Chapter 3.3-Cell transport and Homeostasis Flashcards
Transport Proteins
Substances in the cell membrane that help large molecules, hydrophilic molecules, and charged ions get across
Channel and Carrier
Part of Facilitated Diffusion
Used to help with: Structural support Recognition Communication Transport
Diffusion
The movement of a substance across a membrane, due to a difference in concentration, without any help from other molecules
Passive Transport
Substances that can diffuse through the membrane are generally very small hydrophobic molecules such as oxygen and carbon dioxide
Facilitated Diffusion
Diffusion with the help of transport protiens
Type of Passive transport for large, or hydrophilic molecules, or charged ions
Channel Proteins
Form pores or tiny holes in membrane allows water.
Allows and small ions to pass through without touching the hydrophobic tails on the inside of the membrane
Carrier Protiens
Bind with specific ions or molecules
Change shape
They carry the ions or molecules across the membrane
Bond and drag molecules through lipid bilayer and release them on the opposite side
Passive Transport
Occurs when substances pass through the cell membrane without any energy input from the cell
Happens when things go from high concentration to low concentration
Diffusion
Osmosis
Facilitated Diffusion
Active Transport
Occurs when energy is needed for a substance to move across the cell membrane
Goes from low to high concentration
Energy is from energy carrying molecules called ATP
May involve transport proteins
Sodium Potassium Pump
Active transport
Sodium (Na) ions pumped out, potassium (K) ions pumped in
Both go from lower to higher concentration
Sodium ions bind with a carrier protein
Carrier protein receives a phosphate group from ATP
When ATP loses a phosphate group, energy is released
Carrier protein changes shape, pumps the three sodium ions out of the cell
Potassium ions bind to the carrier protein
Vesicle Transport
Helps very large molecules cross membrane
Active transport
Endotysis
Exotysis
Endocytosis
Vesicle transport/active transport
Moves substances into cell
Plasma membrane completely engulfs the substance, a vesicle pinches off from the membrane, and the vesicle carries the substance into the cell
Exocytosis
Vesicles Transport/Active transport
Moves substance out of the cell
Vesicle containing the substance moves through the cytoplasm to the cell membrane, the vesicle membrane fuses with the cell membrane, and the substance is released outside the cell
Homeostasis
The process of maintaining stable conditions inside a cell or an entire organism
Stable state must be maintained for cell to function normally
Concentration of substances must be kept within a certain range
Requires constant adjustments because conditions inside and outside cell are constantly changing
Processes like Active and Passive Transport help
Equilibrium
Caused by diffusion
State of balance, in which everything is equal, both inside and outside or cell
Hypotonic
Water comes into the cell
Cell gets bigger, may burst
If it bursts, called Cytolysis
Aquaporins
Water Channels
Protein pores used during osmosis
Hypertonic
Water hoes out of the cell
Cell gets smaller
When it shrivels, called plasmolysis
Isotonic
Equal amounts entering and leaving cell
Cell stays the same size
Pinocytosis
Most common form of endocytosis
Takes in dissolved molecules as a vesicle
Forms invagination, pinches off, goes into cell
Called cell drinking
Liquid
Receptor Mediated Endocytosis
Have receptors that take in certain molecules and make vesicles out of that
Phagocytosis
When cell takes in entire cell, such as bacteria or food
Called cell eating
Plasma Membrane
Made of lipid bilayer of phospholipids (double layer)
Hydrophobic molecules pass easily
Hydrophilic do not
Protective Barrier
Regulate transport in and out of cell (selectively permeable)
Allow cell recognition
Provide anchoring sites for filaments of cytoskeleton
Provide a binding site for enzymes
Interlocking surfaces bind cells together (junctions)
Contains the cytoplasm (fluid in the cell)
Phospholipids
Make up cell membrane
Contains two fatty acid chains that are non polar
Polar heads are hydrophilic (water loving)
Non polar tails are hydrophobic (water fearing)
Makes membrane selective in what crosses
Solubility
Materials that are soluble in lipids can pass through the membrane easily
Solute-substance dissolved in another substance
Cytolysis
Hypotonic solution
Cell bursts
Plasmolysis
Hypertonic solution
Cell shrivels
Solvent
Substance in which another substance is dissolved
Forms solution
Contractile Vacuole
Membrane bound organelle that collects water and then expels it to the exterior of the cell
Helps maintain equilibrium in the cell
Concentration Gradient
The way in which the diffusion moves
Ion channel
Channel in which ions move through the membrane
Turgidy
Turgidy of cells changes in different solutions
In hypotonic solutions, gets more turgid, pressured
In hypertonic solutions, gets less turgid, pressured
