AP Bio Unit 1 Test

Bicarbonate Buffer System

• Carbonic acid (H₂CO₃) is a weak acid that forms when CO₂ combines with water

  • This is why CO₂ causes blood to become acidic

• Bicarbonate ions and carbonic acid are in equilibrium in living solutions

  • When blood becomes acidic → bicarbonate ions neutralize

  • When blood becomes alkaline → carbonic acid neutralizes

Primary Protein Structure

• Chain of amino acids connected by peptide bonds

Secondary Protein Structure

• Folding or spiraling of amino acid chain due to hydrogen bonding

Tertiary Protein Structure

• 3D, folded structure due to interactions between R-groups

  • Can included disulfide bridges, hydrogen bonding, hydrophobic interactions, and ionic bonds

Quaternary Protein Structure

• Includes 2 or more amino acid chains interacting/bonded to each other

  • Not all proteins reach this structure

Alpha and Beta Linkages

• Often in reference to glycosidic bonds (covalent bonds between two monosaccharides)

• Alpha

  • OH (hydroxyl) on carbon-1 is below the glucose ring

• Beta

  • OH (hydroxyl) on carbon-1 is above the glucose ring

Functional Groups (CHAMPS)

• Carbonyl

• Carboxyl

• Hydroxyl

• Amino

• Methyl

• Phosphate

• Sulfhydryl

Carbonyl

• =CO

  • oxygen bonded to a carbon skeleton via double bond

• POLAR

• ketones are when carbonyl is within the carbon skeleton

• aldehydes are when carbonyl is at the end of the skeleton

  • aldehyde, to the side

• ketones and aldehydes can be structural isomers with different properties

Carboxyl

• COOH

  • when an oxygen is double bonded to a carbon that is also bonded to an -OH group

• ex: carboxylic acids or other organic acids

• acetic acid, which gives vinegar its sour taste

• acidic properties due to the hydrogen ions because the covalent bond between hydrogen and oxygen is so polar (can release H+ ions more easily)

• ionized with a 1- charge in cellular conditions

Hydroxyl

• OH

  • bonded to a carbon skeleton

  • alcohols with names usually ending in “-ol”

    • ex: ethanol

  • molecules are polar, because the electrons spend more time near the electronegative oxygen atom

  • can form hydrogen bonds with water molecules, helping to dissolve organic compounds such as sugar

Amino

• NH₂

  • when a nitrogen atom bonds to two hydrogen atoms, to the carbon skeleton

• amines, such as glycine

  • glycine is special, because it has an amine group and a carboxylic group, making it an amino acid

• amino groups act as a base; can pick up H+ ions from surrounding solutions (such as water)

• ionized with a 1+ charge in cellular conditions

Methyl

• -CH₃

• methylation = added a methyl group to a molecule

• important for allowing biological molecules to function effectively

• able to form nonpolar covalent bonds

• methylation can modify the function of a gene in DA; does not change its integrity, but changed how/when expressed

Phosphate

• OPO₃²

• think nucleic acids (DNA, RNA, ATP)

• glycerol phosphate: bonds with fatty acids to make phospholipids

• can release energy when interacting with water

• this functional group is acidic due to its ability to release H+ ions

Sulfhydryl

• -SH

  • sulfur atom bonded to a hydrogen atom and carbon skeleton

• thiols, such as cysteine (sulfur-containing amino acids, ao also an amine group)

• 2 sulfhydryl groups can react, forming a covalent bond. this cross linking helps stabilize protein strutture