Unit 2: Biochemistry of the Cell Flashcards
Forms the cell’s flexible outer surface, separating the cell’s internal environment from the external environment
Plasma Membrane
What consists of the structure of the plasma membrane?
Lipid Bilayer
Arrangement of Membrane Proteins
- Basic structural framework of the plasma membrane.
- Two back-to-back layers made up of three type of lipid molecules.
Lipid Bilayer
What lipid molecules make up the lipid bilayer
Phospholipids
Cholesterol
Glycolipids
Why does the bilayer arrangement occur?
Because the lipids are amphipathic molecules, which means that they have both polar and nonpolar parts.
In phospholipids, which parts are the polar and nonpolar parts?
The polar part if the phosphate-containing “head” (hydrophilic)
The nonpolar parts are the two long fatty acid “tails” (hydrophobic hydrocarbon chains.)
Membrane proteins are classified according into what?
Whether they are firmly embedded in the membrane integral proteins extend into or through the lipid bilayer and are firmly embedded in it.
What are the classifications of membrane proteins?
Integral Proteins
Peripheral Proteins
Are transmembrane proteins, which mean that they can span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid.
Integral proteins
Are proteins that are not as firmly embedded in the membrane.
Attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane.
Peripheral proteins.
A passive process where substances move freely through the lipid bilayer of the plasma membrane without the help of membrane transport proteins.
Simple diffusion
What type of molecules move across the lipid bilayer through the process of simple diffusion?
Nonpolar, hydrophobic molecules
- Solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion.
- An integral membrane proteins assists a specific substance across a membrane.
- Integral membrane protein can be either a membrane channel or a carrier.
Facilitated Diffusion
- A type of diffusion in which there is a net movement of a solvent through a selectively permeable membrane.
- A passive process.
Osmosis
In living systems, what is the solvent in osmosis?
Water
What happens to the water as a solvent during osmosis?
Moves by osmosis across the plasma membranes from an area of higher water concentration to an area of lower water concentration.
During osmosis, how does water molecules pass through a plasma membrane?
- By moving between neighboring phospholipid molecules in the lipid bilayer via simple diffusion
- By moving through aquaporins, integral membrane proteins that function as water channels.
Consists of all the cellular contents between the plasma membrane and the nucleus
Cytoplasm
What are the two components of the cytoplasm?
Cytosol
Organelles
- The fluid portion of cytoplasm.
- Also called intracellular fluid
- Contains water, dissolved solutes, and suspended particles.
- The fluid which many of the cell’s metabolic reactions occur.
Cytosol
- A network in the cytoplasm composed of three protein filaments
- Maintains shape and general organization of cellular contents
- Responsible for cell movements
The cytoskeleton
What are the three protein filaments that composes the cytoplasm?
Microfilaments
Intermediate Filaments
Microtubules
- Specialized structures with characteristic shapes
- Has specific functions
Organelles
- Very small rounded bodies found on both ends of the nucleus.
- Regulate the rate of cell division and multiplication
- Contains centriole
Centrosome
