Chapter 12 Study Guide Flashcards
Transformation
When a strain of bacteria (the harmless strand) change into another (the disease-causing strand).
Bacteriophage
A virus that infects and kills bacteria. Composed of a DNA or RNA, the virus attaches to the surface of the cell and injects DNA into it.
Nucleotides
Units that makeup DNA. Each nucleotide is made up of 3 basic parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous (nitrogen-containing) base.
Base Pairing
Under normal circumstances, the nitrogen-containing bases adenine (A) and thymine (T) pair together, and cytosine (C) and guanine (G) pair together. The binding of these base pairs forms the structure of DNA.
Chromatin
Eukaryotic chromosomes contain both DNA and protein, lightly packed together to form chromatins.
Histones
Chromatin consists of DNA that is tightly coiled around proteins.
Replication
Before a cell divides, it duplicates its DNA in a copying process called replication. This process ensures that each resulting cell will have a complete set of DNA molecules.
DNA Polymerase
The principal enzyme involved in DNA replication is called DNA Polymerase because it polymerized individual nucleotides to produce DNA.
Messenger RNA
The RNA molecules that carry copies of instructions for assembling amino acids into proteins.
Ribosomal RNA
Ribosomes are made up of several dozen proteins, as well as a form of RNA known as RIbosomal RNA>
Transfer RNA
The RNA molecule that transfer each amino acid to the ribosome as it is specified by coded messages in mRNA.
Transcription
A process wherein RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary sequence in RNA.
RNA Polymerase
Transcription requires an enzyme known as RNA Polymerase, similar to DNA Polymerase. During transcription, RNA Polymerase binds to DNA and separates the DNA strands. RNA Polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.
Promoter
The enzyme will bind only to regions of DNA known as promoters, which have specific base sequences.
Intron
Large pieces are removed from the RNA molecules transcribed from many eukaryotic genes before they become functional. These pieces, known as introns, are cut out of the RNA molecules while they are still in the cell nucleus.
Exons
The remaining portions, called exons, or expressed sequences, are then spliced back together to form the final mRNA.
Codon
A codon consists of 3 consecutive nucleotides that specify a single amino acid that is to be added to the polypeptide.
Translation
The decoding of an mRNA message into a polypeptide chain (protein) is known as translation. Translation takes place on ribosomes. During translation, the cell uses information from messenger RNA to produce proteins.
Anticodon
The three bases on the tRNA molecule, called the anticodon, are complementary to one of the mRNA codons.
Mutation
Mutations are changes in the DNA sequence that affect genetic information. Gene mutations result from changes in a single gene. Chromosomal mutations involve changes in whole chromosomes.
Point Mutations
Mutations that affect one nucleotide because they occur at a single point in the DNA sequence. Some point mutations simply substitute one nucleotide for another.
Frameshift Mutations
An insertion or deletion involving a number of base pairs that is not a multiple of three, which consequently disrupts the triplet reading frame of a DNA sequence. By changing the reading frame, frameshift mutations affect every amino acid that follows the point of the insertion or deletion.
Operon
A fancy way of regulating genes. Usually made up of a few genes.
Operator
On one side of the operons, three genes are two regulatory regions. In the promoter(P), RNA polymerase binds and then begins transcription. The other region is the operator.
