Carbs Lab Manual Flashcards
Carbohydrates can be grouped into generic classifications based on the number of carbons in the molecule. For example,____ contain three carbons,_____ contain four,_____ contain five, and_____ contain six.
trioses
tetroses
pentoses
hexoses
the smallest carbohydrate is_______, a three-carbon compound.
glyceraldehyde
Carbohydrates are hydrates of _________ derivatives based on the location of the CO functional group.
aldehyde or ketone
The two forms of carbohydrates are
aldose and ketose
The______ form has a terminal carbonyl group (O=CH) called an_____ group
aldose
aldehyde group
The_____ form has a carbonyl group (O=C) in the middle linked to two other carbon atoms (called a_____ group).
ketose
ketone group
Another classification of carbohydrates is based on number of sugar units in the chain:
monosaccharides
disaccharides
oligosaccharides
polysaccharides
chaining of sugars relies on the formation of_____ bonds that are bridges of oxygen atoms.
glycosidic bonds
When two carbohydrate molecules join, a_____ molecule is produced.
water
When they split, one molecule of water is used to form the individual compounds. This reaction is called______.
hydrolysis
are simple sugars that cannot be hydrolyzed to a simpler form.
These sugars can contain three, four, five, and six or more carbon atoms (known as trioses, tetroses, pentoses, and hexoses, respectively).
The most common include (3)
Monosaccharides
glucose, fructose, and galactose
are formed when two monosaccharide units are joined by a glycosidic linkage.
Disaccharides
On hydrolysis,_______ will be split into two monosaccharides by disaccharide enzymes (e.g., lactase) located on the microvilli of the intestine.
These monosaccharides are then actively absorbed.
disaccharides
The most common disaccharides are (3)
maltose
lactose
sucrose
Oligosaccharides are the chaining of ____-_____ sugar units, whereas_____ are formed by the linkage of many monosaccharide units.
2 to 10
polysaccharides
On hydrolysis, polysaccharides will yield more than____ monosaccharides.
10
_____hydrolyzes starch to disaccharides in the duodenum.
Amylase
The most cornmon polysaccharides are____ (glucose molecules) and____.
starch
glycogen
is a primary source of energy for humans.
Glucose
The nervous system, including the brain, totally depends on_____ from the surrounding extracellular fluid (ECF) for energy.
glucose
——-cannot concentrate or store carbohydrates; therefore, it is critical to maintain a steady supply of glucose to the tissue. For this reason, the concentration of glucose in the ECF must be maintained in a narrow range.
Nervous tissue
When the_______ concentration falls below a certain level, the nervous tissues loose the primary energy source and are incapable of maintaining normal function.
glucose
The first step for all three pathways requires glucose to be converted to glucose-6-phosphate using the high energy molecule, ATP.
This reaction is catalyzed by the enzyme______.
hexokinase
Glucose-6-phosphate can enter the (3)
Embden-Meyerhof-Parnas Pathway (EMP Pathway) or…
hexose monophosphate pathway or…
can be converted to glycogen
important for the generation of energy from glucose (2)
Embden-Meyerhof-Parnas Pathway (EMP Pathway) or the hexose monophosphate pathway
is important for the storage of glucose.
glycogen pathway
In the EMP Pathway, glucose is broken down into two, three-carbon molecules of______ that can enter the tricarboxylic acid cycle (TCA cycle) on conversion to acetyl-coenzyme A (acetyl-CoA).
This pathway requires oxygen and is called the______
pyruvic acid
aerobic pathway
______ is the name for the conversion of glucose to glycogen, the most important storage polysaccharide in (2)
Glycogenesis
liver and muscle
the breakdown of glycogen to glucose and other intermediate products, is termed________.
glycogenolysis
The formation of glucose from non-carbohydrate sources, such as amino acids, glycerol, or lactate, is termed_______.
gluconeogenesis
The conversion of glucose or other hexoses into lactate or pyruvate is called_______.
glycolysis
______is the primary hormone responsible for the entry of glucose into the cell.
It is synthesized by the cells of ______ in the _____
Insulin
islets of Langerhans in the pancreas
When these cells detect an increase in body glucose, they release insulin.
The release of insulin causes an increased movement of glucose into the cells and increased glucose metabolism.
Cells of islets of Langerhans in the pancreas
______is a 29-amino-acid polypeptide secreted by the_____ cells of the pancreas.
Glucagon
a cells
The maior target organ for glucagon is the______, where it binds to specific receptors and increases intracellular adenosine 5’-monophosphate (AMP) and calcium.
liver
Glucagon stimulates the production of glucose in the liver by (2)
glycogenolysis and gluconeogenesis
enhances ketogenesis in the liver.
glucagon
A minor target organ for glucagon is_______, where the hormone increases lipolysis.
adipose tissue
_______ is actually a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both.
Diabetes mellitus
In 1979, the________ developed a classification and diagnosis scheme for diabetes mellitus.
This scheme included dividing diabetes into two broad categories: (2)
National Diabetes Data Group
type 1
type 2
insulin-dependent diabetes mellitus (IDDM)
type 1
non-insulin-dependent diabetes mellitus (NIDDM)
type 2
Type 1 diabetes mellitus was formerly known as
IDDM
type I
juvenile-onset diabetes
Approximately ______ of all individuals with diabetes mellitus are type 1
5% to 10%
T1D Symptoms
(e.g., polyuria, polydipsia, and rapid weight loss) usually present acutely;
T1D
individuals have_______ (a deficiency of insulin) because of loss of pancreatic islet fi-cells and depend on insulin treatment to sustain life and prevent ketosis.
Most individuals have antibodies that identify an autoimmune process.
insulinopenia
is characterized by hyperglycemia as a result of an individual’s resistance to insulin with an insulin secretory defect.
This resistance results in a relative, not an absolute, insulin deficiency.
Type 2 diabetes mellitus
Type____ constitutes the majority of the diabetes cases. Most patients in this type are obese or have an increased percentage of body fat distribution in the abdominal region.
T2D
This type of diabetes often goes undiagnosed for many years and is associated with a strong genetic predisposition, with patients at increased risk with an increase in age, obesity, and lack of physical exercise.
Characteristics usually include adult onset of the disease and milder symptoms than in type 1, with_____ seldom occurring.
T2D
ketoacidosis
involves decreased plasma glucose levels and can have many causes–some are transient and relatively insignificant, but others can be life threatening.
Hypoglycemias
Hypoglycemia
The most widely used cutoff is___ mg/dL, but some authors suggest____ mg/dL.
50
60
Hypoglycemia
A transient decline may occur ______ hours after a meal, and it is not uncommon for plasma glucose concentration as low as ____mg/dL to be observed 2 hours after ingestion of an oral glucose load.
Similarly, extremely low fasting blood glucose values may be occasionally noted without symptoms or evidence of underlying disease.
1.5 to 2
50
______produces the classic signs and symptoms of hypoglycemia, namely trembling, sweating, nausea, rapid pulse, lightheadedness, hunger, and epigastric discomfort.
Epinephrine
The most common methods of glucose analysis use the enzyme (2)
glucose oxidase or hexokinase
is the most specific enzyme reacting with only b-D-glucose.
Glucose oxidase
Glucose oxidase converts B-D-glucose to______
gluconic acic
_______may be added to the reaction to facilitate the conversion of a-D-glucose to B-D-glucose.
Oxygen is consumed and hydrogen peroxide (H202) is produced.
Mutarotase
Horseradish peroxidase is used to catalyze the second reaction, and the H202 is used to oxidize a dye compound.
Two commonly used chromogens are (2).
The shift in absorbance can be monitored_______ and is proportional to the amount of glucose present in the specimen.
This coupled reaction is known as the______ reaction.
3-methyl-2-benzothiazolinone hydrazone and N, N-dimethylaniline
spectrophotometrically
Trinder reaction
The_______ method is considered more accurate than the glucose oxidase methods because the coupling reaction using glucose-6-phosphate dehydrogenase is highly specific; therefore, it has less interference than the coupled glucose oxidase procedure.
_______ in the presence of ATP converts glucose to glucose-6-phosphate.
hexokinase
Glucose-6-phosphate and the cofactor NAD are converted to 6-phosphogluconate and
NADPH by ____ (enzyme)
NADPH has a strong absorbance maximum at______, and the rate of appearance of NADPH can be monitored_______ and is proportional to the amount of glucose present in the sample.
glucose-6-phosphate dehydrogenase
340 nm
spectrophotometrically
^$Nonspecific methods** of measuring glucose are still used in the_____ section of the laboratory primarily to detect reducing substances other than glucose.
The method given next is the Benedict’s modification, also called the______ reaction.
urinalysis
Clinitest reaction
