L04: Eukaryotes BIOL 153/L Black Hills State Univ. Ramseys See - - PDF document

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L04: Eukaryotes

BIOL 153/L Black Hills State Univ. Ramseys

See 'Tree of Life' Lecture Three Domains

• f Life
• I. Prokaryotic vs. eukaryotic cells

Prokaryotes Eukaryotes

DNA

X X

Nucleus

X

Mitosis & meiosis

X

Ribosomes

X X

Membrane-bound organelles

X

Cell wall

X

Many (not animals) Multicellularity

Often

• II. Eukaryotic 'Plant' vs Animal cells

for this lecture:

'plant' => land plants + algae

land plants green algae red algae brown algae golden algae diatoms

See 'Tree of Life' Lecture

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'Plant' cells Animal cells

Cell wall

X

Cell type diversity Less More Mitochondria

X X

Chloroplasts

X

Vacuoles Always

(large vacuoles)

Often

(small vacuoles)

• III. Eukaryotic cell components
• A. Nucleus

membrane-bound compartment containing linear DNA (chromosomes) nucleus disassociates during mitosis and meiosis

• B. Cytoplasm

living matter of cell, outside nucleus cytosol is term for the cytoplasm 'goo'

nucleus cytosol cell membrane

• C. Organelles

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• 1. Definition of organelle
• Narrow: membrane-bound structure in cytoplasm
• Broad: any cell structure outside nucleus
• 2. Membrane-bound organelles (examples)
• a. Mitochondria

2x membrane-bound organelle; performs aerobic respiration

• b. Chloroplast

2x membrane-bound organelle; performs photosynthesis

• c. Vacuole

membrane-bound space with water,

• rganic + inorganic molecules, enzymes

functions in storage, materials isolation, turgor pressure

• d. Eyespot apparatus

membrane-bound organelle; senses light direction + intensity

found in many unicellular photosynthetic organisms

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nucleus cytosol mitochondria chloroplast cell membrane vacuole

• 3. Non-bound organelles (examples)
• a. Ribosome

small structure composed of protein + RNA

site of protein synthesis in cell cytoplasm

• b. Flagella

threadlike structure protruding from cell; function in movement

found in many unicellular photosynthetic organisms, sperm of many multicellular photosynthetic organisms

• D. Cytoskeleton

network of microtubules + actin filaments in cytosol

in-cell movement (cell division, cytoplasmic streaming, etc.)

• E. Cell wall

structural layer outside cell membrane; provides support + protection

complex composition usually including carbohydrate polymers and microfibril structures

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eukaryotes very traditionally called 'plants' (prokaryote cell walls different)

• 1. Taxonomic distribution

land plants, algae, fungi, many protists

• 2. Land Plant cell walls
• a. Multiple layers
• 1º cell wall: flexible, exterior
• 2º cell wall: rigid, interior (not always present)
• middle lamella: interface between cells
• b. Composition
• 1º cell wall: cellulose, hemicellulose, pectin
• 2º cell wall: lignin, cutin, suberin
• c. Plasmodesmata

small channels traversing cells walls

allow regulated communication + transport among cells

intercellular space plasmodesmata nucleus cytosol mitochondria chloroplast cell wall cell membrane middle lamella vacuole

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• 3. Other cell walls
• Fungi: chitin

carbohydrate that provides rigidity to fungal cell walls

• Fungi: chitin
• Diatoms: silica (glass)

SiO2 provides strength and ridigity to cell wall

• Diatoms: silica (glass)
• Brown algae: alginate

reacts with calcium in ocean water, creates flexible gel

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• Brown algae: alginate

reacts with calcium in ocean water, creates flexible gel

• Red algae: carageenan, agar, calcium carbonate

provide flexibility (carageenan, agar), rigidity (calcium c.)