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Week One Biochem Review

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Our genetic code is made up of DNA and are expressed in the phenotype as a __________.
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protein
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What are the four characteristics of our DNA?
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Universal, unambiguous, redundant, non-overlapping & commaless
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The genetic code consists of bases, these bases comprise _________.
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codons
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The four bases are:
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A (adenine), T (thymine), C (cytosine), and G (guanine)
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Since there are four bases, there are ____ possible codons
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64
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DNA molecule is a double-helix- __________ _________.
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Rosalind Franklin
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Meselson and Stahl experiment showed replication of DNA to be ________________.
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semiconservative
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___________ unwinds the strand.
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helicase
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_____________ ___________ sets up for the RNA primer
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RNA primase
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_______ ___________ _________adds nucleotides to the 3’ end of the RNA primer and elongates the DNA strand
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DNA polymerase III
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_________ __________ ___ removes the old RNA primer and replaces it with DNA
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DNA polymerase I
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________ _________ catalyzes the formation of the phosphodiester bond linking the Okazaki fragments
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DNA ligase
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___________ __________ action causes the newly forming leading strandto grow in the 5’-to-3’ direction
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DNA polymerase
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________ uses DNA polymerases to repeatedly replicate DNA in the test tube.
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PCR (polymerase chain reaction)
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RNA differs from DNA in 3 ways:
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1)it is single-stranded
2) its sugar molecule is ribose rather than deoxyribose
3) its fourth base is uracil rather than thymine
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Messenger RNA =
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mRNA is the message or direction on how to make a protein
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Transfer RNA =
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tRNA it matches up amino acids with the RNA message
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Ribosomal RNA=
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rRNA used to bind the mRNA message
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recognition sequence: one or two recognition sequences of 50 – 70bp form what?
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the TATA box
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TATA box (rich in thymine & adinine): ___ base pairs upstream from the_____ ______ for transcription
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25; initiation site
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_________ __________ _________ ___ needs transcription factors to initiate transcription
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Eukaryotic RNA polymerase II
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The protein ______ binds to the TATA box
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TFIID
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Finally _____ ______________ ____ binds to the site
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RNA polymerase II
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_____ is transcribed from the DNA template after the ________ __ ____ are exposed by unwinding of the double helix.
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RNA;bases of DNA
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RNA polymerase reads the DNA template strand from __ to __ and produces the RNA transcript from __ to __.
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3’ to 5’ ; 5′ to 3′
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Nucleotides are added at the __ end of the growing RNA
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3′
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One mRNA codon _____ indicates the starting point of translation, also codes for _____________.
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AUG; methionine
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Three stop codons indicate the end of _________.
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translation – UAA, UAG and UGA
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The other 60 codons code only for __________ ________ _________.
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particular amino acids.
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_____ binds the correct amino acid; has an _______ complementary to the mRNA codon.
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tRNA ; anticodon
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The _____________, a family of activating enzymes, attach specific amino acids to their appropriate tRNA’s, forming ________ tRNA’s.
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aminoacyl-tRNA synthetases; charged
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The ribosome is composed of two units:
large subunit that consists of _____ different molecules of rRNA and ___ different ________ ________ .
small subunit of one ___ ________ and ___ different protein molecules
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3; 45; protein molecules;rRNA molecule; 33
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An initiation complex consisting of an _______ _________ __________ _________ and a small ribosomal subunit bound to mRNA triggers the beginning of ____________.
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amino acid-charged tRNA; translation
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On the large subunit of the ribosome there are ___ sites to which tRNA binds.
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four
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T (transfer) site: where ___________.
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tRNA first lands
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A (amino acid) site is where the tRNA anticodon binds to ___________.
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binds to mRNA codon
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P (polypeptide) site is where the tRNA __________.
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adds its amino acid to the growing poly peptide chain
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E (exit) site is where tRNA, without its ______ _______, resides before leaving the________ and going back to the cytosol to pick up another ________ _________.
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amino acid; ribosome; amino acid
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Polypeptides grow from the __ terminus toward the __ terminus. The ribosome moves along the mRNA ___ codon at a time.
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N to C; one
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The presence of a _____ ______ in the __ site of the ribosome causes translation to terminate
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stop codon; A
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Signals contained in the amino acid sequences of proteins direct them to___________ ____________.
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cellular destinations.
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Modifications of proteins after translation include:
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proteolysis, glycosylation, and phosphorylation.
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Cells must regulate how they synthesize molecules to suit their:
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condition, environment, and needs
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cells can control synthesis activity by
___________ or controlling the production
of _________.
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regulating; enzymes
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cells can control synthesis activity by blocking __________ of the gene that codes for a protein.
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transcription
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cells can control synthesis activity by _______ the ______ after it is made.
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hydrolyze; mRNA
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cells can control synthesis activity by ________ __________ of mRNA at the ribosome.
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preventing translation
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cells can control synthesis activity by __________ the protein after it was made
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hydrolyzing
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Point mutations result from alterations in______ ________ ________ of DNA.
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single base pairs
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What are some examples of point mutation?
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silent, missense, nonsense, or frame-shift
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Chromosomal mutations involve _______ regions of a chromosome.
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large
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What are some examples of chromosomal mutations>
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deletions, duplications, inversions, or translocations
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Point mutations result from the _______ or _______ of one base for another in the DNA and as a result in the RNA
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addition or subtraction;
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Some result in no change in amino acid because of the redundancy of the genetic code=
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silent or synonymous mutation
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A ____________ mutation results in an amino acid change
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missense
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____________ mutation results in no protein being made at all, they are disruptive.
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nonsense
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____________ mutation results in no protein being made at all, they are disruptive.
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nonsense
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A _________-__________ mutation, is when single base pairs may be inserted or deleted from DNA
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frame-shift
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___________ remove part of the genetic material
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deletions
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___________ mutations are homologous chromosomes brake at different positions and then reconnect to the wrong partners
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Duplications
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_________ mutations are removal of a segment and its reinsertion into the same location but flipped.
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Inversion
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___________ mutation is when a segment of DNA breaks off and is inserted into a different chromosome
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translocation
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Spontaneous mutations occur because of instabilities in ______ or _____________.
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DNA or chromosomes
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Induced mutations occur when an ________ __________ damages ____.
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outside agent; DNA
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Some of these non-transcribed regions are ________, such as the telomeres; some regulate ______ ________; and some have no known use.
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structural; gene expression
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____________ are 5-50bps are repeated side by side up to a million times.
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Satellites
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________ are 12-100 bps long & are repeated several thousand times. Can be used as ______ _______ for identifying an individual because their numbers can vary
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Minisatellites; genetic markers
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__________ are 1-5bps present in small clusters 10-50 copies. These have been used in sequencing the human genome
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microsatellites
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___________ are repetitive sequences at the ends of chromosomes
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telomeres
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Chromosome _________ occurs after each round of replication. This leads to ____ __________.
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shortening; cell death
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The enzyme_____________ prevents the loss of telomeric ends
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telomerase
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A ___ _______ is added to the 5’ end.
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G cap, GTP
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A _______ __ _______ is added to the 3’ end
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poly A tail
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_______ _____________ particle binds at the 5’ splice site and a second binds near the 3’ splice site
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Small ribonucleoprotein (snRNP) particle
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____________ elements move about the genome
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Transposable
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a _____________ consists of two transposable elements flanking another gene or genes. The entire transposon is copied and inserted as a unit.
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transposon
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If the insertion takes place in a somatic cell, _________ may result
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cancer
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If a transposon replicates not just itself but also an adjacent gene, the result may be _____ _____________.
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gene duplication
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Transposons can result in:
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cancer cells, gene duplication, genetic variability, new genes
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___________ _______ are instructions that specify the primary structures of a protein molecule (those that get transcribed into mRNA)
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structural genes
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_________ are units of transcription; structural genes plus regulatory mechanisms.
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operons
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__________ regions bind activator proteins that stimulate the transcription complex (promoter then binds RNA polymerase & transcription starts)
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enhancer regions
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_________ -when attached to an operon, transcription shuts down
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repressor
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__________ are negative regulatory regions; turn off transcription by binding to repressor
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silencers
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___________ blocks RNA polymerase from binding & transcribing the structural genes, preventing synthesis of tryptophan pathway enzymes
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tryptophan;
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When glucose levels are high:
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1. RNA polymerase cannot bind efficiently
2. Structural genes are not transcribed. This is adaptive when the cell does not require an alternative energy source