12.1 Carbohydrates and Lipids Flashcards
What is a monomer?
Small, identical or similar molecules which can be condensed (joined) to make larger molecules
What is a polymer?
Large molecule made by joining many (3 or more) identical or similar monomers together by covalent bonds
Define catabolic
Making smaller molecules from larger ones
Define anabolic
Making larger molecules from simpler/smaller ones
What are carbohydrate monomers called?
Monosaccharides
What bonds are formed between two monosaccharides?
Glycosidic Bonds (1-4 and 1-6)
Properties and functions of starch
Compact - good for storage in small spaces
Insoluble - does not affect water potential
Large surface area - cannot diffuse out of cells
What is an arbitrary unit?
A relative unit of measurement to show the ratio amount of substance. intensity, or other quantities to a predetermined reference measurement
How are monomers linked together?
Condensation reaction - a water molecule is removed and there is ALWAYS an enzyme catalyst
How are polymers broken?
Hydrolysis - a water molecule is added and there is ALWAYS an enzyme catalyst
What is the monomer, polymer and bond found in starch?
Monosaccharide
Polysaccharide
Glycosidic
What is the monomer, polymer and bond found in enzymes?
Amino acids
Polypeptide
Peptide
What is the monomer, polymer and bond found in DNA?
Nucleotides
Nucleic acid
Phosphodiester
What is the structure of alpha-glucose?
What is maltose made of?
Glucose + glucose
What is lactose made of?
Glucose + galactose
What is sucrose made of?
Glucose + fructose
What are the two monomers that make up starch?
Amylose and amylopectin
Solutions are…
Transparent
What is a precipitate?
A solid suspended in a liquid
True or False: Dimers and lipids are polymers
False
What bonds make up amylose?
1-4 glycosidic
What bond make up amylopectin?
1-6 glycosidic
What does ABBA stand for?
Alpha below, Beta above
What are the characteristics of starch?
1-4 and 1-6 glycosidic bonds (amylose and amylopectin)
Storage polysaccharide
Alpha glucose
Found in plants
What are the characteristics of glycogen?
1-4 and 1-6 glycosidic bonds
Storage polysaccharides
Alpha glucose
Found in animals - liver and muscle cells
What are the characteristics of cellulose?
1-4 glycosidic bonds only - rotate 180*
Structural polysaccharide
Beta glucose and hydrogen bonds
Found in plants - microfibrils
Describe the biochemical test for a reducing sugar
- Add equal parts of Benedicts solution and sample
- Heat to 95 degrees in a water bath
- Red precipitate signals sugar is present
Describe the biochemical test for non-reducing sugars
- Negative result from reducing sugar biochemical test
- Heat with acid (HCl) and mix
- Neutralise with alkali (NaHCO3)
- Repeat biochemical test for reducing sugars
How do you find the concentration of an unknown sugar?
- Use a colorimeter (calibrated with a control)
- Use same volume for each reading
- Always shake samples before testing
- Produce a graph (Calibration curve)
- Use graph to read of unknown concentration
Define immiscible
It doesn’t mix
What is a saturated fat?
It is solid at room temperature and only had single Carbon-Carbon bonds
What is an unsaturated fat?
It is liquid at room temperature and has a double Carbon-Carbon bond within the hydrocarbon chain
What is an ester bond?
A bond formed between glycerol and fatty acid after a condensation reaction
What is a wax?
A wax similar to fats and oils but have no glycerol
What are the characteristics of waxes?
Insoluble and Hydrophobic
Where are waxes seen/used?
Insects and the upper epidermis in plants
Where are triglycerides found?
In food as storage molecules
What are triglycerides made up of?
One molecule of glycerol and three fatty acid molecules
What bonds are found in triglycerides?
Ester bonds
True or Flase: Triglycerides are polymers?
False - the monomers are different
What does glycerol look like?
What does a saturated vs unsaturated fatty acid look like?
Describe the formation of triglycerides?
3 water molecules are lost - condensation reactions
H lost from glycerol
OH lost from fatty acids
What is the equation for a triglyceride (worded)?
Glycerol + 3 fatty acids -> triglyceride + 3 water
What are the characteristics of triglycerides?
Low mass to energy ratio - good stores of energy
Insoluble - does not affect water potential
Good source of water when broken down - high O to H ratio
What do phospholipids do?
help form the cell membrane of a cell
How does the structure of a phospholipid differ to that of a triglyceride?
One fatty acid is replaced by a phosphate group
What is the diagram of triglycerides?
What is the diagram of phospholipids?
What charge is the phosphate group?
Negative - POLAR
What is the charge of the fatty acid tails?
No charge - NON-POLAR
What is the phospho-glycerol head?
Hydrophyllic (attracts water - soluble)
What are the tails vs the head?
Hydrophobic
What do phospholipids form in water?
A bilayer
What is the structure of a bilayer?
The hydrophilic heads face the water on both sides and the hydrophobic tails face each other in the center.
Describe the emulsion test for a lipid
- A small amount of the sample is placed in a test tube with 2cm3 of ethanol
- The mixture is shaken so that the fat dissolves in the alcohol (non-polar solvent)
- Water is then added drop by drop and shaken again
- A cloudy white emulsion of fat droplets should be visible when a fat is present
What is the term used to describe the different structures of alpha-glucose and beta-glucose?
Isomer(ism)
Why is it important for starch to have a spiral shape?
It is compact. It occupies a small space as it is tightly packed
How is the structure of cellulose related to its role in plant call walls?
- Long, straight, unbranched chains of beta glucose
- joined by many weak hydrogen bonds
- form microfibrils
- to provide rigidity and strength to the plant
What are the similarities between starch and cellulose?
- Both are polysaccharides
- Both contain glycosidic bonds
- Both contain Carbon, Hydrogen and Oxygen
What are the differences between starch and cellulose?
- Starch as alpha-glucose // cellulose has beta-glucose
- Starch is coiled // cellulose is straight
- Starch is branched // cellulose is unbranched
- Cellulose forms microfibrils // Starch does not
- Starch has 1-4 AND 1-6 glyosidic bonds // cellulose does not
What are the features of starch?
- Helical SO compact
- Insoluble SO does not affest water potential
- Large molecule SO cannot leave cell
- Branched chains SO rapidly hydrolyses
Why are hydrogen bonds important in cellulose molecules?
- Forms microfibrils via cross links between chains
- Providing strength/rigidity to cell wall
- Hydrogen bond provide strength in large numbers
What are the similarities between triglycerides and phospholipids?
- Both contain ester bonds
- Both contain glycerol
- Both have fatty acids which can be saturated or unsaturated
- Both are insoluble
- Both contain C, H and O
BUT
phospholipids also contain P
What are the differences between triglycerides and phospholipids?
- Triglyceride has 3 fatty acids // phospholipid has 2 fatty acids and 1 phosphate group
- Triglycerides are hydrophobic/non-polar // phospholipids are both hydrophilic and hydrophobic
- Phospholipids form bilayers // triglycerides do not
Describe the structure of a phospholipid molecule and explain how phospholipids are arranged in a plasma membrane
- Glycerol joined to 2 fatty acid tails. Phosphate group joined to glycerol on opposite side
- Phospholipid has a charged, hydrophilic head (phosphate and glycerol) and non-polar hydrophobic tails (fatty acid chains)
- Arrange to form a phospholipid bilayer (Hydrophilic head facing out towards water. Hydrophobic fatty acid chains facing away from water)
