A GENDA Standard Cell Membrane and Cell Transport Practice.
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Transcript of A GENDA Standard Cell Membrane and Cell Transport Practice.
AGENDA
Standard Cell Membrane and Cell Transport Practice
STANDARD Students will analyze the nature of relationships
between structures and functions in living cells. Explain the role of cell organelles for both prokaryotic
and eukaryotic cells, including the cell membrane, in maintaining homeostasis.
Explain the impact of water on life processes.
HOMEOSTASIS “Homeo” – similar; the same “Stasis” – stable Homeostasis is the balanced internal condition of
cells Also called equilibrium Example: body temperature
CELL MEMBRANE The protective boundary that separates the cell
from its environment. Made up of phospholipids in a double layer
Phospholipid bilayer
lipid
phosphate
inside cell
outside cell
PHOSPHOLIPIDS
Contain 2 fatty acid chains (Made of C, H, and O) and a phosphate group
The head is polar and hydrophilic (water loving)
The tails are nonpolar and hydrophobic (water fearing)
CELL MEMBRANE Semi-permeable and Selectively permeable
Needs to allow some materials but not all to pass through the membrane
Controls what gets in or out; the membrane is selective
CELL MEMBRANE Fluid Mosaic Model
Fluid because individual phospholipids and proteins can move side-to-side within the layer, like it is a liquid
Mosaic because of the pattern produced by the scattered protein molecules when the membrane is viewed from above
CELL MEMBRANE Accessory Proteins
Transport proteins allow passage of hydrophilic substances across the membrane Channel proteins are a type of transport protein that have a
channel through which certain molecules or ions can pass Carrier proteins are a type of transport protein that binds to
molecules and changes shape to carry them across the membrane
CHANNEL PROTEIN
CARRIER PROTEIN
CELL TRANSPORT Two Types:
Passive Transport – does not require energy Active Transport – requires energy
CELL TRANSPORT Passive transport
The cell uses no energy Materials move from high concentration to low
concentration 3 types
Diffusion Facilitated diffusion Osmosis
DIFFUSION
Does not require energy on the part of the cell.
Movement of particles from an area of high concentration to low concentration
Continues until all molecules are evenly spaced
Example: oxygen diffusing into a cell and carbon dioxide diffusing out
FACILITATED DIFFUSION Does not require
energy on the part of the cell.
Uses transport proteins to move from areas of high concentration to low concentration
Examples: glucose or amino acids moving from blood into a cell
OSMOSIS Requires no energy on the part of the cell Diffusion of water and ONLY water Moves from high concentration to low
concentration
OSMOSIS Water is very important to life! Cell survival depends on balancing water uptake
and water loss. But the cell doesn’t control water movement through the cell membrane.
Three different solutions cells may be exposed to: Hypotonic Hypertonic Isotonic
HYPOTONIC SOLUTION
The solution has a higher concentration of water and a lower concentration of solute than inside the cell.
Water moves from the solution to the inside of the cell. The cell swells and may eventually burst.
hypo – Swells, envision the cell as an expanding “o”
HYPERTONIC SOLUTION
The solution has a lower concentration of water and a higher concentration of solute than inside the cell.
Water moves from inside the cell into the solution. The cell shrinks
hyper – shrinks; “r” in hyper, “r” in shrink
ISOTONIC SOLUTION
The concentration of water and solutes in the solution is equal to the concentration inside the cell.
Water moves equally in both directions and the cell remains the same size.
iso – equal, no change in the cell’s size
CELL TRANSPORT Active Transport
The cell uses energy Actively moves molecules to where they are needed Movement from an area of low concentration to an area
of high concentration – this is hard, requires work! 3 types:
Ion pumps Endocytosis Exocytosis
ION PUMP Requires energy Molecules move through a
transport protein from low concentration to high concentration
Example: the Sodium-Potassium pump pumps NA+ ions out and K+ in. This pump is very important in nerve cells to help respond to stimuli and transport impulses
ENDOCYTOSIS
Requires energy on the part of the cell. Endo – enter; taking bulky materials into a cell. Phagocytosis – “cell eating”
Forms food vacuole and digests food This is how white blood cells eat bacteria
EXOCYTOSIS Requires energy on the part of the cell. Molecules are moved out of the cell by vesicles
that fuse with the plasma membrane Exo = exit; forces material out of the cell
Examples: hormones or wastes released from cell