Biological Molecules Flashcards
What are polymers?
Large, complex molecules composed of long chains of monomers joined together
What reaction is necessary for a polymer to form?
Condensation reaction
What molecule does a condensation reaction release?
Water
How are polymers broken down?
Hydrolysis reaction
What molecule is added in a hydrolysis reaction?
Water
What are the monomers in carbohydrates?
Monosaccharides
Name three monosaccharides
Glucose, Fructose, Galactose
What type of sugar is glucose?
A hexose sugar
Name the two types of glucose and the differences structurally?
Alpha - H on top of first carbon molecule
Beta - H on the bottom of first carbon molecule
What is a disaccharide?
Two monosaccharides joined together via a condensation reaction
What bond forms between tow monosaccharides?
Glycosidic bond
Sucrose =
glucose + fructose
Maltose =
glucose + glucose
Lactose =
glucose + galactose
What can be used to test for the presence of reducing sugars?
Benedicts test
What is a polysaccharide?
When two or more monosaccharides are joined together by condensation reactions
Name three polysaccharides
Starch
Glycogen
]Cellulose
How do plants store excess glucose?
As starch
What is starch?
A mixture of two polysaccharides of alpha-glucose called amylose and amylopectin. It is insoluble in water so makes it a good storage molecule as it does not affect water potential
Give details about amylose
Long, unbranched chain of a-glucose which is compact so good storage molecule
Give details about amylopectin
Long, branched chain of a-glucose which has side branches to allow enzymes that break down glucose to easily attach
How is excess glucose stored in animals?
As glycogen
Why does glycogen having loads of branches made it a good storage molecule?
Loads of branches means that stored glucose can be released quickly and it is also very compact
What is Cellulose?
Long, unbranched chains of beta-glucose. The cellulose chains are linked together by Hydrogen bonds to form strong fibrils called microfibrils. This provides structural support for cells (e.g. plant cell walls)
What is the function of glycogen?
Acts as an energy store
Give three reasons why Starch is a good storage molecule?
> Can’t leave the cell as it is large
Insoluble in water so does not affect water potential
Compact
How can you test for the presence of starch?
Iodine test / blue-black = positive result
What do the hydrogen bonds between alpha-glucose do in amylose?
Help to hold amylose in its helical structure
What do all lipids contain?
Hydrocarbons
What do Triglycerides contain?
1 glycerol with 3 fatty acids
The tails of the fatty acids are….
hydrophobic - repel water
The heads of fatty acids are…
hydrophilic - attract water