Biology Quiz #2 Flashcards
Particle Model of Matter (4)
- All matter is made of particles with varying size &composition
- Particles are constantly in motion (adding & removing energy affects the movement)
- Particles are attracted to one another or bonded together
- Particles have spaces between them (spaced may be occupied by particles of another substance)
What are the two methods which molecules move in and out of cells?
- Passive Transport 2. Active Transport
Passive Transport
-Does NOT require additional energy -Includes simple diffusion, osmosis, facilitated diffusion
Active Transport
Requires energy & transport proteins because it is the movement of molecules against the concentration gradient
Simple Diffusion
Molecules moving from high concentration to low, until the concentration is equal
- Caused by the collision of particles
- Passive because no extra energy is required
- All molecules diffuse but not at the same rate
Concentration gradient
The difference in concentration between two points
Diffusion Rate is affected by..
- Size of molecules (small molecules=faster diffusion)
- Temperature (high temp.= more energy =faster diffusion)
- Concentration (higher conc. = more collosions =faster diffusion
- Medium through which it travels (solids restrict diffusion)
Osmosis
The diffusion of water across a semipermeable membrane
- relies solely on the concentration gradient
- cells are in extracellular fluid: solution consisting of a solvent and solute
Tonicity
- Used to determine the direction of diffusion
- ability of an extracellular solution to make water move into or out of a cell by osmosis
Hyoptonic
Concentration of water greater on the outside
-movement of water into swell (causes cell to swell)
Hypertonic
Concentration of water is greater on the inside
-movement of water out of the cell (causes cell to shrink)
Isotonic
Concentration equal both in & out of cell
-water moves into & out of the cell at same rate
Crenation
-process of cell losing water and shrinking
Cytolysis
Swelling & bursting of cell
Osmoregulation
The control of water balance
Turgor Pressure
Plants rely on osmosis to regulate the water pressure exerted on the inside of their cell walls
-no turgor pressure = plants wilt
Plasmolysis
Occurs when cell membrane of plant cell shrinks away from cell wall due to being placed in a hypotonic environment
Deplasmolysis
Re-hydration of plant cell due to being placed in a hypotonic environment
Water Potential (4+formula)
- Water uptake/loss must be balanced
- Water moves by osmosis
- Cell walls add physical pressure which affects osmosis
- Water potential (Ψ) takes both solute and physical pressure
- Formula: Ψ = Ψs + Ψp
Adding solute does what to the water potential?
Adding solute lowers water potential because there is less free water molecules (less capacity to do work) -the Ψs is negative
Facilitated Diffusion (5)
Only matter that is soluble in lipids can pass through the lipid bilayer by simple diffusion
- water soluble particles use the protein channels to move across the membrane by diffusion
- small molecules & ions pass through the pores created by the channel proteins
- big molecules are helped across the membrane by the transport proteins
- molecules are moving down the concentration gradient, therefore no extra energy is needed
Membrane Technologies (6)
- industrial use of synthesis to mimic actions of membrane
- study of receptor proteins that bind with specific molecules to bring them into the cell by endocytosis
- useful in the study of HIV & cancer
- focus on recognition of receptor proteins to prevent virus from getting in
- develop drugs that target the unique proteins of cancer
- development of drugs that stimulate the immune system to detect & destroy cancer cells
Synthetic Membrane Technologies (3)
- liposomes are fluid-filled sacs surrounded by a phospholipid bilayer identical to the membrane in human cells
- used to deliver drugs to infected tissues in a controlled delivery system
- inside holds water-soluble medicine while the bilayer holds fat-soluble medicine
Advantages to Synthetic Membrane Technologies
- Liposomes stay in blood for longer than medication on it’s own
- Delivers treatment to target cells only (no harm to other cells)
- Used in gene therapy to inject DNA into cancer cells to kill them
Dialysis
- rid body of toxins, wastes, & excess fluids
- two types available to people with kidney failure (hemodialysis & peritoneal dialysis)
- both based on the principle of diffusion & osmosis
Hemodialysis (“hemo” = bloodcells)
- must be performed in hospital
- blood removed from body, cleansed, returned to body
Peritoneal Dialysis
- soft catheter inserted into abdominal cavity
- sterile dialysate fluid pumped into cavity
- toxins move down the concentration gradient into the fluid which is then removed from body
Surface Area to Volume Ratio (sa/v)
- amount of membrane (sa) around a cell in relation to the size of cell (volume) determines how many molecules will pass in and out of cell
- cells divide to maintain a high surface area to volume ratio
- cell grows larger = sa/v ratio drops til cell is not efficient = growth slows = cell divides
- organisms have specialized structures to help increase overall SA/V ratio