Cell Division: Prokaryotes vs. Eukaryotes

Cell Division: Prokaryotes vs. Eukaryotes

• Prokaryotes (Archaebacteria and Eubacteria) are unicellular organisms
• Eukaryotes (Protozoa, algae, fungi, plants, and animals) can be unicellular or multicellular
• Prokaryotic size: 1-2 μm
• Eukaryotic size: larger than 5 μm
• Prokaryotes lack membrane-bound organelles
• Eukaryotes have membrane-bound organelles
• Prokaryotic nucleus is undefined and membrane-less (nucleoid, no nucleolus)
• Eukaryotic nucleus is defined and membrane-bound (with nucleolus)
• Prokaryotic DNA is small, circular, without histones
• Eukaryotic DNA is large, linear, segmented, with histones
• Prokaryotes reproduce by binary fission
• Eukaryotes reproduce by mitosis and meiosis
• Prokaryotic movement: flagella
• Eukaryotic movement: microtubules

Prokaryotic vs Eukaryotic Transcription and Translation

• Prokaryotic transcription and translation occur simultaneously in the cytoplasm
• Eukaryotic transcription occurs in the nucleus, and translation occurs in the endoplasmic reticulum; not simultaneous
• Prokaryotic mRNA is polycistronic
• Eukaryotic mRNA is monocistronic
• Prokaryotic mRNA lacks RNA splicing
• Eukaryotic mRNA has RNA splicing
• Prokaryotic proteins lack post-translational modifications
• Eukaryotic proteins have post-translational modifications
• Prokaryotes have a wide variety of metabolic pathways and can survive in diverse environments
• Eukaryotes mostly employ glycolysis and/or photosynthesis, and can survive only in limited conditions

The Cell Cycle

• Phases of the cell cycle include G1, S, G2, and M (mitosis)
• Interphase (G1, S, and G2) is the period of growth and preparation for cell division
• G1: Growth and metabolism
• S: DNA synthesis and chromosome duplication
• G2: Preparation for mitosis; the cell prepares for division in terms of energy levels, biochemical components, and so on
• Mitosis is the process of nuclear division (prophase, metaphase, anaphase, and telophase) into two identical daughter cells.
• Meiosis is cell division used for sexual reproduction, which produces four non-identical haploid cells from a single diploid cell. It includes two rounds of division (Meiosis I, and Meiosis II)

Mitosis

• Interphase: Chromosomes duplicate and form sister chromatids; Nucleus is intact
• Prophase: Chromatin condenses into chromosomes; nuclear envelope disappears
• Metaphase: Chromosomes align in the middle of the cell
• Anaphase: Sister chromatids separate and move to opposite poles
• Telophase: Chromosomes decondense; nuclear envelopes reform
• Cytokinesis: Cytoplasm divides, creating two daughter cells

Meiosis

• Prophase I: Homologous chromosomes pair and undergo crossing over
• Metaphase I: Homologous chromosomes align at the cell's equator
• Anaphase I: Homologous chromosomes separate and move towards opposite poles
• Telophase I: Chromosomes arrive at opposite poles and the cytoplasm divides (two haploid cells results)
• Prophase II: Chromosomes condense if not already condensed
• Metaphase II: Chromosomes align at the cell's equator. Sister chromatids are attached to spindle fibers.
• Anaphase II: Sister chromatids separate and move to opposite poles
• Telophase II: Chromosomes arrive at opposite poles and cytoplasm divides (four haploid cells results)

Crossing Over

• Homologous chromosomes exchange segments of DNA during Prophase I.
• This process leads to genetic variation in offspring.

Explore the fascinating differences between prokaryotic and eukaryotic cells in this quiz. Understand their structural characteristics, reproductive methods, and processes of transcription and translation. This quiz will help you grasp fundamental concepts in cell biology.