Cellular Flashcards by Francisco Ávila

Defining characteristics of Ehlers Danlos syndrome (type 1 and 2)

Joint hypermobility
Hyperextensible, fragile skin
Most common cause of EDS

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Defining characteristics of osteogenesis imperfecta

Spontaneous fractures
Bone and tooth malformation
Blue sclerae

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Impairment in osteogenesis imperfecta

Mutation in type 1 collagen

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Impairment in scurvy

Lack of vitamin C impairs collagen hydroxylation

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Name the steps in collagen synthesis

Synthesis
Hydroxylation of proline and lysine
Glycosylation of pro-a-chain hydroxyproline residues and formation of procollagen via hydrogen and disulfide bonds (triple helix!)
Exocytosis of procollagen
Proteolytic processing (cleavage of disulfide-rich terminal regions leads to insoluble tropocollagen)
Cross linking (lysine-hydroxylysine by copper containing lysyl oxidase)

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Pathogenesis of Menkes disease

Defective ATP7A protein (Menkes protein), which is a copper transporter, results in impaired copper absorption and transport - Therefore, enzymes that use copper will function inapropiately

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Affected enzymes in Menkes disease

Lysyl oxidase (crosslinking of collagen fibers) - leads to “kinky”, brittle hair
Cytochrome C oxidase (neurologic abnormalities)
Tyrosinase (hypopigmentation)

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Hereditary mode of transmission of Menkes disease

X-linked recessive

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Name the 2 main divisions of the M phase of the cell cycle

Mitosis

2. Cytokinesis

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Name the 5 subdivision of mitosis

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

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Function of p53 protein

Induces p21, which in turn inhibits CDKs, leading to hypophosphorylation of Rb (activating it) and inhibition of G1-S progression

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Function of the smooth endoplasmic reticulum

Steroid synthesis and detoxification of drugs and poisons

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Cells that are rich in SER

Liver hepatocytes

* Steroid hormone-producing cells of the adrenal cortex and gonads

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Cdk that phosphorylates Rb and promotes progress to S phase

Cdk4

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Protein modification done on the Golgi apparatus to proteins that are transported to lysosomes

Addition of mannose-6-phosphate

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Deficient/defective enzyme in I-cell disease

N-acetylglucosaminyl-1-phosphotransferase

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Pathogenesis of I-cell disease

Failure of the Golgi to phosphorylate mannose residues leads to a decrease in mannose-6-phosphate, therefore proteins are secreted extracellularly rather than delivered to lysosomes

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Signs and symptoms of I-cell disease

Corse facial features
Clouded corneas
Restricted joint movement

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Characteristic laboratory finding in I-cell disease

High plasma levels of lysosomal proteins

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Abundant, cytosolic protein that traffics proteins from the ribosome to the RER

Signal recognition particle (SRP)

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Absent or dysfunctional signal recognition particle (SRP) leads to…

Accumulation of proteins in the cytosol

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Traffic direction of COP1 proteins

Golgi to Golgi (retrograde)

* cis-Golgi to ER

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Traffic direction of COP2 proteins

*ER to cis-Golgi (anterograde)

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Traffic direction of Clathrin

trans-Golgi to lysosomes

* Plasma membrane to endosomes (receptor-mediated endocytosis)

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Protein modification done on the Golgi apparatus to proteins that are destined for secretion

Adding of sialic acid

Function of the peroxisome

Catabolism of: * Very-long-chain fatty acids (beta oxidation) * Branched-chain fatty acids * Aminoacids * Ethanol And synthesis of PLASMALOGENS, important phospholipids in myelin

Signs and symptoms of Zellweger syndrome (peroxisomal disease)

* Hypotonia * Seizures * Hepatomegaly * Early death

Signs and symptoms of Refsum disease (peroxisomal disease)

* Scaly skin * Ataxia * Cataracts/night blindness * Shortening of the 4th toe * Epiphyseal dysplasia

Actin and microvilli are examples of what type of cytoskeletsl filaments

Microfilaments

Cilia, flagella, the mitotic spindle, and the centrioles are examples of what type of cytoskeletal filament

Microtubules

Identified cell type by staining GFAP intermediate filaments

Neuroglia (eg, astrocytes, Schwann cells, oligodendrocytes) *Identifies astrocytomas and glioblastomas

Identified cell type staining Vimentin intermediate filaments

Mesenchymal tissue (eg, fibroblasts, endothelial cells, macrophages)

Identified cell type staining Desmin intermediate filaments

Muscle

Direction of dynein movement in microtubules

Retrograde to microtubules (towards the negative end, Negative Near Nucleus) *Di NO (negativo)

Direction of movement of kinesin in microtubules

Anterograde to microtubules (towards the positive end, Positive Points to Periphery)

Drugs that act on microtubules

“Microtubules Get Constructed Very Poorly” * Mebendazole * Griseofulvin * Colchicine * Vincristine/Vinblastine * Paclitaxel

Microtubular structure of cilia

9 doublet + 2 singlet arrangement of microtubules *Basal body consists of 9 microtubule triplets

Pathogenesis of Kartagener syndrome

Immotile cilia due to a dynein arm defect

Signs and symptoms of Kartagener syndrome

* Decrease in fertility * Increased risk of ectopic pregnancy * Bronquiectasis * Recurrent sinusitis * Chronic ear infections * Conductive hearing loss * Situs inversus

Number of Na and K molecules transported through the Na-K ATPase

For each ATP consumed, 3 Na go out (phosphorylated pump) and 2 K go in (dephosphorylated pump)

Site of the Na-K ATPase that is inhibiten by ouabain

The K site (dephosphorylated state of the pump)

Most common type of collagen

Type 1

Structures with predominantly type 1 collagen

* Bone * Skin * Tendon * Dentin * Fascia * Cornea * Late wound repair

Structures with predominantly type 2 collagen

* Cartilage (including hyaline) * Vitreous body * Nucleus pulposus

Structures with predominantly type 3 collagen (reticulin)

* Skin * Blood vessels * Uterus * Fetal tissue * GRANULATION TISSUE and KELOID FORMATION

Structures with predominantly type 4 collagen

* Basement membrane * Basal lamina * Lens

Type of collagen found in the epiphyseal growth plate

Type 10

Most abundant aminoacid in collagen

Glycine (1/3) *Structure is Gly-X-Y, where X and Y are proline or lysine

Cofactor required for hydroxylation of proline and lysine residues during collagen synthesis

Vitamin C

Residue that gets glycosylated during the third step of collagen synthesis

Hydroxylysine residues

Types of bonds that form procollagen (triple helix of 3 collagen alpha chains)

Hydrogen and disulfide bonds

Collagen synthesis steps that take place in the RER

1. Synthesis (translation of preprocollagen) 2. Hydroxylation of proline and lysine 3. Glycosylation of hydroxylysine residues

Function of procollagen peptidase

Cleavage of procollagen C- and N- terminals (disulfide-rich) to form insoluble tropocollagen

Cofactor required by lysyl oxidase to form covalent lysine-hydroxylysine cross-linkage

Copper

Collagen synthesis steps that take place extracellularly

1. Cleavage of procollagen | 2. Cross-linkage

Deficient/defective enzyme in Menkes disease

Lysyl oxidase

Mutations in which genes can lead to osteogenesis imperfecta

COL1A1 (chromosome 17) and COL1A2 (chromosome 7)

Decreased production of what type of collagen leads to osteogenesis imperfecta

Type 1 collagen

Signs and symptoms of osteogenesis imperfecta

Patients can’t BITE * Bones = multiple fractures * I (eye) = blue sclerae * Teeth = dental imperfections * Ear = hearing loss

Signs and symptoms of Ehlers-Danlos syndrome

* Hyperextensible skin * Tendency to bleed * Hypermobile joints Associated with joint dislocation, berry and aortic aneurysms, organ rupture

Type of collagen mutated in classical Ehlers-Danlos syndrome

Type 5 collagen

Main structural difference between collagen and elastin

Elastin is rich in NONHYDROXYLATED proline, lysine, and glycine residues

Protein modification that gives elastin its elastic properties

Cross-linking

Elastase, the enzyme that degrades elastin, is inhibited by what other enzyme

alpha1-antitrypsin

Pathogenesis of Marfan syndrome

Autosomal dominant connective tissue disorder due to a mutation in the FBN1 gene on chromosome 15 that results in defective fibrillin *Fibrillin forms a sheath around elastin

Signs and symptoms of Marfan syndrome

* Tall with long extremities * Pectus carinatum or excavatum * Hypermobile joints * Aracnodactyly * Cystic medial necrosis of the aorta * Aortic incompetence and dissecting aortic aneurysms * Floppy mitral valve * Subluxation of lenses (upward and temporally)

Pathogenesis of achondroplasia

Missense mutation in the FGFR3 gene (chromosome 4) that leads to irreversible activation of fibroblast growth factor receptor 3, thereby inhibitin chondrocyte proliferation

Cellular Flashcards

(67 cards)