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Nat 5 Biology - Cell Biollogy > Transport across the cell membrane > Flashcards

Flashcards in Transport across the cell membrane Deck (23)
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1

What is the cell membrane made of?

Phospholipids (fats) and proteins

2

How can the cell membrane be described and why?

Fluid because the double layer of phospholipids is constantly moving

3

How is the membrane structure referred to?

Fluid Mosaic Model

4

Where are the proteins located?

Within the phospholipid bilayer

5

What are the functions of the proteins?

- receptors for chemicals such as hormones or antibodies
- Carrier proteins for active transport
- Create pores in the membrane for passive transport

6

Why is the membrane selectively permeable?

It allows small molecules like water and oxygen to freely move about, slightly larger ones like amino acids to move slowly through it and large molecules like proteins and starch are unable to pass through

7

What are examples of passive methods of transport across the cell membrane?

Diffusion and Osmosis

8

What is diffusion?

Diffusion is the movement of molecules or ions from a region of higher concentration to a region of lower concentration, through a selectively permeable membrane. Down a concentration gradient

9

What is the purpose of diffusion?

It allows substances to move within a cell from one area to another, as well as allowing molecules to enter and leave a cell

10

When does diffusion stop?

Diffusion continues until the concentration is even throughout

11

Why is diffusion important for organism?

Oxygen and Glucose enter cells by diffusion for aerobic respiration

12

What is osmosis?

Osmosis is the movement of water molecules from a region of high water concentration to a region of lower water concentration through a selectively a permeable membrane. Down a concentration gradient

13

What is active transport?

The movement of molecules or ions across a cell membrane against a concentration gradient

14

How are the molecules or ions moved in active transport?

By carrier proteins

15

What provides the energy needed by active transport?

ATP

16

If aerobic respiration is limited, how will that affect active transport?

It will limit the rate of active transport

17

What happens if a plant cell is placed in a solution with a greater concentration than within the cell?

Water passes into the cell causing the vacuole to swell, Because the call wall is fairly frigid and strong enough to resist the pressure, the cell does not burst and is described as turgid

18

What happens if a plant cell is placed in a solution with equal concentration to the within the cell?

No net gain or lost of water. The cell will remain unchanged

19

What happens if a plant cell is placed in a solution with a lower concentration than within the cell?

Water passes out the cell to it's surrounding, causing the vacuole to shrink and pulls the cytoplasm inwards. A gap develops between the membrane and the cell wall. The cell is described as being plasmolysed

20

Why does osmosis effect plant and animal cells differently?

Plant cells have cell wall and a vacuole. Animal cells do not.

21

What happens if an animal cell is placed in a solution with equal concentration to the within the cell?

No net gain or lost. The cell will remain unchanged

22

What happens if an animal cell is placed in a solution with a higher water concentration than within the cell?

Water passes into the cell from it's surrounding, causing the cell to swell up. As there is no cell wall it will eventually burst

23

What happens if an animal cell is placed in a solution with a lower water concentration than within the cell?

Water passes out the cell to it's surroundings, causing the cell to shrink and shrivel up