unit 1- cell membrane and crossing of the cell membrane

Question 1

what does the cell membrane do?

Answer 1

controls the molecules that enter and leave the cell. it allows the cytoplasm to have a different composition from the outside environment
helps kept he shape

Question 2

what is the phospholipid bi-layer ?

Answer 2

it is the cell membrane. it is capable of much movement because it is fluid

Question 3

what makes up the phospholipid bi-layer ?

Answer 3

• double layer of lipids

- embedded protein

Question 4

what do the cholesterol molecules in the phospholipid bi-layer do ?

Answer 4

they reduce the amount of fluidity

Question 5

what do proteins do in the phospholipid bi-layer ?

Answer 5

they have openings on both sides of the membrane which allows the Flow of irons

Question 6

what do carbohydrates do in the phospholipid bi-layer ?

Answer 6

are on the outer surface and are important in cell adhesion and cell recognition. these are attached to recognition proteins

Question 7

what is diffusion?

Answer 7

it is when small uncharged particles ( oxygen, carbon, water) move through the phospholipid bi-layer. it moves from high to low concentration and requires no energy

Question 8

what is osmosis?

Answer 8

is when water moves through the phospholipid bi-layer. it is a type of diffusion where the water moves from low concentration to high concentration. it requires no energy

Question 9

what is active transport?

Answer 9

is when nutrient molecules ions such as chloride, sodium ions move through the protein membrane. it move Against the concentration gradient and therefore requires energy

Question 10

what is bulk transport?

Answer 10

is when large molecules such as enzymes, hormones and anti bodies move through a small section of the plasma membrane. It requires energy

Question 11

what is facilitated diffusion?

Answer 11

• follows a concentrated gradient - high to low

- moves through cell membrane via the ( carrier) protein channels. It requires no energy

Question 12

surface area to volume ratio

Answer 12

it effects the rate of exchange that is possible between the cell and its environment

Question 13

do smaller or bigger cells have a better SA:V ratio?

Answer 13

larger cells need to exchange more nutrients and waste. however because of there size they do not have enough SA to do this
smaller cells make it easier for this exchange to happen

Question 14

how can you increase the cells SA:V?

Answer 14

• cell compartmentalisation
• a flattened shape
• plasma membrane extensions

Question 15

monomer vs polymer

Answer 15

amino acid - proteins
monosaccaride ( sugar) - polisaccaride ( cellulose, starch )
nucleotide- nucleic acid ( RNA & DNA)
Fatty acid - triglyceride