Carbohydrates I

Question 1

1. Which three kinds of atoms are found in a carbohydrate?

Answer 1

Carbon
Hydrogen
Oxygen
* think of glucose and the only atoms invovled

Question 2

2. What is the main function (use) of carbohydrates in a cell/ our body?

Answer 2

• Primary energy source for metabolic processes

Question 3

3. What are monosaccharides?

Answer 3

• Simple single sugars (glucose)
• Contains 3-9 carbon atoms
• The specific carbohydrate is identified by the type of carbonyl group
  o Aldehyde > aldose
  o Ketone > ketose

Question 4

4. What are D-glucose and L-glucose and what is the natural form?

Answer 4

• D-glucose: -OH group is positioned right side *most natural form
• L-glucose: -OH group is positioned left side

Question 5

5. What is the pyranose form of a sugar?

Answer 5

• when the hydroxyl group of C5 reacts with the aldehyde at C1
  o think Penta =5 and pyranose starts with P

Question 6

6. Is the dominating form of D-glucose the open-chain form or the furanose form?

Answer 6

• The dominant form of D-glucose is the pyranose form (99% of glucose is found this way)
• But out of the 2, furanose would be most dominant

Question 7

7. What kind of sugar is lactose?

Answer 7

• Lactose is a sucrose which falls under disaccharide (where 2 monosaccharides around bound together by an oxygen atom (glycosidic bond), byproduct formed is H2O

Question 8

8. What is an anomer?

Answer 8

• The variation of cyclic sugars based on the position of the hydroxyl group
  o Face down -OH = alpha glucose
  o Face up -OH = beta glucose
   A comes before B and down comes before up in the alphabet

Question 9

9. What kind of covalent bond is formed between two sugar molecules?

Answer 9

• Glycosidic bond and linkages will bind two carbohydrates together
  o Typically, a hydroxyl group of one carbohydrate binds with the hydrogen of another carbohydrate typically forms a H2O byproduct but the sugars are linked by oxygen

Question 10

10. Which of the 4 major biomolecules contains a ribose, nitrogenous base and a phosphate group?

Answer 10

• Nucleic acids, they are comprised of nucleotides which contain all 3 subunits mentioned
  i. However, nucleosides are missing the phosphate group

Question 11

11. In which important molecule do we find a ribose with the nitrogenous base adenine and 3 phosphate groups attached?

Answer 11

• ATP because of the triphosphate attachment

Question 12

12. What kind of sugar is glycogen?

Answer 12

• Polysaccharide
  i. Composed of alpha 1-4 glucose linkages and alpha 1-6 branches to obtain the >10 monosaccharide binding

Question 13

13. What is an example for a disaccharide?

Answer 13

• Lactose, maltose, sucrose

Question 14

14. What is starch and the two components it consists of?

Answer 14

• Polysaccharide (polymeric carbohydrate) consists of various glucose units joined by glycosidic bonds
• Linear and helical amylose along with branched amylopectin
• Most common carbohydrate in the human diet

Question 15

15. What is the major function of glycogen?

Answer 15

• Is a function of energy storage in the form of carbohydrates and is easily mobile for needs of glucose

Question 16

16. Where in the body is glycogen primarily stored?

Answer 16

• Mainly: Liver and skeletal muscle
• Small amounts: kidney, RBC, WBC, glial and brain

Question 17

17. What are glycosaminoglycans? Can you give one example of a GAG?

Answer 17

• Long linear polysaccharides consist of repeated disaccharide units essential for signal inducing
• Keratin sulfate in the Cornea for the purpose of maintaining corneal hydration

Question 18

18. What is a proteoglycan made of?

Answer 18

• Core protein chain with one or more GAGs attached via covalent bond

Question 19

19. Which proteoglycan is important in neural development and also contributes to glia scar formation – hence preventing axonal growth (regeneration)?

Answer 19

• Chondroitin sulfate proteoglycans (CSPGs)

Question 20

20. Which proteoglycan is the major PG in the cornea?

Answer 20

• Keratin Sulfate Glycans

Question 21

21. What are glycoproteins?

Answer 21

A class of proteins that has oligosaccharide chains (glycans) covalently bound to the polypeptide chain

Question 22

22. What is a form of glycosylation resulting in creating a membrane anchor?

Answer 22

• Glypiation – glycolipid attached to the C terminus of a polypeptide

Question 23

23. Which are 2 examples for glycoproteins and where in a cell or in the body are they found

Answer 23

Mucin - respiratory/ digestive tract
T-cell receptors - T- lymphocytes
Immunoglobulins - all over body
Glycoprotein IIA/IIB - platelets