Eukaryotic vs Prokaryotic Cells

P

Bacteria and Archaea

Lack nuclei and other membrane-enclosed organelles

E

Internal membranes

Compartmentalized

• allows for concentration gradients

• cell components have own function in own space

• prevents molecules from roaming freely in the (selective)

Plant and animal cells have most of the same organelles: a nucleus, endoplasmic reticulum, Golgi apparatus, and mitochondria. Some organelles are found only in plant or in animal cells. Chloroplasts are present only in cells of photosynthetic eukaryotes

Both

Ribosomes

Genetic Material

Cytoplasms: inside of a cell where reactions take place

Cytocol: the liquid in a cell

Plasma Membranes

Cellular Components

Chloroplast

• Photosynthetic

• Membranes contain chlorophyll pigments and e- transport proteins

• Plants, algae

• Own DNA + evolves independently -> endosymbiotic theory

• Double outer membrane

  • Intermembrane space

• Stroma

  • Fluid

  • outside thylakoid

  • Within the inner membrane

  • Site of Calvin-Benson cycle

    • Carbon fixation reactions of photosynthesis

  • Contains ribosomes + DNA

  • Helps synthesize organic materials from CO2 and H2O

• Thylakoid

  • Flattened membranous sac

  • Light in -> chemical energy

• Granum

  • Stack of thylakoids

  • Function in light reaction of photosynthesis

• Plastid

  • Family including chloroplasts, chromoplasts, amyloplasts

  • In cells of photosynthetic eukaryotes

Endoplasmic Reticulum

• Mechanical support, protein synthesis, intracellular transport

Plasma membrane

• Bounds all cells

• hydrophilic heads and hydrophobic tails

  • charged p groups + hydrophobic fatty acid

  • Amino acids with charged side groups are hydrophilic. These hydrophilic amino acids associate with the hydrophilic phosphate region of the cell membrane

• Bilayer of phospholipids

• fluidity

  • cholesterol

    • When temperatures are low, the fluidity of the cell membrane may decrease to a point that makes it nonfunctional. Cholesterol prevents this by packing between the phospholipids in the membrane. This increases the spacing between phospholipids, which increases the fluidity of the membrane

    • 

• The surface area must be large enough to adequately exchange materials

  • Metabolic requirements set upper limits

  • Surface area increases by n^2, volume increases by n^3

  • Small cells have a greater surface area to volume ratio

  • Increase in volume ->

    • Surface area decreases

    • Demand for internal resources increases

• Surface area increases

Plant Cell Walls

• Cellulose fibers embedded in other polysaccharides and proteins

Extracellular matrix

• Support, adhesion, movement, regulation

RIbosomes

• Comprise ribosomal RNA (rRNA) and protein

• Synthesize proteins according to mRNA sequence

• All forms of life

• Free ribosomes in the mitochondrial matrix

Endoplasmic Reticulum

• Rough

  • Membrane-bound ribosomes

  • Compartmentalizes

  • Phospholipid factory for the plasma membrane and organelles (endomembrane system)

• Smooth

  • Detoxification

  • Lipid synthesis

  • Liver cells

Golgi apparatus

• Membrane-bound

• Flattened membranous sacs

• Modifies and packages proteins

• Cis side receives, trans face ships

Mitochondria

• ATP synthesis

• Mitochondrial matrix

  • Pyruvate oxidation

  • Krebs cycle (citric acid cycle)

  • Enclosed by the inner membrane

  • Contains ribosomes, enzymes, and mitochondrial DNA

    • Own DNA + evolves independently -> endosymbiotic theory

• Double membrane

  • Provides compartments for different metabolic reactions

  • Outer smooth

  • inner highly convoluted and folded

    • increases surface area allows for more ATP to be synthesized

    • E- transportation and ATP synthesis occur here

• crista

  • Infolding of the inner membrane

Lysosomes

• Recycle cell's organic materials

• Membrane enclosed sacs

• Hydrolytic enzymes

  • Intracellular digestion

Vacuole

• Membrane-bound sac

• Food

  • Formed by phagocytosis (endocytosis)

• COntractile

  • Freshwater protists, pump out excess water

• Central

  • Mature plant cells, hold organic compounds and water

  • Fills with water -> pressure to cell wall -> maintain cell shape

Cytoskeleton

Cytoskeleton

• Struct support

• Motility

• Signal transmission

• Motor proteins “walk” on

Microtubules

• Shape cell

• Hollow

• Tubulin polymer

• Guide organelle movement

• Separate chromosomes in dividing cells

• Cilia

  • Hair

  • Flutters

  • Brings up mucus

  • The large number on the cell surface

• Flagella

  • One or few

Microfilaments

• Thin rod

• 2 acetone intertwined

  • Actin interacts with myosin

  • Contract muscle cells

  • Amoeboid (crawling) movement

  • Cytoplasmic streaming (circular flow of cytoplasm within cells)

• Muscle contraction, amoeboid movement, cytoplasmic streaming, support microvilli

Intermediate filaments

• Diameter between microtubules and microfilaments

• coiled

• Support cell shape, fix organelles in place

Communication, Transport, and Diffusion

Cell junctions

• Plasmodesmata

  • Perforates cell walls

  • Connects cytoplasm of adj plant cells

  • Lets in water, small solutes, and larger molecules

• tight junctions

  • neighboring cells tightly pressed and bound by proteins

  • Continuous seal

  • The barrier prevents EC leaks

• Desmosomes

  • Cells -> sheets

  • Anchored by int. Fil. (keratin)

  • Attach muscle cells

• Gap/communicating junctions

  • Cytoplasmic channel in adj cells

  • Membrane proteins surround the pore

Most efficient

• sphere - equal distance all sides

• smaller cells - higher surface area to volume ratio

Active vs passive transport

Active transport requires direct energy because it is against concentration gradients

Osmosis

Water travels from low solute to high solute density

solute travels from high to low solute density

Hypotonic SOlution: The solution has a lower solute density which causes the cell to gain water

Hypertonic SOlution: The solution has a higher solute density which causes the cell to lose water

Isotonic SOlution: No net movement of water

Membrne Proteins

Endosymbiont Theory

Membrane-bound organelles evolved from previously free-living prokaryotic cells via endosymbiosis.