Nutrient digestion carbs & proteins Flashcards Preview

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Flashcards in Nutrient digestion carbs & proteins Deck (23)
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1
Q

What are the principal dietary constituents?

A
Carbohydrate 
Protein 
Fat 
Vitamins 
Minerals 
Water
2
Q

What are monosaccharides?

A

Hexose sugars (6C):

Glucose
Galactose
Fructose

3
Q

What are disaccharides?

A

Two monosaccharides linked together by glycosidic bond:

Maltose
Lactose
Sucrose

4
Q

How are disaccharides broken down?

A

They are broken down to constituent monomers by brush border enzymes in small intestine

5
Q

What is maltose, lactose and sucrose composed of?

A

Maltose = glucose + glucose

Lactose = glucose + galactose

Sucrose = glucose + fructose

6
Q

Examples of different polysaccharides

A

Starch

Cellulose

Glycogen

7
Q

What is Starch?

A

Plant storage form of glucose

alpha-amylose: glucose linked in straight chains

amylopectin: glucose chains highly branched

8
Q

What is Cellulose?

A

Constituent of plant cell walls

  • Unbranched, linear chains of glucose monomers linked by beta-1, 4 glycosidic bonds
9
Q

What is Glycogen?

A

Animal storage form of glucose

  • Glucose monomers linked by a-1,4 glycosidic bonds
10
Q

How are glucose monomers linked?

A

They are linked by a-1, 4 glycosidic bonds

11
Q

What does Amylase do?

A

Breaks down Starch, glycogen (glucose polymers) into Maltose

12
Q

What is alpha-amylase?

A

Alpha-amylase, (α-amylase) is an enzyme that hydrolyses alpha bonds of large, alpha-linked polysaccharides, such as starch and glycogen, yielding glucose and maltose.

It is the major form of amylase found in humans and other mammals.

13
Q

What are proteins?

A

Polymers of amino acids linked together by peptide bonds

14
Q

What are proteases/peptidases?

A

Enzymes which hydrolyse peptide bonds and reduce proteins or peptides to amino acids

15
Q

What is the basolateral membrane?

A

Basolateral membrane or serosal membrane refers to the cell membrane which is oriented away from the lumen of the tubule

16
Q

What is the apical membrane?

A

It is the layer of plasma membrane on the apical side (the side toward the lumen) of the epithelial cells in a body tube or cavity, separated from the basolateral membrane by the zonula occludens.

17
Q

What does the SGLT1 (sodium glucose linked transporter) do?

A

It is a glucose transporter found in the intestinal mucosa (enterocytes) of the small intestine.

  • It is the main uptake mechanism for glucose and galactose in the gut.
18
Q

What is the function of GLUT2?

A

It is a facilitative glucose transporter in the liver, pancreas, intestine and brain.

  • Apical GLUT2 also increases fructose uptake.
19
Q

What is the fructose transporter in the small intestine?

A

GLUT5

It is expressed on the apical border of enterocytes in the small intestine.

20
Q

Where do endopeptidases work?

A

In the interior of the protein

21
Q

Where do exopeptidases work?

A

They only act on the terminal amino acid

22
Q

How are small peptides absorbed into the small intestinal epithelial cell ?

A

By cotransport with H+ ions via a transporter called PepT1

23
Q

What is NHE3 (sodium-hydrogen antiporter 3)?

A

It is a protein that in humans is encoded by the SLC9A3 gene

  • It is primarily responsible for maintaining the balance of sodium.