Carbohydrates Flashcards
Name 4 major groups of carbohydrates?
Monosaccharides
Disaccharides
Oligosccharides
Polygosaccharides
What three nutrients are required for the function of insulin?
B3, Chromium and Gluatmine
What are two examples of monosaccharides?
Glucose and Fructose
Name some examples of disaccharides
Lactose, sucrose, and maltose.
What are considered Oligosaccharides?
Many of the disaccharides are considered Oligosaccharides, such as Lactose, maltose and sucrose.
What are some examples of polygosaccharides
Glycogen and starches
Which of the four types of carbohydrate is considered the most healthy?
Polysaccharides, as the body needs to break them down, creating a low GI effect.
What are the hydrolytic enzymes called responsible for the break down of the polygosaccharides?
Glycosidase and Carbohydrase
What are the 3 types of transport?
1) Active transport
2) Facilitated diffusion
3) Simple diffusion
What is active transport?
It is sodium dependant transport that flows against the concentration gradient via a protein channel.
What is facilitated diffusion?
where the use of protein channels aids transport through a cell membrane with the concentration gradient, this means it flows from high concentration to low concentration
What is simple diffusion?
it is passive diffusion, it is the flow with the concentration gradient and does not need any energy or a protein channel.
Where is Glucose and Galactose absorbed and how?
- They are absorbed from the small intestines to mucosal cells via an ATP-sodium/glucose symporter (SGLT1)
- When concentrations are high they are absorbed by a facilitated transport known as the glucose transporter type 2 (GLUT 2)
What are the factors involved in GLUT 2 regulation?
Elevated blood sugar and insulin levels; high fructose diets, high-saturated fat diets and artificial sweeteners.
What is the transporter protein required for the absorption of Fructose?
Facilitated transport via the GLUT 5 transporter. However it is increased when GLUT 2 is present.
What is the digestive enzyme responsible for disaccharides?
Disaccharidase
What are the forms of the 4 disaccharidases?
1) Lactase
2) Sucrase
3) Maltase
4) Isomaltase
what is the enzyme involved in the breakdown of dietary polysaccharides?
alpha amylase (glycosidase)
Where does alpha amylase act?
in the mouth, however the pancreas also produces it and it is utilised in the duodenum.
How is a monosacharide like glucose or galactose digested/absorbed?
- its absorbed from the SI to mucosal cells via ATP- Sodium/glucose symporter (SGLT1)
- However at high conc absorbed by facilitated transport (GLUT2)
How is a Disaccharide such as Lactose is digested/absorbed?
- occurs in the upper SI
- The disaccharide needs to be broken down by disaccharidase
- The disaccharide actively occurs in the microvilli of the brush boarder
How is a a polysaccharide such as starches digested/absorbed?
- the key enzyme involved is alpha amylase (glycosidase)
- the enzyme breaks down the 1,4 glycosidic linkages
- alpha amylase is active in the mouth, then inactivated in the stomach due to high acidity, then it is present in the duodenum from pancreatic alpha amylase
How and where are Glucosee, galactose an fructose absorbed?
across the basolateral border by a facilitated transport (GLUT 2)
What are known to regulate the glucose concentration in the intestinal wall?
GLUT 2 transporters
What other factor are involved in the regulation of GLUT 2?
sweetness receptors, high-fructose diet, high saturated fat diets and artificial sweeteners. All of these cause this GLUT 2 receptor count to go up, therefore more GLUT 2 receptors present mean that there is more glucose absorbed.
Where does Fructose go to, and what influences its uptake?
It goes to the liver first, however its increased when GLUT 2 is present.
What is the name of the transporter that facilitates the absorption of Fructose?
GLUT 5 however it can exit the enterocytes via GLUT 2 but only down a concentration gradient.
Where does disaccharide digestion occur?
in the upper small intestine
What is the name of the digestive enzyme involved in the uptake of a disaccharide and where does the activity occur?
Disaccharidase, in the microvilli of the mucosal cells (brush border).
What is the primary enzyme involved in the breakdown of polysaccharides?
alpha amylase (Glycosidase)
What organ also produces alpha amylase?
The pancreas, which then utilises it within the duodenum
What type of transport do Glucose, Fructose, and Galactose use to cross the basolateral border?
facilitated transport via GLUT 2 receptor
What does the liver do to Galactose and Fructose?
they are metabolised and broken down into glucose derivatives or catabolised for energy depending on the livers requirements.
Why are diabetics told to exercise?
To increase glucose uptake into the muscle via GLUT 4 receptor
What is blood Glucose level controlled by?
Insulin and Glycogon
What makes up a GLUT Glucose transporter?
1) Has a specific binding site for the molecule being transported
2) Undergoes a change in shape upon binding
3) Has the ability to reverse the change in shape without being bound to the molecule
