Mod1-Obj2: Atoms, molecules, chemical reactions, catalysts, electrolytes and pH

Question 1

Atoms and molecules

Answer 1

• All matter is composed of one or more elements

- Atoms are the smallest stable unit of matter

Question 2

What is an element?

Answer 2

An element is a substance in which all the particles that make it up are exactly the same, these particles are called atoms

Question 3

Atoms join together to form…

Answer 3

Atoms form molecules/macromolecules, thus building ‘bigger stuff’

Question 4

Molecules are described by formula

Answer 4

Molecular formula: Identifies elements involved and their number
Structural formula: Identifies elements involves, their number and their arrangement

Question 5

Chemical reactions

Answer 5

A chemical reaction occurs whenever chemical bonds are formed, rearranged, or broken

Question 6

Chemical reactions: Synthesis reactions

Answer 6

Atoms or small molecules are bonded together to form larger, more complex molecules

• Provides the basics of anabolic reactions in cells
• For example amino acids are joined together to form a protein molecule

Question 7

Chemical reactions: Decomposition reactions

Answer 7

Chemical bonds are broken in large molecules, resulting in smaller, less complex molecules

• Underlie all catabolic reactions
• For example the bonds of glycogen molecules are broken to release simpler molecules of glucose sugar

Question 8

Chemical reactions: Exchange reactions

Answer 8

Chemical bonds are both made and broken
-Occurs when ATP reacts with glucose and transfers its end phosphate group to glucose, forming glucose phosphate. At the same time ATP become ADP. Occurs whenever glucose enters a body cell, and traps the glucose molecule inside the cell.

Question 9

Chemical reactions are the result of…

Answer 9

Collisions between atoms or molecules. The more frequently and forcefully they collide the more likely they are to form a chemical bond

Question 10

Actors which increase the rate of chemical reactions…Temperature

Answer 10

Increase in temperature, increases molecule speed, thus frequency and force of collisions, therefore chemical reactions proceed faster at higher temperatures

Question 11

Actors which increase the rate of chemical reactions…Concentration

Answer 11

Chemical reactions progress most rapidly when the reacting particles are present in high numbers, because the chance of successful collisions is greater

Question 12

Actors which increase the rate of chemical reactions…Catalysts

Answer 12

Enzymes increase the rate of the reaction

Question 13

Reversibility of chemical reactions

Answer 13

Reversible reactions aim for equilibrium, the forward and reverse reactions occur at the same rate, so there is a balance between the amount of product and the amount of substrate

Question 14

Catalysts

Answer 14

All cellular reactions require a catalyst, which is a substance that increases the rate of the reaction

Question 15

Enzymes are biological catalysts…

Answer 15

1. Protein molecules
2. Increase the rate of chemical reactions
3. Lower the activation energy
4. Bring substrates together, however do not participate in the reaction
5. Chemical reactions are enzyme specific

Question 16

Enzymes lower activation energy…

Answer 16

The activation energy is the amount of energy needed to break the bonds of the reactants so that they can rearrange themselves and become the product

Question 17

Enzymes bring substrates together…Enzyme action

Answer 17

1. Substrate(s) bind to the enzyme’s active site, temporarily forming an enzyme-substrate complex. Substrate binding causes the active site to change shape so that the substrate and the active site fit together precisely
2. The enzyme-substrate complex undergoes internal rearrangements that form the product
3. The enzyme releases the product(s) of the reaction: The enzyme is not changed and returns to its original shape, available to catalyse another reaction.

Question 18

Electrolytes

Answer 18

Atoms/molecules that have an overall charge are called ions

• Form ions in water
• Able to conduct an electric current in water
• Present in all body fluids

Question 19

Cations

Answer 19

Positive charge

H+, Na+, K+ Ca2+

Question 20

Anions

Answer 20

Negative charge

Cl-, HCO3-

Question 21

Electrolytes are essential for…

Answer 21

Normal body function

Question 22

Sodium ions (Na+)

Answer 22

Major cation in ECF, essential for water balance and normal cell function

Question 23

Potassium ions (K+)

Answer 23

Major cation in ICF, essential for water balance and normal cell function

Question 24

Calcium ions (Ca2+)

Answer 24

Blood clotting, nerve and muscle function

Question 25

Bicarbonate ions (HCO3-)

Answer 25

Acid-base balance, CO2 transport

Question 26

Chloride ions (Cl-)

Answer 26

Major anion in ECF, acid-base balance, digestion

Question 27

Hydrogen ions (H+)

Answer 27

Acid-base balance, digestion, respiration

Question 28

Phosphate ions (HPO4-)

Answer 28

Water balance, bone formation

Question 29

There are three types of electrolytes…

Answer 29

Salts, acids, bases

Question 30

Salts

Answer 30

• Ions other than H+

e. g.) NaCl dissociates in water into Na+ and Cl- ions

Question 31

Acids

Answer 31

Sour taste (citrus)

• Release H+ ions in solution
• The concentration of H+ ions determines the acidity of the solution

Question 32

Bases

Answer 32

Bitter taste, feel slippery (bleach)

-Ions that can bind H+ ions

Question 33

The pH scale

Answer 33

The pH scale is a way to measure the number of H+ ions in a solution (range from 0-14)

Question 34

pH of 7…

Answer 34

The solution is neutral, neither acidic nor basic

-Equal amounts of H+ and a base such as OH ions

Question 35

Solutions below pH of 7…

Answer 35

Are acidic

• Contains more H+ ions that base ions
• The lower the pH of a solution, the more acidic

Question 36

Solution above pH of 7…

Answer 36

Are basic orl alkaline

-Contain more base ions than H+ ions

Question 37

Body pH

Answer 37

Living cells are very sensitive to changes in pH

• Normal (homeostatic) pH range: 7.35-7.45
• Plasma pH7.45=alkalosis

Question 38

Buffers

Answer 38

Acid-base balance of body fluids is carefully controlled

• Involves the kidney and lungs
• plasma buffer systems
  1. ) A buffer is a molecule that can bind or release H+ ions to counter changes in pH
  e. g.) blood proteins such as haemoglobin