1. The Cell Presentation

The Cell Biologists study cells and their interactions.

Objectives

• Compare prokaryotic and eukaryotic cell structures/functions.

• Understand Cell Theory and specialization.

• Explore organelles and membrane-bound structures.

• Compare plant and animal cells.

• Discuss the cytoskeleton and extracellular compartments.

Parts of a Cell Introduction to various cell components.

Cell Theory

• Cells as the building blocks of life.

• Three main tenets of Cell Theory:

  • All living organisms are composed of cells.

  • New cells arise from pre-existing cells.

  • Cells contain hereditary information (DNA).

Size Range of Cells Comparison of sizes, from atoms to adult female cells on a logarithmic scale. Ranges include:

• Atom: 0.1 nm

• Bacteria: 1 μm

• Animal Cells: 10-100 μm

• Chicken egg: 100 mm.

Cell Specialization Different types of cells:

• Nerve cells, Muscle cells (stratified and smooth, cardiac), Gland cells, Blood cells, Sperm, Ovum.

Common Features of All Cells Share essential components, including:

• Lipids & Proteins.

• Nucleic acids & proteins.

• Proteins & carbohydrates.

Prokaryotes vs. Eukaryotes

• Prokaryotes: Smaller, simpler (e.g., bacteria).

• Eukaryotes: Complex, with internal membranes and organelles.

Importance of Prokaryotes Roles in recycling elements, photosynthesis, and bioremediation. Bacteria inhabit various environments (skin, soil, aquatic).

Microbiome Human body: 30 trillion cells; microbiomes consist of 39 trillion microbial cells assisting in various functions, including nutrient extraction.

Cellular Structures Identify cellular structures that are not common to all:

• Nucleus, DNA, ribosomes, cell membrane.

Eukaryotic Cell Structure Overview of organelles and their functions:

• Nucleus, Cytoskeleton, Endoplasmic Reticulum, Golgi apparatus, and Lysosomes.

The Nucleus Contains most genetic material. Nuclear envelope: Double membrane that regulates material export.

Endomembrane System Connection and interaction among membranes:

• Nucleus, ER, Golgi, Lysosomes, and the Plasma membrane.

Endoplasmic Reticulum

• Smooth ER: lipid production and detoxification.

• Rough ER: protein synthesis with ribosomes.

Golgi Apparatus Sorts and ships ER products with tagging instructions.

Enzyme Location Enzymes for lipid biosynthesis are found in the smooth ER.

Lysosomes Function: Digestive enzymes to break down waste and damaged organelles.

Plant Cell Structure Overview of organelles in plant cells, such as chloroplasts and cell wall.

Central Vacuoles Functions include nutrient storage and turgor pressure maintenance in plants.

Chloroplasts and Mitochondria

• Chloroplasts: Convert sunlight to energy (photosynthesis).

• Mitochondria: Energy production through sugar digestion.

Endosymbiotic Theory Eukaryotic cells evolved by engulfing bacteria, leading to organelles like mitochondria and chloroplasts.

Photsynthesis in Sea Slugs Some sea slugs retain algae’s photosynthetic plastids for energy.

Endosymbiotic Evidence Features supporting endosymbiotic theory: double membranes, own DNA, circular genomes of organelles.

Cytoskeleton Structure Composed of three protein fiber classes: microtubules, intermediate filaments, microfilaments.

Microtubules Structure: Hollow rods aiding in organized movement. Motor proteins transport cargo along microtubule tracks.

Cell Motility Flagella for cell propulsion; cilia for movement coordination.

Microfilaments Composed of actin; involved in muscle contraction and amoeba movement.

Intermediate Filaments Durable ropelike fibers found in specific animal cells.

Extracellular Matrix Secreted glycoproteins providing support and communication between animal cells.

Cell Junctions Types of junctions:

• Tight junctions (prevent leakage)

• Adhesion junctions (mechanical stress)

• Gap junctions (communicate small molecules)

Essential Cellular Structures Identify non-essential items for some cells (e.g., mitochondria).

Functional Categories of Cell Structures Categories include:

• Genetic Control (Nucleus).

• Manufacturing, Distribution, Breakdown (ER, Golgi, Lysosomes).

• Energy Processing (Chloroplasts, Mitochondria).

• Structural Support, Movement, Communication (Cell wall, Cytoskeleton, Plasma Membrane).