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| The protoplasm outside the nucleus of a cell. |
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| Mitochondria have two functionally distinct membrane systems separated by a space: the outer membrane, which surrounds the whole organelle; and the inner membrane, which is thrown into folds or shelves that project inward. |
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In chemistry and physics, the nucleus (atomic nucleus) is the collection of protons and neutrons in the center of an atom that carries the bulk of the atom's mass and positive charge.
In cell biology, the nucleus (cell nucleus) is the membrane-bound subcellular organelle found in eukaryotes, visible via microscopy, which contains, primarily, the cell's chromosomes. |
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| A cell is a single unit or compartment, enclosed by a border or wall. |
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| Plants are a major group of living things (about 300,000 species), including familiar organisms such as trees, flowers, herbs, and ferns. Aristotle divided all living things between plants, which generally do not move or have sensory organs, and animals |
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| Animals are a major group of organisms, classified as the kingdom Animalia. These are generally multicellular, capable of locomotion and responding to their environment, and feed by consuming other organisms. Their body plan becomes fixed as they develop, usually early on in their development as embryos, unless they undergo a process of metamorphosis. Humans are animals, though colloquially the term is often taken to exclude them. |
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| Vacuoles are large membrane-bound compartments within some eukaryotic cells where they serve a variety of different functions: capturing food materials or unwanted structural debris surrounding the cell, sequestering materials that might be toxic to the cell, maintaining fluid balance (called turgor) within the cell, exporting unwanted substances from the cell, or even determining relative cell size |
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A chromosome (in Greek chroma = colour and soma = body) is, minimally, a very long, continuous piece of DNA, which contains many genes, regulatory elements and other intervening nucleotide sequences. In the chromosomes of eukaryotes, the uncondensed DNA exists in a quasi-ordered structure inside the nucleus, where it wraps around histones (structural proteins, Fig. 1), and where this composite material is called chromatin. During mitosis (cell division), the chromosomes are condensed and called metaphasic chromosomes. This is the only natural context in which individual chromosomes are visible with an optical microscope. Prokaryotes do not possess histones or nuclei. In its relaxed state, the DNA can be accessed for transcription, regulation, and replication. Chromosomes were first observed by Karl Wilhelm von Nägeli in 1842 and their behavior later described in detail by Walther Flemming in 1882. In 1910, Thomas Hunt Morgan proved that chromosomes are the carriers of genes.
A chromosome (in Greek chroma = colour and soma = body) is, minimally, a very long, continuous piece of DNA, which contains many genes, regulatory elements and other intervening nucleotide sequences. In the chromosomes of eukaryotes, the uncondensed DNA exists in a quasi-ordered structure inside the nucleus, where it wraps around histones (structural proteins, Fig. 1), and where this composite material is called chromatin. During mitosis (cell division), the chromosomes are condensed and called metaphasic chromosomes. This is the only natural context in which individual chromosomes are visible with an optical microscope. Prokaryotes do not possess histones or nuclei. In its relaxed state, the DNA can be accessed for transcription, regulation, and replication. Chromosomes were first observed by Karl Wilhelm von Nägeli in 1842 and their behavior later described in detail by Walther Flemming in 1882. In 1910, Thomas Hunt Morgan proved that chromosomes are the carriers of genes. |
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