Sugars & Polysaccharides, (with Inorganic Ions) Flashcards
What is a condensation reaction?
When two molecules join together with the formation of a new chemical bond and a water molecule is released when the bond is formed.
What is a hydrolysis reaction?
A chemical reaction that separates larger biological molecules into smaller monomers. A water molecule is used to hydrolyse the bond producing two monomers.
Name a property of water.
Any one of:
• strong cohesion between water molecules so helps it flow (supports uninterrupted columns of water in xylem vessel of plants)
• water is cohesive (attraction between molecules) because it is polar
• high specific heat capacity (takes a lot of energy to heat it up. Water doesn’t experience rapid temp changes. Can resist heat)
• large latent heat of vaporisation (takes a lot of heat to break hydrogen bonds between water molecules. A lot of energy is used up when water evaporates/vaporises. This is useful for living organisms because it means they can use water loss through evaporation to cool down without losing too much water.)
• universal solvent. Solvent for metabolic reactions
• ‘metabolite’ meaning it is needed in condensation and hydrolysis reactions.
Explain the differences between a monosaccharide, disaccharide and a polysaccharide.
Monosaccharide - a single carbohydrate monomer.
Disaccharide - 2 monosaccharides bonded together
Polysaccharide - more than 2
What disaccharide is created by two a-glucoses?
Maltose
What is the name for an OH group?
Hydroxyl
What is an isomer?
Monosaccharide that differs in spatial arrangement of atoms. It has the same formula but different arrangement around one or two carbon atoms.
What is a hexose and pentose?
Hexose - 6 carbon atoms
Pentose - 5 carbon atoms
What is the difference between a-glucose and b-glucose?
B-glucose, the carbon 1 is flipped.
What disaccharide does a-glucose and fructose form?
Sucrose
What monosaccharides make up lactose?
Galactose and a-glucose
What is the bond between two monosaccharides?
Glycosidic bond
What is the location of the glycosidic bond?
Between C1 and C4.
What is the test for reducing sugars?
Mix food sample with Benedict’s reagent in a test tube and heat together. Turns from blue to red for strong positive, orange for medium, green for weak.
Describe the test for non-reducing sugars.
(After doing test for reducing sugars and it is negative with blue precipitate unchanging)
Take new sample and boil with acid to break bonds
Add alkali to neutralise
Heat with Benedict’s
If result is positive (red/yellow/brown) then non reducing sugar is a disaccharide of two reducing sugars.
Why is Benedict’s test semi quantitative?
Different colour spectrum (qualitative) indicates concentration of sugar (quantitative)
Blue - no concentration of sugars.
Green - very low
Yellow - low
Brown - medium
Red - high
Features of starch
• insoluble = cannot interfere with osmosis in and out of cells and can’t dissolve into cytoplasm
• large = can’t diffuse into organelles or out of the cell.
• in a helix = compact so can fit many of them to be used in respiration in a small place
• branched = many end points so larger surface area for more glucose to be released at once and faster.
Features of glycogen
• shorter chains, more highly branched. (Grater frequency if 1-6 glycosidic bonds)
• compact, good for storage
Why is glycogen more highly branched than starch?
Glycogen, found in animals unlike starch in plants, has more branches so more end points for glucose released as animals require larger amounts of energy than plants. More branches means more surface area for more energy to be released.
Features of cellulose
• unbranched polymer of b-glucose (straight chains)
• cellulose chains linked by hydrogen bonds are called microfibrils. Many of these together make up cellulose fibres.
Biological importance of cellulose
Make up cell wall in plant cells by providing rigidity and strength.
Describe the test for starch.
Iodine - add to test tube with sample.
Changes from brown/orange to dark blue black colour for positive.
What is a polymer?
A large complex molecule made from chains of monomers joined together
What is a monomer?
A small basic molecular unit
What are carbohydrates made from?
Monosaccharides
What is an ion?
An atom with an electrical charge.
What is a cation?
An ion with a positive charge.
What is an anion?
An ion with a negative charge.
What is an inorganic ion and where is it found?
An ion that doesn’t contain carbon and found, in solution, in cytoplasm of cells and body fluids of organisms. Its properties determine the ions specific role.
What is haemoglobin?
A protein carrying oxygen around the body in red blood cells
Iron ions in haemoglobin
Fe2+ binds to the oxygen. The iron is found in the centre of the four polypeptide chains.
Hydrogen ions
pH is calculated based off concentrations of hydrogen ions. (H+). More hydrogen irons, a lower pH.
Sodium ions
co-transport of glucose and amino acids into cell membranes. (Na+)
Molecules of them can be transported alongside sodium ions.
Phosphate ions.
(PO4 3-) attached to another molecule make up phosphate group. DNA, RNA, ATP contain phosphate group. Bonds between the phosphate group store energy in ATP. Phosphate group in DNA, RNA, allow nucleotides to join to form polynucleotides.
What are examples of a monomer?
Monosaccharides, amino acids, and nucleotides
Why is glucose a hextose sugar?
It is a monosaccharide with six carbon atoms in each molecule.
