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Glossary
A B C D E F G H I J
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saturated
fatty acid
A saturated fat is a fat or fatty
acid in which there are no double bonds between the carbon atoms of the fatty
acid chain. Saturated fats tend to be solid at room temperature. |
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second law of thermodynamics
No transfer of energy is 100% efficient. |
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secondary active transport
Movement of a substance against its
chemical or electrical gradient by cotransport with a second substance moving
with its electrical or chemical gradient; secondary active transport often
utilizes gradients resulting from primary active transport to move substances
against their gradient. |
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secondary structure
Regular, repeated structures found in proteins; most commonly the alpha-helices
and beta-pleated sheets. |
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segregation
The separation of homologous chromosomes during meiosis. |
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selectively permeable
Need Definition...refers to membranes that allow certain types of substances to
move across them, but not others. |
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semi-conservative
The mode of DNA replication, whereby each
new DNA molecule produced contains one parent strand and one newly synthesized
strand. |
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sex-linked genes
Genes that are found on sex chromosomes,
and so are inherited differentially based on the sex of the offspring. |
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sexual reproduction
Sexual reproduction is a biological process by which organisms create
descendants through the combination of genetic material. |
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sigma factors
The subunit of RNA polymerase that directly
interacts with DNA; different sigma factors bind different promoter sequences
more or less effectively, allowing organisms some control of gene expression by
controlling what sigma factors are present. |
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signal sequences
Sequences of amino acids on newly
synthesized polypeptides that direct the polypeptide to the appropriate cellular
destination. |
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signal transduction
Signal transduction describes the
uptake of environmental signals by cells, the intercellular communication
between cells in a multicellular organism, and the signal recognition,
transmission, and resulting action within a cell. |
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spore
Haploid reproductive cells capable of
developing into an adult organism without fusing to other haploid cells. |
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stem cells
Undifferentiated and/or undetermined cells;
cells with unlimited or only slightly limited developmental potential. |
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structural genes
The genes of prokaryotic operons, coding
for polypeptides. |
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substrate level phosphorylation
ATP formation resulting from direct transfer of a phosphate group to ADP from an
intermediate in glycolysis. |
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symports
An integral membrane protein used for
transporting two or more substances across the membrane in one direction only. |
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