Mod1-Obj2: Atoms, molecules, chemical reactions, catalysts, electrolytes and pH Flashcards
Atoms and molecules
- All matter is composed of one or more elements
- Atoms are the smallest stable unit of matter
What is an element?
An element is a substance in which all the particles that make it up are exactly the same, these particles are called atoms
Atoms join together to form…
Atoms form molecules/macromolecules, thus building ‘bigger stuff’
Molecules are described by formula
Molecular formula: Identifies elements involved and their number
Structural formula: Identifies elements involves, their number and their arrangement
Chemical reactions
A chemical reaction occurs whenever chemical bonds are formed, rearranged, or broken
Chemical reactions: Synthesis reactions
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
Chemical reactions: Decomposition reactions
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
Chemical reactions: Exchange reactions
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.
Chemical reactions are the result of…
Collisions between atoms or molecules. The more frequently and forcefully they collide the more likely they are to form a chemical bond
Actors which increase the rate of chemical reactions…Temperature
Increase in temperature, increases molecule speed, thus frequency and force of collisions, therefore chemical reactions proceed faster at higher temperatures
Actors which increase the rate of chemical reactions…Concentration
Chemical reactions progress most rapidly when the reacting particles are present in high numbers, because the chance of successful collisions is greater
Actors which increase the rate of chemical reactions…Catalysts
Enzymes increase the rate of the reaction
Reversibility of chemical reactions
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
Catalysts
All cellular reactions require a catalyst, which is a substance that increases the rate of the reaction
Enzymes are biological catalysts…
- Protein molecules
- Increase the rate of chemical reactions
- Lower the activation energy
- Bring substrates together, however do not participate in the reaction
- Chemical reactions are enzyme specific
Enzymes lower activation energy…
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
Enzymes bring substrates together…Enzyme action
- 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
- The enzyme-substrate complex undergoes internal rearrangements that form the product
- 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.
Electrolytes
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
Cations
Positive charge
H+, Na+, K+ Ca2+
Anions
Negative charge
Cl-, HCO3-
Electrolytes are essential for…
Normal body function
Sodium ions (Na+)
Major cation in ECF, essential for water balance and normal cell function
Potassium ions (K+)
Major cation in ICF, essential for water balance and normal cell function
Calcium ions (Ca2+)
Blood clotting, nerve and muscle function
Bicarbonate ions (HCO3-)
Acid-base balance, CO2 transport
Chloride ions (Cl-)
Major anion in ECF, acid-base balance, digestion
Hydrogen ions (H+)
Acid-base balance, digestion, respiration
Phosphate ions (HPO4-)
Water balance, bone formation
There are three types of electrolytes…
Salts, acids, bases
Salts
- Ions other than H+
e. g.) NaCl dissociates in water into Na+ and Cl- ions
Acids
Sour taste (citrus)
- Release H+ ions in solution
- The concentration of H+ ions determines the acidity of the solution
Bases
Bitter taste, feel slippery (bleach)
-Ions that can bind H+ ions
The pH scale
The pH scale is a way to measure the number of H+ ions in a solution (range from 0-14)
pH of 7…
The solution is neutral, neither acidic nor basic
-Equal amounts of H+ and a base such as OH ions
Solutions below pH of 7…
Are acidic
- Contains more H+ ions that base ions
- The lower the pH of a solution, the more acidic
Solution above pH of 7…
Are basic orl alkaline
-Contain more base ions than H+ ions
Body pH
Living cells are very sensitive to changes in pH
- Normal (homeostatic) pH range: 7.35-7.45
- Plasma pH7.45=alkalosis
Buffers
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
