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126 Cards in this Set
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gene
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a series of nucleotides that codes for the production of a single polypeptide, mRNA, rRNA, or tRNA
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genome
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entire sequence of DNA in an organism
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central dogma
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DNA -> RNA -> protein
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DNA
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deoxyribonucleic acid
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nucelotide
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made of a phosphate group, a 5' carbon sugar and a nitrogenous base (purines or pyrimidines)
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purines
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adenine and guanine
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pyrimidines
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cytosine and thymine
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phosphodiester bond
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bonds between nucleotides
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phosphate backbone
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OH groups on 5' and 3' carbons are joined to phosphate groups by phosphodiester bonds
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5' - 3' directionality
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5' carbon is attached to a phosphate group and the 3' carbon is attached to a -OH group
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antiparallel
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DNA strands lie in opposite directions
Top: 5' - 3' Bottom: 3' - 5' |
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double stranded
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the two strands are connected by hydrogen bonds
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base pairing
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adenine forms two hydrogen bonds with thymine
cytosine forms three hydrogen bonds with guanine |
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complementary strands
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when the the two strands line up with proper base pairing
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double helix
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curled form of DNA
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semi-conservative
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one strand from the original and a newly synthesized strand
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bi-directional process
leading strand lagging strand |
replication on strand reading 3'-5' synthesized in one go since nucleotides are added 5'-3'
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formed in Okazaki fragments since it's being read in pieces
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helicase
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enzyme that unzips DNA helix
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primer
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10 ribonucleotide long RNA added to DNA strand that initiates replication of new strand
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built by RNA polymerase
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DNA polymerase
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enzyme that builds DNA strands by can only add nucleotides to an existing strand
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the existing piece is called the primer
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DNA ligase
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moves along the lagging strand and ties the Okazaki fragments together
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telomeres
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repeated nucleotide units that protect the chromosome from being eroded during replication
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catalyzed by telomerase
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mRNA
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mRNA - delivers DNA code for amino acids from nucleus to cytosol where proteins are manufactured
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rRNA
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synthesized in the nucleolus; combines with proteins to form the ribosome, the complex that directs synthesis of proteins in the cytosol
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tRNA
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collects amino acids in the cytosol and transfers them to the ribosomes for incorporation into proteins
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RNA
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ribonucleic acid; 2' carbon has OH group attached
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transcription
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DNA template used to manufacture RNA in the nucleus on the mitochondrial matrix
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initiation
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beg. of transcription, which incl proteins finding a promoter on the DNA strand
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promoter
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sequence of DNA nucleotides that indicates transcription start point
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located upstream from gene
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elongation
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RNA polymerase transcribes one strand (template/antisense) of DNA into complementary RNA nucleotide sequence
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termination
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end of transcription, which requires a special termination sequence and proteins to dissociate RNA polymerase from DNA
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activators
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bind closely to DNA, close to promoter and activates RNA polymerase
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allosterically regulated by other molecules such as cAMP
binding site located upstream from promoter |
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repressors
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bind closely to DNA, close to promoter to repress RNA polymerase
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allosterically regulated by other molecules such as cAMP
binding site located downstream from promoter |
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operon
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sequence of BACTERIAL DNA consisting of operator, promoter and genes that contribute to a single prokaryotic RNA
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some eukaryotes have them
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primary transcript
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initial nucleotide sequencing arrived at through transcription in nucleus
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5' cap
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attachment site in protein synthesis and as protection against degradation by exonucleases
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poly-A tail
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protection against exonucleases for 3' end
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introns
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portions of mRNA that will get removed from primary transcript BEFORE leaving the nucleus
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exons
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portions of mRNA that will remain in primary transcript
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snRNPs
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recognize nucleotide sequences at the end of introns
w/ proteins, form spliceosome that excises out introns and splices exons together |
small nuclear ribonucleoproteins
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denature
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when two strands of DNA molecules come apart due to disruption of hydrogen bonds by heat, high concentration salt solution or high pH
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nucleic acid hybridization
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when complementary nucleotide sequences spontaneously associate
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combos formed:
DNA - DNA DNA - RNA RNA - RNA |
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restriction enzymes
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digest/cut nucleotide sequences only at specific points in chains
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palindromic
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reads the same backwards as forwards
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recombinant DNA
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two DNA fragments, regardless of origin, that can be joined together if cleaved by the same restriction enzyme
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vector
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DNA molecule that can carry foreign DNA into a cell and replicate there
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can be a plasmid or an ineffective virus
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plasmid
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small ring of DNA that carries accessory genes separate from those of a bacterial chromosome
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clone
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identical cells
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typically formed via recombinant DNA
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clone library
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saved copies of bacterial DNA with foreign DNA inserted
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screening
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finding bacteria which have not taken up the vector/plasmid, as well as the vectors/plasmids which have not taken up the DNA fragment
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probe
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radioactively labeled complementary sequence of a DNA fragment
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complementary DNA (cDNA)
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DNA that is reverse transcribed from mRNA by using reverse transcriptase
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adding DNA polymerase produces the second strand
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polymerase chain reaction (PCR)
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1. DNA is denatured with heat and then cooled
2. primers hybridize to complementary ends of DNA strands 3. heat resistant polymerase adds nucleotides to second strand |
process can be repeated as many times as necessary
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southern blotting
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identifies specific sequences of DNA by nucleic acid hybridization
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northern blotting
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identifies specific sequences of RNA by nucleic acid hybridization
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western blotting
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using antibodies, detects a particular protein in a mixture of proteins
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restriction fragment length polymorphisms (RFLP)
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differences in the restriction sites on homologous chromosomes that results in different restriction fragment patterns
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DNA fingerprints used to ID criminals
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genetic code
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mRNA nucleotides strung together which translate the DNA nucleotide sequence into an amino acid sequence that ultimately makes a protein
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degenerative
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more than one codon sequence can code for a single amino acid
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unambiguous
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any single codon will ONLY code for one amino acid
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codon
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three consecutive nucleotides on a strand
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stop/termination codons
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UAA, UGA, UAG
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start codon
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AUG
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translation
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process of protein synthesis directed by mRNA
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also involves rRNA, tRNA
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anticodon
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carried by tRNA, the nucleotides that are complementary to the codon of mRNA
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ribosome
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complex formed by rRNA and proteins, which provides the site for translation
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composed of small and large subunit
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nucleolus
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organelles that manufacture ribosomes
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prokaryotes do NOT have them
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P site
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holds the tRNA carrying the growing polypeptide chain
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where the tRNA possessing the 5' CAU 3' anticodon sequesters the start codon and settles in
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initiation
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brings together mRNA, tRNA with the first amino acid of the polypeptide and the ribosome
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elongation
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amino acids are added one by one to the preceding amino acid
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A site
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holds the tRNA carrying the next amino acid to be added to the chain
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catalyzed at the expense of two GTPs
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translocation
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ribosome shifts three nucleotides along the mRNA towards the 3' end
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requires the expenditure of GTP
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E site
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location from which discharged (and empty) tRNAs leave the ribosome
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termination
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end of translation, signaled by a stop codon reaching the A site
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ribosome breaks up into subunits to be used for protein synthesis later
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post-translational modifications
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sugars, lipids or phosphate groups may be added to amino acids
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signal peptide
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20 amino acid sequence near the front of the polypeptide that signals the polypeptide to the ER
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recognized by the signal-recognition particle (SRP)
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signal-recognition particle (SRP)
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carries the entire ribosome complex to a receptor protein on the ER
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mutation
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any genomic alteration that is not genetic recombination
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gene mutation
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alteration in the sequence of DNA nucleotides in a single gene
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chromosomal mutation
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when the structure of the chromosome is changed
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mutagens
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chemical agents that can cause mutations
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point mutation
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a mutation that alters a single base pair of nucleotides
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base pair substitution mutation
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when one base pair is replaced by another
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form of a point mutation
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missense mutation
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a base pair mutation that occurs in the amino acid coding sequence of a gene
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may or may not alter the sequence of a protein
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insertion/deletion
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additions or losses of nucleotide pairs in a gene
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frameshift mutation
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when the deletions or insertions occur in multiples other than 3
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often result in a completely non-functional protein
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nonsense muation
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if an insertion or a deletion mutation creates a stop codon
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harmful because they typically prevent translation of functional protein entirely
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chromosomal deletions
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when a portion of the chromosome breaks off or is lost during homologous recombination and/or crossing over events
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chromosomal duplications
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when a DNA fragment breaks free of one chromosome and incorporates into a homologous chromosome
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chromosomal translocation
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when a segment of DNA from on chromosome is inserted into another chromosome
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caused by transposition, which takes place in prokaryotic and eukaryotic cells
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chromosomal inversion
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the orientation of a section of DNA is inverted on a chromosome
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caused by transposition, which takes place in prokaryotic and eukaryotic cells
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transposable elements/transposons
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DNA segments that can excise themselves from a chromosome and reinsert themselves into another location
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they can contain one or many genes, or just a control element; way for somatic cell to alter its genetic makeup without meiosis
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forward mutation
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mutation that tends to change the organism even more from its original state
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refers to mutated organism that is mutating again
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backward mutation
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mutation that tends to change the organism back to its original state
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refers to mutated organism that is mutating again
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wild type
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the original state of the organism
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chromosome
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chromatin associated with each of 46 DNA molecules
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each contains hundreds or thousands of genes
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trait
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a detectable variation in a genetic character
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for example, eye color
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homologues
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chromosome pairs of the same length, centromere position and staining pattern that possess genes for the same characters at corresponding loci
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one comes from mom and the other from dad
same traits, different genes |
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diploid
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any cell that contains homologous pairs
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haploid
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any cell that does not contain homologous pairs
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interphase
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1. the period in the cell cycle when the cell is not dividing
2. metabolic activity is high; chromosomes and organelles are duplicates, and cell size may increase |
G1
S G2 |
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G1 phase
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the first growth phase consisting of the portion of interphase before DNA synthesis begins
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cell grows in size and produces new organelles and proteins
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G0 phase
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non-dividing state in which a cell has left the cell cycle
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not part of interphase
mature neurons and muscle cells remain here permanently |
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S phase
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synthesis phase in which DNA is replicated
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each chromosome is exactly duplicated, but understood to be made of sister chromatids
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chromatids
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replicated forms of a chromosome joined together by the centromere
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G2 phase
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1. second growth phase after DNA synthesis occurs
2. organelles continue to duplicate; RNA and protein are actively synthesized |
G2 checkpoint looks for mitosis promoting factor
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mitosis
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nuclear division without genetic change
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PMAT
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prophase
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1. nucleolus and nucleus disappear
2. centrioles move to opposite ends of the cell 3. spindle apparatus forms 4. chromatin condenses into chromosomes |
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centrioles
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pair of cylinders of microtubule triplets that are involved in cell division
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spindle apparatus
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apparatus that forms from microtubules radiating from centrioles
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centromeres
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the centralized region joining two sister chromatids
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spindle microtubules
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connects the two centrioles
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kinetochores
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a specialized region on the centromere that links each sister chromatid to the mitotic spindle
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metaphase
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1. spindle is complete
2. chromosomes align at the metaphase plate |
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anaphase
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1. sister chromatids split at their attaching centromeres
2. move towards opposite ends of the cell |
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cytokinesis
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actual separation of cellular cytoplasm
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telophase
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1. nuclear membrane reforms
2. nucleolus reforms 3. chromosomes decondense 3. cytokinesis continues |
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meiosis
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double nuclear division that produces four haploid germ cells (genetically distinct)
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prophase I
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1. homologous chromosomes line up, matching genes
2. exchange DNA sequences in crossing over |
chromatids are tetrads
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metaphase I
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1. tetrads remain attached and move to metaphase plate
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anaphase I
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1. homologues (tetrad) are separated from partners
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telophase I
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1. nuclear membrane reforms and cytokinesis begins (humans)
2. |
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secondary spermatocytes/oocytes
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haploid cells with 23 replicated chromosomes
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chromosome here = 2 sister chromatids
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first polar body
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one of the oocytes that is smaller and degenerates to conserve cytoplasm
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may or may not go through meiosis II producing two polar bodies
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meiosis II
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looks very similar to mitosis
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nondisjunction
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if during anaphase I or II, the centromere of a chromosome doesn't split
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