Viewing 1 - 10 of 38 results
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- Chapter Name:
- Chapter 2: DNA
- Description:
- Two DNA strands intertwine to form a double helix. Each strand has a backbone composed of phosphates and sugars to which the bases areattached. The bases form the core of the double helix, while the sugar-phosphate backbones are ...
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- Chapter Name:
- Chapter 3: Genes
- Description:
- Like DNA, RNA strands also pair to form a double helix. The paired nucleotide bases are packed in the middle of an RNA helix, surrounded by the backbone. The RNA helix has a different geometry than a standard DNA helix. For ...
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- Chapter Name:
- Chapter 4: Transcription of DNA to RNA
- Description:
- Transcription is the process by which DNA is copied into RNA in the first step of gene expression. It begins with a bundle of factors assembling at the start of a gene, that is, a linear sequence of DNA instructions, here shown ...
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- Chapter Name:
- Chapter 4: Transcription of DNA to RNA
- Description:
- Eucaryotic RNA polymerase II transcribes all messenger RNA molecules in the cell. It is a huge complex of ten different protein subunits. The active site of the enzyme lies at the interface between the two largest subunits. In ...
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- Chapter Name:
- Chapter 4: Transcription of DNA to RNA
- Description:
- Eucaryotic transcription begins when RNA polymerase II binds to the promoter region of a gene. A crucial part of this initiation process is the recognition and binding of the TATA sequence, a short stretch of DNA rich in thymine ...
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- Chapter Name:
- Chapter 5: Types of RNA Molecule: Messenger RNA
- Description:
- Eucaryotic genes typically contain introns, which have to be removed after transcription. Before the RNA transcript leaves the nucleus, the cell splices out the intron sequences. A few short nucleotide sequences provide the cell ...
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- Chapter Name:
- Chapter 6: Types of RNA Molecule: Noncoding RNA
- Description:
- All tRNAs have a characteristic L-shape, with an amino acid attached to the 3′ end at the tip of the shorter arm. The anticodon loop is positioned at the opposing end of the molecule and contains the anticodon base triplet. The ...
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- Chapter Name:
- Chapter 7: The Genetic Code
- Description:
- The alpha helix is one of the most common secondary structures in proteins. Amino acid side chains project outwards from the polypeptide backbone that forms the core of the helix. The chain is stabilized in this conformation by ...
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- Chapter Name:
- Chapter 7: The Genetic Code
- Description:
- The beta sheet is another common secondary structure. In contrast to an alpha helix, it is formed by hydrogen bonds between backbone atoms on adjacent regions of the peptide backbone, called beta strands. These interactions do not ...
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- Chapter Name:
- Chapter 7: The Genetic Code
- Description:
- Many proteins are composed of multiple polypeptide chains, or subunits. The Cro repressor, for example, is a homodimer formed of two identical subunits. The subunits join in a head-to-head fashion as two small beta sheets--one ...
Viewing 1 - 10 of 38 results
