Chapter 5 Bio
An example of inorganic (without carbon) cofactor is __________ .
an ion, such as iron
When molecules are ____________ there is no net movement of molecules across a membrane.
at equalibrium
Small and nonpolar molecules can easily diffuse through the phospholipid bilayer. Examples of these are:
carbon dioxide and oxygen
All of the functions of proteins on the plasma membrane of a cell:
cell junctions, glycoproteins, receptors, attachment, transport, enzymes, and channel
Organic cofactors are called
coenzymes
Enzymes often need non-protein molecules to help catalyze the reaction. These molecules, often vitamins and minerals, are called __________ .
cofactors
A ______________ is a molecule that blocks the substrate from entering the active site, therefore decreasing enzyme activity.
competitive inhibitor
This exists when the density of molecules in one region is higher or lower than another region.
concentration gradient
The random movement of molecules from an area of high concentration to low concentration is called
diffusion
Molecules will move down their concentration gradient (from an area of high concentration to low concentration). This movement does not require energy and is therefore considered:
diffusion and passive transport
Identify possible enzyme inhibitors you may encounter in society. These molecules may bind permanently to the enzyme or are reversible.
drugs, pesticides, and poisons
True or False: At the end of a chemical reaction, enzymes are used up. The cell must remake the enzyme in order for another chemical reaction to occur.
false
The final product of many metabolic pathways are often inhibitors of an enzyme early in the pathway. This type of inhibition is called _____________ inhibition
feedback
The plasma membrane forms a barrier that prevents some molecules from crossing the membrane. These molecules are often very polar, large, or ions. An example of a polar molecule that cannot diffuse across the membrane unassisted is
glucose
A solution where the concentration is greater than inside the cell.
hypertonic
A solution where the concentration is less than inside the cell.
hypotonic
When an enzyme binds the substrate, it changes shape. This change is shape is called _________ .
induced fit
A solution where the concentration is equal to that inside the cell.
isotonic
Enzymes speed up chemical reactions by __________ the activation energy of a reaction.
lowering
A ________________ is a molecule that binds to the enzyme at a location other than the active site, causing the active site to change shape. This also decreases the enzyme activity, as the active site no longer fits the substrate correctly.
noncompetitive inhibitor
The ability to control water balance inside a cell.
osmoregulation
Nature prefers to be at equilibrium, therefore molecules diffuse down their concentration gradient. When large, polar, or ionic molecules form a concentration gradient, water will move across the membrane an attempt to create equal concentrations on both sides of the membrane. Just like you would dilute really sweet tea. This movement of water is called
osmosis
The fluid mosaic model describes the plasma membrane as having:
phospholipid bilayer and diverse proteins
The substrate of an enzymatic reaction is a
reactant
The plasma membrane all some substances to cross more easily than others. The regulation of exchange of material across the membrane is called
selective permeability
Activation energy is best described as the energy needed to _________ a chemical reaction. This energy is required to break bonds between atoms and make new ones.
start
Choose all of the conditions that may affect the function of an enzyme. Changing these conditions may cause the protein to denature!
temperature and PH
A substrate binds to (attaches to) which region of an enzyme?
the active site
the steps of the catalytic cycle.
the enzyme has empty active sites, the substrate binds the active site, a chemical reaction forms: products are made, and the enzyme releases the products.
The ability of a surrounding solution to cause the cell to gain or lose water
tonicity
An example of a cofactor is
vitamin B
Transport of bulky material into the cell.
Endocytosis
Transport of bulky material out of the cell.
Exocytosis
Many molecules cannot enter the cell because they are either too polar or are ions. Sometimes, these molecules enter the cell through facilitated diffusion. What statements are true about facilitated diffusion?
Facilitated diffusion does not require energy and Facilitate diffusion requires a transport protein on the membrane.
A type of endocytosis referred to as "cell eating"
Phagocytosis
A type of endocytosis that enables the cells to acquire very specific molecules
Receptor-mediate endocytosis
Membranes spontaneously self-assemble. Think back to Chapter 3. Why?
The membrane is composed of 2 layers of phospholipids. The hydrophobic tails of the phospholipids cluster on the inside of the membrane and the hydrophilic heads are on the outside interacting with water.
in animal cells, a hypotonic solution will..
Water moves into the cell. The cell is lysed.
in animal cells, a hypertonic solution will...
Water moves out of the cell. The cell is shriveled.
The opposite of passive transport is active transport. Select all statements that are true of active transport.
Active transport requires energy, Active transport uses a transport protein to move molecules into or out of the cell, Active transport moves molecules from an area of low concentration to high concentration, and Active transport moves molecules against the gradient.
