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Genetics Review Test #3
1. DNA polymerase III adds DNA to the end of the RNA primer on the lagging strand and adds DNA to the leading strand.
The leading strand is the new strand of DNA made continuously.
The lagging strand is made in Okazaki fragments and needs an RNA primer from primase.
Exonuclease works with DNA polymerase I to chew out the RNA primer so that DNA polymerase canreplace the primer with DNA on the lagging strand.
DNA helicase unwinds the helix and single-stranded binding DNA keeps DNA unwound for replication.
Nucleotides are made of and a nitrogenous base, a phosphate, and sugar (deoxyribose). RNA polymerase is used in transcription and chooses correct nucleotides based on a template DNA, doesn’t require a primer and used uracil instead of thymine.
DNAligase reconnects the nicks between fragments on the lagging strand by forming a phosphodiester bond, which are bonds between sugar and phosphates. DNA polymerase replicates DNA by using dATP, dGTP, dCTP, and dTTP and as each nucleotide is made it generates diphosphate (PPi).
The origin (ori) is where replication begins, once in bacteria and multiple ori on multicellular organisms. The terminus isthe amino group at the 5’ end of an amino acid and the terminus carboxyl group is at the 3’ opposite end.
2. Chargaff’s Rules are that (1) purine = pyrimidines, (2) A=T, C=G, (3) A+T ≠ G+C.
3. The Wobble hypothesis is that some tRNA’s recognize more than one codon for one amino acid. The third base of the anti-codon can “wobble” to another base pair but is still recognized as the same aminoacid. Serine has 6 codons with 3 tRNAs, so you can see how the number of tRNAs and codons can be different.
4. Avery, McCarty, and McCleod fractioned S strain (virulent and smooth, kills mice) into polysaccharides, proteins, deoxyribose, ribose, and lipids and mixed with the R strain (avirulent and rough, nonlethal) and only the DNA could transform R into S.
Hershey and Chase usedbacteriophage T2. They labeled the 35-Sulfer in protein and 32-Phosphate in DNA in a bacteriophage and observed which isotopes entered the bacteria. They found it to be DNA.
5. RNA contains the sugar ribose, has an OH on the 2’ carbon, and is sometimes single stranded. and DNA contains deoxyribose and a H on its 2’ carbon.
6. RNA polymerase is composed of 5 units and performs transcription basedon correct nucleotides base pairing with exposed bases on the template DNA. The promoter sequence is when the sigma factor is used in initiation of transcription to bind the core enzymes to the messenger RNA strand. The mRNA will contain the complementary information from the template DNA strand. The rho factor in some cases dissociates the mRNA from polymerase.
7. The information in DNA getsconverted to protein by splitting the DNA and using the DNA template strand to transcribe onto mRNA, via RNA polymerase. Then mRNA codons pair with anti-codons on the tRNA that carries the amino acids, which string together with the help of a ribosome, until there are 20, forming a protein.
Through the one gene-one enzyme hypothesis we know that genes are steps in the biosynthesis pathway, andbiosynthesis pathways affect phenotypic characteristics causing them to show up or not, depending on if there is a mutation in the enzyme.
8. Amino acids are what make up polypeptide chains which make proteins, derived from codons in translation. Amino acids have an amino terminal at the beginning and a carboxyl end with a carbon in the middle. The carbon also contains R groups. There are 20 Rgroups and so 20 amino acids. The peptide bond is a bond that holds amino acids together, between the carboxyl end and amino beginning. Transfer RNA is what contains the amino acid and anticodon to the mRNA. Ribosomal RNA associates with protein for ribosomal synthesis. Ribosomes have a small subunit (30S) and a large subunit (50S) the 30S initiation complex (small) binds the Shine-Dalgarno...