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64 Cards in this Set
- Front
- Back
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Under what circumstances does a cell replicate its DNA?
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To divide.
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DNA is semiconservative. Meaning?
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Each double helix being replicated contains a parent strand and a daughter strand. Each strand in the parent molecule serves a template strand for the synthesis of new strand.
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Enzymes involved in DNA Replication:
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DNA polymerase, Helicase, and Ligase.
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Separates DNA parent strands and unwinds helix.
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Helicase
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New strand synthesized in 5' to 3' direction and net movement is towards the fork.
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DNA Polymerase
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Function of ligase:
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Links okazaki fragments together.
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Segments in lagging strand causing it to be discontinuous.
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Okazaki Fragments
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Holds parent strands stable during DNA replication.
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ssDNA-Binding Proteins
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Adds RNA Primer
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Primase
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RNA Polymerase lays down a short amount of RNA, and is complementary to the parent strand.
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RNA Primer
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Site of DNA Replication.
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Replication Fork
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Where replication begins.
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Orgin of Replication
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DNA Polymerase synthesizes DNA in __' to __' direction and the template strand runs __' to __' direction.
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5' to 3' and 3' to 5'
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New DNA strand is synthesized continuously. Parental strand 3' to 5' and new strand 5' to 3'
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Leading Strand
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Synthesized discontinuously in segments away from fork, however each new segment is closer to the fork then the previous one. Parental strand 5' to 3' and new strand 3' to 5'/
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Lagging Strand
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At the replication fork, why must one of the new DNA strands always be synthesized discontinuously?
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The lagging strand is always synthesized discontiniously because of the direction the parent strand initially goes in.
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Can DNA polymerase move in 3' to 5' direction ever? If so why?
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Yes, so it can remove and incorrect nucleotide.
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Permanent change in DNA sequence and has proofreading capabilities.
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Mutation.
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Covalent Bonds to produce peptide bonds.
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Amino Acid
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Type of covalent bond that joins AA.
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Peptide Bond
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Chain of AA's.
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Polypeptide Chain
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Molecule consisting of one or more polypeptides.
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Protein.
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Segment of DNA that often encodes for a polypeptide of a protein.
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Gene
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The order of AA's in a protein encodes for...
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polypeptide of a protein.
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Each gene has a different combination of nucleotides and so it encodes for a specific...
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polypeptide
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3 types of RNA
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messenger RNA, ribosomal RNA, and transfer RNA.
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mRNA function:
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Sends directions from DNA to ribosomes.
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rRNA function:
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Structural component of ribosomes.
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tRNA function:
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Carries specific AAs to ribosome during translation.
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Where does protein synthesis take place?
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Ribsomes.
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Central Dogma of Molecular Biology refers to
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Protein synthesis.(DNA>mRNA>polypeptide)
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What are the two processes that must occur for the information contained in a gene to be used to make a protein?
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Transcription and Translation.
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The intermediate information molecule that is synthesized in the nucleus and transported to cytoplasm is
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mRNA
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3 Steps of Transcription:
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Initiation, Elongation, Termination.
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RNA polymerase binds to DNA at promoter, unwinds DNA, and reads template strand.
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Initiation
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RNA polymerase extends the RNA transcript in 5' to 3' direction, bubble moves with RNA polymerase, and dsDNA reassembles behind bubble.
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Elongation
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Last nucleotide added, bubble collapses, and RNA and RNA polymerase are released.
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Termination
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What direction is mRNA synthesized?
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5' to 3'
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What is a promoter?
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Defines start of a gene and direction of transcription.
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What enzyme reads the template strand and synthesizes and mRNA strand during transcription?
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RNA polymerase.
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Pre mRNA is modified in what 3 ways after being synthesized in nucleus?
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5' Cap, 3' Poly-A tail, and introns
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Modified guanine nucleotide that serves as a ribosome binding site.
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5' Cap
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150-200 Adenine nucleotides that helps transcript exit nucleus and protects from degradation.
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3' Poly-A tail
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Removed by spliceosomes.
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Introns
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Codons encode for a specific AA.
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Genetic Code
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3 adjacent nucleotides in mRNA.
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Codons
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What does the genetic code being degenerate mean?
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OFten multiple codons encode for one AA.
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What amino acid should be the first one on every protein?
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Methionine.
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What are 2 important parts of tRNA molecule?
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Anticodon and its specific AA at the 3' end.
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Enzymes that attach a specific AA to the correct tRNA molecule.
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tRNA synthetases.
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Anticodons on a tRNA are complementary for a particular ____ in the ______.
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codon, mRNA transcript
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True or False: There are more codons then tRNA molecules.
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True
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Understand Wobble hypothesis:
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Mismatch often allowed at 3rd postion between a codon and anticodon.
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What is the advantage of allowing a mismatch at the third position?
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Because then some tRNA molecules can pair with multiple codons.
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What occurs during translation:initiation?
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Small RU binds to mRNA. 1st tRNA binds AUG. Large subunit binds
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What are the 3 tRNA binding sites and what do they stand for?
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A, P, and E.
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Translation:Elongation?
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Polypeptide chain increases by one AA at a time.
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What does the ribozyme do?
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Catalyzes a peptide bond.
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Elongation continues until...at...
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stop codon.. a site.
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Translation:Termination?
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all subunits are released and polypeptide folds which gives proteins 3-D structure.
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Does the stop codon encode for an AA?
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No
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What do genes produce?
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Proteins
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what is the ratio of nucleotides to AA?
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3:1
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A gene can have no effect, positive effect or a negative effect on the function of a protein? T or F
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True
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