Module 6 Flashcards
three functions of carbohydrates
- storage form of energy
- cell membrane component
- structural component of nucleic acid
classification of carbohydrates according to size of base carbon chain
triose, tetrelise, pentose, hexose, etc
simplest carbohydrate
glycol aldehyde (2-C)
smallest carbohydrate
glyceraldehyde
classification of carbohydrate according to location of the C=O function group
aldose and ketose
the C=O is in the terminal group
aldose
the C=O group is in the middle of the chain
ketose
In ketoses the C2 is always:
carbonyl (C=O)
The aldehyde or ketone in this visualization is at the top of the drawing
fisher projection
this visualization shows the carbihydrate in cyclic form which is more representative of the compound
haworth projection
classification of carbohydrates according to stereochemistry of the compound
L or D form
if the -OH group in the penultimate carbon is in the right of the fisher projection
D-form
if the OH group is found in the left side of the penultimate carbon
L-form
most common enantiomer or stereoisomer in humans
D-form
classification of carbohydrates according to number of sugar units in the chain
monosaccharides, disaccharides, oligosaccharides, polysaccharides
monosaccharides are linked to form disaxcharides through
glycosidic bonds
splitting of glycosidic bonds form ___ and is termed as ___
1 H2O
hydrolysis
simple sugars that cannot be hydrolyzed into simpler form and are always reducing agents
monosaccharides
2 monosaccarides in a glycosidic linkage
disaccharide
monosaccharides components of lactose
galactose
glucose
monosaccharide components of sucrose
glucose
fructose
monosaccharide components of maltose
2 glucose
T or F: sucrose is a reducing sugar
False
Sucrose is non-reducing
disaccharide enzymes like maltase, sucrase, and lactase are found in
intestine microvilli
carbohydrates that consists of 2-10 sugar units
oligosaccharides
most important use of oligosaccharides
components of glycoproteins
integral membrane proteins w/ oligosaccharides covalently linked to extracellular region
glycoprotein
example of glycoproteins
antibodies
hormones
coagulation factors
linkage of 10 or more monosaccharides
polysaccharides
polysaccharide structural support in plants
cellulose
polysaccharide structural support in exoskeletons
chitin
three examples of polysaccharides
starch
glycogen
cellulose
starch is composed of
amylose
amylopectins
component of starch described as 1 long unbranched chain of alpha-1,4 linkages with only the terminal aldehyde is free
amylose
component of starch that have side chains and alpha-1,4 linkages, and alpha-1,6 linkages every 24-30 residues
amylopectins
similar to amylopectin but has more extensive branching every 8-10 residues
glycogen
glycogen is the most abundant in:
liver and skeletal muscle
primary source of energy for humans
glucose
three sources of glucose in the body:
- diet
- body stores (glycogen)
- protein or triglycerides
function of liver
store glucose as glycogen
degrade glycogen as needed
metabolism of glucose molecule into pyruvate or lactate to produce energy
glycolysis
formation of G6P from noncarbohydrate sources like glycerol (triglycerides), lactate (skin and muscles), and pyruvate
gluconeogenesis
breakdown of glycogen to G6P for glycolytic pathway
glycogenolysis
conversion of carbohydrates to fatty acids
lipogenesis
decomposition of fat resulting
lipolysis
product of lipolysis that can be used by the brain through the Tricarboxylic acid cycle
ketone bodies
final common pathway in oxidation of fuel molecules which produce Acetyl CoA
Tricarboxylic Acid Cycle
generates large amounts of ATP when oxidized
Acetyl CoA
Acetyl CoA is oxidized through:
oxidative phosphorylation
The only hypoglycemic agent
insulin
insulin is produced by
beta cells of the islets of Langerhan in the pancreas
actions of insulin
increased uptake of glucose into fat and muscle
increased conversion of glucose to glycogen
increased protein synthesis
decreased glucose production
decreased protein breakdown
nature of insulin
anabolic
4 counterregulatory hormones
- glucagon
- epinephrine
- growth hormone
- cortisol
nature of counterregulatory hormones
catabolic
glucagon is secreted by
alpha cells of pancreas
action of glucagon
increases glycogenolysis, gluconeogenesis, ketogenesis, lipolysis
releaser of glucagon is induced by
stress
exercise
amino acids
two reasons for hyperglucemia
insulin deficiency
increased glucagon
epinephrine is waht compound
catecholamine
epinephrine is secreted by
adrenal medulla
plays key role in glucose counterregulation of glucagon is impaired
epinephrine
causes of increased epinephrine
physical or emotional stress
pheochromocytomas
growth hormone is secreted by:
anterior pituitary gland
action of GH
increases gluconeogenesis, lipolysis
antagonizes insulin-stimulated glucose uptake
cortisol is secreted by
adrenal cortex
cortisol is secreted in response to
adrenocorticotropic hormone (ACTH)
action of cortisol
breakdown of protein and fat
disease when cortisol is increased
Cushing syndrome
hyperplasia of adrenal cortex
disease when cortisol is decreased
Addison’s disease
atrophy of adrenal cortex
disease when cortisol is decreased
Addison’s disease
atrophy of adrenal cortex
two other hormones influencing glucose metabolism
thyroxine
somatostatin
thyroxine is secreted by
thyroid gland
action of thyroxine
increase gastric emptying and intestinal glucose absorption
inhibits growth hormone
somatostatin
somatostatin is found in
GIT
hypothalamus
delta cells of pancreatic islets
action of somatostatin
decreases secretion of GH, insulin, glucagon
modulates relationship of insulin and glucagon
at room temperature, glucose is metabolized at:
7 mg/dL per hour
at 4 degrees Celsius, glucose is metabolized at
2 mg/dL per hour
effect of bacterial contamination on specimen
higher rate of metabolism
effect of glycolysis on specimen
5-7% decrease per hour
effect of fasting on capillary blood glucose concentration
2-5 mg/dL higher than venous blood
effect of glucose load on capillary blood glucose concentration
20-70 mg/dL higher than venous blood
how many hours is refrigerated plasma stable
48 hours
long term storage of specimen at -20 degrees Celsius
progressive and significant decrease
serum should be separated within:
30 minutes
additive that inhibits glycolysis
Sodium fluoride
clinically acceptable delay of separation of serum if without bacterial contamination or leukocytosis
90 minutes
stability of separated, non hemolyzed serum at 25 degrees Celsius
8 hrs
stability of separated, non hemolyzed serum at 4 degrees celsius
72 hours
the standard clinical specimen for glucose determination
plasma
plasma contains this, which can also metabolize glucose
leukocytes
possible additives for plasma that inhibits glycolysis
sodium fluoride
sodium iodoacetate
added to sodium fluoride to prevent late clotting after several hours
potassium oxalate
ratio of sodium fluoride to potassium oxalate
2 mg : 2mg
inhibits in vitro glucolysis better than fluoride
citrate buffer acidificatiob