12.1 Carbs and Lipids Flashcards
Monomer
A monomer is a smaller / repeating) unit / molecule from which larger molecules / polymers are made;
Polymer
- Large molecules made from joining many identical monomers together
- Formed via a condensation reaction
Condensation reaction
Removal of water to form bond for polymer and byproduct of water
Hydrolysis reaction
Addition of water to break bond in polymer
Alpha glucose
6 carbon
12 hydrogen
6 oxygen
OH point downwards- parallel
Beta glucose
6 carbon
12 hydrogen
6 oxygen
One OH points up one points down- diagonal
Bond between 2 glucose molecules
Glycosidic bond
Water is removed from where to form glycosidic bond
H removed from one glucose and OH removed from the other
Monosaccharide examples
Glucose (penguin)
Galactose (rave)
Fructose (witch’s hat)
Disaccharide examples
Maltose
Sucrose
Lactose
Disaccharide formula
C12 H22 O11
Polysaccharide examples
Glycogen
Starch
Cellulose
Maltose
Alpha glucose and alpha glucose
Maltase enzyme
Lactose
Galactose and alpha glucose
Lactase enzyme
Sucrose
Fructose and alpha glucose
Sucrase enzyme
Glycogen
- Only found in animals
- Alpha glucose
- Shorter chains SO more readily hydrolysed into glucose
- Highly branched
- Larger surface area
- Stored in muscle and liver
- Insoluble SO does not affect water potential
Amylose
- Carbon 1:4 glycosidic bonds SO long and linear chains of alpha glucose with coil into a helix
- Compact SO good for storage
- Insoluble SO does not affect water potential
- Large SO does not diffuse out of cell
Two types of starch
Amylose
Amylopectin
Amylopectin
- Branched chain of alpha glucose
- Carbon 1:4 and 1:6 glycosidic bonds
- Provides a large surface area FOR rapid hydrolysis by enzymes to release glucose for respiration
- Insoluble SO does not affect water potential
- Large SO does not diffuse out of cells
A starch molecule has a spiral shape. Explain why this shape is important to its function in cells.
Compact/occupies small space/tightly packed;
The structure of cellulose is related to its role in plant cell walls. Explain how. (3)
- Long, straight, unbranched chains of Beta glucose;
- (Joined by) many WEAK hydrogen bonds;
- Form microfibrils / macrofibrils;
- Provide rigidity/strength/support;
Cellulose
- Only found in plants
- Beta glucose
-Made of B-glucose molecules join together via condensation reactions to form long unbranched chains - Every other b-glucose molecule rotates 180 degrees to allow carbon 1 and 4 to be adjacent to form a GLYCOSIDIC BOND
- Several chains are joined via weak hydrogen bonds to form microfibrils
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);
- Weak Hydrogen bonds provide strength in large numbers;
Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein
- Glucose and galactose
- Joined by condensation
- Joined by glycosidic bond
- Added to polypeptide in Golgi
Describe how the student would show that reducing sugars were present in a solution.
- Add Benedict’s;
- Heat to 95°C;
- Red/orange/yellow/green precipitate (shows reducing sugar present);
Describe how the student would show that non- reducing sugars were present in a solution. (sucrose)
- Test using Benedict’s test to show a no colour change
- Add HCL to a fresh sample
- Boil to hydrolyse glycosidic bonds
- Neutralise the solution by adding solid sodium hydrogen carbonate
- Test using Benedict’s reagent to show a red precipitate
Test for unknown conc. of reducing sugars
- Make up several know conc of reducing sugar
- Carry out the Benedict’s test
- Use a colorimeter to measure the colour of each solution and plot using a calibration curve
- CONC ON X AND ABSORBANCE ON Y
- Find the concentration of the sample using the calibration curve
Describe how you would test a sample of food for the presence of starch.
- Add potassium iodide (KI) solution to the food sample;
- Blue/black/purple indicates starch is present;
Describe how you would test a liquid sample for the presence of lipid box and how you would recognise a positive result.
- (Mix / shake sample) with ethanol, then water and shake;
- Cloudy White / milky (emulsion);
Triglycerides found in…
food
Phospholipids help to…
form cell membrane of cell
Types of lipids
Triglycerides
Phospholipids
Triglyceride structure
1 glycerol head
3 fatty acid tails
Ester bond
Condensation reaction
Saturated fatty acid definition
NO double bonds between carbon atoms within the hydrocarbon chain
Unsaturated fatty acid definition
At least 1 double bond between carbon atoms within the hydrocarbon chain
Triglyceride properties
- Insoluble in water SO do not affect water potential
- Low mass:energy ratio SO good stores of energy
- High hydrogen:water ratio SO good sources of water
Phospholipids
- Similar structure to triglycerides
- One fatty acid replaced by a phosphate group
- Phosphate group is polar
Compare and contrast the structure and properties of triglycerides and phospholipids
- Both contain ester bonds
- Both contain glycerol
- Fatty acids on both may be saturated or unsaturated
- Both are insoluble in water
- Both contain C, H and O but phospholipids are also contain P
- Triglyceride has three fatty acids and phospholipids have two fatty acids plus phosphate group
- Triglycerides are hydrophobic/non-polar and phospholipids have hydrophilic and hydrophobic region
- Phospholipids form monolayer/micelle/bilayer but triglycerides don’t.
Describe the biochemical tests you would use to confirm the presence of lipid, non-reducing sugar and amylase in a sample.
Lipid
1. Add ethanol/alcohol then add water and shake/mix OR Add ethanol/alcohol and shake/mix then pour into/add water;
2. White/milky emulsion OR emulsion test turns white/milky;
Non-reducing sugar
3. Do Benedict’s test and stays blue/negative;
4. Boil with acid then neutralise with alkali;
5. Heat with Benedict’s and becomes red/orange (precipitate);
Amylase
6. Add biuret (reagent) and becomes purple/violet/mauve/lilac;
7. Add starch, (leave for a time), test for reducing sugar/absence of starch;
A student carried out the Benedict’s test. Suggest a method, other than using a colorimeter, that this student could use to measure the quantity of reducing sugar in a solution.
- Filter and dry (the precipitate);
- Find mass/weight;
Lipid functions (extra)
- Conduct heat slowly SO good thermal and electrical insulators
- Stored around delicate organs such as kidneys to protect them
Lipids
- Triglycerides found in food
- Phospholipids help to form the cell membrane of a cell
