the strand of DNA that runs 3' to 5' and is complementary to the sense strand. It acts as a template strand during transcription.
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Bacteriophage
A virus that infects bacteria
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Base Substitution
Aka a point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides. There are 3 types: Nonsense, Missense, and Silent Mutations.
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Cell Differentiation
the process by which a cell becomes specialized for a specific structure or function. Zygotes go through a series of cell divisions in during which the embryo becomes increasingly differentiated.
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Chromosome
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
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Codon
three-nucleotide sequence on messenger RNA that codes for a single amino acid
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Conjugation
In bacteria, the direct transfer of DNA between two cells that are temporarily joined. Can lead to antibiotic resistance. They do this because bacterial fission does not increase their genetic diversity.
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Deletion
A change to a chromosome in which a fragment of the chromosome is removed.
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DNA fingerprinting
analysis of sections of DNA that have little or no known function, but vary widely from one individual to another, in order to identify individuals
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DNA in prokaryotes
DNA is contained in the cytoplasm and consists of a ring of DNA
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DNA ligase
an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments
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DNA polymerase
Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule. Can only add nucleotides to the 3' end of a strand. (5' to 3' direction)
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DNA replication
the process of making a copy of DNA
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DNA sequencing
Determining the exact order of the base pairs in a segment of DNA.
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DNA topoisomerase
An enzyme that unwinds and winds coils of DNA that form during replication and transcription.
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Duplication
change to a chromosome in which part of the chromosome is repeated
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Elongation (Translation)
addition of amino acids to the polypeptide chain; continues until it reaches a stop codon. Peptide bonds form between the amino acids.
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Enveloped virus
A virus enclosed within a phospholipid membrane derived from its host cell.
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Epigenetic changes
stable alterations of chromatin structure that may be passed on to cells or individual organisms (usually occur through the modification of a histone protein; changes the packaging of DNA so that it is harder for transcriptional machinery to access a gene)
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Euchromatin
The less condensed form of eukaryotic chromatin that is available for transcription.
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Exons
Coding segments of eukaryotic DNA.
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Fertilization
Process in sexual reproduction in which male and female reproductive cells join to form a new cell
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Frameshift mutation
mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide
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gel electrophoresis
The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.
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Gene
sequence of DNA that codes for a protein and thus determines a trait
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Gene Regulation
ability of an organism to control which genes are transcribed in response to the environment
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Genetic Engineering
A technology that includes the process of manipulating or altering the genetic material of a cell resulting in desirable functions or outcomes that would not occur naturally.
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Genome
the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes
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Helicase
The beginning of DNA replication. An enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands.
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Heterochromatin
DNA that is densely packed around histones. The genes in heterochromatin are generally inaccessible to enzymes and inactive.
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Histones
protein molecules around which DNA is tightly coiled in chromatin
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Homeotic genes
Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells.
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Host
The thing infected by a virus
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Hox genes
Series of genes that controls the differentiation of cells and tissues in an embryo. Class of homeotic genes. Changes in these genes can have a profound impact on morphology.
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Inducer
A specific small molecule that inactivates the repressor in an operon.
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Initiation (Translation)
mRNA is attached to a subunit of the ribosome, the first codon is always AUG
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Insertion
A mutation involving the addition of one or more nucleotide pairs to a gene.
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Introns
sequence of DNA that is not involved in coding for a protein
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Inversion
A genetic mutation in which the order of a segment of genetic material is reversed. This type of mutation can involve a small number of nucleotides as well as larger sections of a chromosome containing more than one gene
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lagging strand
A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.
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leading strand
the new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5' to 3' direction
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Lysogenic cycle
a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA
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Lytic cycle
a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses
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Messenger RNA (mRNA)
A type of RNA, synthesized from DNA and attached to ribosomes in the cytoplasm; it specifies the primary structure of a protein.
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Missense mutation
A base-pair substitution that results in a codon that codes for a different amino acid.
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Morphogenesis
the development of the form of an organism and its structures
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Mutation
An error in the genetic code
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Nonsense mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
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Nucleosome
repeating subunit of chromatin fibers, consisting of DNA coiled around histones
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Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
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operator
short DNA region, adjacent to the promoter of a prokaryotic operon, that binds repressor proteins responsible for controlling the rate of transcription of the operon
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Operons
In prokaryotic cells, a cluster of genes under control of a promoter.
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origins of replication
Sites where the replication of a DNA molecule begins.
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Phases of Translation
1. Initiation
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2. Elongation
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3. Termination
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Plasmid
A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome. These often have helpful genes put inside the by humans, forming a plasmid vector
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Plasmids
small DNA circles that are physically separated from chromosomal DNA and can replicate independently. Often contain genes for antibiotic resistance
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polyA tail
After an mRNA is transcribed from a gene, the cell adds a stretch of A residues (typically 50-200) to its 3' end.
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Polymerase Chain Reaction (PCR)
A method of producing thousands of copies of DNA segment using the enzyme DNA polymerase
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Post-transcriptional regulation
the control of gene expression at the RNA level, therefore between the transcription and the translation of the gene. RNAi molecules take part in this
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Promoter gene
region where RNA polymerase binds to begin transcription
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Promoters
specific region of a gene where RNA polymerase can bind and begin transcription
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Recombinant DNA
DNA produced by combining DNA from different sources
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regulatory gene
A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
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Repressor
A protein that binds to an operator and physically blocks RNA polymerase from binding to a promoter site
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Restriction enzymes
cut DNA at specific sequences
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Restriction Fragment Length Polymorphisms (RFLPs)
Differences in DNA sequence on homologous chromosomes that can result in different patterns of restriction fragment lengths (DNA segments resulting from treatment with restriction enzymes).
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Retrovirus
An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses. HIV is an example of this. RNA viruses like this mutate quickly since they have no proofreading mechanisms in their replication of genomes.
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Reverse transcriptase
An enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis.
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Ribosomal RNA (rRNA)
Produced in nucleolus, type of RNA that makes up the major part of the ribosomes
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RNA polymerase
Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription. Builds RNA molecule from 5' to 3', so it binds to the 3' end of the template strand. Does not need RNA primers.
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RNA primase
An enzyme that creates an RNA primer for initiation of DNA replication.
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RNA primer
short segment of RNA used to initiate synthesis of a new strand of DNA during replication. After replication, the primer is replaced by DNA so that the final strand contains only DNA.
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RNA processing
Modification of RNA primary transcripts, including splicing out of introns, joining together of exons, and alteration of the 5' and 3' ends.
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RNAi (RNA interference)
RNAi bind to the unwanted parts of the mRNA made during transcription forming a double-stranded RNA. Then a signal is sent out to destroy the double stranded RNA as a form of gene regulation, leaving only the desired parts of the mRNA to be translated
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semiconservative
method of replication that implies that each new strand of DNA is half original and half new
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Sense strand/Coding Strand
The DNA strand which is always represented on paper. The strand is always the one running from the 5' to the 3'. mRNA is identical to the strand except Thymine is replaced with Uracil.
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Silent mutation
A mutation that changes a single nucleotide, but does not change the amino acid created.
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spliceosome
A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons.
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Splicing
the process of removing introns and reconnecting exons in a pre-mRNA
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start codon (AUG)
On mRNA, the specific three-nucleotide sequence (AUG) to which an initiator tRNA molecule binds, starting translation of genetic information.
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Sticky ends
Single stranded ends of DNA left after cutting with enzymes
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stop codon
codon that signals to ribosomes to stop translation (UAA, UAG, UGA)
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Structural Gene
a gene that codes for a product, such as an enzyme, protein, or RNA, rather than serving as a regulator
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Telomeres
DNA at the tips of chromosomes
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Termination (Translation)
occurs when a stop codon in the mRNA reaches the A site of the ribosome. Translation stops and the polypeptide or protein folds up and is released into the cell.
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Transcription
the organic process whereby the DNA sequence in a gene is copied into mRNA. Occurs in the nucleus.
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Transcription Factors
A regulatory protein that binds to DNA and affects transcription of specific genes. Can encourage or inhibit transcription, typically by making it easier or harder for RNA Polymerase to bind to the start site
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Transduction in bacteria
the transfer of DNA between bacterial cells using a lysogenic virus
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Transfer RNA (tRNA)
form of RNA that brings amino acids to ribosomes during protein synthesis
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Transformation
process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria. (Giving bacteria foreign DNA so that it transcribes a helpful human gene)
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Translation
Process by which mRNA is decoded and a protein is produced. Occurs in a ribosome.
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Translocation
Change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome.
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Transposons
(jumping genes) short strands of DNA capable of moving from one location to another within a cell's genetic material
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Viruses
tiny particles, smaller than bacteria and other pathogens, which must invade living cells in order to reproduce; when they invade, the cells are damaged or destroyed in the process releasing new particles to infect other cells