biology 8th grade

Glycolysis and Fermentation

• Glycolysis provides NAD+ to continue producing ATP.
• Fermentation is defined as an anaerobic process.

Alcoholic Fermentation

• Occurs in yeasts and some microorganisms.
• Produces ethanol and carbon dioxide as waste products.
• Takes place in the cytoplasm of cells.
• Equation for alcoholic fermentation:
  • $\text{Pyruvic acid} + \text{NADH} \rightarrow \text{ethanol} + \text{CO}_2 + \text{NAD}^+$

Components of Alcoholic Fermentation:

• Inputs: 2 Pyruvate, 2 NADH
• Outputs: 2 Ethanol, 2 CO2, 2 NAD+

Lactic Acid Fermentation

• Occurs in bacteria, fungi, and muscle cells of animals.
• Equation for lactic acid fermentation:
  • $\text{Pyruvic acid} + \text{NADH} \rightarrow \text{lactate} + \text{NAD}^+$

Components of Lactic Acid Fermentation:

• Inputs: 2 Pyruvate, 2 NADH
• Outputs: 2 Lactate, 2 NAD+

Cellular Respiration and ATP Production

Oxidative Phosphorylation

• Reduction: A reaction where a molecule gains electrons.
  • Molecule that gains electrons in the electron transport chain (ETC) is NADH.
• Oxidation: A reaction where a molecule loses electrons.
  • Molecule that loses electrons in the ETC is NADH.
• The loss of electrons from NADH generates energy that phosphorylates ADP, termed oxidative phosphorylation.

ATP Production Details:

• In the ETC:
  • Each NADH yields approximately 3 ATP.
  • Each FADH2 yields approximately 2 ATP.
• Complete breakdown of glucose in cellular respiration yields 36-39 ATP molecules.
• Cellular respiration produces 18 times more ATP than glycolysis alone.

Overview of Fermentation

• Occurs under anaerobic conditions (absence of oxygen).
• In anaerobic conditions, cellular respiration cannot fully occur, but glycolysis can continue.
• Fermentation allows glycolysis to continue by regenerating NAD+.
• Key limitation for glycolysis in anaerobic conditions is the concentration of NAD+.
• During fermentation, high-energy electrons from NADH are given back to pyruvate, recycling NAD+.

Characteristics of Living Things

• D: DNA
• C: Cells – basic unit of life.
• G: Grow and Develop.
• S: Sensitivity and Response to Stimuli.
• E: Obtains and Uses Energy.
• R: Reproduce.
• A: Adapt and Evolve.

Three Tenets of Cell Theory

1. All living things are composed of cells.
2. All organisms are made of one or more cells.
3. All cells arise from existing cells.

Cell Characteristics

• All cells:
  • Have a cell membrane.
  • Contain DNA at some point in their lifecycle.
  • Have various sub-cellular structures.

Prokaryotic Cells

• Lack membrane-bound organelles and a nucleus.
• Contain a cell membrane, ribosomes, a nucleoid (non-membrane-bound DNA region), and plasmids (accessory genes).
• Example: Bacteria and Archaea.

Cell Structure and Function

Key Organelles and Structures

• Cell Membrane: Defines and protects the cell; semi-permeable.
• Nucleus: Control center of the cell, contains DNA.
• Cytoplasm: Fluid that fills the cell.
• Ribosomes: Sites of protein synthesis.

Endoplasmic Reticulum (ER)

• Rough ER: Studded with ribosomes; synthesizes proteins.
• Smooth ER: Involved in lipid synthesis and detoxification.

Golgi Apparatus

• Modifies, packages, and ships proteins received from the ER.

Lysosomes

• Contains enzymes for breakdown of cellular waste.

Mitochondria

• Powerhouse of the cell; produces ATP through cellular respiration.

Vacuoles

• Storage for materials like water, nutrients, and waste products.

Chloroplasts

• Site of photosynthesis in plant cells, converts sunlight into glucose.

Cytoskeleton

• Provides structural support; consists of microtubules, intermediate filaments, and microfilaments.

Plant vs. Animal Cells

• Plant cells have chloroplasts and cell walls; animal cells have centrioles and lysosomes.

Enzymes and Chemical Reactions

Enzyme Characteristics

• Enzymes are biological catalysts that speed up chemical reactions.
• Most enzymes end in -ase (e.g., urease).
• Example enzyme: Uroporphyrinogen decarboxylase, which catalyzes a reaction for hemoglobin production.

Reaction Types

• Activation Energy: The minimum energy required for a reaction to occur.
• Enzymes lower the activation energy needed for reactions.
• Catalysts: Substances that lower activation energy to increase the reaction rate.

Types of Chemical Reactions

• Endergonic Reaction: Requires a net input of energy.
• Exergonic Reaction: Releases a net output of energy.

Energy Diagrams

• Energy diagrams illustrate changes in energy during a chemical reaction, highlighting activation energy and overall energy changes.

Macromolecules

Types and Functions

Lipids

• Non-polymers, hydrophobic.
• Examples: Fats/Triglycerides, Phospholipids, Steroids.
• Functions include energy storage and structural components of cell membranes.

Nucleic Acids

• Composed of nucleotides, responsible for storage and transmission of genetic information.
• Examples: DNA, RNA.

Carbohydrates

• Composed of monosaccharides.
• Functions include energy storage; form chains (polymers) known as polysaccharides.
• Examples: Glucose, Sucrose.

Protein

• Composed of amino acids.
• Example: Enzymes, structural proteins, etc.

Properties of Water

1. Good Solvent: Water's polarity allows it to dissolve many substances.
2. Cohesion: Attraction between water molecules.
3. Adhesion: Attraction between water and different molecules.
4. Surface Tension: Water's ability to behave like a cohesive liquid.

Acids, Bases, and pH

• pH Scale: Ranges from 0 - 14, indicates the hydrogen ion concentration.
  • Acid: pH < 7 (donates H+ ions).
  • Neutral: pH = 7.
  • Base: pH > 7 (accepts H+ ions).

Organic Molecules and Water

• Hydrophilic: Water-loving; polar compounds.
• Hydrophobic: Water-fearing; nonpolar compounds.
• Amphipathic: Molecules containing both hydrophilic and hydrophobic regions.

Covalent Bonding in Water

• Water forms due to covalent bonds between oxygen and hydrogen.
• Water is polar, enabling hydrogen bonding among molecules.