Chapter 3lecture

8/3/2019 Chapter 3lecture

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Chapter 3: The Molecules of Life

Inorganic Molecules

WATER >>>>>>>!!!!!!!

The important properties of water are attributed to its polar covalent bonds

and its V shape.These properties make a good solvent, transport medium, coolant, and

lubricant, as well as a ready participant in chemical reactions.

Solvency

Solvency is the ability to dissolve matter, water is called the universal

solvent.

Molecules that dissolve readily in water are hydrophilic (WATER

LOVING) those that do not are hydrophobic (WATER HATING).

When NaCl is dissolved in water, water molecules form a hydration

sphere around each sodium and chloride ion.

Adhesion and Cohesion

Adhesion is the tendency of one substance to cling to another.

Cohesion is the tendency of molecules of the same substance to cling together.

Water is highly cohesive, as evidenced by its high surface tension.

Thermal stability Water has a high heat capacity, meaning that it takes a large

amount of heat to change the temperature of water.

Chemical Reactivity. Water is a reactant or product I numerous chemical reactions

within the body.

Minerals.


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Minerals are inorganic elements passed to us through the food chain. They

make up about 4% of the human body by weight.

Most of the mineral content of the body is calcium and phosphorus, whichcontribute to the structure of body parts (BONE)

Minerals also take part in many metabolic reactions as cofactors or

electrolytes.

Gases

Carbon dioxide and oxygen are the two most important gases in the body.

Certain gases are also used as chemical messengers, such as nitric oxide.

CARBON and ORGANIC MOLECULES

Carbon.Carbon is used extensively by organisms. It reacts readily to form four

covalent bonds, giving it the ability to form long chains.

Functional Groups.

A functional group is a small cluster of atoms that determines many of the

properties of the organic molecule.

Monomers and PolymersLarge organic molecules are called macromolecules. These are mostly

polymers- repeating series of subunits (building blocks) called monomers.

The joining of monomers to form a polymer is called polymerization. This

occurs by dehydration synthesis.

Breaking polymers apart requires the addition of water through hydrolysis.

Carbohydrates

Monosaccharides.


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Fatty Acids, Triglycerides, phospholipids, steroids, Eicosanoids,

Fatty Acids. One type of lipid = hydrophobic organic molecules with a high ratio

of H to O.

Fatty acids are chains of 4 to 24 carbon with a carboxyl group at one end and

a methyl group at the other.

Fatty acids are saturated with a hydrogen at every position along the carbon

chain, or unsaturated (missing a carbon, and with a double bond).

Polyunsaturated fatty acids have multiple C=C bonds.

TriglyceridesA triglyceride is a neutral fat made up of three fatty acids bound to a

molecule or glycerol.

Dietary triglycerides take the form of oils (from plants) and animal fat.

In the body, triglycerides store energy in adipose tissue and provide

insulation and cushioning.

PhospholipidsPhospholipids contain two fatty acids and a phosphate group

They have a polar hydrophilic region (phosphate group end) and a

hydrophilic fatty acid tails (hydrophobic area)

They serve as the structural foundation of cell membranes.

EicosanoidsProstaglandins, the most functionally diverse eicosanoids, are fatty acids

modified into a ring structure.

Prostaglandins are produced in almost all types of tissue and serve as

intercellular messengers.

SteroidsSteroids are lipids with complex ring structures

Examples include cholesterol and steroids formed from it.

Proteins

Amino Acids


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A protein is a polymer of amino acids

An amino acid has a carboxyl end and an amino end as well as a variable R

group

Twenty kinds of amino acids are used in protein structure.

PeptidesA peptide is two or more amino acids joined by peptide bonds.

The peptide bond is formed between the amino group on one amino acid and

the carboxyl group of the next.

Peptides vary according to size: Dipeptides, ipeptides..polypeptides.

Levels of Protein Structure

1. Primary structure refers to the order of the amino acids in the peptide.

2. Secondary structure is a coiled or folded shape held together by hydrogen bonds.

3. Tertiary structure is formed by further bending and folding of the proteins.

4. Quaternary structure occurs between two or more polypeptide chains.

Protein Conformation and DenaturationProtein conformation refers to its overall shape. It cannot function properly

if the shape is altered.

Denaturation due to heat or changes in pH causes a protein to unwind and

destroys it.

Conjugated ProteinsConjugated proteins have a non-amino prosthetic bound to them, such as

hemoglobin.

Protein FunctionsProteins serve as structural components and as enzymes in catalysis as well

as for communication, membrane transport, cell recognition and protection, and

movement and adhesion.


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Enzymes and Metabolism

Enzyme structure and Action

1. Enzymes are proteins that function as catalysts.2. Enzymes serve to lower the energy of activation in a chemical reaction,

causing it to proceed.

3. Enzymes are not altered by acting as catalysts.4. Enzymes are named for the substrate upon which they act, adding the suffix

ASE to the substrate name.

5. Portions of enzyme molecules serve as active sites where substratemolecules attach.

6. Enzymes are specific for their substrates (enzymesubstratespecificity) adjusting shape slightly to accommodate the substrate

(induced fit) and thus forming an enzyme-substrate complex.

7. Enzymes are temperature and pH sensitive, since slight changes can disruptthe hydrogen bonds holding the molecule in its s\proper conformation.

Cofactors

1. Many enzymes require nonprotein cofactors to function properly.2. Many enzymes work in conjunction with organic coenzymes.

Metabolic Pathways

1. Metabolic pathways require a sequence of enzymes to catalyze each reactionin turn.


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2. By activating or deactivating enzymes, cells can turn on metabolic pathwayswhen their end products are needed and shut them down when those

products are not needed.

Nucleotide and Nucleic Acids

Adenosine Triphosphate ATP

1. Adenosine triphosphate (ATP) is the universal energy carrying molecule.2. ATP consists of a double carbon-nitrogen ring (adenine) , a five carbon

sugar ( ribose) and a chain of three phosphate groups.

3. Most energy transfers involve removing the terminal phosphate group,employing ATPases.

4. ATP is short-lived but is regenerated via phosphorylation.5. The oxidation of glucose is the primary source of energy to synthesize ATP.6. The first stage of oxidation is glycolysis, in which glucose is split into two

threecarbon molecules or pyruvic acid.

7. If no oxygen is available, pyruvate enters anaerobic fermentation, a moreinefficient pathway.

8. If oxygen is available, aerobic respiration occurs within the mitochondria.

Other Nucleotides.

Guanosine triphosphate (GTP) is another energy-transferring molecule.

Cyclic adenosine monophosphate (cAMP) is a molecule that acts as a secondmessenger to activate metabolism within a cell.


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Nucleic Acids

1. Nucleic acids are polymers of nucleotides.2. Deoxyribonucleic acid (DNA) is the largest nucleic acid and the one that

constitutes our genes and is responsible for transferring hereditary

information.

3. Ribonucleic acid (RNA) exists in three forms and functions to synthesize thebodys proteins by assembling amino acids in the order described by the

DNA.

Chapter 3lecture

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