Cell Membrane

Question 1

Cell Membrane

Answer 1

all living cells have a plasma membrane.

It is thin, selectively-permeable that controls the exchange of materials, receives hormone messages and separates the cell from its surroundings

made up of a phospholipid bi-layer

Question 2

Fluid-Mosaic Model

Answer 2

The plasma membrane is fluid as it continuously moves from side to side.

this mosaic (made up of different components) comes from proteins and carbohydrates embedded in the membrane.

Question 3

Polar

Answer 3

when molecule is not charged overall but parts are slightly positive and other parts are slightly negative

Question 4

Non-Polar

Answer 4

When a molecule is not charged because all the positive and negative charges are distributed evenly

Question 5

charged

Answer 5

when a molecule is overall negative or positive

Question 6

Hydrophobic

Answer 6

a molecule that is repelled by water

Question 7

Hydrophilic

Answer 7

A molecule that is attracted to water

Question 8

Lipids

Answer 8

example- phospholipid

chemical properties- usually uncharged/non-polar

usually hyrdophobic

Question 9

Carbohydrates

Answer 9

Example- glucose

chemical properties- are polar in their singular form. but can become difficult to dissolve if they form polymers like cellulose

hydrophilic as monomer

Question 10

Proteins

Answer 10

Example- Enzymes

Chemical Properties- proteins vary in properties. can be uncharged/ non-polar or polar and have charged groups

depend on the protein

Question 11

Nucleic acid

Answer 11

example- DNA

Chemical Properties- negatively charged

hydrophilic

Question 12

Phospholipids

Answer 12

Consist of a polar head and a non-polar tail.

Fatty acid tail and phosphate head.

Question 13

Crossing the membrane

Answer 13

Hydrophobic particles can dissolve in the membrane and easily diffuse across it

Hydrophilic substances are unable to dissolve in the membrane

Question 14

Proteins- membrane

Answer 14

various proteins are found in the cell membrane.

some are permanently fixed to the membrane (integral) while other are only temporary (peripheral)

some of the membrane proteins span the width of the membrane (transmembrane). some are only on the inner layer and some on the outer layer.

Question 15

channel protein

Answer 15

most of the membrane have non-polar tails. uncharged molecules can move through unaided.

they are tunnels that allow selected substances to pass through them from one side of the membrane to the other

some are open all the time and some have gates that block the flow unless triggered.

substances pass through by diffusion and require no energy

Question 16

carrier proteins

Answer 16

bind to molecules or ions on one side of the membrane, change shape and release the molecules or ions on the others side of the membrane

carry against the concentration gradient. requires energy and called active transport.

Question 17

Glycoproteins and Glycolipids

Answer 17

are lipids or proteins with a chain of sugars attached that protrudes into the external surroundings

Glycoproteins play a role in cell recognition and signaling. they have receptors. hormones or neurotransmitters bind to them, triggering a series of chemical reactions within the cell.

glycolipids provide energy and also play a role in cell-to cell recognition.

Question 18

Cholesterol

Answer 18

scattered in the lipid bilayer. maintain a stable membrane fluidity.

keeps phospholipid bound at higher temperatures

disrupts the fatty acid tails, stopping phospholipids form becoming sold in cold temperatures.