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Biology HL 11 > Cell Transport > Flashcards

Cell Transport Flashcards

Unit 1, Cell Biology

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1
Q

How to cells maintain homeostasis?

A

They need to bring in food, water, oxygen and eliminate wastes

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2
Q

What are two general types of transport into and out of the cell

A
  1. Passive transport, no energy required.
  2. Active transport, requries energy
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3
Q

Define brownian motion

A

All particles being under random movement

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4
Q

Define Diffusion

A

Movement of particles from an area of high concentration to low concentration, no energy required (Passive)

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5
Q

Define concentration gradient

A

When the concentration of something builds up in one area

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6
Q

Define equilibrium

A

Equal distribution of all particles in the area

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7
Q

When does diffusion occuer?

A

They occur until the particles have reached equilibrium

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8
Q

Define dynamic equilibrium

A

When at equilibrium the particles are still in motion but there is no net change

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9
Q

Define simple diffusion

A

When particles pass through the phospholipid bilayer from high to low concentration without energy being required

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10
Q

Define Osmosis

A

The passive movement of water from an area to low solute concentration to high solute concentration through a semipermeable membrane
Low to High

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11
Q

Why is the net movement of water from low [solute] to high [solute]?

A

Areas with high [solute] have a lower [freely movable water] than areas with a lower [solute]

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12
Q

Define Aquaporins

A

Water channels present in some cells (ie. kidney cells, plant root hair cells), greatly increase permeability of water

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13
Q

Categorisation of solutions

A

Solutions can be categorised as hypertonic, hypotonic or isotonic according to their relative solute concentrations

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14
Q

Define hypertonic

A

Solutions with relatively higher solute concentrations are categorised as hypertonic (high solute ⇒ gains water)

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15
Q

Define hypotonic

A

Solutions with relatively lower solute concentrations are categorised as hypotonic (low solute ⇒ loses water)

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16
Q

Define isotonic

A

Solutions that have equivalent solute concentrations are categorised as isotonic (same solute ⇒ no net water flow)

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17
Q

Define Osmolarity

A

A measure of solute concentration

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18
Q

Concentration

A

Amount of solute (moles) per unit volume (v-3 or dm-3) of solution

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19
Q

Define Osmotically active solutes

A

They are solutes that have intramolecular attractions between them and water

20
Q

What does difference in [solute] mean?

A

Cell membrances are very permeable to water and less permeable to solutes so it means that water moves not solute

21
Q

Is osmosis passive or active

A

PASSIVE

22
Q

How to cells change the speed of osmosis?

A

They change the speed of osmosis by changing the permeability of membrane to water

23
Q

Define water potential

A

Water potential is a measure of the potential energy of water per unit volume (symbol is ψ, unit is kPa)

24
Q

What is the movement of water

A

Water moves from an area of higher water potential to lower water potential (minimizes potential energy)

25
Q

What does having a higher concentration of dissolved solutes mean

A

High the concentration of dissolved particles, the lower the potential energy of water. If there are no solutes, Ψs is 0. As [solutes] increases the Ψs becomes more negative (less free water, therefore less potential kinetic energy of water)

26
Q

What does having a higher pressure mean?

A

Higher pressure means higher potential energy of water.

27
Q

Movement of water in plants

A

Water always moves from high potential to low potential

28
Q

What happens after the water moves in the plant cell?

A

The Ψp increases inside the cell due to the force/pressure of the cell wall pushing back against the cell membrane (Being squashed)

29
Q

What is a turgid plant cell?

A

Occuring of potential pressure increasing until the water potential equalts the distilled water potential. (Pressure of the cell wall pushing back against the cell membrane)

30
Q

What happens to plants in hypertonic solutions?

A

A hypertonic solution has a more negative Ψs than inside the cell. the Ψp is 0.

31
Q

Why does water move out in plant cells

A

The Ψp inside the cell will be higher than outside solutions due to plant cells typically being turgid
Ψ is therefore higher in the cell than out, so water will more out

32
Q

What is flaccid plant cells?

A

When water loss of a cell reduces the pressure inside and it drops to atmostpheric pressure, the pressures are equal!

33
Q

Notes/Reminder for plants in hypertonic solutiosn (NOT FOR MEMORIZATION)

A

The Ψs will rise due to the water loss, if it is higher than the solution’s Ψs water continues to move out
This causes the cell membrane to detach from the cell wall and shrink, this process is called plasmolysis
Once the Ψs inside and outside the cell are equal there will be no net movement of water due to equal water potentials

34
Q

What happends to animal cells in hypotonic solutions?

A

Animal cells will swell (gain wtaer) and becuase they lack cell walls, they will easily burst

35
Q

What happends to animal cells in hypertonic solutions?

A

Animals cells will shrink/shrivel (lose wtaer), crenations or indentations can occur.

36
Q

What do unicellular organisms lacking cell walls do to prevent swelling?

A

They will pump water out to prevent swelling (contrctile vacuoles)

37
Q

Define facilitated diffusion

A

Passive transport of molescules through a membrane with the help of proteins

38
Q

Define channel proteins

A

Integral transmembrane proteins iwht a pore that has specific size to allow only certain molecules through

39
Q

When does active transport occur?

A

It occurs during a movement against the concentration gradient (low to high) with the use of energy

40
Q

How does active transport occur?

A

It is dont by pump proteins, only in one direction by the use of energy, most from an energy molecule called ATP

41
Q

Given an example of indirect active transport

A

Glucose can move against its concentration graident because sodium is movign down its gradient
When [Na+] builds up it will flow down a glucose transporter from high to low, bringing glucose along with it (no energy)

42
Q

Selective permeability in facilitated diffusion and active transport

A

They are selective in what is passing through the cell membrane, both have pump proteins that are specific to the molecules they are transporting

43
Q

What happens in endocytosis?

A

Vesicles made by small pieces of the cell membrane being pulled away and pinched off (done by proteins, using energy)

44
Q

Define endocytosis

A

When large substances enter the cell without crossing the membrane

45
Q

Define exocytosis

A

When large substances (or bulk amounts of small substances) exit the cell without corssing the membrane

46
Q

What happens in the process of exocytosis

A

During the process, it adds phospholipids to the cell membrane, replacing those lost when vesicles are formed via endocytosis

47
Q

Why is exocytosis important?

A

It gets rid of waste or unwanted substances and to secrete cell products like hormones and enzymes

Biology HL 11 (13 decks)

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