Biological Molecules - CARBS Flashcards
What is a polymer?
A large, complex chain of monomers
What are monomers?
Small, basic molecular units that can be joined to make polymers
e.g., monosaccharides, amino acids, nucleotides
What three elements are carbohydrates made of?
C H O
Clue is in the word:
carbo - carbon
hydr - hydrogen
-ate - oxygen (anything ending in -ate has O in it)
Name a hexose sugar
glucose
It has six carbons in each atom
What is an isomer - give an example
Isomers have the same molecular formula but are arranged differently.
E.g., alpha and beta glucose molecules
Draw a glucose molecule and then check the answer
What is a condensation reaction?
When two molecules join together, their reaction gives off water, H2O
(water - steam - condenses to water on cold glass…)
What is the name of the bond that forms when two monosaccharides form?
A glycosidic bond
What is a glycoside?
A ring shaped molecule, e.g, glucose
Glucose and fructose create which disaccharide?
Sucrose
Glucose and galactose create which disaccharide?
Lactose
What does hydrolysis do?
Breaks down polymers
hydro - water
This time the separation of the monomers from each other attracts a water molecule to reform the monomers which makes them more chemically stable again.
What are reducing sugars?
They donate electrons
They can be detected using the Benedict’s test
Examples: glucose, fructose, maltose
What are non-reducing sugars?
How can their presence be detected?
Non-reducing sugars cannot donate electrons, therefore they cannot be oxidised
e.g. sucrose
To test non-reducing sugars, add hydrochloric acid to boiled water; neutralise the acid with sodium hydrogencarbonate then proceed with Benedict’s test.
USEFUL QUICK VIDEO LINK:
What is the main energy storage in a plant?
Starch.
Plants store EXCESS GLUCOSE as STARCH.
When energy is needed, the starch is broken back down into glucose.
What is starch made up of?
Amylose and amylopectin
amylose = long, unbranched chain of alpha-glucose; it coils like a cylinder making it compact
amylopectin - long branched chain of alpha-glucose; its side branches allow it to be broken down by enzymes so glucose can be easily released.
What’s useful about starch?
- insoluble in water,
- therefore unaffected by osmosis and hence makes it great for storage (think of wrapping books up in vacuum sealed bags to protect them from damp in humid conditions)
- also when mixed with water acts as a thickening agent
- added to food as a replacement for fat (hmm - good idea?)
What is the test for starch?
Iodine test
dark, blue-black = starch is present!
What is the main energy storage in material in animals?
Glycogen
Animals store excess glucose as glycogen (polysaccharide of alpha glucose)
Glycogen has lots of branches which can be broken off easily by enzymes to release energy quickly.
It’s compact and therefore good for storage.
Name three disaccharides found in food
SLM
sucrose
maltose
lactose
Which saccharides cause blood sugar swings?
eating monosaccharides rather than complex carbohydrates
Which sugar is found in milk?
lactose
What process can be used to remove lactose from milk?
Hydrolysis which converts the discharride into monosaccharides glucose and galactose using the enzyme lactase
What is cellulose? (3pts)
- aka ‘dietary fibre’ or a ‘non-starch polysaccharide’
- up to 10,000 glucose molecules join to form a straight chain
- it is indigestible in the human gut but helps the movement of material through the intestines
