BISC 130 - Chapter 6: Metabolism

What is energy defined as?

The ability to do work.

What are the two types of energy mentioned?

Potential energy and Kinetic energy.

What is potential energy?

Stored energy, which includes chemical energy. When chemical bonds are broken, it produces kinetic energy

How does chemical energy relate to potential energy?

There is energy in chemical bonds; breaking these bonds releases energy.

What is kinetic energy?

The energy of motion, which includes heat.

What does the first law of thermodynamics state?

Energy cannot be created or destroyed, only converted from one form to another.

What are the two types of chemical reactions?

Exergonic reactions and Endergonic reactions.

What characterizes an exergonic reaction?

Products are at lower energy than the reactants and it releases energy. The overall chemical reaction requires no energy input, and releases energy at the end (ATP).

What is an endergonic reaction?

Products are at higher energy than the reactants and it requires input of energy. Some instances of this are: DNA replication, proteins synthesis, and active transport (anabolism).

What is activation energy?

Additional energy input needed for reactions to proceed or even get started. Ensures that substances don’t automatically undergo chemical reactions without the right level of input.

Ex: Stack of wood needs the right amount of fire to chemically break down into carbon dioxide and other elements (products)

What role can heat energy play concerning activation energy?

Heat energy can be used to overcome the activation energy threshold, but it is not feasible in cells of living things.

What lowers the activation energy?

Catalysts; makes reactions happen quicker and much easier.

What are catalysts and their function?

They hold reactants and strain chemical bonds to lower the activation energy required for a reaction to take place.

Endergonic and Exergonic reactions are influenced by what substance?

Catalysts

What are biological catalysts called?

Enzymes.

Most enzymes are what? What do they do?

Proteins; they lower activation energy, so that chemical reactions can occur more easily.

What occurs during enzyme catalysis?

Substrate(s) bind at the enzyme's active site, forming the enzyme/substrate complex. Enzyme strains substrate to lower activation energy

What does 'induced fit' refer to in enzyme catalysis?

The slight change in enzyme shape to better fit the substrate(s).

Can any substrate bind to an enzyme’s active site?

No; each enzyme is designed specifically for a certain substrate to bind. There are several enzymes for each substrate.

What happens to the enzyme after the reaction?

The enzyme assumes its original shape and is free to work again.

What energy is enough to overcome the activation energy requirement in an exergonic reaction?

Ambient heat energy (surrounding heat in an environment)

Are enzymes permanently changed after undergoing catalysis?

No, they return back to their original shape. Only the binding reactants/substrates are changed.

What is the effect of enzyme inhibitors?

They are chemical compounds that reduce an enzyme's function - prevent substrates from binding to enzymes.

What do enzyme activators do?

They increase an enzyme's function by better shaping the active site to fit a substrate.

What are cofactors and/or coenzymes?

Substances required by SOME enzymes to function properly. Some enzymes require 1 or the other, and some require none.

Cofactors

An inorganic ion (small simple ions) that is required for optimal enzyme activity. Ex: Zinc, Iron, Magnesium.

Coenzyme

A small organic molecule that is required for optimal enzyme activity. Ex: Vitamins. Essential for one’s diet.

How is a complicated molecule like glucose built and broken down?

When a bunch of enzymes work together in an assembly line fashion.

What are Anabolic Pathways?

When complex molecules are built with an input of energy.

What are Catabolic Pathways

When complex molecules are broken down, releasing energy in the process, likely from those chemical bonds that store them.

What processes collectively are referred to as metabolism?

Anabolic and Catabolic Pathways

How many high energy bonds are found in ATP?

2 high-energy bonds between 3 phosphate groups. Breaking them releases energy

What type of reaction does ATP undergo when its bonds are broken?

Exergonic Reaction