AP Biology: chapter 16-19 quetsions

the elongation of the leadng strand during DNA synthesis...

does not require a template strand.

which is NOT true of RNA processing?

exons are cut out before the mRNA leves the nucleus; 1) mRNA doesnt cut anything out before it leaved the nucleous 2) exons stay on the strand, introns are cut off

which is NOT true for a codon?

it may code for more than one nucleotide.

using the experiment explained in the previous question, which centrifuge tube would represent the band distribution obtained after one replication showing that DNA replication is semiconservative?

one in which that had a single band in the center of the tube; between the heavy and light isotopes of nitrogen.

in eukaryotic cells, transcription cannot begin until...

several transcription factors have bound to the promoter

in his work with pneumonia-causing bateria and mice, Griffith found that...

some substance from pathogenic cells was transferred to nonpathegenic cells, making them pathogenic

in an analysis of the nucleotide composition of DNA which is true?

A + C = G + T

a particular triplet of bases in the coding sequene of DNA is AAA. the anticodon on the tRNA that binds to the mRNA codon is...

AAA

which component in NOT directly involved in translation?

DNA

a biochemist isolates and purifies various molecules needed for DNA replication. when she adds some DNA, replication occurs, but each DNA consists of a normal DNA strand paired with numerous segments of DNA a few hundred nucleotides long. what has she probably left out of the mixture?

DNA lilgase; it wasnt there to join the okazaki frangments together after replication.

what is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

DNA polymearsecan join new nucleotides only to the 3' end of a growing strand.

what is the relationship among DNA, a gene, and a chromosome?

a chromosome contains hundreds of genes which are compsed of DNA.

imagine the following expirament is done: bacteria is first grown for several generations in a medium containing the lighter isotope of nitrogen, 14N, then switched into a medium containing 15N. the rest of the experiment is identical to the Meselson and Stahl experiment. which of the following represents the band positions you would expect after two generations?

a tube with one band in the heavier isotope of nitrogen and one in the middle of the tube between the heavy an light isotopes because this mutation would be made in a conservative model which would make one replication to be all heavy genes, but the other in the middle because the mixing of the DNA making the band be half of heavy and half of light.

tobacco mosaic virus has RNA rather than DNA as its genetic material. in a hypothetical situation where RNA from a tobacco mosaic virus mixed with proteins from a related DNA virus, the result could be a hybrid virus. if that virus were to infect a cell and reproduce, what would the resulting "offspring" viruses be like?

a virus with a double helix made up of one strand of DNA complementary to a strand of RNA surrounded by a viral protein.

synthesis of a new DNA strand usually begins with...

an RNA primer.

a part of mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). the following activated transfer RNA molecules are available. two of them can correctly match the mRNA so that adipeptide can form. the dipeptide that will form will be...

anti-codon would be GGC-UGC aka: proline-threonine

you are trying to support your hypothesis that DNA replication is conservative, i.e. parental strands separate; complementary strands are made but these new strands rejoin. you take E. coli that had grown in a medium containing only heavy nitrogen isotopes and transfer a sample to a medium containing light nitrogen. after allowing time only one DNA replication, which band location would support your hypothesis of conservative DNA replication?

because it is a conservative replication, the two bands of DNA would be in two separate levels of the Nitrogen isotope, one is in 14N and the other in 15N because of how conservative replication works.

if protiens were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides?

1

cytosine makes up 38% of the nucleotides if a sample of DNA from an organism. what percent of the nucleotides in this sample will be thymine?

12%

A space probe returns with a culture of microorganism found on a distant planet analysis shows that it is a carbon-based life form that has DNA. you grow the cells in 15N medium for several generations and then transfer it to 14N medium. which pattern in this figure would you expect if the DNA were replicated in a conservative manner?

Because it is conservative and moved from the 15N to 14N, the tube would have one band at the top (in 14N) and one at the bottom (in 15N); meaning that it is generating offspring that are only exactly part of one piece of the DNA, not combined with another piece that would usually cause it to be in the middle of the tube.