2.1.2 Biological molecules Flashcards
What happens due to the sharing of the electrons in water being uneven between the oxygen and hydrogen atoms?
The oxygen atom attracts the electrons more strongly than the hydrogen atoms, resulting in a weak negatively charged region on the oxygen atom (δ-) and a weak positively charged region on the hydrogen atoms (δ+), this also results in the asymmetrical shape
What is a polar molecule?
When a molecule has one end that is negatively charged and one end that is positively charged
As a result of the polarity of water, … form between the positive and negatively charged regions of adjacent water molecules
Hydrogen bonds
Ice is … dense than water
less
Benefits of ice being less dense than water
ice floats on water, creating an insulating layer and insulating the water below, increases chance of survival of organisms in large bodies of water as it prevents them from freezing and allows aquatic animals to move
Strong … between water molecules enables effective transport of water in tube like cells
cohesion
What property of water allows it to act as a medium for chemical reactions and transport dissolved compounds?
water is a solvent
What is the benefit of water having a high specific heat capacity?
It requires a lot of energy to warm it up which minimises temperature fluctuations and allows it to act as a buffer (enzymes, living organisms= remain a constant environment)
Condensation reaction definition:
a reaction which joins monomers by chemical bonds and it involves the elimination of a water molecule.
Hydrolysis reaction definition:
when water is added to break a
chemical bond between two molecules.
What elements do carbohydrates contain
carbon, hydrogen and oxygen
What is a monosaccharide?
a single sugar unit
Examples of a monosaccharide:
glucose, fructose, ribose
Glucose formula:
C6H12O6
What type of sugar is glucose?
a hexose sugar (6 carbon sugar)
What are the 2 types of glucose?
alpha and beta glucose
What is the difference between alpha and beta glucose?
In alpha glucose the hydroxyl (OH) group is below on carbon 1, whereas in beta glucose the hydroxyl group is above on carbon 1
Properties of glucose:
soluble in water, bonds store large amounts of energy
What is a disaccharide?
2 monosaccharides joined together via a condensation reaction
What bond is formed during the condensation reaction?
a glycosidic (covalent) bond
Name 3 disaccharides:
maltose, sucrose and lactose
How is maltose formed?
a condensation reaction between two glucose molecules
How is sucrose formed?
a condensation reaction between glucose and fructose molecules
How is lactose formed?
a condensation reaction between glucose and galactose
What is a polysaccharide?
formed from many monosaccharides joined via glycosidic bonds
Glycogen and starch are examples of polysaccharides formed from …. glucose
alpha
What two polysaccharides is starch made of?
amylose and amylopectin
Cellulose is an example of a polysaccharide formed from …. glucose
beta
Is amylose branched?
No it is a long, unbranched chain
What bonds are found in amylose?
1-4 glycosidic bonds only
What do the 1-4 glycosidic bonds in amylose cause?
They cause the chain to coil into a helix due to the angle of the bonds
What does the coiling of the amylose chain cause?
It makes it compact meaning a lot of energy is stored in a small space
Is amylopectin branched?
Yes it is a long, branched chain
What bonds are found in amylopectin?
1-4 and 1-6 glycosidic bonds
What does the branching in amylopectin cause?
it means that it can be rapidly digested by enzymes so energy can be released quickly
Features of starch:
insoluble, large, coiled, branched
What does it mean if starch is insoluble?
it doesn’t affect water potential
What does it mean if starch is large?
it cannot diffuse out of cells
What bonds are found in glycogen?
1-4 and 1-6 glycosidic bonds
Is glycogen branched?
Yes it is highly branched (more branches than amylopectin)
Glycogen is …. meaning it doesn’t affect water potential
insoluble
How does glycogen maximise the amount of energy that is stored?
it is large but compact
What bonds are found in cellulose?
1-4 glycosidic bonds
How does cellulose form 1-4 glycosidic bonds?
every other beta glucose molecule is inverted 180 degrees (flipped upside down) to bring the OH groups close enough to react
Properties of cellulose:
long, straight, unbranched chains, lots of hydrogen bonds and made of microfibrils
What do lots of hydrogen bonds in cellulose cause?
high tensile strength
