Cell Structure, Energy, and Measurement Units

Cell Structure and Function

• Cells are the smallest units of life, capable of growth, reproduction, function, and response to stimuli.
• Studying cells is vital to understanding energy and matter flow between organisms.
• Photosynthesis and respiration are key cellular processes driving energy and matter transfer between organisms.

Energy Source for Life

• The sun is the ultimate source of energy for life on Earth.
• Photosynthetic organisms capture solar energy to create chemical energy.
• Humans indirectly use solar energy by consuming plants and other organisms.

Units of Measurement

• 1 meter (m) = 100 centimeters (cm) = 1000 millimeters (mm) = 1,000,000 micrometers (µm) = 1,000,000,000 nanometers (nm)

• 1 nm = 1 × 10^-9 m

• 1 µm = 1 × 10^-6 m

• 1 mm = 1 × 10^-3 m

• 1 cm = 1 × 10^-2 m

• Appropriate units for various sizes: human cell (micrometers); molecule (nanometers); bacterium (micrometers); pinky finger width (centimeters); fingernail thickness (millimeters).

Cellular Components (Simple to Complex)

• Organic chemistry (carbon, water, bonding)
• Fundamental building blocks (nucleotides, amino acids)
• Macromolecules (DNA, protein, lipid, carbohydrate)
• Structures (vesicles, organelles)

Energy and Val the Waitress

• Electrons shift from higher energy to lower energy levels to stabilize, similar to Val switching jobs for less energy.
• Stability equates to lower energy.

Valence Electrons and Number

• Valence electrons participate in bonding – the outer shell.
• Valence number is the number of electrons needed to fully bond (octet/doublet).

Bond Formation and Energy

• Bonds release energy when they form and stabilize a system, which has less energy movement. A single balloon flows in the air, but a group of balloons is more stable.
• Less energy = more stable system.
• Specific bonds' formation releases different amounts of energy to other compounds leading to different combustion levels (higher energy release leads to higher temperature during combustion)
• Catalysts initiate/speed up chemical reactions by lowering the activation energy.

Hydrocarbons as Fuels

• Hydrocarbons are composed of carbon and hydrogen.
• They are good fuels because of abundant combustion with water.
• Smaller hydrocarbon molecules are better fuels due to higher combustion output

Water Properties

• Polar and cohesive: unequal charge distribution, holding water molecules together.
• Stabilizes temperature: high specific heat capacity (absorb/release heat significantly without temperature variation).
• Good solvent: dissolves polar and ionic substances; crucial for nutrient/waste transport and cellular interactions.

Hydrophilic and Hydrophobic Molecules

• Hydrophilic molecules (sugars, nucleic acids) interact with water.
• Hydrophobic molecules (lipids, insoluble proteins) avoid water interaction.

Covalent vs. Hydrogen Bonds

• Covalent bonds (atoms sharing electrons) are much stronger than hydrogen bonds (electrostatic attraction).

Polymers

• Polymers are long molecules made of repeating monomers.

Biological Macromolecules (Polymers)

• Carbohydrates: monosaccharides
• Proteins: amino acids
• Nucleic acids: nucleotides

Monomer Activation

• Monomers activate with carrier molecules, usually proteins, facilitated by energy (e.g., from ATP).

Condensation and Hydrolysis

• Condensation (dehydration) reactions join monomers, releasing water (bond making).
• Hydrolysis adds water to break apart polymers (bond breaking).

Polymerization

• Continued addition of monomers to a growing chain

Non-Polymeric Lipids

• Lipids are non-polymeric chains, showing continuity rather than a chain-like structure.

Protein Classes/Functions

• Enzymes, structural, motility, regulatory, transport, signaling, receptors, defensive, storage

Amino Acids (Structure)

• (Card 28 is missing information; general structure details for all amino acids)

Determining Hydrophobic/Hydrophilic Amino Acids

• Hydrophobic: nonpolar side chains; internal protein structure.
• Polar uncharged: O, OH, SH side chains; interact with water.
• Polar charged: + or – charged side chains; interact with water; acidic or basic.

Number of Amino Acids

• 20 primary amino acids

Amino Acid Examples (Abbreviations)

Protein Folding Levels

• Primary: amino acid sequence
• Secondary: local structures (α-helices, β-sheets)
• Tertiary: overall 3D structure from interactions
• Quaternary: multiple polypeptide chains interacting

Sugars and Carbohydrates

• Sugars are hydrates of carbon (Cn(H2O)n).
• Formed through photosynthesis, using solar energy.

Glucose Structure

• Linear and ring forms.
• Alpha and beta forms due to OH positioning.
• Alpha glucose relevant for energy storage (starch, glycogen).

Glucose Views (Simple vs. Complex)

• Simple: reactive groups/bonds visualization
• Complex: 3D representation

Common Sugars (Disaccharides)

• Maltose: two alpha-D glucose.
• Lactose: beta-D glucose.
• Sucrose: alpha and beta glucose (fructose and glucose in sucrose).

Glucose Storage (Short-Term)

• Glycogen

Plant Polysaccharides (Digestion)

• Our bodies can't digest cellulose; plants use it for structure.

Lipid Classes

• Fatty acids, triglycerides, phospholipids, glycolipids, steroids, terpenes

Lipid (Structure)

• Long hydrocarbon chains

Saturated/Unsaturated Fats

• Unsaturated: double/triple bonds, liquid at room temperature.
• Saturated: solid at room temperature.

Triglyceride Structure

• Three fatty acid chains

Phospholipid Structure (vs. Triglycerides)

• Two fatty acids and glycerol plus a phosphate group.
• Phospholipids form cell membranes.

Cholesterol Structure

• 27 carbons
• Hydrocarbon tail, sterol nucleus (four rings), hydroxyl group.

Vitamin A Type

• Terpene

Nucleic Acid Bases

• Adenine (A), Guanine (G), Cytosine (C), Thymine (T), Uracil (U)

Purines/Pyrimidines

• Purines: two rings (A, G)
• Pyrimidines: one ring (C, T, U)

Ribose/Deoxyribose

• Ribose: OH at 2' carbon (RNA)
• Deoxyribose: H at 2' carbon (DNA)

DNA/RNA Base Pairing

• A pairs with T (or U in RNA)
• C pairs with G

DNA Strands (Antiparallel)

• One strand in 5’ to 3’; other in 3’ to 5’

DNA Helix and Base Pairs

• Right-handed helix, 10.5 base pairs per turn

DNA Types (A/Z)

• A-DNA: 11 base pairs, right-handed
• Z-DNA: 12 base pairs, left-handed

Chromatin

• DNA plus proteins

Histones and Nucleosomes

• Histones (octamer) organize DNA into nucleosomes.

Chromatin Function

• Tightly packs DNA
• Protects DNA
• Regulates gene expression

Histone Tail Modifications

• Acetylation: relaxes chromatin, allows gene expression.
• Methylation: condenses chromatin, prevents gene expression.

Histone Code

• Hypothesis: histone modifications control gene expression.

DNA Organization (Chromosome)

• DNA double helix to nucleosomes to coils to supercoils to chromosome

DNA Polymerization Challenges

• Four different nucleotides
• Double helix, specific base pairing
• Large chromosome size

DNA Replication (Semi-conservative)

• Original strands serve as templates for new strands.

DNA Replication Template

• Complementary strands serve as templates during DNA replication

Multiple Origins of Replication

• Eukaryotic chromosomes need multiple origins for efficiency.

Replication Origins (A/T Rich)

• A/T base pairs easier to separate.

Replicon vs. Replication Bubble

• Replicon: DNA region replicating from one origin.
• Replication bubble: site of DNA replication.

DNA Polymerase III Directionality

• DNA polymerase adds nucleotides 5' to 3'

Explore cell structure, energy sources such as the sun, and units of measurement. Understand photosynthesis, respiration, and the flow of energy and matter in organisms. Convert between meters, centimeters, millimeters, micrometers, and nanometers.