Cell Walls

What are the main roles of Cell Walls? (P, S, W)

Protect, maintain shape, prevent excessive water uptake

What is the Order of Taxonomy? (Dear King Phillip Came Over For Great Soup)

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What are Cell Walls made of?

Cellulose fibres embedded in other polysaccharides and protein

Do Cell Walls have more than one layer?

Multiple layers

Describe the Primary Cell Wall

Relatively thin and flexible, microfibrils

Describe the Middle Lamella

Thin layer btwn primary walls of adjacent cells

Describe the Secondary Cell Wall

Added btwn plasma membrane and primary cell wall

Do all Cells have a Secondary Cell Wall?

Some

How are microfibrils packed in the Secondary Cell Wall?

TIghtly packed + sucessive layers arranged at different angles

What are Plasmosdesmata?

Channels that perforate cell walls

What is the Plasmodesmatas role in communication?

Ensures communication between cells despite cell walls

What can pass through Plasmosdemata? (W, SS, P/R)

Water, small solutes, sometimes proteins/RNA

What is Chitin?

Structural polysaccharide used to make some cell walls

What is the Frustule?

Cell wall of Diatoms

What are Diatoms made of?

Silica (hydrated SiO2)

What can Diatoms potentially be used for?

Bio-production

What are Gram Positive Bacteria?

• Structure

• Layers

Simple structure, single layer - peptidoglycan

How do we know Bacteria are Gram Positive?

Contain crystal violet, franine masked so purple

What are Gram Negative Bacteria?

• How do they compare to positive?

• Membranes

• Layers

• Exterior

More complex, 2 membranes, thin peptideglycan layer, exterior liposaccharides

How do we know Bacteria are Gram Negative?

Crytal violet rinsed, red safranine revealed, pink

Is Gram Negative or Positive worse in terms of causing disease?

Negative, harder to treat becuase of complex cell wall and more antibiotic resistant

What is the main job of the Extracellular Matrix (ECM)?

Hold animal cells together

What does the ECM consist of?

Glycoproteins eg collagen, proteoglycons, fibronectin

What is EDS?

Problems when collagen is altered

What is Skin ECM primarily composed of?

Collagen and proteases

What is the Deterioration of ECM?

Loss in collagen production = wrinkles

How does Vitamin C affect collagen?

Increases Collagen production

How does UV Light affect fibroblasts?

UV damage kills fibroblasts

How do Plant Cells communicate?

Plasmodesmata

How do Animal Cells communicate?

Gap junctions

What are the Adhesion Types in Animals?

Tight junctions, desmosomes

What is the role of Gap Junctions?

Provide cytoplasmic channels between adjacent cells

What are Tight Junctions?

Membranes of neighbouring cells pressed together, preventing leakage of extracellular fluid

What are Desmosomes?

Anchoring junctions, fastens cells together into strong sheets