UNIT 4 - Carbohydrates Flashcards
Main carbohydrate analyte tested in clinical chemistry
glucose
Carbohydrates are compounds containing
C, H, and O
functional groups of Carbohydrates
C=O and –OH
we have the presence oxygen covalently bonded to a hydrogen atom
hydroxyl group
contains carbon and oxygen that is connected by a double bond
Carbonyl
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
Contains active aldehyde and ketone group carbohydrates
Reducing substances
Reducing substances examples
glucose,
maltose,
fructose,
lactose, and
galactose
do not have active an aldehyde and ketone groups which cannot reduce other compounds
Non-reducing substances
Non-reducing substances Example
the most common non-reducing substance,
sucrose or table sugar
primary source of energy for humans
Glucose
it is carbohydrates (in particular, glucose) that provide energy for the
brain,
erythrocyte and for the
human retinal cells.
contain three carbons
Trioses
contain four carbons
Tetrose
contain five carbons
Pentoses
contain six carbons
Hexoses
would have a carbonyl group located on the terminal part
Aldose
would have a carbonyl group located in the middle and is connected to other carbon atoms
Ketose
simple sugar that cannot be hydrolyzed into a simpler form
Monosaccharides
Monosaccharides examples
glucose, fructose, and galactose
form from the joining of two carbohydrates molecules or two monosaccharides joined by glycosidic linkage
Disaccharides
Disaccharides examples
maltose, lactose, and sucrose
contain 2-10 sugar units
Oligosaccharides
Oligosaccharides examples
raffinose and stachyose
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