Chapter 4 The Energy of Life (Biology)

Energy

Energy

The ability to do work or move matter.

Chemical bonds

Store potential energy in molecules like glucose and triglycerides.

Stored energy is released.

What happens when chemical bonds are broken?

First law of thermodynamics

States that energy is converted from one form to another, but never created or destroyed.

It must be captured, stored, and converted (chemical energy to food).

What has to happen to energy (from the sun) before it can be used for cellular work?

Yes, heat cannot be converted back into a useful form of energy (inefficient).

Is heat energy lost at each step of energy transformations?

More energy, takes a lot of energy to stay ordered (life requires energy input).

Do you use more or less energy when you are more active?

Yes

Metabolism (food to energy) includes all chemical reactions in a cell. Do chemical reactions rearrange atoms?

Electrons

What do some chemical reactions transfer?

From donor (oxidation) to acceptor (reduction).

How are electrons transferred?

Oxidation

Loss of electrons from an atom or molecule, releasing energy out.

In the electrons

Where is the energy that's released from the oxidation molecule stored?

Reduction

Gain of electrons by an atom or molecule which requires energy (increases negative charge).

The energy stored in the electrons.

What does the reduction molecule gain?

Adenosine Triphosphate (ATP)

A nucleotide that temporarily stores energy (in the bond) for cellular use.

Because they need it to power chemical reactions.

Why do all cells rely on the PE stored in ATP?

Hydrolosis of ATP

Bonds of phosphate in ATP are broken releasing stored energy. The cell then uses this energy to do work. (ATP TO ADP)

Chemical reactions in cells must be fast to sustain life, and without these enzymes many reactions would be far too slow.

Why are enzymes important to speed biochemical reactions?

Enzymes

Proteins that speed up biochemical reactions without being consumed. These are in all chemical reactions, and without them animals and humans would die. CAN BE BUILT AND BROKEN DOWN.

The word ends with "ase".

What's a sign for if something is an enzyme?

Substrate

Binds to active site (where chemical reaction occurs). The enzyme acts on this.... ENZYME FITS SHAPE OF THIS

Product

Released after chemical reaction occurs. The enzyme returns to original form, and ________ are what the reaction produces.

Yes, some break a substrate into two products where others break two substrates into one product.

Do ezymes speed a variety of different reactions?

Activation energy

The energy required to start a reaction, lowered by enzymes.

Benefits of enzymes in activation energy

Without an enzyme the activation energy (energy required to start a reaction) would be high and slow (when binded activation energy is lowered).

Cofactors

Partners of enzymes that help catalyze reactions, such as metal ions and vitamins. INCREASE ENZYME ACTIVITY

Cells control the rate of biochemical reactions.

How is the activity of enzymes limited?

Inhibitors

Molecules that can block or reduce enzyme activity (SPECIFICALLY SUBSTRATES FROM BINDING).

Noncompetitive Enzyme Inhibitor

Changes shape of active site to prevent binding to the enzyme.

Competitive Enzyme Inhibitor

Block access to active site by creating a molecule right at the active site to prevent binding to the enzyme.

Yes, in most cases the inhibitor is the product, and once there is enough product in the cell it would be a waste of energy to produce more of that product.

Do inhibitors shut down unneeded reactions?

Range of temperatures, but have an optimal temp where they perform best. LOOK AT HIGH POINT AND THEN X AXIS.

What's the temperature enzyme activity is the greatest?

A optimal salt concentration and ph.

What chemical factors causes enzymes to function quickly?

Yes, it maintains this difference by regulating transport of dissolved substances (solutes) across the membrane.

Is a cells interior chemically different than the exterior?

Regulating and maintaining a stable internal environment within a cell.

What's an example of Homeostasis?

Concentration gradient and the chemical nature of the substance (polarity, charge, and size).

Solutes enter and exit the cell membrane by different methods depending on what two factors?

Concentration gradient

Describes a difference in solute concentration between neighboring regions. In tea the concentration is higher near to tea bag forming a concentration gradient (SPONTANEOUS).

Down the concentration gradient

From an area of high concentration to an area of low concentration (GRADIENTS ARE DIRECTIONAL).

Dissipated gradient

When there is no energy input, and the concentration is uniform.

Energy due to tendency to dissipate.

What does maintaining a gradient require?

Passive transport

Movement of substances down a concentration gradient without energy input (NEEDS NO ENERGY TO MOVE SUBSTANCES).

Simple diffusion (spontaneous)

Passive transport of molecules down their concentration gradient across a membrane (dissipates).

ONLY small, nonpolar molecules.

What molecules can cross membranes (hydrophobic barrier) by simple diffusion?

Osmosis (spontaneous)

Passive transport of water across a selectively permeable membrane (down concentration gradient).

By osmosis driven by the concentration gradient of water.

How does water move across a cell membrane?

Isotonic solution

Equal solute concentration inside and outside the cell (water equal)

Hypotonic solution

Higher solute concentration inside the cell (water rushes into cell from outside of cell).

Hypertonic solution

Lower solute concentration inside the cell (water rushes out of cell).

Blood cells

Water always moves to higher salt level and there is no cell wall to help it not burst.

The water content (solute concentration inside cell lower than outside cell).

What does osmosis determine in plant cells?

Loss of water which shrinks the large central vacuoles, causing plant to wilt (don't die because of vacuoles).

What does hypertonic surroundings result in?

Facilitated diffusion (spontaneous)

Passive transport of substances across a membrane with the help of membrane proteins by passing through a protein channel (doesn't need energy but needs protein). Substances move down their concentration gradient. Polar.

ATP, because the protein uses potential energy in the concentration gradient.

What does facilitated diffusion produce?

Active transport

Movement of substances against their concentration gradient (low concentration to high) using cellular energy (NEEDS ENERGY TO MOVE SUBSTANCES). Can be referred to as the "pump".

nonpolar

can pass easily through membrane

polar

can’t pass easily through membrane