Some eukaryotes are single-celled. The cell is an entire organism capable of performing all the fundamental functions e. These single-celled organisms are exemplified by protists. Prokaryotes are organisms characterized by lacking a nucleus and other membrane-bound cytoplasmic structures. They are considerably smaller than eukaryotes. They also have a greater surface area to volume ratio and therefore have greater metabolic rates. Examples of prokaryotes are eubacteria and archaea.
Eukaryotes have a nucleus that contains nuclear DNA. The nucleus has a lipid bilayer membrane that is perforated with nuclear pores. The DNAs inside the nucleus are complexed with histone proteins forming chromatin. In cell division, the chromatin condenses into a chromosome. The chromosomes are linear strands of DNA as opposed to the chromosomes of prokaryotes that are mostly circular. Both eukaryotes and prokaryotes have genetic information stored in genes. Their main source of metabolic energy is ATP.
Both of them also have ribosomes that assist during protein synthesis. However, the ribosomes of eukaryotes are 80S. In prokaryotes, the ribosomes are 70S. Both prokaryotic and eukaryotic ribosomes are made up of two ribosomal subunits. The prokaryotic ribosome 70S is made up of 50S large subunit and 30S small subunit. The eukaryotic ribosome 80S consists of 60S large subunit and 40S small subunit. All eukaryotes belong to Domain Eukaryota. Organisms belonging to this domain are animals, plants, fungi, and protists.
Animals are eukaryotes that distinct from the other groups of eukaryotes by being heterotrophic, motile, and multicellular, a body organized into cells, tissues, organs, and systems, lacking cell walls and chloroplasts, and growing from a blastula during embryonic development.
Plants are photosynthetic eukaryotes. They have chlorophyll and other pigments that help in photosynthesis. They have a cell wall comprised mainly of cellulose. It provides structural support. They are not as motile as the animals. Movements are limited but their growth is not. Eukaryotes are differentiated from another class of organisms called prokaryotes by way of the presence of internal membranes that separate parts of the eukaryotic cell from the rest of the cytoplasm.
These membrane-bound structures are called organelles. In eukaryotes, the cell's genetic material, or DNA, is contained within an organelle called the nucleus, where it is organized in long molecules called chromosomes. Eukaryotic cells also contain other organelles, including mitochondria, which generate energy; the endoplasmic reticulum, which plays a role in the transport of proteins; and the Golgi apparatus, which sorts and packages proteins and lipids for transport throughout the cell.
Plant cells additionally contain organelles called chloroplasts, which are used to collect energy from sunlight. The nucleus is where eukaryotes store their genetic information. In prokaryotes, DNA is bundled together in the nucleoid region, but it is not stored within a membrane-bound nucleus.
The nucleus is only one of many membrane-bound organelles in eukaryotes. Prokaryotes, on the other hand, have no membrane-bound organelles. Another important difference is the DNA structure. Eukaryote DNA consists of multiple molecules of double-stranded linear DNA, while that of prokaryotes is double-stranded and circular.
A comparison showing the shared and unique features of prokaryotes and eukaryotes. All cells, whether prokaryotic or eukaryotic, share these four features:. Plasma membrane. In prokaryotic cells, transcription and translation are coupled, meaning translation begins during mRNA synthesis. In eukaryotic cells, transcription and translation are not coupled.
Transcription occurs in the nucleus, producing mRNA. Prokaryote definition Prokaryotes are unicellular organisms that lack membrane-bound structures, the most noteworthy of which is the nucleus.
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