LO 3.1-3.2 Cellular level of organization & Protein Synthesis Flashcards
How many cells are in the human body?
100 trillion cells
200 types, and they vary in size
Define: Cell
Basic, living, structural and functional unit of the body
Define: Plasma Membrane
- Separates the internal part of the cell from the outside environment
- Regulates what enters and leaves the cell
- Also called the fluid mosaic model
- Composed of a phospholipid bilayer
Define: Cytoplasm
Everything in the cell between the membrane and the nucleus
- contains cytosol and organelles
Define: Nucleus
- largest organelle
- contains most of the cell’s DNA
What is found within the phospholipid bilayer?
1) Cholesterol
2) Integral proteins
3) Peripheral proteins
4) Carbohydrates
Define: Cholesterol in the phospholipid bilayer
- Found on both sides of the phospholipid bilayer
- Adds a bit of stiffness to the membrane
Define: Integral proteins in the phospholipid bilayer
- “Channel proteins”
- Inserted in lipid bilayer, extending through the entire bilayer
- Allow passage of non-lipid soluble materials in and out of cell
Define: Peripheral proteins in the phospholipid bilayer
- Loosely attached to inner and outer surface of membrane
- Some are enzymes required for movement of materials
- Cytoskeleton of cytoplasm anchored to these proteins helps maintain shape of cell
Define: Carbohydrates in the phospholipid bilayer
- Provide recognition sites for cell interactions
- Attached to the outer surface of some lipid molecules (glycolipids)
- Attached to the outer surface of some integral proteins (glycoproteins)
- identifies cells the same to yours for organ transplants
Which factors affect the passage of materials?
Lipid Solubility, Size, Charge, Channels and Carriers
Define: Lipid solubility
- Most of the membrane is lipid and hydrophobic
- Lipids pass freely through the membrane
- Polar material (water, salts, acids, etc.) do NOT pass
Define: Size
Small molecules generally cross more readily than large molecules
Define: Charge
Charges on the membrane attracts ions of opposite charge, then move them through the protein channels
Define: Channels and Carriers
- Channels in integral proteins facilitate passage of charged and polar molecules
- Carrier molecules carry large molecules through protein channels
Define: Passive transport
- does not use energy from the cell, uses only kinetic energy of molecules involved
Define: Concentration gradient
- Molecules move from HIGH to LOW concentration.. Down the concentration gradient
How does passive transport move along the concentration gradient?
In passive transport, molecules tend to move from an area of high concentration to an area of lower concentration
Passive Transport:
Simple diffusion
- Takes place through the phospholipid bilayer or without a membrane as with sodium chloride in water
Passive Transport:
Facilitated Diffusion
- Accomplished with the assistance of an integral membrane protein that serves as a carrier or transporter
- Allows lipid insoluble and large molecules such as amino acids and CHOs to enter and exit the cell
- No energy needed
- Moves down the concentration gradient (high to low)
Facilitated diffusion allows molecules to move faster then by simple diffusion. What is this rate affected by?
- Concentration gradient
- Amount of carrier protein available
- How quickly the molecule attaches to the carrier
Passive Transport:
Osmosis
Movement of water across a selectively permeable membrane to an area where there are more water molecules to an area with less water molecules
- No energy needed
- Moves from high to low H2O concentration
Passive Transport:
Isotonic solution
When the water and solute concentration of intracellular and extracellular fluid is identical
- Water movement into the cell equals movement of water out of the cell
- Isotonic solution of saline for RBC = 0.85%
Passive Transport:
Hypotonic Solution
Hypotonic = When a cell is placed in a solution having a lower concentration of solute than found inside the cell
- Water will move inside the cell
- Cell will swell and burst
- In a RBC this is called hemolysis
