Molecular Genetics

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mRna

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provides instructions for assembling amino acidsinto a polypeptide chain

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mRNA

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linear

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rRna

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globular

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rRNA

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– combines with proteins to form ribosomes

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tRNA

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delivers amino acid to ribosome for assembly ofpolypeptide.

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tRNA

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(clover-leaf shape)

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DNA gyrase/Topoisomerase

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Relaxes supercoiled DNA by breaking a single DNA strand orboth strands, allowing DNA to rotate into a relaxed molecule.

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Helicase

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unzips the DNA by breaking the hydrogen bonds or “melting” DNA.

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Single-strand binding (SSB)proteins

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prevents the two strands from coming back together

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DNA pol III

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adds nucleotides in the 5’ to 3’ direction of the newly synthesized (template has 3’ to 5’) this goes toward the replication fork and synthesize smoothly. proofreads, has 3’ to 5’ exonuclease (goes back to check and remove the wrong nucleotides)

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Okazaki fragments

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– short stretches of newly synthesized DNA, this is going away from the replication fork, thus, cannot go on for long

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Primase

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– synthesizes theprimer

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primer

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initiates thesynthesis of both leading strand and each Okazaki fragments because DNApolymerase alone cannot start a chain.

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DNA pol I –

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removes primers and replace them with DNA. 5’ to 3’ exonuclease

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Ligase

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– connects theadjacent fragments in Okazaki fragments

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Telomerase

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- attaches to the3’ end fragment so that the place where the primer was located can also getreplicated.

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GTP

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the energy used in translation

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aminoacyl-tRNA–

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attachment of amino acids to 3’ of tRNA.

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. silent mutation –

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new codon still codes for the same aminoacid (mutation occurred in the third codon)

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missense

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– new codon codesfor new amino acid

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nonsense

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–new codon codes for stop codon

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mutagens-

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radiations or chemicals that cause mutations.

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1. proofreading

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– DNA polymerase goes back to check if any base pairings are incorrect.

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Mismatch repair

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–enzymes repair error that the DNA polymerase missed.

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Excision repair –

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enzymes remove nucleotides that are damaged by mutagens. Checking which strandis defective, and then use the complementary strand as the template strand tofix the nucleotide does repair.

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Transposons(jumping genes)

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–DNA segments that move location on the same chromosome or to a differentchromosome. -theycan cause mutation.

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Bacteriophage/phage –

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virus that infects bacteria.

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lytic cycle

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– incorporates the nucleic acids of virus to the bacteria,so that it can reproduce.

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Retrovirus

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– use reverse transcriptase. Use their RNA to make the complement DNA. Thecomplement DNA can then be used to make more mRNA that can be incorporated inthe lysogenic cycle.

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Lysogenic cycle –

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when viralDNA is temporarily incorporated in the DNA of the host cell and is inactiveuntil something triggers it to go back to lytic cycle.

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Prophage –

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virus in thelysogenic stage.

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Bacteria reproducethrough

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binary fission

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episomes

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– plasmid that canbe incorporated to bacterial chromosome.

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Gel Electrophoresis

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– used toseparate restriction fragments.

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Restriction Fragment Polymorphism(RFLPs) –

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when fragments have different lengths, slightdifferences in DNA sequences.

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Short Tandem Repeats ( STR)

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–are the repeating sequences of nucleotides.

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Complementary DNA

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– when the DNA obtained comes from mRNA or reverse transcriptase.