4. CARBOHYDRATES Flashcards by 횐호 강

Main carbohydrate analyte tested in clinical chemistry

glucose

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Carbohydrates are compounds containing

C, H, and O

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functional groups of Carbohydrates

C=O and –OH

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we have the presence oxygen covalently bonded to a hydrogen atom

hydroxyl group

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contains carbon and oxygen that is connected by a double bond

Carbonyl

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can reduce other compounds and in order for a certain carbohydrate to be a reducing substance, it should contain an

active aldehyde and ketone group

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Contains active aldehyde and ketone group carbohydrates

Reducing substances

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Reducing substances examples

glucose,
maltose,
fructose,
lactose, and
galactose

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do not have active an aldehyde and ketone groups which cannot reduce other compounds

Non-reducing substances

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Non-reducing substances Example

the most common non-reducing substance,

sucrose or table sugar

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primary source of energy for humans

Glucose

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it is carbohydrates (in particular, glucose) that provide energy for the

brain,
erythrocyte and for the
human retinal cells.

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contain three carbons

Trioses

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contain four carbons

Tetrose

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contain five carbons

Pentoses

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contain six carbons

Hexoses

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would have a carbonyl group located on the terminal part

Aldose

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would have a carbonyl group located in the middle and is connected to other carbon atoms

Ketose

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simple sugar that cannot be hydrolyzed into a simpler form

Monosaccharides

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Monosaccharides examples

glucose, fructose, and galactose

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form from the joining of two carbohydrates molecules or two monosaccharides joined by glycosidic linkage

Disaccharides

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Disaccharides examples

maltose, lactose, and sucrose

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contain 2-10 sugar units

Oligosaccharides

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Oligosaccharides examples

raffinose and stachyose

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Raffinose consists of

1 glucose, 1 fructose, 1 galactose

Stachyose consists of

2 galactose, 1 fructose, 1 glucose

raffinose and stachyose are found in

sugar bits (malasses) and in whole grains

contain more than 10 monosaccharides

Polysaccharides

Polysaccharides examples

starch and glycogen

(hydroxyl group is located on the right of fisher projection) / projected on carbon 5

D series: dextrorotatory

(hydroxyl group is located on the left part of fisher projection) / projected on carbon 5

L Series: Leverotatory

Glucose is broken down into two- and three-carbon molecules of pyruvic acid that can enter the tricarboxylic acid (TCA) cycle on conversion to acetyl-coenzyme A (acetyl-CoA).

EMBDEN – MEYERHOF PATHWAY

EMBDEN – MEYERHOF PATHWAY is what type of pathway

Aerobic

Other substrates that can enter EMP

Glycerol, fatty acids, ketones, some amino acids

is the formation of glucose from non-carbohydrate sources

Gluconeogenesis

means formation or synthesis

genesis

is the breaking down of glucose

Glycolysis

Conversion of glucose-6-phosphate to 6-phosphogluconic acid, which permits the formation of ribose-5-phosphate and NADPH

HEXOSE MONOPHOSPHATE SHUNT

protect the lipid bilayer and other cell enzymes from destruction

Function of NADP

This pathway permits pentoses to enter the glycolytic pathway

HEXOSE MONOPHOSPHATE SHUNT

Glucose is converted to __________- for storage

glycogen

Glucose-6-phosphate is converted to glucose-1phosphate, which is then converted to uridine diphosphoglucose and then to glycogen by glycogen synthase

GLYCOGENESIS

Once glucose enters a ________, it remains as glycogen unless catabolized (Glycogenolysis)

muscle cell

Synthesis of glycogen from glucose to glycogen

GLYCOGENESIS

What happens in Glycolysis

plasma concentration [of glucose?] is decreased

What happens in Gluconeogenesis

increased plasma concentration [of glucose?]

What happens in Glycogenolysis

glucose concentration is elevated

What happens in Glycogenesis

decreased plasma concentration [of glucose]

What happens in Lipogenesis

glucose concentration will be decreased

What happens in Lipolysis

glucose concentration will increase

Two main hormones that control blood glucose

insulin and glucagon produced by pancreas

INSULIN  Is synthesized by the

beta cells of islets of Langerhans in the pancreas

Normally released when glucose levels are high Is responsible for the entry of glucose into the cell

INSULIN

Insulin regulates glucose by increasing ________ and inhibiting ______________

glycogenesis, lipogenesis, and glycolysis glycogenolysis

conversion of glucose from lactate to pyruvate

Glycolysis

It inhibits glycogenolysis because glycogenolysis is the formation of glucose from glycogen or the conversion of glycogen into consumable glucose units and you need to remember that insulin is the only hormone that decreases blood sugar level that is why it is known as

Hypoglycemic agent

GLUCAGON  Is synthesized by the

alpha cells of islets of Langerhans in the pancreas

Is released during stress and fasting states When alpha cells of Langerhans detect low blood glucose levels, then they will release

GLUCAGON

GLUCAGON Regulates glucose by increasing

glycogenolysis and gluconeogenesis

is the formation of glucose from noncarbohydrate sources such as Glycerol, Amino Acids and Fats

Gluconeogenesis

Among different types of the agent, this is the primary agent or hormone that increases glucose level, in short, glucagon is a

Hyperglycemic agent

increase in blood glucose

Hyperglycemia

Insulin also stimulates the ___________cells to store this excess glucose unit in the form of glycogen.

liver and muscle

low blood glucose level

Hypoglycemia

Function of glucagon in terms of liver cells

break down glycogen to consumable glucose make glucose from amino acids through the process called, gluconeogenesis

OTHER HORMONES THAT AFFECT CHO METABOLISM: INCREASE GLUCOSE

Epinephrine Glucocorticoids (cortisol) Growth hormone Adrenocorticotropic hormone (ACTH) Thyroxine or T4 Somatostatin

Epinephrine - which is a catecholamine, is released by

adrenal medulla.

This inhibits insulin secretion, increases glycogenolysis and lipolysis

Epinephrine

Glucocorticoids (cortisol) – is released by

adrenal gland in particular, the adrenal cortex.

decreases intestinal entry into the cell, increases gluconeogenesis and lipolysis

Glucocorticoids (cortisol)

Growth hormone: is released by the

anterior pituitary gland

o It decreases the entry of glucose into the cells and increases glycolysis; its release from the pituitary is stimulated by decreased glucose levels and inhibited by increased glucose o It is a hyperglycemic hormone yet it is also capable of increasing glycolysis or the conversion of glucose into lactate or pyruvate

Growth hormone

Adrenocorticotropic hormone (ACTH) is released by the

anterior pituitary gland

ACTH release is stimulated by

decrease levels of cortisol

stimulates the adrenal cortex to release cortisol and increases plasma glucose by glycogenolysis and gluconeogenesis

Adrenocorticotropic hormone (ACTH)

Thyroxine or T4 is released by the

thyroid gland

regulates glucose by increasing glycogenolysis, gluconeogenesis, and intestinal absorption of glucose

Thyroxine or T4

Somatostatin is released by

delta cells of islets of Langerhans

regulates glucose by the inhibition of insulin, glucagon, growth hormone, and other endocrine hormones

Somatostatin