AP151 Study Guide Chemical Composition of the Body

 components of an atom

Protons +

Neutrons no charge 

Electrons -  

Atomic number → # of protons and weight 

What makes an atom chemically reactive (forms bonds)? Can you describe why this is?

Valence electrons determine if the atom is reactive 

Vacancies → unstable 

Given an atom common in organic molecules could you tell me which is more electronegative and what does that mean?

Electron negative → how strongly an atom attracts shared electron 

Common elements O→ N → C → H

What makes a molecule polar? Could you determine the polarity of a molecule if given the molecule structure?

A molecule is polar when electrons are distributed unevenly → practical positive and negative 

H2o is polar  O → slightly negative  H → slightly positive 

hydrophobic vs hydrophillic

Hydrophilic → polar → loves water 

Hydrophobic →  nonpolar → hates water 

Given the structure of molecules, could you determine which are hydrophobic or hydrophilic?

O and N → hydrophilic 

C and H bonds → hydrophobic 

What are the different bonds? Could you describe the difference between those bonds? How do they rank in the strength of the bond?

1. Covalent bonds → share electrons 1

2. Ionic bonds → transferred electrons 2 

3. Hydrogen  bonds → weak 3

What are positive and negative ions termed? What differs between ions and an atom?

Positive ion → cation 

Negative ion → anion 

Atom → electrically neutral 

Ion → has net charge 

What happens to ionic bonded atoms when they are placed in solution?

Ionic compound enter a solution, the water molecules surround it and separate the ions → dissociation 

What does a solution contain? What does concentration tell you about a solution? What is the unit or measurement for concentration?

Solute + solvent = solution 

Concentration → how much solute is in the solvent 

moles → unit or measurement of concentration 

Do all chemical reactions move in one direction? What is the purpose of an enzyme in a reaction?

Chemical reactions are reversible

Reactants → ← products 

Enzymes catalyze reaction (bind to the active site) 

What is meant by the law of mass action? How can you determine the direction of reaction and the rate of reaction when reactant is either added to the solution or taken away from the solution?

Law of mass action → the rate/direction of reversible reactions depends on the concentration of the reactants and products 

Remove product → reaction goes toward products 

Remove reactant → reaction goes toward reactants 

What is an acid and base? What determines the strength of these (what makes it strong or weak)?

Acid → donates H+

Base → accepts H+

Strong acid → denatures 

Weak acid → lil bit denature

What is pH a measure for? Where does blood pH lie on the pH scale (acidic or basic)?

pH measure concentration of H+ ions 

Blood pH should be 7.35-7.45 (lil bit basic) 

What is a buffer? What is the major buffer system in the body? How does a buffer system operate to keep wide fluctuations in pH?

A buffer is to help resist large changes in pH 

Bicarbonate ion (HCO3-) → can accept H+

Carbonic acid (H2CO3) → neutralizes excess base (release H+)

Given a scenario involving large changes in pH could you describe how the body’s buffer system would keep pH within homeostatic range? Which way would the buffer equation be pushed (thin: law of mass action)?

If H+ increase → more acidic/ going to the left reactants ← products 

If H+ decreases → more basic  / going to the right reactants → products 

Why is carbon the most prevalent organic molecule?

Can form 4 covalent bonds 

What is the basic chemical composition of a carbohydrate?

CH2O

How are di and polysaccharides formed? What other large chain molecules are formed this way?

Dehydration synthesis (condensation) 

→ removes water and makes molecules form together

Proteins and nucleic acids are formed through dehydration synthesis/ condensation 

What is the reaction that breaks down polysaccharides? As well as other larger biological molecules?

Hydrolysis breaks down polysaccharides (opposite of dehydration synthesis/condensation)

→ water added to break down bonds 

Dehydration synthesis → removes H2O → builds 

Hydrolysis → adds H2O → breaks down 

What is the chemical make-up of triglycerides?

1 glycerol + 3 fatty acids  Insoluble in polar solvents → triglycerides are hydrophobic 

How do phospholipids differ from other lipids? Where would you find these?

Phospholipids → glycerol, 2 fatty acid tails and phosphate head 

Head → hydrophilic (loves water)

Tails → hydrophobic (hates water)

Found in the cell membrane –. Phospholipid bilayer

What are ketone bodies formed from? What would large amounts of these do to the body?

Ketones are made from acetyl CoA 

Made when liver need to break down a lot of fatty acids and carbohydrates are limited  Large amounts of ketones make blood acidic → ketoacidosis (atkins diet)

What are steroids formed from? Are these molecules polar or non-polar?

Steroids are made from cholesterol → 4 fused carbon rings 

Steroids are nonpolar/lipid soluble (can cross cell membrane)

What is the basic structure of an amino acid? What functional groups do all amino acids contain?

Aminogroup→ NH2 Carboxyl group COOH  Hydrogen  R group → determines properties and amino acid 

What are the different levels of protein structure? How are these structures formed?

Primary structure →amino acid sequence 

→ used peptide bonds 

Secondary structure →alpha helix and beta pleated sheat/folded

→ uses hydrogen bonds 

Tertiary structure → 3D shape of one polypeptide

→ used ionic bonds, hydrogen bonds, covalent bonds, and van der Waals forces 

quaternary structure → multiple polypeptide chains 

→ multiple subunits 

What are some of the different functional types of proteins in the body?

Enzymes → catalyzes 

Immunologica → antibodies 

Receptors → binds to hormones and neurotransmitter creating response in the cell 

How do ligands and proteins bind? What factors affect ligand-protein binding? How are protein functions regulated?

Ligands bind to proteins through forming a weak non-covalent interaction 

Properties  Proteins bind only to one molecule or group

Affinity → strength in which  protein binds to ligrand 

→ specific shape and strength of interaction 

Saturation → amount of proteins in a population of proteins that are occupied by a ligand 

→ affected by concentration and affinity 

Competition → several ligands can competent for the same binding site on a protein  → one ligand is bound the other ligand cant bind 

Regulated through allosteric modulators –. Bind to protein away from ligand binding site and result in change of protein 

Covalent modulators –. Chemical binds to the protein covalently 

→ Adding a phosphate group (kimase)

Removing a phosphate group (phosphatase)

What is the structure of nucleotides and nucleic acids?

Nucleotide   Sugar Phosphate group  Nitrogenous base  Nucleic acids → long chains of nucleotides

What is the difference between RNA and DNA? What bases pair with each other?

RNA → single stranded, ribose, AUCG, less stable 

DNA → double stranded, deoxyribose, ATCG, more stable 

DNA  a→t c→g

RNA  a→u c→g

What makes DNA such a stable molecule?

Double stranded structure  Hydrogen bonds  Sugarphosphate backbone → strong backbone (phosphodiester bonds)

What are the other functions of nucleotides?

Houses our genetic information  Nucleotides bind together through dehydration  Energy carriers  Electron carriers