Cell Connections Flashcards
*Compare how animal and plant cells support their tissues.
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*Know the process of collagen formation and its function
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*Describe how cells link to the extra cellular matrix
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*Differentiate the components found in Extra-Cellular Matrix (ECM)
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*Evaluate the various types of cellular junctions with respect to their component
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*Understand how the components of junctions relate to their functions.
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Describe the structure and function of plant cell walls.
Plant cell walls are composed of polysaccharides like
1. Cellulose (primary sugar in plants), has rigid secondary walls; most abundant macromolecule
2. Pectin- in primary cell wall of growing cell (round, circles)
Plant cell wall function- provide support, LACK intermediate filaments and resist tearing and pulling force of tissues.
What is the most abundant macromolecule in a cell?
Cellulose
Describe where plant cell walls are made and include its components like Cellulose, and synthase complex.
Plant cell walls are made outside the plant cells.
Cellulose is synthesized on the outer surface of the cell.
Cellulose synthase complex travels along microtubules (spans PM with its portion facing externally and microtubule anchoring internally)
Synthase is then able to squeeze out cellulose, since PM is fluid mosaic.
List the 4 types of Tissues in animal cells and their funcions.
- Epithelial- forms boundaries (ex: outer surface of skin)
- Muscle- functions to contract
- Nervous- sends electrochemical signal, transmit information.
- Connective- cells form ECM (extra-cellular matrix)
What structures make collagen? How does collagen become collagen fiber.
Fibroblasts make collagen fibers.
Mammalian cells has over 20 types of collagen
Collagen (like intermediate filaments) RESIST STRETCHING.
Formation order:
1 collagen molecule (triple-stranded) will become one main collagen fibril and form a collagen fiber
(Collagen molecule to collagen fibril to collagen fiber (smallest to largest group)
What kind of tissue is collagen a huge component of?
Connective tissue.
Describe the process of Collagen formation.
Collagen formation:
1. initial collagen will be procollagen that forms.
2. The procollagen will then be excreted out and have terminal procollagen extensions.
3. Procollagen proteinases will cleave terminal extensions or ends, leaving only collagen molecule
4. Collagen molecule will then self-assemble into fibrils (Spontaneously)
procollagen ends can only be cleaved once outside.
Describe the pathology associated with collagen defects.
people with collagen defects can develop:
Ehlers-Danlos Syndrome- genetic defect in collagen or procollagen proteinases.
This INCREASED stretchiness of skin (able to resist pulling)
Describe collagen organization and its different components and examples.
Collagen organization is dependent on tissue
- Tendons- organize collagen in parallel sheets (to resist a lot of tension and pulling
tendon fcn: (anchor muscle to bone)
-Skin- wicker-like pattern
Fibroblasts organize the fibers they secrete.
Tendons and ligament composed primarily of collagen.
When depositing new collagen, get breaking, uneven pattern- stretch marks.
What are the collagen collectors that connect collagen to extracellular matrix?
Fibronectin is a collagen connector.
fibronectin is an extracellular protein, that binds to collagen fibers, and changes confirmation (hair pin shape). Fibronectin also binds to extracellular portion of INTEGRIN
Describe the function of integrins in the extracellular matrix.
What does integrin bind to intracellularly vs extracellularly?
Integrins are transmembrane proteins that ANCHOR cell to ECM (extracellular matrix).
Integrins bind to fibronectin on extracellular side
and bind to actin or cytoskeletal elements on intracellular side (to adaptor proteins)
Integrins are HETERODIMERS.
Describe one of the two other Extracellular Matrix (ECM) molecules?
GAGS- Glucosaminoglycans) - sugar type of molecule in ECM of connective tissue.
-resist compression
form chains- negatively charged repeating disaccharides (- charge able to attract water)
GAGS also link to Core proteins like PROTEOGYLCANS.
What kind of ECM molecule does cartilage have?
Cartilage has a lot of GAG’s that provide cushion to resist compression.
tissue with high GAGs will have a lot of water present which is important for resisting compression.
what is the other Extracellular Matrix molecule?
Proteoglycans are another ECM molecule. Proteoglycans form large aggregates
-they are hydrophilic- attract water
functions:
-Guide cell migration
-influence cellular function (cell division, cancer activity)
proteoglycans use GAGS and Proteins (core proteins, link proteins)
What are GAGS in comparison to proteoglycans?
GAGS are smaller building blocks of proteoglycans.
Provide examples of GAGS and how they also serves a joint supplements.
GAGS can include Chondroitin sulfate, Keratan sulfate, and Hyaluronan.
These three GAGS are also joint supplements that help build up cartilage and maintain tissue.
What are Epithelial sheets composed of and their function?
Epithelia:
made of multicellular sheets
-polarized- different top surface and different bottom surface
-Apical- Top surface
Basal- bottom surface
Epithelia are held together with junctions
anchored to basement membranes aka Basal lamina
Function of epithelia:
in connective tissues, they form boundaries and
specialized cells- secretion and absorption
also aid in movement of cilia; glandular epithelia- secrete mucus.
How do you determine the type of epithelia? what are the questions one needs to ask? What can further ID the top layer of tissue?
To determine types of Epithelia, you need two things: 1. How many layers? -one layer= simple -multiple layer= stratified 2. what shape are the cells? -Rectangular- Columnar -square-shaped- cuboidal shape -Flat-shaped- Squamous to ID top layer of tissue, you can look at shape of nuclei( columnar- elongated ovals, round nuclei and squished my nucleus).
