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Cellular Physiology > Dr. Guglielmo introduction to cell phys > Flashcards

Dr. Guglielmo introduction to cell phys Flashcards

1
Q

What is cell physiology?

A

Study of how cells work together to perform functions in a living organism

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2
Q

State the similarities and differences of cells

A

Similarities:
-Contain DNA
-Cytoplasm - require energy
-Cells enclosed in plasma membrane
Differences:
-Variability of cell shape
-Organelle #
-Membrane protein composition
-Genome expresion

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3
Q

What is the Morula?

A

Stage of development when there are 32-64 cells (Mulberry in latin)

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4
Q

What are the two populations of cells you get during development?

A
  1. Outer cell mass trophoblasts = becomes placenta
  2. Inner cell mass embryoblasts = some become embryo
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5
Q

What are the two types of inner cell embryoblasts?

A
  1. Hypoblasts - connected to blastocyst cavity - attach to sides and become part of this
  2. Epiblasts become the embryo
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6
Q

What does the blastocyst cavity become?

A

The primitive yolk sack

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7
Q

Where does the blastocyst get planted?

A

In the uterine wall

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8
Q

Why does amniotic fluid wrap around the embryo?

A

Helps cells on top get nutrients

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9
Q

What is the significance of the primitive streak?

A

Cells on either side divide and migrate. Populate bottom first, then middle

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10
Q

What are the three germ layers, in order from top to bottom?
*Where do they come from?

A

Ectoderm
Mesoderm
Endoderm
Nutrients and oxygen available in embryo location dictate what kind of cells they become.
*These are established from the epiblast cells in the embryo.

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11
Q

What is the Ectoderm?

A

Exterior of the embryo, precursor to epidermis and the nervous system.
-Nervous system and epidermis (skin, hair and nails)
-Top layer
*Memory trick
- ecto = outside - outer of embryo
- attractoderm, can be attracted to someones looks and brains

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12
Q

What is the Endoderm?

A

Interior of the embryo, precursor to the gut and its appendages (alveolar cells, thyroid cells, pancreatic cells).
-Digestive tract, liver, pancreas, respiratory systems, and bladder
-Bottom layer
*Memory trick
- endo = internal, everything inside your body

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13
Q

What is the mesoderm?

A

Cells in between the two layers, precursor to muscle and connective tissue (red blood cells, tubule cells, cardiac muscle, skeletal muscle, and smooth muscle).
-Skeleton, muscle, circulatory and lymphatic systems, and gonads
-Middle layer
*Memory trick
- movederm = everything required to move

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14
Q

What are the different tissue types?

A
  1. Nervous tissue (brain, spinal chord - mental activity, sensory input and integration, regulates homeostasis, regulates muscles and glands)
  2. Muscular tissue (skeletal, cardiac, smooth muscle - contraction, movement and support)
  3. Connective tissue (2 branches, fat vs collagen based - provides energy storage and organ protection vs tendons and cartilage)
  4. Blood (red blood cells, platelets - regulate nutrient and oxygen transport, metabolic waste, immune system)
  5. Epithelial (lines surfaces and cavities - secretion, absorption, protection, etc)
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15
Q

What is the ECM?

A

Extracellular matrix
Meshwork of proteins and polysaccharides. Secreted by cells into the spaces that surround them (specialized cell make a lot of the ECM)

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16
Q

What does the ECM do?

A

-Holds cells and tissues together
-Organized environment for cells to move and interact
-Bidirectional transfer of information (outside - neurosn)
-Regulates proliferative capacity, differentiation and survival
Functions as: structural (bone + teeth), tensile strength (tendons), transparent matrix for sight (cornea), control cell behaviour (basal lamina @ interface between epithelium and connective tissue.

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17
Q

Describe epithelial cells

A

-In the epidermis
-Polarized: simple epithelium, apical surface faces lumen of a tube or external environment
-Spindle orientation and cell fate determination (knows which side is outside vs inside)
-Basal surface rests on and associates with the basal lamina
-Connected with adjacent cells by specialized attachments including tight junctions, desmosome and gap junctions.
*Minor role in producing matrix

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18
Q

What is the basal lamina?

A

ECM that supports epithelial cells

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19
Q

Describe fibroblasts

A

-In the dermis
-Not attached to adjacent cells (can move around)
-do not have apical-basolateral polarity (don’t have orientation)
-have leading edge and lagging end polarity (migration)
-are in contact with ECM (via focal adhesions) - cells sparsely distributed in the matrix
*Major role in producing matrix

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20
Q

What are hemidesmosomes?

A

Integrins (transmembrane proteins) bind to intermediate filaments - stable, don’t move

21
Q

What are focal adhesions?

A

Integrins (transmembrane proteins) bound to Actin cytoskeleton - transient, can be released.
Found in all cells but usually those that migrate more

22
Q

What are the 3 types of cell junctions?

A

Anchoring junctions (only one that can be both cell-matrix and cell-cell, other two just cell-cell), occluding junctions (block junctions - e.g. block water), and communicating junctions.

23
Q

What is collagen?
*structure, where are they made

A

-Major component of the ECM - most abundant protein in mammals (1/3 of whole body protein content)
-28 types in human genome (family)
-3 polypeptides come together to form trimeric structure (3 amino acid motif that repeat in corkscrew mostly -alpha- always Glycine, then Proline and hydroxy proline+ hydroxylserine are common = GXY - can have other amino acids)
-Made by fibroblasts
-Form insoluble fibers

24
Q

Describe the collagen biosynthesis steps

A
  1. Polypeptide synthesis
  2. Post-translational modifications (dependent on vitamin C)
  3. Multimer assembly - procollagen assembly (defect = osteogenesis imperfecta, brittle bone disease)
  4. Higher order assembly
  5. N-linked oligosaccharide modification
  6. Procollagen processing - C- and N-terminal propeptide cleavage (defect = Ehlers- Danlos)
  7. Fibrillogenesis (crosslinking)
  8. ECM superstructure formation.
25
Q

What are the differences between collagen types?

A

-# of helix repeats (length of triple helix)
-shape of globular C + N domains
-Covalent modification differences to triple helix (e.g. other amino acids present than core 3)

26
Q

Describe type I collagen
-structural feature
-representative tissue
-gene(s)

A

-structural feature: Fibrillar, heterotrimeric (more than one gene)
-representative tissue: skin, bone, ligaments
-gene(s): COL 1 A1, COL1 A2 (two proteins from one gene, one from the other, not set which)

27
Q

Describe type II collagen
-structural feature
-representative tissue
-gene(s)

A

-structural feature: Fibrillar, homotrimeric (one gene)
-representative tissue: cartilage, vitreous humour
-gene(s): COL 2 A1

28
Q

Describe type IV collagen
-structural feature
-representative tissue
-gene(s)

A

-structural feature: Sheet-forming, heterotrimeric
-representative tissue: basal lamina
-gene(s): COL 4 A1 - COL 4 A6 (6 genes)

29
Q

Describe type VI collagen
-structural feature
-representative tissue
-gene(s)

A

-structural feature: Beaded microfilaments, heterotrimeric
-representative tissue: skeletal muscle
-gene(s): COL 6 A1, A2, A3, A5

30
Q

Describe type VII collagen
-structural feature
-representative tissue
-gene(s)

A

-structural feature: Fibril-associated (anchoring), homotrimeric
-representative tissue: Dermis
-gene(s): COL 7 A1

31
Q

Describe type XIII collagen
-structural feature
-representative tissue
-gene(s)

A

-structural feature: Transmembrane, homotrimeric
-representative tissue: hemidesmosomes in skin
-gene(s): COL 13 A1

32
Q

What is Osteogenesis Imperfecta? What causes it?

A

“Brittle bone” disease (type I collagen).
Autosomal dominant genetic disorder (COL 1 A1, and A2 genes). Causes improper helix formation due to glycine substitution to other amino acids.
Impaired pro-collagen transport to Golgi apparatus, therefore low collagen - fibril failure during stress (bone has collagen fibrils that go through - allows bones to bend a little - less brittle, like rebar in concrete).

33
Q

What are Glycoproteins?

A

Proteins that have sugar(s) attached to protein core

34
Q

What are Proteoglycans?

A

Specialized repeating sugars mostly attached to a protein core: Glycosaminoglycans (GAGs).
-Bind cations and water, regulate the movement of molecules through the matrix, cushioning (e.g. Perlecan in basal lamina and Aggrecan in joints - most common)

35
Q

What are GAGs?

A

Glycosaminoglycans
Long, linear carbohydrate polymers
e.g. Chondroitin sulphate (cartilage), Keratan sulphate (cornea, cartilage and bone), Heparan sulphate (ubiquitously expressed, binds ligands involved in angiogenesis and tumor metastasis.
-Possible to mix GAG types in a structure - doesn’t have to be the same type throughout.

36
Q

What are multi-adhesive proteins?

A

-Long flexible macromolecules -Like glue in the ECM
e.g. Laminin
-Bind to a variety of components (collagen, polysaccharides, cell surface receptors, growth factors, hormones, etc.)
-Major role is to attach cells to the extracellular matrix by cross-linking the matrix to the cell membrane e.g. Fibronectin
-Important in wound healing and cell migration. Functions to help cells attach to other ECM components.

37
Q

Describe integrins

A

‘Bridge’ between ECM and the cytoskeleton. Adhesive receptors. Bind the matrix as heterodimers.

38
Q

What is Epidermis Bullosa?

A

Group of inheritable disorders
Characterized by epidermal fragility with blistering and erosions - weakening between epidermis and dermis
Regardless of where mutation occurs phenotype is same
-several mutations/ diseases under umbrella EB
e.g. butterfly children - skin is delicate as butterfly wing (benign - playing w friends, severe - putting on clothes)

39
Q

What are CAMs?

A

Cell adhesion molecules:
-integrins
-selectin
-ig-Superfamily
-Cadherin

40
Q

What are selectins?

A

-Divalent cation dependent (Mg2+, Ca2+) opens up binding site, removed & binding sites will close- e.g. starved cells detach
-Heterophilic binding
-Carbohydrate binding: E-selectin (endothelial), L-selectin (leukocyte), P-selectin (platelet)
-Play an important role in host defense mechanisms

41
Q

Describe the Ig Superfamily

A

Calcium independent
Characteristic immunoglobulin domains
Homophilic: 2 identical Ig CAMs binding to each other e.g. two NCAMs (neural)
Heterophilic: e.g. binding of Ig family member ICAM (intercellular) to lymphocyte function associated antigen-1 (LFA-1) s T-cell specific integrin

42
Q

What are Cadherins?

A

Calcium dependent - Homophilic binding
Cadherins bunch together and then reach across and make a stronger bond with another bunch of cadherins
-Subclasses: P-cadherin (placental), N-cadherin (neural- also in mesenchymal cells), E-cadherin (epithelial)

43
Q

What are properties that affect cell-cell adhesion strength?

A

-Binding affinity
-Spatial distribution (how many can you bunch up)
-Activity state of adhesion molecules (e.g. phosphorylated)
-External forces surrounding the cells (more stress on cell = larger chance of breaking bond)

44
Q

What are anchoring junctions? Give examples

A

Mechanically attach cells to neighbouring cells or ECM
Cell-matrix: hemidesmosomes (integrins to intermediate filaments), focal adhesions (integrins to actin)
Cell-cell: adherens junctions (actin and cadherins), desmosomes (intermediate filaments and cadherins)

45
Q

What are Occluding junctions?
Give examples of permissive and not permissive occluding junctions

A

Tight junctions - Prevent small molecule passage, commonly found in polarized epithelia
Protect self from non-self - “leakiness” altered due to tight junction changes allowing or not allowing for paracellular transport
Permissive: Claudin 2, and claudin 16
Not permissive: Claudin 8, and claudin 4

46
Q

What is paracellular transport?

A

Transport between two cells

47
Q

What are communicating junctions? What is the protein that makes up communicating junctions?

A

Gap junctions - Channels that mediate passage of ions/ solutes or electrical signals from one cell to its partner
- Connexin (protein that make up communicating junctions
-6 Connexins come together to make connexon, connexon A + B make a bridge from one to the other and dock to make junction
-Most fragile junction, can be broken easily

48
Q

What is cardiac myocyte junction disease?

A

Arrythmogenic Right ventricular cardiomyopathy (ARVC)
-Anything affecting the gene creating desmosome + adherens causing issues to gap junctions

49
Q

What is Carcinoma?

A

Cancer of skin or tissues that line internal organs
-Subtypes: adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, etc.

Cellular Physiology (7 decks)

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