Cell Biology Overview and Structures

Cell Biology Overview

• Cell Theory: All living things are made of cells, the fundamental units of life. New cells arise from pre-existing cells.

• Cell Diversity: Cells have varied structures and functions, tailored to specific roles in organisms.

• Prokaryotic vs. Eukaryotic Cells:

  • Prokaryotes: Simpler, lack a nucleus and membrane-bound organelles (e.g., bacteria).
  • Eukaryotes: More complex, possess a nucleus and membrane-bound organelles (e.g., animal and plant cells).

Eukaryotic Cell Structure

• Plasma Membrane: A phospholipid bilayer controlling substance entry and exit.

• Cytoplasm: Jelly-like substance within the cell membrane, holding organelles and cytosol (cellular fluid).

• Nucleus: Houses DNA (genetic material) in chromosomes. Surrounded by a nuclear envelope with regulating pores.

• Nucleolus: Dense region within the nucleus, site of ribosome synthesis.

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

• Ribosomes: Sites of protein synthesis, made of RNA and protein; free in cytoplasm or bound to rough ER.

• Golgi Apparatus: Modifies, packages, and transports materials from ER for cellular use or secretion.

• Lysosomes: Sacs containing digestive enzymes to break down waste and worn-out parts.

• Mitochondria: "Powerhouses" of the cell, conduct cellular respiration to create ATP.

• Cytoskeleton: Network of protein fibers providing structure, support, and movement (microtubules, microfilaments, intermediate filaments).

• Vacuoles: Sacs for storage of materials like water, nutrients, and waste; large vacuole common in plant cells.

Prokaryotic Cell Structure

• Cell Wall: Provides rigidity and protection to the cell.

• Cytoplasm: Contains DNA (single chromosome), ribosomes, and essential molecules.

• Plasma Membrane: Similar to eukaryotic membranes.

Cell Transport

• Passive Transport: Movement across the membrane without energy investment; includes diffusion (high to low concentration), osmosis (water diffusion), and facilitated diffusion (with protein help).

• Active Transport: Movement against the concentration gradient, requiring energy (ATP).

Cell Division

• Cell Cycle: Ordered sequence of growth, DNA replication, and cell division. Includes interphase (G1, S, G2) and mitosis (prophase, metaphase, anaphase, telophase, cytokinesis).

• Mitosis: Produces two identical daughter cells (somatic cell division).

• Meiosis: Produces four genetically diverse daughter cells with half the chromosomes (gamete formation).

Cell Specialization

• Differentiation: Cells specialize in function by expressing specific genes; leads to different tissues.

Stem Cells

• Unspecialized: Can divide and differentiate into various specialized cell types.
• Types: Embryonic (from blastocysts, differentiate into any cell type) and adult (found in tissues, differentiate into limited cell types).
• Potential: Regenerative medicine, treating diseases through tissue replacement.

Importance of Cell Biology

• Fundamental to understanding all living organisms.
• Crucial in various fields (medicine, agriculture, biotechnology) particularly in medical advancements.

Explore the fundamental concepts of cell biology, including the Cell Theory and the differences between prokaryotic and eukaryotic cells. Learn about key structures within eukaryotic cells, such as the plasma membrane, nucleus, and endoplasmic reticulum. This quiz will help solidify your understanding of cellular organization and function.