THE CELL TIM Flashcards
CHECK ON LEARNING
what is the matrix very plentiful in?
connective tissue, forming the framework of the body like the bone, skin, tendons, lens of the eye
in the case of the epithelium, what does the matrix form? what is the key role of the matrix?
basil lamina
development, migration, proliferation, shape and function of cells
what are the two important cells in the fibroblast that give rise to specialized connective tissue?
chondroblast, make cartilage
osteoblasts, make bone
what are the matrix elements?
GAGs (form proteoglycans) fibrous proteins (collagen, elastin, keratin for structure and fibronectin, laminin as adhesives)
in addition to these proteins, cells also make and incorporate into their cell membrane, these proteins allowing cells to attach to the scaffolding and hold together as a tissue?
integrins and selectins
collagen, elastin, keratin (scaffold)
intern, selectin (cell binding)
fibronectin, laminin (adhesion)
these molecules are incorporation into the matrix, highly hydrated and help keep the tissue inflated?
what is the benefit of being hydrated?
GAGs and proteoglycans
elastin (stretchability)
collagen (strength)
proteoglycans (compressibility)
diffusion of nutrients, signals and wastes
T/F, GAGs are unbranched polysaccharide chains composed of repeating disaccharides?
T
what is unique about the disaccharide of the GAG?
one of the sugars is an amino sugar and sulfated, making them negative thus attracting water and causing neighboring chains to repel
the second sugar is a uronic acid, adding more negative charge
so,
N-acetylglucosamide and glucronate
or
N-acetylglucosamide and iduronate
what are the four main GAG groups?
hyaluronan
chondroitin sulfate and derma tan sulfate
heparan sulfate and heparin
keratan sulfate
what is unique about the GAGs?
they don’t fold easily
negative charges make them extend
attracts Na+ and water creating turgor in tissue (cartilage in joints, providing cushioning)
this is the simplest of the GAGs, consists of 25,000 non-sulfated disaccharides each of which contains 1 glucuronate and 1 N-acetylglucosamine, found in all tissue and abundant in early embryos?
Hyaluronan
in the adult this GAG is important as a space filler/retainer, like styrofoam?
Hyaluronan
this GAG is important in wound repair and an important component of synovial fluid as lubricant?
Hyaluronan
these specific hyaluronan building proteins are found in the matrix and on cell membranes?
hyaladherins
how are hyaluronans different from the other three classes of GAGs?
simply a GAG
much larger than other GAGs
contains no sulfate
other GAGs have combination of different disaccharides
this GAG is similar to Hyaluronan but shorter and each disaccharide consists of glucuronate + N-acetylgalactosamine
also, this gag, in the same group has carboxyl groups epimerized on a glucuronate resulting in this GAG
chondroitin sulfate
dermatan sulfate
this GAG has a high number of sulfates added to the backbone, the very negative charge of heparin is important in binding antithrombin III and has a potent anticoagulant effect
heparan sulfate and heparin
this GAG has repeating B-1-3 and B-1-4 bonds but each disaccharide is made of galactose and N-acetylglucosamine?
this is also the shortest of the GAGs and the carbon 6 is sulfated
Keratan sulfate
how are proteoglycans distinguished from glycoproteins?
up to 95% of the mw is sugar
types of sugars vary and many GAGs are highly structured except hyaluronan
GAGs are repeating, straight chain disaccharides
this type of proteoglycan is a major constituent of cartilage, it has over 100 GAGs or about 1 GAG every 20 amino acids?
other proteoglycans have only 1-10 GAGs attached. This proteoglycans is made by fibroblasts and has only 1 GAG chain?
aggrecan
decoran
what are the functions of proteoglycans?
regulation of signal molecule activity (FGF, TGF-B)
organizing the ECM
cell surface receptors
this proteoglycan contains many Heparan Sulfates and functions in the basil lamina of the renal glomerulus participating plasma filtration during urine formations?
perlecan
this type of proteoglycan is used in organizing the ECM, found in cartilage?
aggrecan aggregate
this type of proteoglycan is a cell surface receptor because their core protein is transmembraneous? this glycoprotein serves an important role in orienting the ECM to the cytoskeleton?
syndecans
this proteoglycan is 130 GAGs, found in cartilage, and functions as mechanical support, aggregates with hyaluronan?
aggrecan
this proteoglycan is 1 GAG long, found in connective tissue, and functions to bind type I collagen and TGF-B?
decoran
this proteoglycan is 1-3 GAG long, found in the fibroblast and epithelial cells, and functions for cell adhesion and binds FGF?
syndecan-1
what is the major protein of the matrix?
collagen
these are a family of fibrous proteins that are secreted by connective tissue cells, as well as by other cells?
collagens
what are collagens rich in? what are these important in?
proline, lysine and glycine
calcified tissue
what type of chain comprises the three collagen polypeptide chains to make a collagen molecule?
alpha chains
what are the 5 abundant amino acids found in the alpha chain?
glycine lysine proline hydroxylysine hydroxyproline
this collagen type accounts for 90% of all body collagen and found in bone, skin, tendons, cornea, and internal organs?
type I, 2 alpha 1 I chains, and 1 alpha 2 I chain
what’s the difference in alpha chain?
each alpha chain is 1000 aa long and made of repeating 3 aa sequences
so every 3rd AA in alpha1 or alpha2 is glycine:
every 3rd AA in a1 is HP
X or Y is proline
z is HP or HL
T/F, hydroxyproline and hydroxylysine are common outside of collagen?
F, rare, they are a good collagen marker and produced via post translational processing
how are proline and lysine R groups hydroxylated?
by Prolyl Hydroxylase or Lysyl Hydroxylase
how is proline or lysine converted to hydroxyproline or hydroxylysine?
prolyl hydroxylase or lysyl hydroxylase with oxygen, alphaketogluturate and ascorbate
what does a Vit C (Ascorbate) deficiency reduce and cause?
hydroxylation, tripe helix is impaired and weak bones and vessels result
scurvy