Carbohydrates

Question 1

What is the difference between aldoses and ketoses

Answer 1

An aldose has and aldehyde group on C1 while a ketose has a keto group on C2

Question 2

What is a sugar with an amino group called?

Answer 2

Amino Sugars

Question 3

What is starch a polymer of?

Answer 3

Glucose

Question 4

Define glycogen

Answer 4

a storage polymer of glucose in animals

Question 5

Where is glycogen mainly stored?

Answer 5

The liver and muscles

Question 6

What comprises a sugar acid?

Answer 6

Terminal carbon has a carboxylic acid (COO-)

Question 7

What comprises a sugar alcohol?

Answer 7

The carbonyl group is reduced to an alcohol group (-OH)

Question 8

What polymer is comprised of amino sugars and uronic acids?

Answer 8

Glucosaminoglycans

Question 9

Describe the path and significant enzymes involved in carbohydrate digestion before entering metabolism in the liver

Answer 9

-Mouth: digestive amylase
-Small Intestine: pancreatic alpha amylase breaks down polysaccharides to dia- and monosaccharides
-Brush border of small intestine: enzymes hydrolyze diasaccharides to monosaccharides
-Monosaccharides enter enteric circulation
-Released into portal vein

Question 10

What are the 3 fates of monosaccharides after digestion?

Answer 10

-oxidation into energy
-storage as glycogen
-fatty acid synthesis

Question 11

What organ is the major regulator of glucose metabolism?

Answer 11

the liver

Question 12

What cells store glycogen but DOES NOT export glucose?

Answer 12

muscle cells

Question 13

What two protein hormones regulate blood glucose concentration?

Answer 13

Insulin
Glucagon

Question 14

Where is insulin released from?

Answer 14

pancreatic beta cells

Question 15

Where is glucagon released from?

Answer 15

pancreatic alpha cells

Question 16

What processes does insulin trigger?

Answer 16

-Speeds up entry of glucose into cells
-Fatty acid synthesis
-Glycogen synthesis
-Protein synthesis

Question 17

What processes does glucagon trigger?

Answer 17

Glycogenolysis
Lipolysis
Gluconeogenesis
Ketogenisis

Question 18

What transporters allow glucose to enter cells?

Answer 18

GLUTs
SGLTs

Question 19

Which GLUT transporter do liver cells, small intestinal cells, and renal cells have?

Answer 19

GLUT 2

Question 20

What GLUT transporter do adipocytes, skeletal, and cardiac muscle cells have?

Answer 20

GLUT 4

Question 21

What is the difference between GLUT2 and GLUT4 transporteres?

Answer 21

GLUT2s are bidirectional and not insulin dependent
GLUT4s are regulated by insulin

Question 22

Once in cells how are glucose molecules kept in the cells? what enzymes perform this function?

Answer 22

Phosphorylation

Glucokinase and Hexokinase

Question 23

What are the 4 characteristics of hexokinase?

Answer 23

-In most mammalian cells
-Low Km (works efficiently at low glucose concentrations)
-Strongly inhibited by G-6-P
-NOT regulated by insulin

Question 24

What are the characteristics of Glucokinase?

Answer 24

-ONLY in liver and pancreatic beta cells
-Higher Km
-NOT inhibited by G-6-P

Question 25

How is glucokinase regualted?

Answer 25

Increase of insulin and decrease of glucagon regulate glucokinase transcription

Question 26

How do you get glucose out of a cell?

Answer 26

dephosphorylate with Glucose - 6- phosphatase

Question 27

What are the only two organs with Glucose-6-phosphatase?

Answer 27

the liver and kidneys

Question 28

How is glucose-6-phophatase regulated?

Answer 28

Insulin regulates gene expression

Question 29

Where does glycogen synthesis primarily occur? what part of the cell?

Answer 29

the cytosol of muscle and liver cells

Question 30

What is the rate limiting step of glycogen synthesis?

Answer 30

Protein phosphatase 1. This activates glycogen synthase

Question 31

What is the rate limiting step of glycogenolysis?

Answer 31

Glycogen phosphorylase. Shortens chains from branch, releases G-1-P

Question 32

Where can you regulate glycogenolysis?

Answer 32

-Activation of glycogen phosphorylase by cAMP second messenger - Ca2+ messaging, increase in Ca activate phosphorylase kinase, which activates glycogen phosphorylase

Question 33

Define glycogen storage diseases

Answer 33

Affect enzymes associated with glycogen synthesis or glycogenolysis depending on the type

Question 34

What is the glycogen storage disease in horses?

Answer 34

Polysaccharide storage myopathy -Affects glycogen synthase causing too much muscle glycogen

Question 35

What part of the cell does glycolysis occur?

Answer 35

cytosol

Question 36

Where does anaerobic glycolysis mainly occur?

Answer 36

-Where quick energy is needed -Areas w/ limited blood supply -cells w/out mitochondria

Question 37

What enzymes are you able to regulate glycolysis with?

Answer 37

-Hexokinase/glucokinase (inhibited by glucagon) -Phosphofructokinase 1 (inhibited by ATP) - Pyruvate kinase (inhibited by ATP and glucagon)

Question 38

What are the 4 different fates of G-6-P?

Answer 38

1. glycolysis 2.HMS 3. Uronic acid pathway 4. glycogen

Question 39

What are the products of HMS? where are they later used?

Answer 39

Ribose-5-phosphate (nucleotide and nucleic acid formation) NADPH (fatty acid synthesis and steroid biosynthesis)

Question 40

What are the two phases of HMS?

Answer 40

Oxidative and non oxidative

Question 41

What two products does the uronic acid pathway yield?

Answer 41

Ascorbic acid (Vit.C) and UDP-Glucuronate

Question 42

What 6 enzymes are used in glycogen synthesis?

Answer 42

Hexokinase/Glucokinase Protein phosphatase 1 Glycogen synthase Phosphoglucomutase UDP pyrophosphorylase Branching enzyme

Question 43

What 4 enzymes are used in glycogenolysis?

Answer 43

Glycogen phosphorylase Debranching enzyme Phosphoglucomutase Glucose 6 phosphatase

Question 44

What 9 enzymes are used in glycolysis?

Answer 44

Hexokinase/Glucokinase Phosphohexose isomerase Phosphofructokinase Aldose Phosphotriose isomerase Phosphoglycerate kinase Phosphoglycerate mutase Enolase Pyruvate transferase

Question 45

What 4 enzymes are used in the Uronic Acid Pathway?

Answer 45

Phosphoglycomutase UDP-Glc pyrophosphorylase NAD dependent UDP-Glc dehydrogenase L-Gulonolactone oxidase