 11

describe facilitated diffusion

Answer 11

• movement of hydrophilic molecules that requires membrane proteins called channels and carriers
• aid the movement if specific substances down their concentration gradient
• no energy requires, but some channels open and close in response to signals

Question 12

describe carriers and channel membrane proteins

Answer 12

• carriers undergo a shape change to help guide molecules

- movement across the cell membrane requires channels called aquaporins

Question 13

what is active transport and the 2 subtypes

Answer 13

• is movement across the membranes that requires energy
• active transport
• co-transport

Question 14

describe Active transport

Answer 14

• requires transport proteins which are carriers that use ATP
• move specific substances against their concentration gradient
• It allows a cell to have an internal concentration of a substance that is different from its surroundings
• example the sodium-potassium pump

Question 15

describe Co-transport

Answer 15

• indirect active transport (still needs energy)
• one substance pump across the membrane
• and its concentration gradient used to power the movement of a second substance against its concentration gradient

Question 16

what are the roles of Membrane Proteins

Answer 16

• they are transporters

- they have more roles that are often specific to a cell type