BIO U2 ORGANELLES

AP BIO organelle descriptions

Light Microscopes

to study stained/living cells using light to magnify their structure up to 1000x

Electron Microscopes

to study the ultrastructure of cells and organelles using beams of electrons by magnifying up to millions

Prokaryotic Cells

• smaller & simpler

• filled w cytoplasm

• lack membrane-bound organelles (ex:nucleus)

• small ribosomes

• genetic material: 1 continuous, circular DNA molecule

• cell wall: lipid layer of peptidoglycans

• asexual

Eukaryotic Cells

• larger & more complex

• contain membrane-bound organelles (ex: nucleus)

• genetic material: linear DNA molecules

• may reproduce sexually or asexually

Plasma Membrane

lipid bilayer

surrounds and protects cell

regulates movement of substances in & out

Peripheral Proteins: lightly connected to the lipid bilayer

Integral Proteins

embedded in or attached to the plasma membrane to control transport, signaling, & cell recognition

Amphipathic: bound to plasma membrane

Transmembrane: extend through plasma membrane

Fluid-Mosaic Model

arrangement of phospholipids and proteins for flexibility in lipid bilayer

Adhesion Proteins

form junctions between adjacent cells

Receptor Proteins

docking sites for arrivals at the cells

ex: hormones

Transport Proteins

form pumps that use ATP to transport solutes across the membrane

Channel Proteins

form channels to selectively allow passage to certain ions/molecules

Glycoproteins & Glycolipids

cell surface markers for cell recognition/adhesion on extracellular surfaces

Carbohydrate Side Chains

on outer plasma membrane

polysaccharides, disaccharides, monosaccharides

Nucleus

largest

directs cell activity/reproduction

hereditary info (DNA) into chromosomes

Chromosomes

Where rRNA is made & ribosomes assemble

Ribosomes

protein synthesis

free floating or on ER

subunits: large and small

made of ribosomal RNA & proteins

Endoplasmic Reticulum

mechanical support & transportation

smooth ER: no ribosomes, makes lipids, hormones, steroids, & toxic chemical breakdown

rough ER: ribosomes, compartmentalizes cell

Golgi Complex

• modify, process, sort products of ribosomes on rough ER (protein synthesis)

• packaging + distribution for materials sent out of cell

Vesicles

liquid-filled membrane sacs that transport materials throughout and to the outer cell

Mitochondria

stations that convert energy from organic molecules

• most common energy molecule: ATP

Inner Portion: inner mitochondrial membrane form folds (Cristae) and separates innermost area (Matrix) from inter-membrane space

Outer Portion: separates inter-membrane space and cytoplasm

Lysosomes

sacs to carry digestive enzymes and break down old organelles, debris, injected particles

• made when vesicles w/ specific enzymes from trans golgi fuse w/ vesicles made during endocytosis

• essential for Apoptosis

Apoptosis

programmed cell death

Trans Golgi

last compartment in golgi complex proteins pass through before packaging vesicles

Vacuoles

fluid filled sacs: store water, food, wastes, salts, or pigments

multiple functions in plant cells

Peroxisomes

detoxify various substances: Hydrogen Peroxide byproduct

• enzymes to break H2O2 → O & H2O

Cytoskeleton

network of protein fibers determining shape

• microtubules: made of the protein tubulin, work in cell division and movement

• microfilaments: important for movement. Rod-like Actin structures. Actin monomer joined and broken apart to allow microfilaments to grow & shrink

Cilia & Flagella

locomotive properties in single-celled organisms

• beating motion of structure allows movement

Plant vs. Animal cells

Plant

• have cell wall (cellulose) and chlorophyll

• central vacuole pushes cytoplasm to edges

• no centrioles: structures for cell division aid

Transport

molecule movement across membrane

• Semipermeability of plasma membrane

• size & charge of the passing particle

• “Like Dissolves Like“

  • Nonpolar/hydrophobic pass through the phospholipid bilayer/cell membrane bc they are like

  • large/hydrophilic/polar need assistance to pass (facilitated transport)

Passive Transport

Subastance moving bye diffusion w/ no outside energy

Simple Diffusion: when diffusing molecule is hydrophobic; the small/Nonpolar molecule drifts through

Facilitated Diffusion: diffusion requiring help from a channel-type protein

Osmosis

diffusion vs. osmosis, no membrane permeable to solute

plant cell wall defends against osomtic changes (shifts in concentration of solutes)

Plasmolysis

cell loses water and membrane shrinks from the wall

Deplasmolysis: cell gains water and membrane expands and squeezes against the wall

Tonicity

how much water moves in/out of cells based on concentration of solutes on the outside—osmotic gradients

Hypo-tonic: water outside>, water→cell

• dissolved solutes<cell dissolved solutes

Hyper-tonic: water inside>, water ← cell

• dissolved solutes>cell dissolved solutes

Iso-tonic: equal water & solutes, no movement

Osmotic Gradients

water differences, moves from high concentration to low concentration

Water Potential (Ψ)

measure of potential energy in water; eagerness of water to flow from high→low water potential

pressure potential (Ψp)

solute potential (Ψs)

• Ψs = -iCRT

• added solute = lower water potential

Active Transport

movement against the natural flow

• some plasma membrane proteins powered by ATP

  • pump depends on ATP to get ions across to lower concentration regions

Primary Active Transport: ATP is directly utilized in transport

Secondary Active Transport: When transported using secondhand energy—captured from movement of another substance flowing down the concentration gradient

Endocytosis

cell takes in substances from outside by engulfing it in its cell membrane

• when particles too large want to enter vacuole or vesicle forms around it

Pinocytosis: cell ingests liquids

Phagocytosis: cell takes in solids

Receptor-Mediated Endocytosis: cell surface receptor work w/ endocytic pits lined w/ protein clathrin

• when particle/ligand binds to a receptor, it is folded into membrane

Bulk Flow

one-way movement of fluids caused by pressure

ex: blood through blood vessel

Dialysis

diffusion of solutes across a selectively permeable membrane

• Kidney DIalysis: specialized process to filter blood w/ machines and concentration gradients

Exocytosis

cell ejects waste products or specific secretion products like hormones by the fusion of a vesicle w/ plasma membrane

• expels content into extracellular space