5. Lipids, cell membranes & transport across cell membranes Flashcards
Are triglycerides hydrophobic or hydrophilic?
Hydrophobic
Are triglycerides soluble or insoluble in alcohol?
soluble
Which molecules have a structural formula containing C=O bonds? 2
Fatty acids and glucose
Describe the oxygen:carbon ratio in triglycerides compared to carbs
Triglycerides have a lower ratio of oxygen to carbon
Name 4 features of triglycerides
Non-polar,
less dense than water,
higher energy value than carbs,
higher proportion of hydrogen than carbs
When hydrolysed, which molecules have products containing a carboxyl group? 2
phospholipids and proteins
What is used to test for the presence of sugars?
Benedict’s reagent
What is the sign of a positive test for sugars
Benedict’s reagent goes from blue to brick red
What is used to test for starch?
iodine solution
What is a sign of a positive test for starch
solution goes from orange/brown to blue/black
What is used to test for proteins
biuret solution
What are the signs of a positive test for proteins?
Goes from light blue to purple/lilac
What is used to test for lipids?
ethanol
What is the sign of a positive test for lipids?
Solution turns cloudy
q6 which molecule is a protein?
Z
q6 which molecule is a lipid?
W
q6 which molecule is a non- reducing sugar molecule?
Y
The enzyme lactase is formed by a single polypeptide that folds to give 3 regions: an active site with the free amino group outside the cell, a short section inside the membrane, a short section inside the cell. Which sections are hydrophobic or hydrophilic?
Outside cell: hydrophilic
Inside membrane: hydrophobic
Inside cell: hydrophilic
q8 what is 1
phospholipids
q8 name 2
protein
q8 name 3
glycoprotein
q8 name 4
Channel protein
q8 name 5
cholesterol
q8 which molecules have hydrophobic and hydrophilic regions?
phospholipids, proteins, channel proteins and cholesterol
Increasing which type of bond helps increase the fluidity of the cell surface membrane?
C=C (carbon-carbon)
q10 which would enable a hormone to recognise its target cell?
B, transmembrane protein
Which two components contribute to the fluidity of the cell membrane?
Cholesterol & phospholipid fatty acid chains
How does cholesterol affect cell fluidity?
It provides stability and reduces fluidity by fitting between phospholipids
How do phospholipid tails affect fluidity?
Longer fatty acid tails mean less fluidity and more unsaturated fatty acids means less impacted by temperature
What is the width of the cell surface membrane?
5-10nm
