Chapter 5: The Working Cell Flashcards
Understand how cells intake substances.
Biologists use what model to describe the cell membrane’s structure?
They use the fluid mosaic model- diverse protein molecules suspended in a fluid phospholipid bilayer.
What other terms are used to denote “Cell Membrane”?
Plasma Membrane, Plasmalemma, Phospholipid Bilayer
What property does the phospholipid bilayer exhibit?
Selective permeability
What functions do membrane proteins perform?
-attachment
-receptors
-diffusion
-facilitated diffusion
-active transport
-intercellular junctions
-enzymatic reactions
-cell signaling (glycoprotein labels)
What is passive transport?
Diffusion across a cell membrane, which requires no ATP. Diffusion is the tendency of particles to spread evenly out.
What is osmosis?
Diffusion of water across a selectively permeable membrane. Water crosses the membrane, moving down the water’s concentration gradient, until the solute concentration on both sides is equal.
Tonicity
the ability of a surrounding solution to cause a cell to gain or lose water by osmosis
Hypertonic
Cells shrink in this type of solution
Hypotonic
Cells swell in this type of solution.
Isotonic
In this type of solution cells neither swell nor shrink.
What type of organelles deal with tonicity?
-water vacuoles
-contractile vacuoles
Hydrophobic
These substances easily diffuse across a cell membrane.
Polar/Charged
These substances do not easily cross cell membranes. They move across via specific transport proteins.
Facilitated Diffusion
The use of transport proteins to move substances across the membrane.
-Does not require ATP
-Relies on a substance’s concentration gradient
One such protein is called aquaporin, allowing very rapid diffusion of water.
Active Transport
Costs energy to move a solute against it’s concentration membrane. ATP is used.
-Transport protein is bonded to by solute
-ATP provides energy for the change in protein shape
-Protein returns to original shape, more solute can bind
Exocytosis
Used to export (send out) large, bulky molecules, such as proteins or polysaccharides. Material to be transported is packaged within a vesicle that fuses with the membrane.
Endocytosis
Used to import (take in) large, bulky molecules. Material to be transported is packaged within a vesicle that fuses with the membrane.
Kinds of Endocytosis
Phagocytosis is the engulfment of a particle by the cell wrapping cell membrane around it, forming a vacuole.
Receptor-mediated endocytosis uses membrane receptors for specific solutes.
***In both cases, material to be transported is packaged within a vesicle that fuses with the membrane.***
Energy and The Cell
Energy is the capacity to cause change.
Kinetic energy is the energy of motion.
Potential energy is energy stored in the location or structure of matter. It includes gravitational potential energy and chemical potential energy.
According to the laws of thermodynamics,
energy can change form but cannot be created or destroyed, and
energy transfers or transformations increase disorder, or entropy, with some energy being lost as heat.
Exergonic Reaction
-Release energy
Endergonic Reaction
-requires energy and yields products rich in potential energy.
Cell Metabolism
-encompasses all of a cell’s chemical reactions.
Adenosine triphosphate (ATP) powers nearly all forms of cellular work.
The transfer of a phosphate group from ATP is involved in chemical work, transportation work, and mechanical work.
Hydrolysis
Hydrolysis is a chemical reaction in which a chemical compound is broken down by reaction with water.
It is a chemical process in which a molecule is cleaved into two fragments by the addition of a molecule of water.
What are enzymes?
Catalysts that Speed Up Cellular Reactions by Decreasing the Activation Energy (EA) Needed for a Reaction to Begin, Without Being Consumed by the Reaction.
Steps of enzyme catalyst in cellular reactions
- the enzyme is available with an empty active site
- The substrate enters the active site, which enfolds the substrate with an induced fit.
- The substrate is converted to products.
- The products are released.
Enzyme Inhibitors
A competitive inhibitor reduces an enzyme’s productivity by blocking substrate molecules from entering the active site.
A noncompetitive inhibitor does not enter the active site. Instead, it binds to a site elsewhere on the enzyme, and its binding changes the enzyme’s shape so that the active site no longer fits the substrate.
Feedback inhibition helps regulate metabolism.
