Protein and Carbs - Skildum

Question 1

What are the disaccharides lactose and sucrose made up of?

Answer 1

Lactose = Galactose and glucose

Sucrose = Fructose and glucose

Question 2

What kind of linkages do amylose and amylopectin have?

Answer 2

Amylose = alpha 1,4 linkages

Amylopectin = alpha 1,4 linkages with alpha 1,6 branches

Question 3

What kind of linkages are forms in lactose, sucrose, and trehalose disaccharides?

Answer 3

Lactose = beta 1,4 (gal,glu)
Sucrose = alpha 1,2 (fru,glu)
Trehalose = alpha 1,1 (glu,glu)

Question 4

What enzyme is responsible for the first steps of breaking down starches?
Where is it active in the GI system?

Answer 4

Amylase!

Salivary amylase in the mouth
Pancreatic amylase in the small intestine
HIGHEST activity in the duodenum!

Question 5

Is glucoamylase in the brush border an exoglycosidase or an endoglucosidase?

What is it responsible for?

Answer 5

It is an exoglucosidase because it can only cleave off ends rather than starting in the middle like an endoglycosidase

Glucoamylase (AKA maltase) is responsible for cleaving alpha 1,4 bonds to create free glucose molecules off of starch

Question 6

What kinds of bonds does alpha-amylase break?

Answer 6

Cuts alpha 1,4 bonds in polysaccharides

It’s an endoglucosidase so it cleaves bonds in the middle of the starch rather than just at the ends like the exoglucosidases

Question 7

Where is glucoamylase most active?

Answer 7

In the ileum

Question 8

What is the Sucrase-Isomaltase Complex responsible for?

Answer 8

2 Domains, with the sucrase part further distal from the membrane into the lumen

Sucrase domain chops sucrose into Glu and Fru

Isomaltase chops alpha 1,6 branch bond in isomaltose

Question 9

Where is sucrase-isomaltase activity highest?

Answer 9

In the jejunum

Question 10

What enzyme chops up disaccharides made up of 2 glucose molecules with a 1,1 linkage?

Answer 10

Trehalase

Question 11

What is beta-glucosidase responsible for?

Answer 11

2 Catalytic Domains:

1) Cuts glucose and galactose from glucosylceramide and galactosylceramide
2) Splits beta-1,4 lactose bond to form galactose and glucose

Question 12

Loss of beta-glucosidase in the gut brush border is no biggie, but losing function of the same enzyme in the lysosomes can cause what disorder?

Answer 12

Gaucher Disease

(A build up of sphingolipids because ceramides can’t be broken down)

Manifestations may include enlarged spleen and liver, liver malfunction, skeletal disorders and bone lesions that may be painful, severe neurologic complications, swelling of lymph nodes and (occasionally) adjacent joints, distended abdomen, a brownish tint to the skin, anemia, low blood platelets, and yellow fatty deposits on the white of the eye (sclera)

Question 13

Once carbohydrates are broken down into monosacchardides, how do they go about crossing the brush border membrane and entering the blood?

Answer 13

1st - They cross by simply passing down their concentration gradient. Once equilibration is achieved, ATP must be used.
2nd - Na/K ATPase is used to create a large Na gradient in the gut lumen. A Na/Glu/Gal con-transporter uses the high energy of the Na gradient to bring Glu and Gal into the epithelium by facilitated diffusion.

Question 14

Where is Beta-glucosidase activity the highest?

Answer 14

In the jejunum

Question 15

Explain the pathology of lactose intolerance:

Be concise!

Answer 15

• Without lactase, bacteria ferment lactose into lactic acid (and gas)
• This creates an osmotic gradient pulling water into the gut lumen to balance out the proton concentration
• Causes diarrhea

Question 16

What is the fancy name for protein malnutrition?

Answer 16

Kwashiorkor

Presentation: edema, irritability, anorexia, ulcerating dermatoses, and an enlarged liver with fatty infiltrates.

Sufficient calorie intake, but with insufficient protein consumption, distinguishes it from marasmus

Question 17

Where does fatty acid synthesis occur?

Answer 17

Liver

Question 18

Where does glycolysis occur in the body?

Answer 18

all tissues

Question 19

Where does gycogenogenesis occur?

Answer 19

all tissues

Question 20

Where does amino acid synthesis occur?

Answer 20

Mainly liver, all tissues though

Question 21

Where does cholesterol synthesis occur?

Answer 21

Liver

Question 22

An individual lacks a key cofactor for amino acid metabolism. She is unable to do transaminations, deaminations, or carbon chain transfers.
What is the cofactor?

Answer 22

Pyridoxal Phosphate (PLP)
Vit. B-6

Question 23

An individual lacks a cofactor that would enable them to convert Phenylalanine to tyrosine (ring hydroxylation).

What cofactor are they missing?

Answer 23

BH4

Tetrahydrobiopterin

Question 24

A patient presents with megaloblastic anemia and deficiency in a cofactor required to make one-carbon transfers.
What are they lacking?

Answer 24

FH4
Tetrahydrofolate

(folate deficiency is often seen in elderly alcoholics)

Question 25

In what sort of energy state will AMPK be activated?

What will be the result of the activation?

Answer 25

AMPK activation occurs in the low energy state.

It will inhibit protein synthesis and promote autophagy
catabolic state

Question 26

In what sort of energy state will mTORC1 be activated?

What will be the result of the activation?

Answer 26

mTORC1 activated in high energy state

Promotes protein synthesis and inhibits autophagy

Question 27

What does metformin target?

Answer 27

Targets AMPK