Chapter 5 - The Working Cell

What has a shape and chemistry that fits the substrate molecule?

active site

What does ATP act like?

acts like an energy shuttle

Some of these enzyme inhibitors are actually?

actually substrate imposters that plug up the active site

What does ATP stand for?

adenosine triphosphate

An inhibitor disrupts the function of an enzyme by?

altering its shape

An isotonic solution has?

an equal concentration of solute

What is passive transport

is the diffusion of a substance across a membrane without the input of energy

Kinetic energy is?

is the energy in motion

What is activation energy?

is the energy that must be invested to start a reaction

What is diffusion?

is the movement of molecules to spread out evenly into the available space

If a plant cell and its surroundings are?

isotonic

What does a animal cells survival depends on?

its ability to balance water uptake and loss

In passive transport if a substance diffuses down?

its concentration gradient from where the substance is more concentrated to where it is less concentrated.

In a hypertonic environment plants cells?

lose water

A hypotonic solution has?

lower concentration of solute

Active transport allows cells to?

maintain internal concentrations of small solutes that differ from environmental concentration

What variety of functions do the cell continuously and efficiently performs?

movement energy processing production of various products

The plasma membrane consists of what?

of a double layer of fat (a phospholipid bilayer) with embedded proteins

The sodium and potassium ions move in?

opposite directions, the pump is an antiporter

The control of water balance is called?

osmoregulation

Transport proteins allow?

passage of hydrophilic substances across the membrane because they have a hydrophilic channel that certain molecules or ions can use as a tunnel

Water moves into and out of cells by?

passive diffusion

The membrane pulls away from the cell wall causing the plant to wilt, a usually lethal effect called?

plasmolysis

Water can move into a cell more readily by facilitated diffusion using?

protein channels called aquaporins

In the ATP cycle cellular work spends A T P, which is

recycled when A D P and phosphate are combined, using energy released by cellular respiration

In membrane function cells must also?

regulate the flow of materials to and from the environment

What does anabolism require?

requiring an input of energy, ATP

Plant cells have?

rigid cell walls

Plasma membranes are?

selectively permeable, regulating the cell's molecular traffic

What does ATP store?

stores energy obtained from food then releases it later as needed

Each enzyme recognizes a?

substrate

Transporters that move two molecules in the same direction are called?

symporters or cotransporters

A physical principle known as conservation of energy explains?

that it is not possible to destroy or create energy

What is tonicity?

the ability of a surrounding solution to cause a cell to gain or lose water

What is the key characteristic of enzymes?

the ability to function repeatedly

Enzymes enable metabolism to occur by reducing?

the amount of activation energy required to break the bonds of reactant molecules

What is a calorie?

the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius

What is anabolism?

the building of molecules from smaller units, requiring an input of energy, ATP

Energy is defined as?

the capacity to cause change

What is osmosis?

the diffusion of water across a selectively permeable membrane

What is cellular respiration?

the energy-releasing chemical breakdown of fuel molecules and the storage of that energy in a form the cell can use to perform work

What happens after the products are released from the active site?

the enzyme can accept another molecule of its substrate

What is chemical energy?

the molecules of food, gasoline, and other fuels have a form of potential energy

What is 2/2 things are body does with cellular respiration?

the rest of the energy released by the breakdown of fuel molecules generates body heat

What is primary active transport?

the sodium-potassium pump is one type of active transport system

A transport protein is specific for?

the substance it moves

The energy in phosphate transfer enables?

the transport of ions and other dissolved substances across the membranes and drives the production of a cell's large molecules

Enzymes are named by?

their substrates, but with an -ase ending.

Cellular energy is used to drive a?

transport protein that pumps a solute against the concentration gradient

If a substances do not cross membranes spontaneously, or otherwise cross very slowly it can be?

transported via proteins that act as corridors for specific molecules

An enzyme is?

very selective in the reaction it catalyzes (speeds up)

Low potential is a example of?

a ball not moving at the bottom of the stairs

High potential energy is a example of?

a ball not moving at the top of the stairs

Kinetic energy is a example of?

a ball rolling down the stairs

What is a substrate?

a certain reactant molecule

Each step in metabolism is catalyzed by?

a specific enzyme

When is entropy increases?

every time energy is converted from one form to another

What are enzymes?

proteins that speed up chemical reactions without being consumed by the reaction

What do molecules constantly do?

vibrate and wander randomly

Hydrophobic (nonpolar) molecules are?

water hating

Hydrophilic molecules are?

water loving (polar)

What does catabolism do?

The breakdown of molecules into smaller units, producing ATP

What does metabolism do?

The building and breaking down of carbon sources to harness or release energy

In metabolism many of the reactions are linked in such a way that?

The products of one are the reactants of the next, forming pathways

What may be used to power microscopic robots?

Cell-based nanotechnology

What is metabolism?

Is the totality of an organism's chemical reactions

Potential energy is?

is stored energy

What is entropy?

is a measure of disorder, or randomness, in a system

In what cases are an inhibitor disrupts the function of an enzyme by altering its shape?

Enzyme and substrate binding normally Enzyme inhibition by a substrate imposter (competition) Inhibition of an enzyme by a molecule that causes the active site to change shape (non-competitive)

What can you think of a cell as?

A machine that continuously and efficiently performs a variety of functions

What does a metabolic pathway begin with?

A specific molecule and ends with a product

What does catabolism produce?

ATP

What is heat?

is a type of kinetic energy contained in the random motion of atoms and molecules

What factors that may affect enzyme activity?

General environmental factors, such as temperature and pH Chemicals that specifically influence the enzyme Each enzyme has an optimal temperature in which it can function Each enzyme has an optimal pH in which it can function Optimal conditions favor the most active shape for the enzyme molecule

How does ATP drives cellular work?

Motor protein performing mechanical work (moving a muscle fiber) Transport protein performing transport work (importing a solute) Chemical reactants performing chemical work (promoting a chemical reaction)

What does catabolic pathways do?

Release energy by breaking down complex molecules into simpler compounds

What do carrier proteins do?

bind to molecules and change shape to shuttle them across the membrane

Certain molecules inhibit a metabolic reaction by?

binding to an enzyme and disrupting its function

How does activation energy reaction start?

by activating the reactants and triggering a chemical reaction

What are hydrophobic (nonpolar) molecules?

can dissolve in the lipid bilayer and pass through the membrane rapidly

The energy in phosphate transfer helps?

cells change shape

In the ATP cycle cells cellular work spend how much?

cells spend A T P continuously

What is used to generate molecules of A T P?

chemical energy released by the breakdown of organic molecules during cellular respiration

What is 1/2 things are body does with cellular respiration?

convert about 34% of our food energy to useful work

Energy can only be?

converted from one form to another

What is a concentration gradient?

difference in the concentration of a substance from one location to another

How many branches does metabolism divided into?

divided into two branches

Cells control their chemical environment using?

energy, enzymes, and the plasma membrane

Most metabolic reactions require the assistance of?

enzymes

Active transport requires that a cell?

expend energy to move molecules across a membrane

What do channel proteins called aquaporins do?

facilitate the passage of water

A type of passive transport that helps assist?

facilitated diffusion

When their is no net movement of water into the plant cell; the cell becomes?

flaccid

Where does the water move in osmosis?

from areas of low concentration of solute to areas of high concentration of solute

What does chemical energy arises from?

from the arrangement of atoms and can be released by a chemical reaction

For an animal to survive a hypotonic or hypertonic environment the animal must?

have a way to balance the uptake and loss of water

A hypertonic solution has?

higher concentration of solute

What do do not cross the membrane easily?

hydrophilic molecules including ions and polar molecules

What is it called when the entry of the substrate induces the enzyme to change shape slightly, making the fit between the substrate and active site snugger?

induced fit

What is phosphate transfer?

is ATP energizes other molecules in cells by transferring phosphate groups to those molecules