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MICR2208 > 10 - Eukaryotic structure and function* > Flashcards

10 - Eukaryotic structure and function* Flashcards

1
Q

Multicellular forms of eukaryotic organisms

A

vertebrate and invertebrate animals, plants, algae and some fungi

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2
Q

Unicellular forms of eukaryotic organisms

A

protists (protozoa, microalgae), yeasts, many other fungi

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3
Q

what do all eukaryotic cells have in common

A
  • membrane-delimited nuclei
  • membrane-bound, compartmentalised organelles that perform specific functions
  • intracytoplasmic membrane complex serves as transport system
  • more structurally complex and generally larger than bacterial or archaeal cells
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4
Q

different ways of protection and retention of cell contents

A
  • Plasma membrane
  • Cell wall
  • Glycocalyx
  • Cytoplasm and cytoskeleton
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5
Q

Plasma membrane

A
  • All eukaryotic cells have plasma membranes
  • Similar in structure and function to that of prokaryotes
  • Retains cell contents
  • Controls exchange with the external environment
  • Consists of a phospholipid bilayer with sphingolipids and sterols that effect permeability and transport
  • Heterogenous with lipid rafts
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6
Q

Cell wall

A

Only plants, algae, fungi and some stages of parasites have cell walls.

Animal, protozoan and other eukaryotic cells lack cell walls and have less rigid cell shapes

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7
Q

What is the composition of eukaryotic cell walls

A
  • Different to prokaryotes
  • Plants: cellulose
  • Fungi: Chitin, glycans, protein
  • Algae: Pectins, cellulose
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8
Q

How is cell shape maintained in a cell membrane

A
  • Chemicals (sterols) embedded in plasma membrane (lipid rafts)
  • The cytoskeleton (network of flexible fibres and microtubules)
  • Some protists have a thin protein ‘pellicle’ layer supporting the membrane
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9
Q

Glycocalyx

A
  • Gel like external cell coating
  • Usually carbohydrate
  • Anchored to membrane
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10
Q

Functions of glycocalyx

A
  • Strengthens cell surface
  • Helps attach cells together
  • Cell-cell recognition/signalling
  • Protection
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11
Q

Cytoplasm

A

Complex structure of liquid component with structural framework that support the various different organelles

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12
Q

Cytoskeleton

A

The cytoskeleton is a scaffold within the cytoplasm that is composed of three types of filaments providing structural integrity and transport

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13
Q

3 filaments of the cytoskeleton

A
  • Actin filaments (microfilaments)
  • Intermediate filaments
  • microtubules
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14
Q

Structures that control cell activities and processes

A

The nucleus and ribosomes

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15
Q

The nucleus

A

Cell control centre determining cellular activities, most prominent organelle. Information for cell control is encoded on numerous long, linear DNA chromosomes.

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16
Q

Nuclear envelope

A

A double membrane system that encloses the nucleus

Pores allow exchange with cytoplasm (eg movement of ribosome subunits)

17
Q

Ribosomes

A
  • Found in both eukaryotic and prokaryotic cells
  • Eukaryotic cells have both 70S and 80S ribosomes (prokaryotic just 70S)
  • 70S inside organelles (mitochondria, chloroplasts)
  • 80S free in cytoplasm or rough ER
  • Sites of protein synthesis
18
Q

Structures that generate energy

A

Mitochondria and chloroplasts

19
Q

Mitochondria

A
  • Generate ATP (plasma membrane in prokaryotic)
  • Smooth outer membrane and highly convoluted inner membrane (cristae)
  • Fluid matrix contains all the chemicals necessary to make ATP from nutrient chemicals in cell
  • Have 70S ribosomes and their own circular DNA, divide independently of cell
20
Q

Chloroplasts

A
  • Sunlight used to convert CO2 and water to ATP for cell use
  • Double outer membrane enclosing thylakoids (Light harvesting pigments)
  • 70S ribosomes, their own circular DNA, and divide independently of the cell
21
Q

Constraints imposed by increasing cell size

A
  • S/V ratio
  • Chemical diffusion rates
  • Chemical concentration rates
22
Q

Surface to volume ratio

A
  • Cells need a sufficient S/V ratio to enable nutrient uptake and waste removal that meets cell needs
  • As cells get bigger, increase in V outstrips increase in S
  • Exchange becomes limiting
23
Q

Chemical diffusion rates

A
  • Prokaryotes rely on diffusion of chemicals throughout the cytoplasm
  • Diffusion takes longer with increasing cell size and hence increased diffusion distance
24
Q

Chemical concentration

A
  • Prokaryotes rely on random chemical collisions
    in the cytoplasm
  • To maintain chemical concentrations, 8 times more chemical must be made for every doubling in size
  • Manufacturing chemicals puts a big energy drain on cells
  • Eukaryotic cells keep chemicals concentrated in packages within organelle
25
Q

Two organelles that are essential network elements

A
  • Rough endoplasmic reticulum (Construction of proteins and post transcriptional modification)
  • Smooth endoplasmic reticulum (mainly protein and glycoprotein construction)
  • Golgi apparatus
26
Q

Endoplasmic reticulum

A
  • A continuous, interconnected network of membrane tubes and flattened sacs spreading the cytoplasm
  • Involved in protein and lipid synthesis
  • Transports materials through the cell
  • Rough ER is studded on its outer surface with ribosomes
  • Proteins may be for: Membrane synthesis, Export from the cell or Transport within the cell
27
Q

Golgi apparatus

A
  • GA prepares materials for secretion
  • ER buds off ‘transitional vesicles’ for transport of ER products to the GA
  • Consists of stacked membrane sacs
  • ER products are further modified in the GA for specialised use by the cell (e.g. addition of polysaccharides or lipids)
28
Q

Products of the GA

A
  • Glycocalyx
  • Cell wall/membrane repair kits
  • Digestive or degradative enzymes
  • Antibodies and receptors
29
Q

Functions of flagella and cilia

A
  • Find food/prey/new hosts
  • Orientate in the environment
  • aid dispersal
  • enable mating
30
Q

Flagella and cilia

A
  • Similar structure and action
  • Extensions of the plasma membrane
  • Cilia are shorter
  • Both whip like and beat to move cell along
  • Movement driven by sliding of microtubules in extended section (causes wave like movement)
31
Q

how to eukaryotic flagella differ from prokaryotic flagella

A

prokaryotic flagella are rigid protein spirals and their action occurs by rotation

32
Q

Name one other type of cell movement

A

Amoeboid movement

33
Q

Lysosomes

A
  • membrane bound bodies
    help destroy/digest intracellular components

MICR2208 (26 decks)

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