Cellular Respiration: Hydrocarbon Combustion

Step-by-Step Method for Balancing Combustion Reactions

Combustion reactions involve the reaction of a hydrocarbon with oxygen to produce carbon dioxide and water. Balancing these reactions is essential for understanding cellular respiration and energy production.

• Balance carbon (C) first: The number of CO2 molecules produced equals the number of carbon atoms in the hydrocarbon.

• Balance hydrogen (H) next: The number of H2O molecules produced is half the number of hydrogen atoms in the hydrocarbon.

• Balance oxygen (O) last: Count total oxygen atoms required on the product side, then divide by 2 to get the number of O2 molecules needed.

• Clear fractions if needed: Multiply the entire equation by 2 if you get a fraction.

Example: Methane (CH4)

• CH4 + 2O2 → CO2 + 2H2O

• Balanced in one pass.

Example: Propane (C3H8)

• C3H8 + 5O2 → 3CO2 + 4H2O

General formula for hydrocarbon combustion:

Microscopy and Cell Structure

Microscopy: Principles and Types

Microscopy is essential for visualizing cells and their components, allowing scientists to study cell structure and function.

• Resolution: The minimum distance two points can be separated and still be distinguished as separate objects.

• Magnification: The ratio of an object's image size to its real size.

• Contrast: The difference in brightness between light and dark areas in an image.

Types of Microscopy

• Light Microscopy: Uses visible light to visualize specimens. Maximum magnification up to 1000x; resolution about 200 nm.

• Electron Microscopy: Uses beams of electrons for much higher resolution (up to 10,000,000x) and can visualize much smaller structures (down to 2 nm).

Cytology

Cytology is the study of cell structure, made possible by advances in microscopy.

Eukaryotic Cells

Key Features and Differences from Prokaryotic Cells

Eukaryotic cells are defined by the presence of a nucleus and other membrane-bound organelles. They are found in plants, animals, fungi, and protists.

• Nucleus: Contains DNA; surrounded by a double membrane.

• Plasma Membrane: Semi-permeable barrier composed of a lipid bilayer.

• Cytoplasm: The interior of the cell, excluding the nucleus, containing organelles suspended in cytosol.

Comparison of Animal and Plant Cells

Endomembrane System

The endomembrane system is a group of organelles involved in the synthesis, modification, and transport of proteins and lipids.

• Nucleus: Contains genetic material (DNA), chromosomes, and proteins. Surrounded by a double membrane (nuclear envelope).

• Ribosomes: Complexes of rRNA and protein; sites of protein synthesis. Can be free in cytosol or bound to the endoplasmic reticulum (ER).

• Endoplasmic Reticulum (ER): Network of membranes; rough ER has ribosomes and synthesizes proteins, smooth ER synthesizes lipids.

• Golgi Apparatus: Stack of flattened sacs; modifies, sorts, and packages proteins and lipids for transport.

• Lysosomes: Membranous sacs containing hydrolytic enzymes for digestion of macromolecules.

• Vacuoles: Large vesicles for storage and maintaining cell rigidity (especially in plants).

Learning Objectives and Key Concepts

• Understand the function and origin of mitochondria and chloroplasts.

• Know the properties of the cytoskeleton and extracellular components.

• Know the differences between eukaryotic and prokaryotic cells.

Mitochondria

The mitochondrion is known as the "powerhouse" of the cell. It is the site of cellular respiration, producing ATP from fuels and oxygen.

• ATP (Adenosine Triphosphate): The main energy currency of the cell.

• Cellular Respiration Equation:

Summary Table: Main Organelles and Their Functions

Additional Info

• Autophagy: The process by which cells recycle their own organelles and macromolecules using lysosomes.

• Phagocytosis: The process of engulfing large particles or microorganisms for digestion.

• Endosymbiotic Theory: Mitochondria and chloroplasts are thought to have originated from free-living prokaryotes engulfed by ancestral eukaryotic cells.