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49 Cards in this Set
- Front
- Back
Bacteriophage
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A virus that transfers its genome to bacteria; used in Hershey and Chase's experiment
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Ligase
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Enzyme that closes gaps in DNA during replication after primer is replaced on lagging strand; also used to splice in foreign DNA, creates a bond between nucleotides
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Polymerase
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An enzyme that elongates a nucleic acid, either DNA or RNA; binds only to DNA's 3' end, causing leading/lagging strand mechanic; DNA pol. III simply extends DNA, DNA pol. I replaces RNA primers with DNA
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Helicase
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Enzyme that untwists DNA molecule at replication forks; assisted by topoisomerase, relieves tension further along the molecule
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Lagging strand
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The strand where local DNA elongation occurs opposite the general direction of replication; Okazaki fragments are formed, more enzymes used
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Leading strand
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The strand where local DNA elongation and general replication directions match; only one primer, DNA pol. III takes over replication, no need for ligase or pol. I
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Nuclease
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Corrects errors in DNA by cutting out erroneous DNA nucleotides, allowing DNA polymerase to fix the error
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Okazaki fragment
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A short fragment of DNA in the lagging strand; multiple fragments are created as DNA replication moves further and primers are attached further and further up
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Primer
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A short RNA segment added by primase to begin an Okazaki fragment (DNA pol. III cannot function without having a primer to attach to)
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Replication fork
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The place where DNA splits to allow replication to continue; begins at replication bubble
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Semiconservative model
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Model of DNA replication wherein each new molecule contains one strand of new DNA and one strand from the previous generation; proved by Meselson and Stahl's experiment
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Telomere
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The repeated series of nucleotides at the end of DNA that shortens in each replication, preserving a person's life; replenished in germ cells by active telomerase
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5' cap
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A modified guanine nucleotide with 3 phosphate groups attached attached to the 5' end during mRNA modification; helps to bind to ribosome, protect against hydrolysis; noncoding
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Anticodon
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The 3 nucleotides at one end of a tRNA that bind to the mRNA molecule's codon; the opposite of the codon
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Codon
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Series of 3 nucleotides on the mRNA that code for one amino acid; must be in correct reading frame in order to work properly
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Exon
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The part of an mRNA molecule that is left after mRNA splicing in the spliceosome; the part that is expressed; opposite of an intron; can be useful in alternative RNA splicing
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Mutation
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Changes in genetic material; can be a base-pair substitution, insertion, or deletion; can be passed down via inheritance
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Intron
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The segment of DNA that is removed in spliceosomes and not expressed
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mRNA
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Messenger RNA, that delivers DNA information to the cytoplasm or endoplasmic reticulum and is transcribed by ribosomes
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Promoter
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The sequence in eukaryotes and prokaryotes where the RNA polymerase attaches to DNA and begins transcription; noncoding
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tRNA
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Attaches to amino acids at aminoacyl-tRNA synthetase; binds to codon at A site, contains anticodon; responsible for peptide chain elongation
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Spliceosome
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Contains snRNPs which contain snRNA; cuts up mRNA, leaving only exons and no introns
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TATA box
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Nucleotide sequence containing TATA, upstream from transcription start point, where transcription factors must bind
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Transcription
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The process of creating mRNA from DNA; involves a large protein called RNA polymerase II
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rRNA
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The most abundant type of RNA; makes up 2/3 of ribosomes, processed and assembled from proteins in the cytoplasm
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Translation
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The creation of proteins from mRNA; involves... well, you know the process, basically; I mean, come on, now
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Triplet code
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The system of DNA expression where each amino acid is represented by three distinct nucleotides
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Capsid
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The outside envelope of a virus, which protects the DNA or RNA inside; virus uses cell's enzymes to produce more capsomeres for new capsids to form
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Conjugation
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Bacterial rape; where one bacteria extends its sex pilus, drawing two bacteria close together, and then a mating bridge forms; if F plasmid is present separately, the plasmid is transferred; if it is integrated into the bacteria's genome, recombination results
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Episome
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Any DNA that can replicate independently of the bacterial chromosome, such as temperate phages and plasmids
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Operon
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A group of genes controlled by one promoter that all relate to the same process; part of the promoter is operator, which repressors can bind to to stop the genes from being expressed
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Plasmid
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A small circular self-replicating DNA molecule that can be transferred to a bacteria; can be useful to bacteria in certain environments
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Prophage
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The segment of a virus's DNA after it integrates itself into the bacterial genome in the lysogenic cycle
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Restriction enzymes
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Enzymes that cut up foreign DNA as part of a bacteria's defense against viruses; cuts DNA at a restriction site, leaving sticky ends; bacteria's own DNA protected naturally via methylation
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Reverse transcriptase
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Present in retroviruses; forms a DNA molecule from RNA, allowing the DNA to become a provirus; used in cDNA production
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Transformation
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A bacteria's change in genome from uptaking foreign DNA, becoming recombinant via surface proteins that recognize and bring in DNA from similar species
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Transposable element
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A length of DNA that moves from one place to another within the chromosome; brought to its new site by folding
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Cell differentiation
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The process of cells slowly developing to have a specific purpose, so that only certain genes are expressed
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Differential gene expression
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The expression of different genes by cells with the same genome
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Histone
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Proteins with tails that form groups of 8; acetylation of these histone tails causes the histones to drift apart, making the chromatin less dense and allowing genes to be expressed
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Oncogene
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A gene that facilitates cell replication once it becomes overactive and causes cancer
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P53 gene
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Responds to DNA damage by producing a protein that halts the cell cycle by producing P21, turning on DNA repair genes, or (in the case of irreparable DNA damage) causing apoptosis
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Tumor suppressor gene
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A gene that produces a protein that inhibits cell division; damaging this gene may lead to increased risk of cancer
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Apoptosis
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Cell "suicide"; can lead to the suppression of cancer, when the p53 gene causes apoptosis; can play a role in morphogenesis
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Cytoplasmic determinants
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Molecules present in the cytoplasm of an egg that affect the egg's development; usually unevenly distributed, and distributed to different cells, depending on which side the cell was on; contributes to cell differentiation, as nucleus is exposed to different determinants
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Homeotic genes
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Genes that specifically help the cells designate which sections of the growing embryo should be where, specifying orientation of parts
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Morphogenesis
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Physical processes that give rise to an organism's shape and function, and which cells will become which part of the organism; occurs throughout the life of plants
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Stem cells
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Cells that can both reproduce indefinitely and differentiate to any type; examples are bone marrow; adult stem cells are pluripotent, not able to give rise to any cell but able to give rise to multiple ones
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Totipotent
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Any cell that has the potential to dedifferentiate and give rise to all other specialized cells in that organism; testable by seeing if the single cell can replicate into a whole organism; tested by FC Steward
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