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Chapter 5: The Working Cell
Terms in this set (25)
Which best describes the structure of a cell membrane?
proteins embedded in a bilayer of phospholipids.
Consider the following: chemical bonds in the gasoline in a car's gas tank and the movement of the car along the road; a biker at the tip of a hill and the ride he took to get there. The first parts of these situations illustrate potential energy, and the second parts illustrate kinetic energy.
potential energ...kinetic energy
A plant cell placed in distilled water will become turgid; and an animal cell placed in distilled water will burst.
The sodium concentration in a cell is 10 times less than the concentration in the surrounding fluid. How can the cell move sodium out of the cell?
Active transport- (only active transport can move solute against a concentration gradient.)
The synthesis of ATP from ADP and P...
stores energy in a form that can drive cellular work.
Facilitated diffusion across a membrane requires transport proteins and moves a solute down its concentration gradient.
transport proteins ...down
What are aquaporins?
Aquaporins are water transport channels that allow for very rapid diffusion of water through a cell membrane. They are found in cells that gave high water transport need, such as blood cells, kidney cells, and plant cells.
How do the two laws of thermodynamics apply to living organisms?
Energy is neither created or destroyed but can be transferred and transformed. Plants transform the energy of sunlight into chemical energy stored in organic molecules. Almost all organisms rely on the products of photosynthesis for the source of their energy. In every energy transfer or transformation, disorder increases as some energy is lost to random motion of heat.
What are the main types of cellular work? How does ATP provide the energy for this work?
The work of cells falls into three main categories; mechanical, chemical, and transport. ATP provides the energy for cellular work by transferring a phosphate group to a protein (movement and transport) or to a substrate (chemical).
Why is the barrier of the activation energy beneficial for organic molecules? Explain how enzymes lower EA.
Energy is stored in the chemical bonds of organic molecules. The barrier of EA prevents these molecules from spontaneously breaking down and releasing that energy. When a substrate fits into an enzyme's active site with an induced fit. Its bonds may e strained and thus easier to break, or the active site may orient two substrates in such a way as to facilitate the reaction.
How do the components and structure of cell membranes relate to the functions of membranes?
Cell membranes are composed of a phospholipid bilayer with embedded proteins. The bilayer creates the hydrophobic boundary between cells and their surroundings (or between organelles and the cytoplasm). The proteins perform the many functions of membranes, such as enzyme action, transport, attachment, and signaling.
Sometimes inhibitors can be harmful to a cell; often they are beneficial. Explain.
Inhibitors that are toxins or poisons irreversibly inhibit key cellular enzymes. Inhibitors that are designed as drugs are beneficial, such as when they interfere with the enzymes of bacterial or viral invaders or cancer cells. Cells use feedback inhibition of enzymes in metabolic pathways a important mechanisms that conserve resources.
A molecule that has the same shape as the substrate of an enzyme would tend to...
slow metabolism by blocking the enzyme's active site.
Examples of kinetic energy...
a ball rolling down a hill-heat
The movement of molecules from an area of higher concentration to an area of lower concentration is called:
Energy of activation...
gets a reaction going.
The laws of thermodynamics state that whenever energy changes occur, ____ always increases.
A plant cell is placed in a solution whose solute concentration is twice as great as the concentration of the cell cytoplasm. The cell membrane is selectively permeable, allowing water but not the solutes to pass through. What will happen to the cell?
The cell will swell because of osmosis.
acts as a biological catalyst; is a protein; supplies energy to start a chemical reaction; is specific
is the process by which cells absorb molecules (such as proteins) by engulfing them. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane. The process which is the opposite to endocytosis is exocytosis.
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via
Phospholipid molecules in a membrane are arranged with their____ on the exterior and their____ on the interior.
hydrophilic heads . . . hydrophobic tails
enables a cell to pick up and concentrate a specific kind of molecule
Living things transform kinetic energy into potential chemical energy in the ____ , when ____ is made.
chloroplast . . . glucose
Why does heating interfere with the activity of an enzyme?
It changes the enzyme's shape.
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