4.1. Dietary Nutrients and Absorption - Carbohydrates Flashcards
What are Carbohydrates?
A series of linked Hexose (6 Carbon) Sugars
What are Monosaccharides?
The Breakdown product of complicated Carbohydrates (Many Hexose Sugars linked together)
What are the names of the 3 Monosaccharides?
- Glucose
- Galactose
- Fructose
Where are Monosaccharides absorbed into the Bloodstream?
The Small Intestine (Jejunum)
What are Disaccharides?
2 Monosaccharides linked together
What kind of Bond links 2 Monosaccharides together in Disaccharides?
A Glycosidic Bone
What are the names of 3 Disaccharides?
- Lactose
- Sucrose
- Maltose
What is Lactose a combination of?
- Glucose
2. Galactose
What is Sucrose a combination of?
- Glucose
2. Fructose
What is Maltose a combination of?
2 x Glucose
What breaks Lactose down?
Lactase
What breaks Sucrose down?
Sucrase
What breaks Maltose down?
Maltase
Where can the Enzymes which break down Disaccharides be found?
On the Brush Border of the Small Intestines
What are the 3 Types of Polysaccharides?
- Starch
- Cellulose
- Gylcogen
What is Starch?
The Plant storage form of Glucose
What is Cellulose?
A Constituent of Plant Cell Walls
What is Glycogen?
The Animal storage form of Glucose
What are the 2 ways the Glucose molecules can be linked in Starch?
- In straight chains
2. In branched chains
What type of bond links the Glucose together in Straight Chains?
Alpha-Amylose (1-4 Glycosidic Bonds)
What type of bond links the Glucose together in Branched Chains?
Amylopectin (1-6 Glycosidic Bonds)
How are Alpha-Amylose (1-4 Glycosidic) bonds broken down?
They are hydrolysed by Alpha-Amylases?
Where can Alpha-Amylases be found?
- In the Saliva
2. Released from the Pancreas
How are Amylopectin (1-6 Glycosidic) bonds broken down?
They aren’t
What happens to the Amylopectin (1-6 Glycosidic) bonds?
They are translocated by a different enzyme, to form Alpha-Amylose (1-4 Glycosidic) bonds
How does the Enzyme which translocates part of the Starch Molecule work?
- It cleaves the Amylopectin (1-6 Glycosidic Bonds)
- It attaches the “Open End” of the detached molecule onto the “Free End” of the straight chain
This forms more Alpha-Amylose (1-4 Glycosidic) bonds which can be broken down
How are the Glucose Molecules in Cellulose linked?
In straight chains
What type of bonds connect the Glucose Molecules in Cellulose?
Beta 1-4 Glycosidic Bonds
Do Beta 1-4 Glycosidic Bonds have any enzymatic action?
No
Can Beta 1-4 Glycosidic Bonds be absorbed?
No
What can digest Cellulose?
The Bacteria Cellulase, found within the Gut Flora
What type of bonds connect the Glucose Molecules in Glycogen?
Alpha-Amylose1-4 Glycosidic Bonds
What are the 2 Monosaccharides humans can absorb?
- Glucose
2. Fructose
How is Glucose Absorbed?
- Sodium Glucose Transporter Protein - 1 (SGLT-1) transports both Glucose and Sodium from the Lumen of the Alimentary Tract, into the Epithelium of the Jejunum
- Sodium is transported, via the NaKATPase Transporter Protein, into the Capillaries
- Glucose is transported, via the Glucose Transport Protein - 2 (GLUT-2) into the Capillaries
How is Fructose Absorbed?
- Glucose Transporter Protein - 5 (GLUT-5) transports Fructose from the Lumen of the Alimentary Tract, into the Epithelium of the Jejunum
- Glucose Transport Protein - 2 (GLUT-2) transports Fructose from Epithelium of the Jejunum into the capillaries
