a human cell containing 22 autosomes and a Y chromosome is
which life cycle stage is found in plants but not animals
homologous chromosomes move toward opposite poles of a dividing cell during
meiosis 2 is similar to mitosis in that
sister chromatids separate during anaphase
if the DNA content of a diploid cell in G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis 1 would be
if we continued to follow the cell image from question 5, then the DNA content of a single call at metaphase of meiosis 2 would be
how many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n=8)?
how can you tell when a cell is undergoing meiosis
because homologous chromosomes are associated with each other at the metaphase plate; this does not occur in mitosis
what is a gene
a heritable unit that determines a character; can exist in different forms
what is a allele
an alternative version of a gene
what is a character
a heritable feature that varies among individuals
what is a trait
a variant for a character
what is a dominant allele
determines phenotype in a heterozygote
what is a recessive allele
has no effect on phenotype in a heterzygote
what is a genotype
the genetic makeup of an individual
what is a phenotype
an organism's appearance or observable traits
what is a homozygous
having two identical alleles for a gene
what is a heterozygous
having two different alleles for a gene
what is a testcross
a cross between an individual with an unknown genotype and a homozygous recessive individual
what is a monohybrid cross
a cross between individuals heterozygous for a single character
in his work with pneumonia-causing bacteria and mice, Griffith found that
some substance from pathogenic cells was able to transform nonpathogenic cells, making them pathogenic
what is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
DNA polymerase can join new nucleotides only to the 3' end of a growing strand
in analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?
the elongation of the leading strand during DNA synthesis
depends on the action of DNA polymerase
In a nucleosome, the DNA is wrapped around
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?
one low-density and one intermediate-density band
a biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. when she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?
The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?
nuclease, telomerase, primase
in eukaryotic cells, transcription cannot begin until
several transcription factors have bound to the promoter.
which of the following is not true of a codon?
it extends from one end of a tRNA molecule
the anticodon of a particular tRNA molecule is
complementary to the corresponding mRNA codon
which of the following is not true of RNA processing?
exons are cut out before mRNA leaves the nucleus
which component is not directly involved in translation
which of the following mutations would be most likely to have a harmful effect on an organism?
a single nucleotide deletion near the end of the coding sequence
if a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then
the amino acid acts a corepressor
muscle cells differ from nerve cells mainly because they
express different genes
the functioning of enhancers is an example of
transcriptional control of gene expression
cell differentiation always involves
the production of tissue-specific proteins, such as muscle actin
which of the following is an example of post-transcriptional control of gene expression?
the removal of introns and alternative splicing of exons
what would occur if the repressor of an inducible operon were mutated so it could not bind the operator?
continuous transcription of the operon's genes
absence of bicoid mRNA from a Drosophilia egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene
normally leads to formation of tail structures
which of the following statements about the DNA in one of your brain cells is true?
it is the same as the DNA in one of your heart cells
within a cell, the amount of protein made using a given mRNA molecule depends partly on
the rate at which the mRNA is degraded
proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?
proto-oncogenes normally help regulate cell division
which following characteristics, structures, or processes is common to both bacteria and viruses?
genetic material composed of nucleic acid
emerging viruses arise by
mutation of existing viruses, the spread of existing viruses to new host species, the spread of existing viruses more widely within their host species
to cause a human pandemic, the H5N1 avain flu virus would have to
become capable of human-to-human tranmission
a bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have
T4 protein and T4 DNA
RNA viruses require their own supply of certain enzymes because
host cells lack enzymes that can replicate the viral genome
which of the following tools of recombinant DNA technology is incorrectly paired with its use?
DNA ligase-- cutting DNA, creating sticky ends of restriction fragments