Biology: Prokaryotes and Eukaryotes

• Prokaryotic cells do not have a nucleus and membrane-bound organelles within its cytoplasm
• Prokaryotes are small, single-celled organisms that can utilize different nutrients and energy sources and inhabit all types of environments on Earth
• All bacteria, including organisms of domains Archaea and Bacteria, are considered as prokaryotes
• Eukaryotic cells are characterized by the presence of a nucleus and membrane-bound organelles within its cytoplasm
• Domain Eukarya includes protists, fungi, plants, and animals as examples of eukaryotes
• Eukaryotic cells have a nucleus with a nuclear membrane enclosing genetic materials, while prokaryotic cells have genetic materials concentrated in a region of the cytoplasm called the nucleoid
• Cell wall and cell membrane provide shape, rigidity, and protection in both prokaryotic and eukaryotic cells
• Cell wall in prokaryotes is made up of peptidoglycan, while in eukaryotes it is made up of cellulose (plants) and chitin (fungi)
• Prokaryotes have a sterol-like lipid component called hopanoid in the cell membrane, while eukaryotes have sterols like cholesterol (animals), phytosterol (plants), and ergosterol (fungi)
• Endomembrane system, rough and smooth endoplasmic reticulum, Golgi apparatus, lysosome, endosome, and vacuole are present in eukaryotic cells but not in prokaryotic cells
• Mitochondria and chloroplasts are present in eukaryotic cells but not in prokaryotic cells
• Ribosomes are present in both prokaryotic and eukaryotic cells and are involved in protein synthesis
• Prokaryotic cells, mitochondria, and chloroplasts contain 70S ribosomes, while eukaryotic cells have 80S ribosomes
• DNA in prokaryotic cells is found in the nucleoid region of the cytoplasm, while in eukaryotic cells it is wrapped around histones inside the nucleus
• Prokaryotes, mitochondria, and chloroplasts have covalent, closed, circular DNA, while eukaryotes have linear DNA coiled around histones
• Prokaryotes usually have one chromosome and an extrachromosomal DNA called a plasmid, while eukaryotes have more than one chromosome
• Eukaryotes use histones to package DNA into nucleosomes and condense it into chromatin to fit multiple chromatins into the nucleus
• Prokaryotic cells are smaller compared to eukaryotic cells
• Typical prokaryotic cells can range from 0.1 to 5μm in diameter
• Eukaryotic cells are typically 10 to 100μm in diameter
• Prokaryotes are unicellular or made up of only one cell
• Eukaryotes are either unicellular or multicellular
• Most protists and yeast are unicellular eukaryotes
• Plants, animals, most fungi, and some protists are multicellular eukaryotes
• Most prokaryotic cells reproduce through binary fission and some reproduce through spores
• Binary fission is a process of reproduction wherein one cell is divided into two new cells
• In eukaryotic cells, individual cells reproduce through mitosis and meiosis
• Mitosis produces two identical, diploid daughter cells important for growth, development, and tissue repair
• Meiosis produces four, non-identical, haploid daughter cells important in sexual reproduction
• DNA replication is the process of synthesizing a new DNA strand using an old DNA strand as a template
• In prokaryotic cells, DNA replication occurs in two opposing directions at the same time in the cytoplasm
• In eukaryotic cells, DNA replication occurs in the nucleus with multiple points of origin and unidirectional replication
• Eukaryotes have more DNA than prokaryotes, leading to longer DNA replication time in eukaryotes
• Transcription refers to the synthesis of RNA using DNA as a template
• Translation is the process of protein synthesis
• In prokaryotic cells, transcription and translation can be done at the same time in the cytoplasm
• In eukaryotic cells, transcription occurs in the nucleus and translation occurs in the cytoplasm
• Eukaryotic DNA contains exons (coding part) and introns (non-coding part) requiring post-transcriptional processing