Deevska Review Flashcards
Why is vitamin C (ascorbic acid) important for collagen
Required as a cofactors for the enzymes involved in hydroxylation of proline and lysine residues in collagen
What does a deficiency in vit C do?
Lack of proline and lysine hydroxylation lead to impairment of the interchain H bond formation which prevents the formation of a stable triple helix and affects proper cross-linking
What is the effect of vitamin C deficiency on collagen directly
Greatly decrease the tensile strength of the assembled fiber
What disease is caused by vitamin c deficient and what are the symptoms
Scurvy
- easy bruising
- loose teeth an bleeding gums
- poor wound healing
- poor bone development
What is the main difference between the structure of elastin and collagen?
Collagen contains hydroxyproline and hydroxylysine whereas elastin contains scant amounts of this
Extensively interconnected, rubbery network that can stretch and bend in any direction when stressed, giving connective tissue elasticity
Elastin
What is the makeup of elastin
- insoluble protein polymer synthesized from a precursor tropoelastin
- rich in proline and lysine but contains scant amounts od hydroxyproline and hydroxylysine
_________ modifies lysyl side chains in tropoelastin forming a desmosine corsslinking which produces ______
Elastin
What AA are both elastin and collagen abundant in
Proline and glycine
Fibrous proline composed of alpha chains forming triple stranded helix
Collagen
What does collagen have that elastin does not have much of
Contains hydroxyproline and hydroxylysine formed by post translational hydroxylation of proline and lysin residues
Collage requires what as a reducing agent
O2, Fe2+, and vit C
What is the most abundant protein in the human body
Collagen
What types of collagen in cornea
I and VIII
What types of collagen in vitreous
II
Large complexes of heteropolysaccharide chains associated with a small amount of protein
95% carbohydrates
5% protein
Proteoglycans
Protein with a variable but typically small amount of carbohydrate
Glycoproteins
Produce a gel like matrix, form basis of the body’s ground substance, function to form ECM, serves as flexible support for ECM, sieve influencing the movement of materials through the ECM, contributes to the viscous lubricating properties of mucous secretions
Proteoglycans
What are proteoglycan aggregates composed of?
1 proteoglycan monomers
- GAGs
- a core protein
2. Hyaluronic acids
3. Link protein
What is the anchor point for the proteoglycan
Hyaluronic acid
Small protein that stabilizes the association between the core protein and hyaluronic acid in a proteoglycan
Link protein
Part of the proteoglycan monomer that us linked to a serine residue with 100s of monosaccharide chain extending out from it
Core protein
Long unbranched, heteropolysaccharide chains, six different types, always found external to the cytosol in the proteoglycan
GAGs
Characteristics of GAGs
- unbranched
- repeating disaccharide units
Large complexes of NEGATIVELY charged heteropolysaccharide chains
What gives the GAGs their unique function
Negative charge
What kind of charge does a GAG have and why
Negative because carboxyl groups and sulfate groups
What does the negative charge on the GAGs contribute to
- hydraulic absorption and resilience of synovial fluid and vitreous humor of the eye
- lubricating effects of mucous and synovial fluid
Functions of membrane bound glycoproteins
- cell surface recognition by other cells, hormones, viruses
- cell surface antigenicity
- formation of ECM and mucins
non membrane bound glycoproteins
- almost all globular proteins secreted in the plasma are glycoproteins
- many of the lysosomal proteins are glycoproteins
Structure of the carbohydrate chain of a glycoprotein
- short
- no serial repeats
- often branched
- may/may not be negatively charged
- highly variable in amount and comp of carbohydrate
Structure of the linkage between carbohydrate and protein in a glycoproteins
- N-glycosidic link: sugar chain attached to abide group of asparagine
- O-glycosidic link: sugar chain is attached to the hydroxyl group of either serine or threonine
Glycoprotein can contain one of these or both of these
What are the 6 major classes of GAGs
- chondroitin sulfate
- keratin sulfate I and II
- hyaluronic acid
- dermatan sulfate
- heparin
- heparin sulfate
What is the most abundant GAG in the body?
Chondroitin sulfate
Where is chondroitin sulfate (GAGs) found
Cartilage, tendones, ligaments, and aorta
Where is keratin sulfate I and II found
KSI: in coreans
KSII: loose connective tissue proteoglycan aggregates with chondroitin sulfate
What is the only GAG not attached to a core protein?
Hyaluronic acid
What is the only GAG not sulfated?
Hyaluronic acid
Where is hyaluronic acid found
- animal and bacteria
- synovial fluid in joints, vitreous, umbilical cord, loose connective tissue, cartilage
Where is dermatan sulfate found
Skin blood vessels, and heart valves
What is the only GAG that is intercellular
Heparin
Where is heparin found and what does it do
Intracellular component of mast cells that line arteries, especially in liver, lungs, and skin
Serves as an anticoagulant
Where is heparin sulfate found
Basement membrane
What is the difference between heparan and heparin sulfate?
Heparin sulfate-some glucosamine are acetylated and there are fewer sulfate groups
What is the most heterogenous GAG
Keratin sulfate
A defect in the sulfation of the growing glysoaminoglycan chains results in one of several disorders that affect the proper development and maintainence of the skeletal system
Chondrodystrophy
What kind of inherited disorder is chondrodystrophy
Autosomal recessive
Characteristics of chondrodystrophy
- dwarfism
- over 100 specific skeletal dysplasias
- rare
Progressive disorders characterized by glycosaminoglycans accumulating in the lysosomes of various tissues results in oligosaccharides in the urine
Mucopolysaccharides
What kind of inheritance is mucopolysaccharidoses
Autosomal recessive
Diagnosis of mucopolysaccharidoses
- the specific MPS is determined by identifying the structure present at the non-reducing end of the oligosaccharide
- diagnosis is confirmed by measuring the patients cellular level of lysosomal hydolases
Symptoms of mucopolysaccharidoses
- apparently normal at birth, gradually deteriorate, could cause childhood mortality
- skeletal and extracellular matric deformities and mental retardation
What are all the MPS diseases
- hurler
- hunter
- sanfilippo
- sly
Ocular symptoms of hurler syndrome (MPS)
Corneal clouding
Ocular symptoms of hunter syndrome (MPS)
None
Ocular symptoms of sanfillipo syndrome
None
Ocular symptoms of sly syndrome (MPS)
Corneal clouding
Which 2 MPS cause corneal clouding
Hurler and Sly
Deficiency in the ability to phosphorylate mannose.
I-cell disease
What kind of disease is I-cell
Lysosomal storage disease. Accumulation of large lysosomal inclusion bodies composed of the missing hydrolase substrate
Symptoms of I cell
- skeletal abnormalities, restricted joint movement, coats dysmorphic facial features, severe psychomotor impairment
- death likely prior to 8 years old
What is the genetic predisposition for DM type I
Moderate
What is the genetic predisposition for DM type II
Very strong
What biochemical and physiological changes is often seen in type I but not type II
Ketosis
Which type of DM has no insulin
Type I
What type of diabetes has insulin, but has a resistance
Type II
Metabolic changes in type I DM
Hyperglycemia
Ketosis and ketoacidosis
Hyperlipidemia
Symptoms of type I DM
- Polyuria, polydipsia, and polyphagia
- ketoacidosis
- fatigue
- weight loss
How does the body react in type I DM
As if it is in starvation state
What is type II Dm a result of
- insulin resistance
- dysfunctional beta cells
The decreased ability of target tissues, such as liver, adipose, and muscle, to respond properly to normal (or elevated) circulating concentrations of insulin
Insulin resistance
Why does insulin resistance alone not type II DM?
Type II DM develops in insulin resistance individuals who also show impaired B cell function that cannot longer secrete sufficient insulin to compensate for elevated blood glucose levels
What is the leading cause of adult blindness?
Retinopathy
- an abnormal metabolic change from diabetes
- in tissues in which glucos uptake is not dependent on insulin, hyperglycemia causes an increase in uptake
What is BMI
Body mass index
- provides indirect measure of body fat
- moderately correlated with more direct measures of body fat obtained from other more direct methods
- NOT a diagnostic of the body fatness or the health of an individual
What is normal BMI
18.5-<25
Waist to hip ratio
- Reflects central abdominal fat amount
- excess central fat correlates with higher risk for morbidity and mortality
What is a better measurement for obesity, BMI or waist to hip ratio?
Waist to hip ratio
Why is hip to waist ratio a better tool for assessing obesit?
Visceral fat ( around the middle) is linked with metabolic syndrome
What was the first identified adipocytes peptide hormone
Lepton
What kind of signal does lepton give
Anorexigenic signal (loss of appetite)
Where does lepton get secreted
From white adipose tissue
What recognized leptin
Leptin receptors in the hypothalamus
Highest levels in evening hours
Secreted in proportion to the size of fat stores
“Not all fats are the same”
Data not show that the type of fat is a more important risk factor for disease than the total amount of fat consumed
Which fats are the best?
Monounsaturated fats
What are bad fats
Trans fats
Some saturated fats
PUFA to some degree
A wasting disorder characterized by loss of appetite and muscle atrophy
Cachexia
Protein deprivation is relatively greater than the reduction in total calories
Kwashiorkor
Fatty liver and edema
Calorie deprivation is relatively greater than the reduction in proline
Marasmus
No edema
Protein energy malnutrition
- decreases appetite
- alter how nutrients are digested or absorbed
- inadequate intake of protein and/or energy is the primary cause
- depressed immune system
- death from secondary infection is common
What are the fat soluble vitamins
DEAK
Usually precursors of coenzymes for different enzymes
Water soluble vitamins
What is the only fat soluble vitamin that functions as coenzyme
Vitamin K
Where is vitamin A stored?
Liver and adipose tissue
What is another name for vitamin A
Retinoids
Deficiencies of vitamin A
- night blindness
- severe: xerophthalmia
What is a component of rhodopsin
Vit A
Hypervitaminosis of vitamin A
- dry skin
- cirrhotic liver
- mimic brain tumor
Where is vitamin D stored
Plasma
What is the active form of vitamin D
Calcitrol
Precursors of active form of vit D
D2 and D3
Functions of vit D
Maintain adequate plasma levels of calcium
Deficicneis in vit D
-demineralization of bone resulting in rickets in children and osteomalacia in adults
Hyperviatminosis of vit D
-hypercalcemia-lead to deposition of calcium in many organs, particularly the arteries and kidneys
What are the different forms of vit K
K1 in plants
K2 produced by intestinal bacteria
Functions of vit K
Posttranslational modification of a number of proteins involved with blood clotting
Deficiencies of vit K
- unusual because intestinal bacteria usually produce sufficient amounts
- in condition associated with loss of bacteria functions
- newborns receive single dose
Hypervitaminosis of vit K
Hemolytic anemia and jaundice in the infants in prolonged use
