Biologically Important Molecules

Question 1

What are the 4 molecules of life?

Answer 1

• carbohydrates
• lipids
• proteins
• nucleic acids

Question 2

What are the most prevalent naturally occurring elements in the human body?

Answer 2

• oxygen
• carbon
• hydrogen
• nitrogen

Question 3

What is the name of the most important carbohydrates in biochemistry?

Answer 3

saccharides

Question 4

What is the ratio of carbon, hydrogen and oxygen in organic molecules?

Answer 4

generally 1:2:1

Question 5

What are the key roles of carbohydrates?

Answer 5

• energy source
• energy storage
• structural support
• cell recognition/signalling
• present in ribose/deoxyribose sugars

Question 6

What are carbohydrates built from?

Answer 6

monosaccharides

Question 7

What variation in monosaccharides can be present?

Answer 7

• variation in number of carbons
• variation in position of carbonyl group
• variation in orientation of carbons

Question 8

Why does glucose predominantly exist in acyclic form (rings)?

Answer 8

linear structure is less stable

Question 9

When does glucose become acyclic?

Answer 9

when it is introduced to an aqueous solution

Question 10

Define disaccharide.

Answer 10

2 monosaccharides joined together

Question 11

What are some examples of disaccharides?

Answer 11

• sucrose (glucose + fructose)
• lactose (glucose + galactose)
• maltose (glucose + glucose)

Question 12

What reaction occurs when a disaccharide is formed?

Answer 12

condensation reaction (water produced)

Question 13

What bond joins disaccharides together?

Answer 13

glycosidic bond

Question 14

What is the benefit of having a highly branched polysaccharide?

Answer 14

branching increases the solubility of the molecule, providing multiple terminal ends for enzymatic action

Question 15

Define heteropolysaccharide

Answer 15

carbohydrate composed of 2 or more different types of monosaccharide

Question 16

What are the benefits of a heteropolysaccharide?

Answer 16

opens up different structural and functional possibilities

Question 17

Give an example of a heteropolysaccharide

Answer 17

hyaluronic acid

Question 18

What is hyaluronic acid composed of?

Answer 18

repeating disaccharide units of N-acetylglucosamine and glucoronic acid

Question 19

What is the function of hyluronic acid?

Answer 19

• ecm
• synovial fluid
• vitrous humour
• supports tissue hydration
• contributes to wound healing

Question 20

True or False: Carbohydrates are the 3rd major component of plasma membranes?

Answer 20

True

Question 21

What are carbohydrates in the cell membrane attached to?

Answer 21

• lipids (glycolipids)
• proteins (glycoproteins)

Question 22

What is the function of membrane carbohydrates?

Answer 22

act as molecular tags that allow cells to recognise and communicate with each other

Question 23

List some examples of membrane carbohydrates and their function.

Answer 23

• blood group antigens
• cell adhesion
• selectins mediate adhesion of white blood cells

Question 24

List the functions of lipids (triglycerides)

Answer 24

• structural component of cell membrane
• energy sources
• cell signalling pathways
• hormone
• vitamins A,D,E and K

Question 25

Describe the structure of a phospholipid

Answer 25

resembles lipid with one of the fatty acids being replaces by a phosphate

Question 26

Where would you find sphingolipids?

Answer 26

• abundant in cell membranes of lipids
• abundant in the myelin sheath

Question 27

What is the function of sphingolipids?

Answer 27

• essential for nerve function/signalling

Question 28

Why is the regulation of sphingolipids important?

Answer 28

• regulation underpins cell growth differentiation and apoptosis
• regulation plays important roles in neurodegenerative diseases, cancer and inflammatory conditions