Biology- Unit 1

What are the four main macromolecule classes?

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids

What is the skeleton of most organic molecules?

Carbon chains, which vary in length and shape

Hydrocarbons

Organic molecules consisting of only carbon and hydrogen

• Non-polar → no partial charges, equal sharing of valence electrons, hydrophobic

Isomers

Compounds with the same molecular formula but different structures and properties; 3 main types

1. Structural isomers

2. Geometric isomers (AKA cis-trans isomers)

3. Enantiomers

Structural isomers

Have different covalent arrangements of their atoms (straight vs. branched)

Geometric isomers (AKA cis-trans isomers)

Have the same covalent arrangements but differ in spatial arrangements due to inflexibility (double bonds)

Enantiomers

Isomers that are mirror images of each other

Most of the time, when a drug has enantiomer forms… (+ give an example)

one form is biologically active while the other is not.

Ex. Celexa (50% active, 50% inactive) and Lezapro (100% active), Ibuprofen (active S version, inactive R version)

Functional groups

Essentially, molecule “tags” that give hydrocarbons unique properties/function and make them polar

Functional groups give hydrocarbons a glow-up, making them more attractive

What are the eight most important functional groups?

1. Hydroxyl

2. Carbonyl

3. Carboxyl

4. Amino

5. Sulfhydryl

6. Phosphate

7. Methyl

8. Acetyl

Hydroxyl

• —OH, HO—

• Alcohols

  • Ex. ethanol

• Polar

  • Can form hydrogen bonds with water molecule, helping dissolve organic compounds such as sugars

Carbonyl

• C=O

• Ketones (if it’s within a carbon skeleton), aldehydes (if it’s at the end of a carbon skeleton

  • Also found in sugars, giving rise to two major groups of sugars: ketoses and aldoses

• Polar

Carboxyl

• OH—C=O

• Carboxylic acids, or organic acids

  • Ex. Acetic acid

• Found in carboxylate ions, which are ionized cells with a charge of -1

• Polar

  • Acts as an acid

    • Sometimes, the H pops off and makes the substance more acidic

Amino

• H—N—H

• Amines

  • Ex. glycine (has both an amine and a carboxylic acid; compounds with both groups are called amino acids)

• Polar

  • Acts as a base

    • Can pick up an H+ from the surrounding solution

      • Ionized with a charge of 1+ under certain cellular conditions

Sulfhydryl

• —SH, HS—

• Thiols

  • Ex. cysteine

• When two sulfhydryl groups react, they form a covalent bond known as a disulfide bridge

• Polar

Disulfide bridge

A strong covalent bond (-S-S-) formed between the sulfur atoms of two cysteine amino acids in a protein

Causes curly hair; the chemical found in perms breaks disulfide bridges

Phosphate

• (x3) O—P=O

• Organic phosphates

  • Ex. glycerol phosphate (ATP), which provides the backbone for cell membranes

• Polar

  • Acts as an acid

    • Contributes a negative charge to the molecule it’s a part of (2- when it’s at the end of a molecule, 1- when it’s located internally in a chain of phosphates)

    • Has the potential to react with water, releasing energy

Methyl

• (x3) H—C

• Methylated compounds

  • Ex. methyl cytidine

• Shuts down damaged DNA strands

• Found in sex hormones, and the arrangement of methyl groups affects their shape and function

• Non-polar

Acetyl

• H₃C—C=O

• Has a carbonyl and a methyl group

• Reactivates genes/DNA shut down by methyl; serves as an “on switch”

• Polar

Adenosine triphosphate (ATP)

The primary energy-transferring molecule in the cell (releases energy after reacting with water)

Adenosine + 3 phosphate groups

Which elements go with each macromolecule class?

1. Carbohydrates- CHO

2. Lipids- CHO (P in phospholipids)

3. Proteins- CHONS

4. Nucleic acids- CHONP

Polymer

A long molecule consisting of many similar building blocks (monomers) covalently bonded together

Monomer

The building blocks that covalently bond to form polymers

Which macromolecule classes are polymers?

Carbohydrates, proteins, and nucleic acids

Dehydration reaction

Occurs when two monomers bond together through the loss of a water molecule

Hydrolysis

A reaction that disasembles polymers into monomers (essentially, it’s the reverse of the dehydration reaction)

Carbohydrates include…

the sugars and the polymers of sugars.

Monosaccharides

Single sugars, the simplest carbohydrates

Have molecular formulas that are usually multiples of CH₂O

Glucose (C₆H₁₂O₆) is the most common monosaccharide

Polysaccharides

Carbohydrate macromolecules/polymers composed of many monosaccharides

What is the formula for glucose?

C₆H₁₂O₆

Glucose

• A monosaccharide in the carbohydrate family

• Ratio of CH₂O; formula is C₆H₁₂O₆

• Contains OH functional groups, making it polar

• Has linear and ring forms

• Galactose is an isomer of glucose

What molecule is this?

Glucose (linear form)

What molecule is this?

Glucose (ring form)

What molecule is this?

Glucose (ring form)

Disaccharide

Formed when a dehydration reaction joins two monosaccharides (with a glycosidic linkage)

Ex. maltose, sucrose