Chapter 3: Cells Flashcards
Plasma Membrane
Separates internal metabolic events from the external environment and controls the movement of materials into and out of the cell.
Cell
The basic functional unit of all living things.
Cytoplasm
Made of organelles suspended in the cytosol
Cytosol
A fluid matrix which consists of water and dissolved substances such as proteins and nutrients
Double phospholipid membrane
Has polar hydrophilic heads forming the two outer faces and non-polar hydrophobic tails pointing inside the membrane.
Fluid Mosaic Model
The mosaic nature of scattered proteins within a flexible matrix of phospholipid molecules.
How does the fatty acid makeup influence the fluidity of the membrane?
Saturated fatty acids- pack tightly- more rigid membrane
Unsaturated fatty acids- Bend at their double bonds, not at tightly packed- more flexible
What can and can’t get through a selectively permeable membrane?
Can: Small, uncharged, polar molecules (H20). Hydrophobic molecules (O2, CO2, and lipid-soluble molecules like hydrocarbons)
Can’t: Large Polar Molecules (Glucose), All Ions
Channel Proteins
Intrinsic Proteins, provide open passageways for certain hydrophilic (water-soluble) substances such as polar and charged molecules.
Ion Channels
Allow the passage of ions across the membrane
Gated Channels
Open and close in response to stimuli to allow passage of certain ions.
Carrier Proteins
Bind to specific molecules which are then transferred across the membrane after the carrier protein undergoes a change of shape.
Transport Proteins
Uses energy (in ATP form) to transport materials. Often called Active transport. Sodium-Potassium pump uses ATP.
Recognition Proteins
Give each cell type a unique identification. Helps distinguish between self and foreign cells.
Glycoproteins
Made up of proteins with short, polysaccharide chains that extend away from the surface. Same as recognition proteins
Receptor Proteins
Provide binding sites for hormones or other trigger molecules.
In response to hormone or trigger molecule, a specific cell response is activated.
Adhesion Proteins
Attach cells, provide anchors for internal filaments, give stability to cell.
Cholesterol
Molecules that provide some stability to the plasma membranes of animal cells.
High Temps: Maintains Firmness
Low Temps: Makes Flexible
Organelles
Bodies within the cytoplasm that physically seperate the various metabolic reactions.
Contents of the Nucleus
DNA
Nuclear Envelope
Binds the Nucleus, made up of two phospholipid bilayers
chromatin
DNA which it is spread out within the nucleus as a thread-like matrix
Chromosomes
The DNA when it is condensed into rod-shaped bodies
Makeup of Chromosomes
Before division is made up of two long DNA molecules and various histone (protein) molecules.