Lecture 4 Chemical Bonds

Question 1

Organic Molecules

Answer 1

contain carbon and hydrogen atoms

Question 2

Biomolecules (Organic Molecules)

Answer 2

Carbohydrates
Lipids
Proteins
Nucleic Acids

Question 3

Inorganic vs. Organic Molecules

Answer 3

Inorganic usually contain positive & negative ions, while Organic always contain Carbon and Hydrogen

Inorganic is usually ionic bonding, while Organic is always covalent bonding

Inorganic always contain a small number of atoms, while Organic is often quite large with many atoms

Inorganic is associated with non living matter, while Organic is associated with living organisms

Question 4

Carbon

Answer 4

Shares well with elements

Question 5

Functional Groups

Answer 5

clusters of specific atoms that always act the same way, bonded to the carbon skeleton with characteristic structures and functions

Question 6

Isomers

Answer 6

organic molecules that have identical molecular formulas but a different arrangement of atoms. You would naturally expect these guys to react differently than one another in chemical reactions

Question 7

Monomer & Polymer

Answer 7

Monomer- A repeating unit

Polymer- A Molecule composed of monomers

Ex: amino acids (monomer) are joined together to form a protein (polymer)

Question 8

Dehydration Reaction

Answer 8

a chemical reaction in which subunits are joined together by the formation of a covalent bond and water is produced during the reaction

Question 9

Hydrolysis Reaction

Answer 9

a chemical reaction in which a water molecule is added to break a covalent bond

Question 10

Enzymes

Answer 10

a molecule that speeds up a chemical reaction

• Enzymes are required for cells to carry out dehydration synthesis and hydrolysis reactions.
• Enzymes are not consumed in the reaction.
• Enzymes are not changed by the reaction.

Question 11

Carbohydrates

Answer 11

•Functions:
●Energy source
●Provide building material (structural role)

• Contain carbon, hydrogen and oxygen in a 1:2:1 ratio
• Varieties: monosaccharides, disaccharides, and polysaccharides

Question 12

Monosaccharide

Answer 12

a single sugar molecule

•Examples:
●Glucose (transported in blood, gets broken down & converted into ATP), fructose (fruit) and galactose
•Hexoses - six carbon atoms
●Ribose and deoxyribose (in nucleic acids RNA & DNA)
•Pentoses – five carbon atoms

Question 13

Disaccharide

Answer 13

contains two monosaccharides joined together by dehydration synthesis.
•Examples:
●Lactose (milk sugar) is composed of galactose and glucose.
●Sucrose (table sugar) is composed of glucose and fructose.
●Maltose is composed of two glucose molecules.

Question 14

Polysaccharide

Answer 14

A polymer of monosaccharides. These are often used as short-term energy storage molecules.
•Examples:
●Starch provides energy storage in plants.
●Glycogen provides energy storage in animals.
●Cellulose is found in the cell walls of plants (most abundant carbohydrate & organic molecule on earth)

Question 15

Lipids

Answer 15

•Lipids are varied in structure.
•Large nonpolar molecules that are insoluble in water
•Functions:
●Long-term energy storage
●Cell communication and regulation
●Protection

•Varieties: fats, oils, phospholipids, steroids, waxes

Question 16

Triglycerides: Long-Term

Energy Storage

Answer 16

●Also called fats and oils
●Functions: long-term energy storage and insulation
●Consist of one glycerol molecule linked to three fatty acids by dehydration synthesis

Question 17

Unsaturated and Saturated

Answer 17

●Unsaturated - one or more double bonds between carbons
•Tend to be liquid at room temperature
–Example: plant oils

●Saturated - no double bonds between carbons
•Tend to be solid at room temperature
–Examples: butter, lard

Question 18

Phospholipids: form membranes (like cell membranes)

Answer 18

•Structure is similar to triglycerides
●Consist of one glycerol molecule linked to two fatty acids and a modified phosphate group
•Function: form plasma membranes
•In water, phospholipids aggregate to form a lipid bilayer.
●Polar phosphate heads are oriented towards the water.
●Nonpolar fatty acid tails are oriented away from water.
•Nonpolar fatty acid tails form a hydrophobic core.

Question 19

Waxes

Answer 19

• Long-chain fatty acid bonded to a long-chain alcohol
• Solid at room temperature
• Waterproof
• Resistant to degradation
• Function: protection
• Examples: earwax, plant cuticle, beeswax

Question 20

Proteins

Answer 20

•Proteins are polymers of amino acids linked together by peptide bonds.
●A peptide bond is a covalent bond between amino acids.

•Two or more amino acids joined together are called peptides.
●Long chains of amino acids joined together are called polypeptides.

•A protein is a polypeptide that has folded into a particular shape and has function.

Question 21

Functions of Proteins

Answer 21

•Metabolism
●Most enzymes are proteins that act as catalysts to accelerate chemical reactions within cells.
•Support
●Keratin (make up hair & nails) and collagen (gives strength to ligaments, tendons & skin)
•Transport
●Hemoglobin and membrane proteins transport oxygen to cells!
•Defense
●Antibodies
•Regulation
●Hormones are regulatory proteins that influence the metabolism of cells.
•Motion
●Muscle proteins (actin & myosin) allow muscle contraction & therefore movement!

Question 22

Levels of Protein Structure

Answer 22

•Proteins cannot function properly unless they fold into their proper shape.
●When a protein loses it proper shape, it said to be denatured.
•Exposure of proteins to certain chemicals, a change in pH, or high temperature can disrupt protein structure.

•Proteins can have up to four levels of structure:
●Primary
●Secondary
●Tertiary
●Quaternary

Question 23

Four levels of protein structure

Answer 23

●Primary
•The sequence of amino acids
●Secondary
•Characterized by the presence of alpha helices and beta (pleated) sheets held in place with hydrogen bonds
●Tertiary
•Final overall three-dimensional shape of a polypeptide
•Stabilized by the presence of hydrophobic interactions, hydrogen bonding, ionic bonding, and covalent bonding
●Quaternary
•Consists of more than one polypeptide

Question 24

Protein folding diseases

Answer 24

•Chaperone proteins help proteins fold into their normal shape.
●Defects in chaperone proteins may play a role in several human diseases such as Alzheimer disease and cystic fibrosis.
•Prions are misfolded proteins that have been implicated in a group of fatal brain diseases known as TSEs. (transmissible spongiform encephalopathies). Prions are hypothesized to cause other proteins to mis-fold as well, so they are kind of like bad influence proteins!

Question 25

Nucleic Acids

Answer 25

•Nucleic acids are polymers of nucleotides that store this information, including instructions for life, and conduct chemical reactions!

•Two varieties of nucleic acids:
●DNA (deoxyribonucleic acid)
•Genetic material that stores information for its own replication and for the sequence of amino acids in proteins.
●RNA (ribonucleic acid)
•Perform a wide range of functions within cells which include protein synthesis and regulation of gene expression

Question 26

Structure of a Nucleotide

Answer 26

•Each nucleotide is composed of three parts:
●A phosphate group
●A pentose sugar
●A nitrogen-containing (nitrogenous) base
•There are five types of nucleotides found in nucleic acids.
●DNA contains adenine, guanine, cytosine, and thymine.
●RNA contains adenine, guanine, cytosine, and uracil.
•Nucleotides are joined together by a series of dehydration synthesis reactions to form a linear molecule called a strand.

Question 27

Structure of DNA & RNA

Answer 27

●The backbone of the nucleic acid strand is composed of alternating sugar-phosphate molecules.
●RNA is predominately a single-stranded molecule.
●DNA is a double-stranded molecule.
•DNA is composed of two strands held together by hydrogen bonds between the nitrogen-containing bases. The two strands twist around each other to form a double helix.
–Adenine hydrogen bonds with thymine
–Cytosine hydrogen bonds with guanine
•The bonding between the nucleotides in DNA is referred to as complementary base pairing.

Question 28

DNA structure compared to RNA structure

Answer 28

DNA has deoxyribose sugars and is double stranded while

RNA had ribose sugars and is single stranded

Question 29

A special Nucleotide: ATP

Answer 29

•ATP (adenosine triphosphate) is composed of adenine, ribose, and three phosphates.
•ATP is a high-energy molecule due to the presence of the last two unstable phosphate bonds.
•Hydrolysis of ATP yields:
●The molecule ADP (adenosine diphosphate)
●An inorganic phosphate
●Energy to do cellular work
•ATP is called the energy currency of the cell.