Tài liệu Khoa Học Tự Nhiên

Bioluminescence is an example of the multitude of energy conversions that a cell can perform. Many of a cell’s reactions take place in organelles and use enzymes embedded in the membranes of these organelles. This chapter addresses how working cells use membranes, energy, and enzymes.

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Magnification is the increase in the apparent size of an object. Resolution is a measure of the clarity of an image. In other words, it is the ability of an instrument to show two close objects as separate.

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Methane and other compounds composed of only carbon and hydrogen are called hydrocarbons. Carbon, with attached hydrogens, can bond together in chains of various lengths.

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About 25 elements are essential to life. Four elements make up about 96% of the weight of most living organisms. These are oxygen, carbon, hydrogen, and nitrogen. Trace elements are essential but are only needed in minute quantities.

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Organism—an individual living thing, Organ system—several organs that cooperate in a specific function, Organ—a structure that is composed of tissues and that provides a specific function for the organism, Tissues—a group of similar cells that perform a specific function, Cells—the fundamental unit of life,

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In prokaryotes, translation of mRNA can begin before transcription has finished In a eukaryotic cell, the nuclear envelope separates transcription from translation Eukaryotic RNA transcripts are modified through RNA processing to yield the finished mRNA

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When he mixed heat-killed remains of the pathogenic strain with living cells of the harmless strain, some living cells became pathogenic He called this phenomenon transformation, now defined as a change in genotype and phenotype due to assimilation of foreign DNA

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Human somatic cells (any cell other than a gamete) have 23 pairs of chromosomes A karyotype is an ordered display of the pairs of chromosomes from a cell The two chromosomes in each pair are called homologous chromosomes, or homologs Chromosomes in a homologous pair are the same length and shape and carry genes controlling the same inherited ch...

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All the DNA in a cell constitutes the cell’s genome A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) DNA molecules in a cell are packaged into chromosomes

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Leaves are the major locations of photosynthesis Their green color is from chlorophyll, the green pigment within chloroplasts Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf Each mesophyll cell contains 30–40 chloroplasts

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