EXAM II

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🧬 DNA / NUCLEOTIDES (HIGH PRIORITY)

Purines (2 rings)

    •    Adenine (A)

    •    Guanine (G)

Pyrimidines (1 ring)

    •    Cytosine (C)

    •    Thymine (T) → DNA only

    •    Uracil (U) → RNA only

Base Pairing

    •    A–T = 2 hydrogen bonds

    •    G–C = 3 hydrogen bonds

DNA strands = antiparallel

DNA denaturation breaks = hydrogen bonds

NOT backbone (phosphodiester).

A nucleotide =

    •    Phosphate

    •    Sugar

    •    Base

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🧬 MACROMOLECULE TABLE (MEMORIZE)

Carbohydrate

    •    Monomer: monosaccharide

    •    Polymer: polysaccharide

    •    Bond: glycosidic

Protein

    •    Monomer: amino acid

    •    Polymer: polypeptide

    •    Bond: peptide

Nucleic acid

    •    Monomer: nucleotide

    •    Polymer: DNA/RNA

    •    Bond: phosphodiester

Lipid

    •    Glycerol + fatty acids

    •    Bond: ester

    •    Not true polymers

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🧪 PROTEINS

Primary = amino acid sequence

Secondary = α-helices & β-sheets

Tertiary = interactions between R groups

    •    Hydrogen

    •    Ionic

    •    Disulfide

    •    Hydrophobic

If primary changes → structure changes.

Proteins do NOT store genetic info.

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🔥 ENZYMES

    •    Lower activation energy

    •    Do NOT change if reaction is exergonic or endergonic

    •    Denature in heat

Competitive inhibitor → active site

Noncompetitive → different site

Feedback inhibition → product shuts pathway off

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⚡ TRANSPORT (MEMBRANE)

Simple diffusion

    •    High → Low

    •    No protein

    •    No ATP

Facilitated diffusion

    •    High → Low

    •    Protein

    •    No ATP

Active transport

    •    Low → High

    •    Protein

    •    ATP

If lightning bolt shown → ACTIVE.

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⚛ ATOMS & BONDS

Protons determine element.

Group number = valence electrons.

Period number = electron shells.

Carbon forms 4 bonds.

Organic molecules must have C–H.

Nonpolar covalent = electrons shared equally.

Hydrogen bonds = weak attraction.

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💧 WATER & pH

Cohesion = water sticks to water.

Adhesion = water sticks to other things.

High specific heat = hydrogen bonds.

Lower pH = more H+.

10⁻³ is more acidic than 10⁻⁷.

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🔥 THERMODYNAMICS

Energy cannot be created or destroyed.

Exergonic = releases energy.

Endergonic = requires energy.

Photosynthesis = endergonic.

Break big → small = catabolic.

Build small → big = anabolic.

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🧈 LIPIDS

Triglyceride = long-term energy storage.

Phospholipid = membrane.

Phospholipid head = phosphate + polar group + glycerol.

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🧬 DNA DETAILS

A–T = 2 H bonds

G–C = 3 H bonds

NAD+ → NADH = reduction (gained electrons)

Glycolysis produces → pyruvate + ATP

Mitochondria make ATP.