prokaryotes are a single-celled organism that has no nucleus has one chromosone, with naked DNA that is not associated with protein reproduces

ribosomes synthesize protein according to the mRNA sequence within the cell

made of ribosomal RNA (rRNA) and proteins
has a large and small subunit
either free (majority) or bound ribosomes
- free ribosomes produce proteins
- bound ribosomes are used to exporting

✦﹒the endoplasmic reticulum (ER) is a network of membrane tubes

rough ER synthesizes with proteins that are generally secreted by the cell
- has ribosomes attached to membrane
- compartmentalizes the cell
  - packages newly synthesized proteins made by attached ribosomes for possible export from the cell
  - as proteins are produced by rough ER, polypeptide chains travel across ER membrane and into cisternal space
smooth ER functions in diverse metabolic processes, varies in cell type
- has no attached ribosomes
- processes include synthesis of lipids, metabolism of carbs, detoxification of drugs and poisons, and storage of calcium ions

✦﹒the golgi apparatus is the warehouse of receiving, sorting, manufacturing, and shipping proteins

involved in the correct folding and chemical modification of newly synthesized proteins and packaging for protein trafficking

✦﹒the mitochondria is the powerhouse of the cell (had to say it)

functions in production of ATP energy that is used for cell work
has a double membrane
- outer membrane is smooth
- inner membrane is highly convoluted, forming folds called cristae
  - cristae help increase the surface area to enhance the productivity of cellular respiration, allows more ATP to be made
  - electron transport and ATP synthesis occur there

✦﹒the lysosome is the trashcan of the eukaryotic cell

a membrane-enclosed sac of hydrolytic enzymes that are used to digest (hydrolize) macromolecules or damaged cell parts
works best in a acidic environment
- breaking open/leaking will result in malfunctioning of enzymes

✦﹒vacuoles are membrane-bound sacs that are found in eukaryotic cells

perform a variety of functions—
- contractile vacuoles pumps excess water out of the cell to maintain concentration of ions + molecules and water balance
- releases waste from a cell
- stores water
central vacuoles play a major role in plant cell growth
- a major difference between animal and plant cells
- can take up 80% of volume, typically the largest compartment of cell

✦﹒chloroplasts are the site of photosynthesis

found in photosynthetic eukaryotic cells
has a double outer membrane
captures energy from the sun and producing sugar for the organism
contains thylakoids that are highly folded to increase the efficiency of light dependent reactions

cells are small because they have a high surface area-to-volume ratio (SA:V)

a high SA:V makes a more efficient exchange of materials with the environment
limitations can restrict cell size and shape
to calculate the SA:V—
- SA = 4πr²
- V = 4/3πr³
- SA/V = SA:V
- a high value = high SA:V = smaller cell cell membranes provide a boundary between the interior of the cell and the outside environment
  - this is thanks to phospholipids, which form a bilayer in the environment
    - is amphipathic, with a polar head and nonpolar tails
  - embedded proteins on the membrane are either hydrophilic or hydrophobic
    - peripheral proteins are loosely bound to the surface of the membrane
      - hydrophilic with charged and polar side groups
    - intergral proteins can be either hydrophobic/philic
      - hydrophobic protein has nonpolar side groups that penetrate the hydrophobic interior of bilayer
    - these proteins have a variety of functions like transport, cell-cell recognition, enzymatic activity, signal transduction, etc.
  ✦﹒the fluid mosaic model illustrates the the framework of the cell membrane
  - structure is not static and is held together mostly by hydrophobic interactions
  - a mosaic of protein molecules in a fluid bilayer of phospholipids
  - consists of lipids, proteins, cholesterol, and carbs
    - cholesterol is a hydrophobic steroid that regulates bilayer fluidity under certain conditions
      - high temp →less fluid membrane
      - low temp → helps retain fluidity
  fluid mosaic model with labeled areas of the membrane proteins’ functions
  ✦﹒the cell membranes are selectively permeable
  - small nonpolar molecules (N₂, O₂, CO₂) can pass freely
  - hydrophilic substances (large polar molecules + ions) cannot pass the membrane freely
    - to pass the membrane, they go thru transport proteins
      - channel proteins are a hydrophilic tunnel that allows specific molecules to pass through
      - carrier proteins change shape to move a target molecule from one side of the membrane to the other
  - small molecules like H₂O can pass the membrane, but at a relatively small amount
    - large amounts of H₂O pass thru channel proteins called aquaporins
  - plants, fungi, and prokaryotes have cell walls which have permeability as well
    - permeable via the plasmodesmata which are small holes between the plant cells
    - composed of complex carbohydrates
      - plants → cellulose, fungi →chitin, prokaryotes →peptidoglycan passive transport is the movement of molecules from a high to low concentration, without the use of energy
        diffusion is a type of passive transport in which small nonpolar molecules (O₂, N₂, CO₂) pass freely
        facilitated diffusion is also a type of passive transport that involves transport proteins
        typically for transferring hydrophilic molecules
        visual of the passive transport types
        ✦﹒active transport is the movement of molecules from a low to high concentration (against the concentration) using energy (ATP)
        uses carrier proteins called pumps
        cotransport is a secondary active transport that uses energy from a electrochemical gradient to transport two different ions across the membrane through a protein
        visual of cotransport osmosis is the diffusion of water across a selectively permeable membrane
        water likes to go to an area of high solute concentration (low→high)
        solutes like to go to an area of low solute concentration (high→low), goes along their own gradient
        tonicity is the measurement of the relative concentrations of solute between two solutions (inside and outside of cell)—
        hypotonic is more solute, less solvent
        too much of this can cause the cell to burst/be lysed
        isotonic is equal concentrations
        hypERtonic is less solute, more solvent
        cell is shriveled, likely would die
        visual of tonicity with red blood cells
        ✦﹒water potential measures the tendency of water to move by osmosis
        in this case, water moves from high water potential→low water potential
        the more negative the water potential, the more likely water would move into the area
        ✦﹒osmoregulation is the regulation of and organism’s internal solute composition and water potential and water balance
        increase in amount of solute in water will cause..
        inc in solute potential
        dec in water potential
        decrease in pressure potential → decrease in water potential
        ✦﹒there are equations for calculating potentials…
        in an open system, the pressure potential is zero, so water potential is equal to the solute potential →ψ = ψ_p + ψ_s
        ψ_p= pressure potential, ψ_s = solute potential
        ψ_s = -iCRT
        i = ionization constant, c = molar concentration, r = pressure constant, t = temp in kelvin (temp in Celsius + 273 = temp in Kelvin)