Carbs And Lipids Flashcards
Give 4 ways in which the structure of starch is similar to cellulose
• Both are polymers
• Both contain carbon hydrogen and oxygen
• Both contain glycosidic bonds
• Both have 1-4 links
Give ways in which the structure of starch is different to cellulose
• Starch contains A-glucose, has 1-6 bonds, branched chains, glucose monomers are the same way up, No H-bonds between molecules, no microfibrils
WHEREAS
• Cellulose has B-glucose, no 1-6 bonds, unbranched chains, every other B-glucose monomer is inverted, has microfibrils, has H-bonds between molecules
Other than energy storage, state two advantages to a mammal of having fat in its tissues
• Insulation
• Protection of organs
Cotton is a plant fibre used to make cloth Explain how cellulose gives cotton its strength
• Many hydrogen bonds form between cellulose molecules to form microfibrils
• cellulose fibres and other molecules form a matrix
Similarities and differences between structures of starch and glycogen
SIMILARITIES
• Both are made of Alpha-glucose
• Both are branched molecules
• Both have 1,4 glycosidic bonds and 1,6 glycosidic bonds
DIFFERENCES
• Glycogen more highly branched
• Starch made up of amylose and amylopectin polysaccharides
Describe how the student could separate a mixture of monosaccharides in solution
•Paper chromatography
• A spot of the solution is placed on chromatography paper and the paper is suspended in a solvent
• Larger molecules will move slower on the paper
• The original mixture to separate out into different spot/bands
Colorimeter would be used over a comparison done by eye to eye because
• Because it provides a quantitative measurement
Advantages of storing food as starch rather than sugar are
• Starch is compact
• Starch is insoluble so doesn’t affect water potential
• Starch is easily broken down when needed
What does qualitative mean?
The test shoes the presence of the sample, not how much sample is present
Define the term unsaturated fatty acid (3)
• Long hydrocarbon chains
• With a carboxylic group
• At least 1 carbon to carbon double bond within the hydrocarbon chain
Using your knowledge of the structure of triglycerides, explain why the solution goes cloudy
• Triglycerides are non-polar molecules
• Therefore they are hydrophobic molecules
• Triglycerides form micelles in water,which causes the cloudy appearance
Phospholipids can form cell membranes because
• Phospholipids have a polar head group/phosphate group
• Phosphate group can form hydrogen bonds with water
• Fatty acids are hidden from water
• Phospholipids form a bilayer
Describe and explain the function of micelles
STRUCTURE
• spherical arrangement of phospholipids in water
• Hydrophilic heads around the edge/hydrophobic tails in the middle
FUNCTION
• aft as emulsifiers
• can transport hydrophilic or hydrophobic contents across membranes
A starch molecule has a spiral shape. Explain why this shape is important to its function in cells.
Compact/occupies small space/tightly packed;
Explain one way in which starch molecules are adapted for their function in plant cells.
- Insoluble;
- Don’t affect water potential;
OR - Helical;
Accept form spirals - Compact;
OR - Large molecule;
- Cannot leave cell.
The structure of cellulose is related to its role in plant cell walls. Explain how
Long/straight/unbranched chains of b-glucose
(Joined by) hydrogen bonds;
Form (micro)fibrils/(macro)fibrils;
Provide rigidity/strength/support;
Hydrogen bonds are important in cellulose molecules. Explain why
- Holds chains/cellulose molecules together/forms cross links between chains/cellulose molecules/forms microfibrils;
- Providing strength/rigidity (to cellulose/cell wall);
- Hydrogen bonds strong in large numbers;
Describe how the student would show that reducing sugars were present in a solution
- Add Benedict’s;
- Heat;
- Red/orange/yellow/green
(shows reducing sugar
present);
Sucrase does not hydrolyse lactose. Use your knowledge of the way in which enzymes work to explain why.
1) Lactose has a different shape / structure;
2) Does not fit / bind to active site of enzyme / sucrase;
Describe how a triglyceride is formed
One glycerol and 3 fatty acids
Condensation reactions and removal of 3 water molecules
ester bonds formed
Explain how digestion of starch in the gut (small intestine) leads to an increase in the concentration of glucose in the blood. Details of co-transport are not required.
Hydrolysed by enzymes / hydrolysed by amylase / maltase;
If named enzyme given, it must relate to the correct substrate
- Produces glucose (in the gut);
- Small enough to cross the gut wall (into the blood) / monomers / monosaccharides (can) cross the gut wall (into the blood);
Accept cell membranes / epithelium / cells for ‘gut wall’
Suggest a method you could use to estimate the concentration of glucose in several different solutions that all turned brick red with Benedict’s reagent in 3 minutes.
time how long it took to go brick red
weigh precipitate
dilute glucose samples
Describe how structure of glycogen is related to its function
Helical so compact
Polymer of glucose so easily hydrolysed
Branched so larger SA so more ends for faster hydrolysis
Insoluble so doesn’t affect water potential
Suggest a method other than colorimetry that can be used to measure quantity of reducing sugar in solution
Filter and dry precipitate
Find mass
