Topic 1A - Biological Molecules Flashcards
What is the theory of evolution?
The theory that all organisms on Earth are descended from one or a few common ancestors and that they have changed and diverged over time.
What is the evidence for the theory of evolution?
The fact that a huge variety of different organisms share the same biochemistry (i.e. they all contain the same groups of carbon-based compounds that interact in similar ways) suggests that animals and plants have a common ancestor, which provides indirect evidence for evolution
What are polymers?
Polymers are large, complex molecules composed of long chains of monomers joined together
What are monomers?
Monomers are small, basic molecular units that can form a polymer
How are polymers formed?
Polymers are firmed from their monomers by condensation reactions, which forms a chemical bond between the monomers and releases a molecule of water
How are polymers broken down?
Polymers can be broken down into monomers by hydrolysis reactions, which breaks the chemical bond between monomers using a water molecule
What are monosaccharides?
Monosaccharides are the monomers that carbohydrates are made of
What are the two isomers of glucose?
Alpha glucose
Beta glucose
What does alpha glucose look like?
—-
What does beta glucose look like?
—-
What are disaccharides?
Disaccharides are two monosaccharides joined together by a glycosidic bond
How are disaccharides formed?
Disaccharides are formed by condensation reactions; they form a glycosidic bond and release a water molecule
What are some examples of monosaccharides? (3)
Glucose
Galactose
Fructose
What are some examples of disaccharides? (3)
Sucrose
Lactose
Maltose
What are the monosaccharides which make up the common examples of disaccharides?
Maltose - glucose & glucose
Sucrose - glucose & fructose
Lactose - glucose & galactose
What are examples of reducing sugars?
All monosaccharides Some disaccharides (e.g. maltose and lactose)
What are examples of non-reducing sugars?
Some disaccharides
How do you test for reducing sugars?
Heat sample with Benedict’s reagent
What does a positive test look like for reducing sugars?
Sample forms green - yellow - orange - brick red precipitate
What does a negative test look like for reducing sugars?
The sample stays blue
How do you test for non-reducing sugars?
Heat sample with Benedict’s reagent
Negative result for reducing sugar
Heat a new sample with dilute HCl then neutralise with sodium hydrogencarbonate.
Heat sample with Benedict’s reagent
What does a positive result for non-reducing sugars look like?
Sample forms green - yellow - orange - brick red precipitate
What does a negative result for non-reducing sugars look like?
Sample stays blue
Which elements do all carbohydrates contain?
C - Carbon
H - Hydrogen
O - Oxygen
