Cell Structure and Organelles

• Cell: The basic unit of life, with Theodor Schwann concluding that animals are made of cells.
• Mathias Schleiden concluded that all plants are made of cells.
• Rudolf Virchow concluded that all living things are made of cells.

Basic Composition of a Cell

• Protoplasm: All contents inside the cell except the nucleus.
• Cell Membrane: The outermost part of the cell.
• Organelles: Small cellular organs with specific functions.
• Eukaryotic cells have a nucleus where genetic material is separate from the cytoplasm.
• Prokaryotic Cell: A cell lacking a nuclear envelope.

Cell Organelles

• Cell Wall: Provides tensile strength and protection against mechanical and osmotic stress.
• The cell wall is a double phospholipid layer with embedded proteins, allowing certain molecules to pass through.
• Cytoplasm: The liquid filling the inside of a cell and the location of most of the organelles.
• Nucleus: The control center of the cell with pores for substance passage, and contains chromatin (genetic material).
• Mitochondria: Known as the powerhouse of the cell.
• Mitochondria produce energy for cell survival and functioning.
• They break down glucose into adenosine triphosphate (ATP), which is the energy currency.
• Cristae are inner folds in the mitochondria where cellular respiration occurs.
• Lysosome: Functions as the suicide bag of the cell.
• Lysosomes contain digestive enzymes, maintain and repair organelles, and trigger apoptosis (cell death).
• Rough Endoplasmic Reticulum: Has ribosomes attached to it and assists in protein synthesis.
• Smooth Endoplasmic Reticulum: Responsible for synthesizing essential lipids like phospholipids and cholesterol.
• The smooth endoplasmic reticulum is responsible for the production of steroid hormones and carbohydrate metabolism.
• Golgi Bodies: Help process and package proteins and lipid molecules, especially proteins destined for export.
• Ribosomes: Attached to rough endoplasmic reticulum and responsible for protein synthesis.
• Centrioles: Paired barrel-shaped organelles located in the cytoplasm near the nuclear envelope.
• Centrioles organize microtubules that serve as the cell's skeletal system.
• Motility Organelles:
  • Cilia: Hair-like protrusions.
  • Flagella: Whip-like structures.
  • Pseudopodia: Arm-like projections.
• Plastids: Double-membrane organelles in plant and algae cells (autotrophs/photosynthetic organisms).
• Plastids manufacture and store food.

Most Common Plastids

• Chloroplast: The site of photosynthesis, converting light energy to chemical energy and contains chlorophyll (green).
• Chromoplast: Carotenoid (orange colored plastid).
• Leucoplast: Colorless and used for fat or oil storage.
• Cell Wall: Found only in plant cells.
• Cell walls are made of cellulose.

Introduction to Cellular Metabolism

• Glycolysis: Breakdown of glucose to ATP (adenosine triphosphate).
• Glycolysis yields 2 pyruvic acid molecules, 8 ATP for aerobic respiration, and 2 ATP for anaerobic respiration.
• Krebs Cycle: Pyruvic Acid > Acetic Acid > Acetyl-CoA end result is 6 CO2, 8 NADH2, 2 FADH2, 2 ATP (GTP).
• Electron Transport: A series of reduction/oxidation reactions facilitated by electron carriers.

Summary of ATP Production per process

• Glycolysis yields 8 ATP (aerobic).
• Krebs cycle and electron transport yields 28 ATP + 2 GTP or 30 ATP.
• 1 glucose molecule yields 38 ATP.
• Fermentation: Anaerobic breakdown of glucose.
• Final fermentation products include 2 ATP, CO2, and ethyl alcohol.

Introduction to Cellular Division

• Mitosis: Cell division in somatic cells, resulting in a diploid number.
• Meiosis: Cell division in gonads (sex cells).
• Female sex cell: Ovum/Egg Cell.
• Male sex cell: Sperm Cell.
• Meiosis always results in a haploid number.