Cells and transport across cell membrane HARD PPQs

explain why phospholipids can form a bilayer but triglycerides can’t

1. phospholipids have hydrophilic heads and hydrophobic fatty acid tails

2. triglycerides have hydrophobic fatty acid tails only

3. hydrophilic group attracts water to either side of bilayer

describe 3 differences between the structure of triglyceride and a phospholipid

• triglyercide has 3 fatty acids, phospholipid has 2

• triglyceride doesn’t have phosphate group, phospholipid does 

• triglyceride has 3 ester bonds, phospholipid has 2

U.marinum cells ingest bacteria and digest them in the cytoplasm 

Describe the role of one named organelle in digesting the bacteria

1. lysosomes 

2. fuse with vesicle with bacteria in it 

3. secrete hydrolytic enzymes 

Describe how substances can cross a cell surface membrane- MODEL ANS

1. simple / facilitated diffusion down a concentration gradient

2. non polar/ lipid soluble molecules pass via phospholipid bilayer OR polar/ water soluble molecules go through proteins

not finished