Clinical diagnostic biochemistry 1 18 (PDF)

Clinical diagnostic biochemistry -1

CLS 334

What is
carbohydrates?

Carbohydrates, including sugar and starch, are widely distributed in
plants and animals. They perform multiple functions, ranging from
being structural components of deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA) (ribose and deoxyribose sugars) to serve as
sources of energy (glucose).

Introduction
Definition
The term carbohydrate refers to hydrates of carbon (one molecule
of water per carbon atom).

Glucose is derived from:
(1) The breakdown of carbohydrates in the diet or in body stores

(glycogen).
(2) Endogenous synthesis from protein or from triglycerides.

When caloric intake exceeds needs:
the excess is converted to fat for storage in adipose tissue and
glycogen for storage in liver.
When energy needs exceeds caloric intake:
Endogenous

glucose

formation

from

the

breakdown

carbohydrate stores and from non - carbohydrate sources.

of

Classification
Monosaccharide:
Monosaccharides, or simple sugars, consist of a single sugar unit and
cannot be hydrolyzed to a simpler form. Sugars containing three,
four, five, six, and seven carbon atoms are known as trioses, tetroses,
pentoses, hexoses, and heptoses respectively..

Disaccharides:
Two monosaccharides join covalently with the loss of a molecule of
water, to form a disaccharide, so it can be hydrolyzed to simpler
form.

The most common disaccharides are:
Maltose = glucose + glucose
Lactose = glucose + galactose
Sucrose = glucose + fructose

‫سلم‬

Polysaccharides:
The linkage of multiple monosaccharide units results in the
formation of polysaccharides. The major storage carbohydrates are

starch in plants and glycogen in animals, both of which form
granules inside cells.

Story of glucose

After a meal, carbohydrate is broken
down to glucose, absorbed into the
bloodstream, and carried to the body’s
cells. On seeing, the glucose level in
blood, pancreas secret’s insulin that
help the cell to consume glucose for its
energy.