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Chapter 16-17
Vocabulary required by my teacher for Chapter 16-17 in the Campbell Biology Book
42
Biology
11th Grade
04/30/2012

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Term
DNA ligase
Definition
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3’ end of a new DNA fragment to the 5’ end of a growing chain.
Term
DNA polymerase
Definition
An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain.
Term
double helix
Definition
The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
Term
helicase
Definition
An enzyme that untwists the double helix of DNA at the replication forks.
Term
lagging strand
Definition
A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.
Term
leading strand
Definition
The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5’ ( 3’ direction.
Term
mismatch repair
Definition
The cellular process that uses special enzymes to fix incorrectly paired nucleotides.
Term
nuclease
Definition
An enzyme that hydrolyzes DNA and RNA into their component nucleotides.
Term
nucleotide excision repair
Definition
The process of removing and then correctly replacing a damaged segment of DNA using the undamaged strand as a guide.
Term
Okazaki fragment
Definition
A short segment of DNA synthesized on a template strand during DNA replication. Many Okazaki fragments make up the lagging strand of newly synthesized DNA.
Term
primase
Definition
An enzyme that joins RNA nucleotides to make the primer.
Term
primer
Definition
A polynucleotide with a free 3´ end, bound by complementary base pairing to the template strand, that is elongated during DNA replication.
Term
replication fork
Definition
A Y-shaped region on a replicating DNA molecule where new strands are growing.
Term
semiconservative model
Definition
Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand.
Term
single-strand binding protein
Definition
During DNA replication, molecules that line up along the unpaired DNA strands, holding them apart while the DNA strands serve as templates for the synthesis of complementary strands of DNA.
Term
telomere
Definition
The protective structure at each end of a eukaryotic chromosome. Specifically, the tandemly repetitive DNA at the end of the chromosome’s DNA molecule. See also repetitive DNA.
Term
transformation
Definition
A change in genotype and phenotype due to the assimilation of external DNA by a cell.
Term
anticodon
Definition
A specialized base triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
Term
base-pair substitution
Definition
A type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides.
Term
codon
Definition
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
Term
deletion
Definition
A mutational loss of one or more nucleotide pairs from a gene.
Term
exon
Definition
A coding region of a eukaryotic gene. Exons, which are expressed, are separated from each other by introns.
Term
frameshift mutation
Definition
A mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the following nucleotides into codons.
Term
insertion
Definition
A mutation involving the addition of one or more nucleotide pairs to a gene.
Term
intron
Definition
A noncoding, intervening sequence within a eukaryotic gene.
Term
messenger RNA (mRNA)
Definition
A type of RNA, synthesized from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.
Term
missense mutation
Definition
The most common type of mutation, a base-pair substitution in which the new codon makes sense in that it still codes for an amino acid.
Term
mutagen
Definition
A chemical or physical agent that interacts with DNA and causes a mutation.
Term
mutation
Definition
A rare change in the DNA of a gene, ultimately creating genetic diversity.
Term
nonsense mutation
Definition
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
Term
point mutation
Definition
A change in a gene at a single nucleotide pair.
Term
promoter
Definition
A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA.
Term
ribosomal RNA (rRNA)
Definition
The most abundant type of RNA, which together with proteins forms the structure of ribosomes. Ribosomes coordinate the sequential coupling of tRNA molecules to mRNA codons.
Term
ribozyme
Definition
An enzymatic RNA molecule that catalyzes reactions during RNA splicing.
Term
RNA polymerase
Definition
An enzyme that links together the growing chain of ribonucleotides during transcription.
Term
RNA processing
Definition
Modification of RNA before it leaves the nucleus, a process unique to eukaryotes.
Term
spliceosome
Definition
A complex assembly that interacts with the ends of an RNA intron in splicing RNA, releasing the intron and joining the two adjacent exons.
Term
TATA box
Definition
A promoter DNA sequence crucial in forming the transcription initiation complex.
Term
transcription
Definition
The synthesis of RNA on a DNA template.
Term
transcription factor
Definition
A regulatory protein that binds to DNA and stimulates transcription of specific genes.
Term
transfer RNA (tRNA)
Definition
An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA.
Term
translation
Definition
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of languagefrom nucleotides to amino acids.
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