Chapter 5.10-5.16

5.10

Cells- small units that house chemical reactions.

Cells use chemical reactions for

  • cell maintenance

  • creation of cellular parts

  • cell replication

A cell can’t be a cell without chemical reactions

Energy- the capacity to cause change or to perform work

There are two kinds of energy

  1. Kinetic energy- the energy of motion

  2. Potential energy- the energy of location or structure

    In bio potential energy is found in

    • the arrangement of atoms in molecules

    • the covalent bonds that holds molecules together

    Making and breaking these bonds release the potential energy

Heat or thermal energy- a type of kinetic energy associated with random movements of atoms or molecules

Light- a type of kinetic energy that can be harnessed from the sun and be used to power photosynthesis

Law of conservation of energy- energy can’t be created nor destroyed

Chemical energy- the potential energy(found in the covalent bonds of a molecule) that is available for release in a chemical reaction

It is the most important type of energy for living organisms to power the work of cells

Thermodynamics- the study of energy transformations that occur in a collection of matter

Scientists use the words

  • System - what they study. ex: a single cell

  • Surroundings- the environment of the system. ex: blood stream

Laws of thermodynamics

First law- energy in the universe is constant aka can’t be created or destroyed

Second law- energy conversions increase the disorder of the universe

Entropy- the measure of disorder or randomness

*The universe leans towards disorder

*Humans are endothermic and endergonic

Cellular respiration- The transfer of energy from the chemical energy of the food we eat and the oxygen we breathe to the chemical energy of ATP.

This reaction is very controlled and releases energy slowly

In this reaction the oxygen we breath is used as a key component

5.11

Types of chemical reactions

Exergonic-

  • Releases the energy in Covalent bonds of the reactants

  • Easier for cells to accomplish compared to endergonic reaction

  • Downhill reaction

  • Spontaneous

  • EX: Burning wood, Cellular respiration, hydrolysis

  • Macromolecules → Monomers

Endergonic-

  • Requiere a constant input of energy

  • Uphill reaction

  • Not spontaneous

  • EX: dehydration synthesis, protein, carb, nucleic, lipid synthesis and photosynthesis

*All chemical reactions require:

  1. An enzyme

  2. ATP

  3. Addition or removal of water

Metabolism- The total number of an organisms chemical reaction

Metabolic pathway- A series of chemical reactions that

  • Builds a complex molecule or

  • Breaks down a complex molecule

Energy coupling- Uses the energy released in exergonic reactions to fuel endergonic reactions.

Usually uses the energy stored in ATP molecules

5.12

ATP(Adenosine triphosphate)-

  • Powers all terms of cellular work.

  • Is renewable source of energy

  • Energy form an exergonic reaction goes into an endergonic reaction to produce ATP

ATP consists of:

  • Nitrogenous base Adenine

  • Five carbon sugar Ribose

  • Three phosphate groups

Phosphorylation- A hydrolysis reaction that releases energy by transferring its third phosphate group to some other molecule

Most cellular work depends on ATP energizing molecules by phosphorylating them

* There are three main types of cellular work

  1. Chemical

  2. Mechanical

  3. Transport

ATP drives all three of them

  • ADP + P → ATP

  • ATP gives away the last phosphate group and becomes ADP

  • ADP + P → ATP

5.13

Although biological molecules contain a lot of potential energy, It is not released spontaneously

An energy barrier must be overcome before a chemical reaction can begin called Activation Energy

Activation energy is the energy needed for a reactant molecule to move up hill to a higher but unstable energy before the rest of the reaction happens

One way to speed up a reaction is Adding heat but that kills our cells

Enzymes

  • Organic catalysts that are safe and can be used in living organisms to speed up a chemical reaction.

  • Reduces the Activation energy barrier

  • Increases the rate of the reaction without being consumed into the reaction

  • Usually proteins and sometimes RNA molecules

  • Does not add or remove energy of the final product

  • Very selective and has a shape that determines the enzyme specifically

  • Enzymes are specific because their active site fits only specific types of substrate

Substrate- The specific reactant to an enzyme

Active site- The space where the enzyme and substrate connect

5.14

Every enzyme has optimal conditions where its most effective

Most human enzymes work best at 35-40*C

Denaturation- happens when the PH, Salinity or Temperature is too high. It changes the shape of an enzyme making it not function

Most enzymes require a Non-protein helpers called cofactors

Cofactors-

  • Binds to the active site and functions in catalysis

  • Some are inorganic like zinc, iron and copper

Coenzyme-

  • An organic cofactor

  • Always vitamins

5.15

Inhibitor-

  • A chemical that interferes with an enzymes activity

  • Important in regulating cell metabolism

Enzyme inhibition- An inhibitor that prevents the enzyme from doing its work

Competitive inihibitor

  • Block the substrate from entering an enzymes active site

  • Reduces an enzyme’s productivity

Noncompetitive inhibitor-

  • Binds to an enzyme somewhere other that the active site

  • Changes the shape of the active site

  • Prevents the substate from binding

*Both competitive and non competitive prevent the substrate from bonding with the enzyme

Feedback inhibition- When the product acts as an inhibitor of one of the enzyme’s in the pathway that produced it

5.16

Many beneficial drugs act as enzyme inhibitors including

  • Ibuprofen- inhibits the production of prostaglandins

  • Blood pressure medicines

  • Antidepressants

  • Antibiotics

  • Protease- inhibitors used to fight HIV

Enzyme inhibitors have also been developed as pesticides and deadly poisons for chemical warfare