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Cells and Proteins

Rana Al-Khayat Year 1 Englisch 76 Karten

Karten in diesem Stapel (76)

  1. 1What are the different epithelial surfaces?apical and basolateral
  2. 2What are the two main types of epithelia?Covering and glandular epithelia
  3. 3What is the function of glandular epithelia?its fundamental function is to secrete and all epithelial cells have some secretion activity
  4. 4What is the function of covering epithelia?its fundamental function is to protect
  5. 5What are the different types of covering epithelia?TRANSITIONAL (urothel), PSEUDOSTRATIFIED (ciliated with multiple nuclei rows, microvilli or stereocilia with 2 nuclei rows), SIMPLE (cuboidal, columnar and squamous: endothelium and mesothelium) and STRATIFIED (columnar, cuboidal or squamous: non-keratinising and keratinising)
  6. 6Composition of cilia, stereocilia and microvillicilia - microtubule
    stereocilia - actin
    microvilli - actin
  7. 7What are the stages of tissue processing?1. fixation - freezing or chemical fixation
    2. embedding - into a large paraffin wax or mould or frozen sample
    3. sectioning - mould is cut into slices for higher resolution
    4. staining - haematoxylin eosin, PAS, Masson or Azan, alcian blue or toluidine blue
  8. 8How does haemotoxylin eosin work?haemotoxylin is blue and a base so it stains acids like DNA blue whereas eosin is red and is an acid so it stains bases blue
  9. 9What does acidophilic and basophilic mean?acidophilic means that it is attracted to acids so it is a base itself and basophilic means that it is attracted to bases so it is an acid itself
  10. 10What are the differences between light and electron microscopy?light microscopy involves low resolution and you cannot see inside the cell whereas electron microscopy involves high resolution and structures inside the cell can be viewed
  11. 11What are the features of eukaryotes?large genome, complex set of organelles, generally larger than prokaryotes, organised and compartmentalised, extensive actin cytoskeleton and includes fungi, plants and animals
  12. 12What are some of the features of a prokaryote?they are smaller than eukaryotes, they have no cytoskeleton and no/few organelles, small genome and includes bacteria
  13. 13What is parenchyme?working tissue
  14. 14What is stroma?scaffold and nutrition
  15. 15What are lipid rafts in the plasma membrane?organisation of the phospholipid bilayer into biologically and functionally distinct regions, they are enriched in certain phospholipids and cholesterol and are concentrated cell signalling proteins
  16. 16What are the layers of the nuclear membrane?outer membrane, inner membrane and the nuclear lamina
    (the outer membrane is attached to the endoplasmic reticulum)
  17. 17What is the nuclear lamina?a scaffold of intermediate filaments that the nuclear membrane is attached to and it helps to position the nuclear pores which allow for the movement of molecules in and out of the nucleus
  18. 18What is chromatin?a DNA, RNA and protein complex
  19. 19What is the nucleolus?it is present during interphase and it is the site of ribosomal DNA synthesis
  20. 20Other than organelles, what else is used to segregate molecules?multicomponent complexes
  21. 21What is the endoplasmic reticulum?a continuous system of flattened membranes that continue from the outer nucleus membrane
  22. 22What is the difference between rough ER and smooth ER?RER is ribosome associated ER that is involved in protein synthesis whereas SER is involved in lipid synthesis and calcium store
  23. 23What is the Golgi apparatus and its functions?an organelle consisting of flattened membranes, sacs and vesicles, it sorts protein before they go to their final cell destination - proteins going through the Golgi may undergo specific enzymatic modifications that label them e.g. the addition of mannose-6-phosphate to proteins that will end up in the lysosome
  24. 24What are the vesicles in the cytoplasm?peroxisomes, lysosomes and endosomes
  25. 25What is the function of endosomes?they are involved with the transport of molecules from the plasma membrane to the lysosome
  26. 26What is the function of lysosomes?they degrade defective, old organelles, macromolecules and particles taken from outside the cell (defective lysosomes results in Tay-Sachs disease), they have a low pH and contain hydrolytic enzymes
  27. 27What is the function of peroxisomes?compartments of enzymes involved in oxidative reactions
  28. 28What is the function of the cytoskeleton?supports the plasma membrane, resists against mechanical stress, transports intracellular cargo and facilitates cell division and locomotion
  29. 29Describe intermediate filamentsfound in cells that require strength, allows for stretching found in desmosomes and hemidesmosomes and is composed of lamins (nuclear lamina)
  30. 30Describe microfilamentsactin powered by myosin, actin adherent junctions an focal adhesions, they form cells projections (microvilli), contractile rings and membrane extensions
  31. 31Describe microtubulesthese are found in tubulin, cilia and flagella, tubulin is made of dyneins and kinesins, defective dyneins causes Kartagener's syndrome, usually dyneins move cargo towards the centrosome whereas kinesins move cargo way from the centrosome, cilia and flagella are also composed of microtubules and dynein
  32. 32What are axonemes?cytoskeletal components of cilia and flagella
  33. 33What are the two components that make up human ribosomes?60S and 40S
  34. 34What are the steps of protein synthesis?1. all proteins except mitochondrial proteins, start synthesising in the cytosol
    2. ribosome
    3. ER or cytosol
    4. if the protein goes to the ER then the default secretory pathway will take it to the Golgi and then outside the cell whereas variations in the pathway involve the protein going to the plasma membrane or lysosomes from the Golgi
    5. if the protein goes to the cytosol form the ribosome then the protein can either stay put or go to the nucleus, mitochondria or peroxisomes
  35. 35What is the default secretory pathway?1. signal peptide is an N-terminal sequence of amino acids
    2. signal recognition particle binds to the signal peptide which halts translation
    3. SRP with the ribosomal complex binds to the SRP receptor on the ER membrane
    4. binding causes GTP->GDP+Pi which allows translocon pore in the ER membrane to open
    5. from the ribosome the protein peptide chain is threaded through a pore in the ER
    6. in the ER signal peptidase enzyme cleaves off the signal peptide and the finished protein ends up in the ER lumen
    7. transport vesicles containing the protein in their lumen bud from the ER to the Golgi
    8. vesicles carrying the proteins fuse to become the cis cisternae of the Golgi
    9. the proteins move through the Golgi stack (cis maturation model) and they undergo enzymatic modifications
    10. modifications label the proteins for a specific destination
  36. 36Describe the different post-translational modificationsacetylation, farnesylation (a farnesyl group is added), ubiquitination (an ubiquitin group is added), phosphorylation and glycosylation
  37. 37What substances can lysosomes degrade?lysosomes can degrade substances with a long half life, membrane proteins and extracellular proteins, pathogens can be brought into the cell via phagocytosis, autophagy is used to destroy the cells own proteins, membrane proteins can be brought into the cell via endocytosis
  38. 38How can proteins be degraded?lysosomally or proteosomally
  39. 39What is the proteosomal degradation?proteins with a short half life are often marked with a PEST sequence of amino acids, proteosomal degradation is used for proteins with short lives, key metabolic enzymes and defective proteins (proteins that need to be removed quickly), proteosomes are protein complexes in the cytosol and during degradation the protein binds, unfolds and translocates (it is ATP dependant)
  40. 40What is the process of ubiquitin proteosomal degredation?proteins to be degraded are covalently tagged with ubiquitin, E1 is ubiquitin activating enzymes, E2 is ubiquitin conjugating enzyme and E3 is ubiquitin ligase, ubiquitinated proteins are taken to the proteosome and proteins are degraded to give peptides, peptides are extruded and digested by cytosolic peptidases
  41. 41What is the Kozak sequence?it is the next AUG in untranslated mRNA where translation should start
  42. 42What is the functions of the poly(A)tail on the 3' end of DNA?protects mRNA from degredation
  43. 43What are the main groups of amino acids?small, hydrophobic, aromatic, nucleophilic, amine, basic and acidic
  44. 44What is the function of the skin?protection, sensation and regulation
  45. 45Describe sensation in the skinfree nerve endings, pacinian corpuscles (sensitive to rapid vibrations), Merkel cells, Ruffini endings (detect tension and stretch) and meissner's corpuscles (fast adapting touch receptors)
  46. 46Describe the embryology of the skinthe epidermis is derived from the ectoderm, by week 5 the embryo is covered by simple cuboidal epithelium, by week 7 a single squamous layer and basal layer forms, by month 3 epidermal stratification occurs with the appearance of melanocytes, langerhans and Merkel cells and by 6 months the mature epidermis is complete
  47. 47What are langerhans cells?they are antigen presenting cells in the skin that originate from the bone marrow, UV light causes depletion and decreases the cells ability to present antigens, it releases pro inflammatory cytokines to neutralise antigens
  48. 48What are melanocytes?they make up 10% of the basal layer, they are cells that are triggered by light to make melanosomes and it transforms an amino acid into melanin
  49. 49What are the glands of the skin?eccrine glands, apocrine glands (Hidradenitis Suppurativa) and sebaceous glands (acne vulgaris)
  50. 50What are the stages of hair growth?Anagen: hair growth phase that lasts 2-6 years
    Catagen: transitional stage that lasts 2-4 weeks
    Telogen: resting phase that lasts 3 months
    Exogen phase: shedding phase
  51. 51Describe the stages of wound healing1. Haemostasis: vasoconstriction, platelet aggregation, initiated clotting cascade, releasing growth factors, mesh formed, mesh traps blood cells, blood clot forms, fibroblasts form a platelet plug (scab)
    2: Inflammation: vasodilation, neutrophils and macrophages kill microorganisms and secrete growth factors
    3. Proliferative: re-epithelialisation and neo-vascularisation
    4. Tissue remodelling: granulation tissue becomes mature scar tissue, type III to type I collagen, cross-linked collagen
  52. 52Describe the types of wound healingPrimary intention healing: occurs in wounds with dermal edges that are closer together
    Secondary intention healing: occurs in wounds that do not have opposing edges so healing must occur from the bottom of the wound upwards, myofibroblasts are vital cells in secondary intention
  53. 53What are the parts of the basement membrane?Basal lamina: a sheet-like extracellular matrix that is in direct contact with epithelial cells
    Reticular lamina: supports the basal lamina and it is continuous with the connective tissue
  54. 54What are the different epithelial domains?apical, basal and lateral
  55. 55What is the function of lamellar bodies in the skin?lipids are produced by lamellar bodies and are brought between the corneal scales (stratum corneum)
  56. 56What are Merkel cells?they are found in the stratum basal and resemble modified keratinocytes, they serve as touch cells and will detect sustained pressure
  57. 57What are the different types of cell junctions?tight junctions, gap junctions, hemidesmosomes, desmosomes, anchoring junctions, adherent junctions and focal adhesions
  58. 58What are tight junctions?specialised cell-to-cell contact that prevents diffusion between adjacent cells by creating a seal, it is associated with actin filaments
    gate function: regulation of paracellular permeability
    fence function: separates the apical and basolateral domains of the cells which prevents the movements of lipids and proteins between them so it determines epithelial cell polarity
  59. 59What are gap junctions?they are formed by integral proteins called connexins and are intracellular channels that cytoplasm of adjacent cells, it permits the passage of inorganic irons and other smaller molecules
    mutations in connexinx26 leads hearing loss
  60. 60What are anchoring junctions?junctions that provide mechanical stability to groups of epithelial cells so that they can function cooperatively
    - adherens junctions: associated with actin filaments and helps to hold epithelial cells together
    - focal adhesions: associated with actin filament and holds epithelial cells to the basal lamina
    - hemidesmosomes: associated with intermediate filaments, made of tonofilaments which are keratinised intermediate filaments and anchors cells to the basal lamina
    - desmosomes: associated with intermediate filaments, is also made of tonofilaments and strongly links epithelial cells
  61. 61What are the main functions of bone?supports the body, protects vital structures, mechanical basis for movement, storage of salts such as calcium and phosphate and a continuous supply of new blood vessels
  62. 62What are the different bone classifications by appearance?short
    long
    flat
    irregular
    sesamoid (bones that are part of/within a tendon)
  63. 63What is the microscopic structural unit of compact bone?Haversian system which consists of parallel rings of calcified matrix called lamellae
  64. 64Describe compact boneat the centre of each osteon is the Haversian canal which contains blood vessels, nerves and lymphatics, vessels branch off at a right angle through Volkmann's perforating canal, osteocytes are in lacunae at the lamellar borders, osteocytes receive nutrients via long cytoplasmic processes that extend through canaliculi (channels within the bone matrix)
    concentric and circumferential lamellae
  65. 65Describe trabecular bonered bone marrow can be contained in the spaces of spongey bone, lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabecullae, trabecullae form along lines of stress to provide strength to bone
  66. 66Describe the acellular composition of bonewater, hydroxyapatite crystals, collagen type I, extracellular and cellular proteins
  67. 67Describe the cellular composition of boneosteoprogenitor cells, osteoblasts, osteocytes, osteoclasts
  68. 68What is the role of osteoblasts?they synthesise collagen, osteocalcin and osteopontin which all make up the osteoid, they fill cavities by using calcium and phosphate from the blood and produce alkaline phosphatase which is the enzyme that allows hydroxyapatite to form
  69. 69What is endochondral ossification?bone develops by replacing hyaline cartilage which is a much longer process
  70. 70What is intramembranous ossification?bone develops directly from sheets of mesenchymal connective tissue e.g. cranial bone and clavicle
  71. 71How do osteoclasts cause bone resorption?anchor themselves to the surface of bones which creates a sealed zone with its own microenvironment, the ruffled membrane of the osteoclast creates an acidic environment that dissolves the mineral content of the bone and enzymes remove the remaining collagenous matrix to complete resorption
  72. 72Describe parathyroid hormones role in bone remodellingreceptors for PTH are located on osteoblasts, they signal the fusion of bone marrow derived osteoclast precursors, PTH causes the upregulated expression of RANKL and binding of the ligand causes osteoclast activation
    PTH levels are regulated by free calcium, when levels of free calcium decreases so does the levels of PTH
  73. 73Describe the role of osteoprotegerin in bone remodellingits production is controlled by oestrogen, it is expressed by osteoblasts and binds to RANKL which prevents the stimulation of osteoclastogenesis
  74. 74Describe the stages of the bone remodelling cycleformation: matrix is synthesised (+mineralisation)
    quiescence
    resorption: ends when osteoclasts undergo apoptosis or are removed
    reversal: osteoblast recruitment, differentiation and activation
  75. 75How is calcium homeostasis achieved?when calcium levels get too high calcitonin is released by the thyroid gland, this results in the inhibition of osteoclasts and decreases calcium resorption by the kidneys
    the cells of the parathyroid gland have calcium receptors so when calcium binds to the receptor PTH is released which results in osteoclast activation
    PTH also stimulated vitamin D synthesis and vitamin D results in increased calcium absorption from digested food in the small intestine
  76. 76What is the state of calcium in serum?it is either unbound, ionised, bound to albumin or complexed

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Beschreibung
Cells, proteins, skin and the basics of bone
Erstellt von
Rana Al-Khayat
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