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134 Cards in this Set
- Front
- Back
Meiosis
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a division of the genetic material in the nucleus to produce daughter cells with one-half the amount of hereditary material found in the parent cell
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gametes
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it is the basis of sexual reproduction and genetic inheritance
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Mitosis
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division of the genetic material in the nucleus that produces daughter cells genetically identical to the parent cell.
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somatic cells
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body cells
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M phase
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dividing phase
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interphase
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nondividing phase
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cell cycle
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the orderly sequency of events that occurs starting form the formation of wukaryotic cell through the duplication of its chromosome to the time it undergoes cell division
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2 key events of the cell cycle
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1. replication
2. partitioning of the copied chromosomes |
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chromatid
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each of the two DNA strands in a replicated chromosome
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sister chromatids
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attached at the centromere
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centromete
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exact copies of the same genetic information
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mitotic spindle
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microtubule--organizing center
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prophase
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the chromosome replicates and condenses and becomes visible in the light microscope
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prometaphase
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the nucleat envelope breaks down and spindle fibers from each mitotic spindle attach to one of the two sister chromatids of each chromosome at the kinetochore
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kinetochores
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located at the centromere region of the chromosome
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metaphase
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chromosome line up along the imaginary plane called the metaphase plate
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anaphase
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centromeres split and sister chromatids are pulled toward opposite poles
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telophase
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a new nuclear envelope begins to form around each set of chromosomes
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cytokinesis
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the division of the cytoplasm to form two daughter cells
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cleavage furrow
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a ring of actin and myosin filaments contracts inside of the cell mebrane causing it to pinch inward
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Mitosis promoting factor MPF
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induces mitosis in all eukaryotes
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protein kinase
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catalyzes phosophorylation of a target protein by ATP and a cyclin
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cell-cycle chechpoint
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critical point in the cell cycle is regulated
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Sex chromosomes
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determine the sex of individual
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autosomes
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all other chromosomes
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homologous chromosomes or homologs
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chromosomes of the same tyoe with the same genes in the same locations
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gene
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a section of DNA that indluence one of more hereditary traits in an individual
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alleles
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different versions of a specific gene
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karyotype
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the number and types of chromosomes present in an organism
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haploid number
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the nubmer of distinct types of chromosomes present
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ploidy
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the number of each type of chromosome present
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crossing over
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genetic recombination occuring in late prophase 1 of sister chromatin
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genetic diversity
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random seperation of homologous chromosomes in anaphase 1
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genetic recombination
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greatly increases the genetic variability of gametes producted by meiosis beyone that produced by random addortment of choromosomes
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outcrossing
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gametes from different individuals combine to form offspring
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fertilization
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when an egg and sperm come together to form a new individual
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nondisjunction
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the failure of homologous chromosomes to seperate
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model organism
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it is easy to grow, has a short reproductive cycle, and produces large numver of seeds
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phenotypes
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physical traits
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pure lines
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produce identical offspring when self-pollinated
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hybrids
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mating 2 different pure lines that differ in one or more traits
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reciprocal cross
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a set of matinds inwhich the mother's phenotype in the first cross is the father's phenotype in the second cross, and the father's phenotype in the first cross is the mother's phenotype in the second cross were identical
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recessive
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takes 2 alleles for the gene to show
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dominant
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only takes 1 allele for the gene to show
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genotype
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alleles in an individual
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principle of segregation
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allels aegrate into different gemetes during egg and sperm formation than come back together when an egg is fertilized by a sperm to form o zygotes
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homozygous
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indviduals with two copies of the same alleles
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heterozygous
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individuals with different copies
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monohybrid cross
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mating between parent that are both hereozygous for a trait
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punnett square
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used to predict the genotypes and phenotypes of the offspring from a cross
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genetic model
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a set of hypotheses that explains how a particulat trait is inherited
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principle of independent assortment
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alleles of different genes are transmitted independently of each other
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sex-linked inheritance
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the various inheritance patterns that can occur when genes are carried on the sex chromosomes, such that female and males have different numbers of allels of that gene
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linkage
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the physical association of genes on the same chromosome
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recombination
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when the combination of alleles on the X chromsome of progeny is differnet from the combinations of alleles present in the parent generation
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genetic map
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a diagram that shows the relatice locations of specific genes on a certain chromosomes
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multiple allelism
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genes that have more than two alleles
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polymorphic
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different combinations of alleles produce more that two ditince phenotypes
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incomplete dominace
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the heterozygotes have an intermediate phenotype
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codominance
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a heretozygous organism that displays the phenotype of both alleles of a single gene
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pleotropic
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a gene that influences many traits rather than just one
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epistasis
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one gene affects the action of another gene
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discrete traits
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characteristic that are qualitatively different
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polygenic inheritance
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which each gene addes a small amount to the value of the phenotype
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pedigrees
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family tree that are used to analyze the human crosses that already exist
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carriers
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the indiviuals with the trait must be homozygous and the parents are heterozygous carriers
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double helix
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antiparallel strands twisted together
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complementary base pairing
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the double helis is stabilized the hydrogen bonds
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semiconservative replication
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each old DNA strand is copied to generate a new strand. each new chromosome is composed of one strand of old DNA and one strand of newly synthesized DNA
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conservative replication
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the original chromosome is copied but remains unchanged. one chromsome is composed of old strands and the other of new strands
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dispersice replication
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the replication process generares two new chromosmes with new and old sections of DNA mixed together randomly
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DNA polymerase
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add deoxyribonucleotides only to the 3' end of a growing DNA cain, so DNA synthesis always processds in the 5'------>3' direction
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deoxynucloside triphosohates (dNTPs)
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the monomers for DNA polymerization
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origin of replication
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the replication process begins
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replication bubble
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grows in both directions becuase DNA synthesis is bidirectional
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replication fork
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different suite of proteins initiates replication
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DNA helicase
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the brakafe of hydrogen bonds between the two DNA strands to seperate them
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Single-strand DNA-binding proteins (SSBPs)
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attach to the separated strands to prevent them from closing
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Topoisomerase
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cuts and rejoins the DNA downstream of the replication fork, relieving this tension
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primase
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a type of RNA polymerase that synthesizes a short RNA segment that serves as primer for DNA synthesis and supplis that free 3'-hydroxyl group for addition of the first nucleotide
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leadign strand
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the DNA is synthesized continuously
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lagging strand
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synthesize in the opposite direction of the replicaiton fork and lags behind the fork
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Okazaki fragments
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the lagging strand is synthesized as short discontinuous fragments
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DNA ligase
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joins the Okazaki fragments to form a continuous DNA strands
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Telomeres
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the regions at the ends of linear chromsomes
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telomerase
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adds more six-base repeats to the end of the leading strand
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exonuclease
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remoces deoxyribonucleotides from DNA
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Mismatch repair
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mismatched bases remain after DNA synthesis is complete
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nucleotide excision repair system
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recgnizes thymine dimers and other types of damaged bases that produce an irregularity in the DNA
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one-gene, one-enzyme hypothesis
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gnes contain the information needed to make proteins, many of which function as enzymes
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genetic screen
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a techinique for picking a certian types of mutants our of many thousands of randomly generated mutants
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RNA polymerase
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catalyzes the synthesis of RNA according to the information provided by DNA
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central dogma
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DNA--> RNA-->Proteins
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DNA is ____to RNA
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transcribed
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mRNA is ___to protein
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translated
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genetic code
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the rules that specify the relationship between a sequence of nucleotides in DNA or RNA and the sequence of amino acids in a protein
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triplet code
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reduntant, with some amino acids being specified by more than one codon
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reading frame
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a gene could be destroyed by mutation by then resotred if the total number of deletions or additions were multiples of three
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start codon
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signifies the start of the protein encoding sequence in mRNA
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stop codons
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the genetic code that signal the end of the protein coding sequence
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Polymerase chain reaction (PCR)
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in vitro DNA synthesis reaction in which a specific section of DNA is replicated over and over to amplify the number of copies of that sequence
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transcription
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the first step in converting genetic information into proteins
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holoenzyme
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made up of the core enzymw which has the ability to synthesize RNA and the sigma subunit, which is required for initiation of transcription
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elongation phase
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RNA polymerase moves along the DNA template in the 3'->5' direction and synthesizes RNA in the 5'->3' direction
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transcription termination signal
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casues the RNA to form a hairpin structure
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exons
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the regions of eukaryotic genes that will be part of the final mRNA
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primary transcript
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containts exons and introns
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splicing
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the process that removes introns
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small nuclear ribonucleoproteins (snRNPs) and spliceosomes
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they catalyze the splicing reaction
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aminoacyl rRNA
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a tRNA covalently linked to its corresponding amino acid
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aminoacyl tRNA synthestases
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catalyze the addition of amino acids to tRNA
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wobble hypothesis
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proposes that the third of the tRNA anticodon can form a nonstandard base pair with the codon
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point mutation
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a single base change
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missense mutation
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a point mutation that causes a change in the amino acids sequence of the protein
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silent mutations
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mutations that do not chande the amino acid sequence of the protein
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inducer
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a molecule that stimulated the expression of a specific gene
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negative control
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when a regulatory protein binds to DNA and shuts down transcription
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positive control
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regulatory protein binds to DNA and triggers transctiption
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reressor
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exerts negative control over the lac Z and lac Y genes
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operon
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a set of coordinately regulated bacterial gene that are transcribed together into one mRNA
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motif
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a domain that is observed in many different proteins
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helix-turn-helix motif
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a common stuructural design in the lac repressor
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recognition sequence
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the section of the helix-turn-helix motif that binds inside the mjor groove
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chromatin
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DNA is wrapped around proteins to create a protein-DNA complex
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chromatin remodeling
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the DNA neat the promoter must be released from tight interactions with protein before transcription
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nucleosomes
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repeating beadlike structures
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hisone
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nucleosomes consist of negatively charged DNA wrapped twice around eight positively charged proteins
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chromatrin-remodeling complexes
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reshape chromatin
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enhancers
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unique regulatory sequences that can influence gene expression from a long distance
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silencers
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varied lcoations and distances from the regulated gene, but tey repress tather than activated gene expression
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coactivators
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additional proteins involved in intitating transcription
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alternative splicing
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different exons are spliced together to produce different mature mRNAs leads to production of different proteins
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tumor suppessor genes
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slow or stop the cell cycle
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oncogenes
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promote cancer development
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