Biology Chapter 3
BSCS Biology: A Molecular Approach Chapter 3 Notes
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- Cell membranes have 2 thin phosphlipid layers that are
- fluid with embedded proteins.
- Waste excretion also needs special structures
- contractile vacuoles in unicellular organisms; kidneys in animals.
- Endocytosis
- molecules move in
- Ex. of Multicellular Organisms
- gills in fish; lungs in animals; spiracles in insects; stomates in plants.
- Hypertonic
- too little water and can shrivel (crenation)
- In drought or dark the guard cells
- close the stomata (minimizing transpiration-loss of water.)
- Semi permeable helps to
- maintain homeostasis balance.
- Many ions and other substances necessary for life processes need to
- get in the cell.
- Exocytosis
- molecules move out
- Membranes may fold in and
- close over molecules that its taking in - phagocytosis
- Passive transport
- no energy needed
- Transport proteins can
- "carry" charged/uncharged particles across membranes.
- 3 Types of Concentration
- isotonic; hypotonic; hypertonic
- Hypotonic
- too much water and can lyse
- Ex. of small molecules permeating freely
- water and alcohol
- Transport proteins can bind to
- charged particles (ions) or large uncharged polar molecules (glucose nucleotides)
- Ex. of Diffusion
- CO2; O2; food.
- Diffusion
- movement of molecules from an area of greater to lesser concentration until they're equal.
- Osmosis
- diffusion of H2O from high to low concentration
- Small molecules permeate
- freely.
- Isotonic Concentration
- equal amounts of solute + water in and out of the membrane.
- Hypertonic Concentration
- high amount of solute + low amount of water outside the cell-water moves out; cell shrinks; in plants this is plasmolysis (wilting).
- The function of the membrane is to regulate what is
- permitted entry/exit.
- Sugars attached to the lipids & the proteins form the
- surface of the cell and are unique for recognition purposes.
- Concentration gradient
- amount of difference in concentration
- Materials are transported
- with or without energy; depending on the concentration.
- Both passive transports continue until they are
- evenly distributed
- Phagocytosis uses
- psuedspods - WBC
- High osmotic pressure
- high solute = hypertonic
- Plants guard cells on each side of the stomates well with
- water and open to allow CO2 in and H2O + O2 out.
- Osmosis - diffusion
- movement of water form high to low
- Many chemical reactions can dissolve (soluble) directly into the
- water surrounding the cell.
- Transport proteins are a.k.a.
- carrier proteins.
- Hypotonic Concentration
- low amount of solute + high amounts of water outside the cell-water moves in; turgid
- Humans air travels from
- nose-pharynx-tracheae-bronch-alveoli (60m2)-lungs
- Facilitated Diffusion
- passive transport that needs a carrier protein.
- Multicellular organisms require:
- specialized structures with lg. surface area.
- Gases exchanged by diffusion in unicellular organisms is
- diffused directly into the water.
- Low osmotic pressure
- low solute = hypotonic
- Active Transport
- energy (ATP) needed to move against concentration gradient.
- Humans; blood plasma filtered by nephrons in kidneys after reabsorption of
- Na; K; and water-ureter-urinary bladder-urethra out of the body
- Isotonic
- equal amt. of solute on both sides