Mastering Biology Ch. 17
If a cell normally has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis?
12.
A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?
24.
By the end of meiosis II, a cell that had entered meiosis I with 32 chromosomes would have produced __________ daughter cells, which are genetically __________ and which each has __________ chromosomes.
4; nonidentical; 16
Which of the following would indicate a base pairing mutation in DNA?
A C paired with a T.
Which of the following checkpoints does not occur late in G1?
A check that chromosome replication has been successfully completed.
How can we best define the term chromatid?
A chromatid is an individual strand (DNA molecule) in a replicated chromosome.
_____ bind(s) to DNA enhancer regions.
Activators
During which phase of meiosis do sister chromatids separate?
Anaphase II.
The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
Anaphase.
What is cytokinesis and when does it occur?
Cytokinesis is the division of the cytoplasm. This process begins toward the end of mitosis and does not end until after mitosis has been completed.
At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.
Cytokinesis.
Which of the following would NOT occur if the cleavage furrow were unable to form?
Cytokinesis.
Which statement about DNA replication is FALSE?
DNA ligase adds nucleotides to the lagging strand.
The molecule that seals the gaps between the pieces of DNA in the lagging strand is
DNA ligase.
Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
DNA polymerase can assemble DNA only in the 5' to 3' direction.
Which of the following build(s) new strands of DNA?
DNA polymerases.
Which of the following terms describes most cells in the human body?
Diploid somatic cells.
When considering meiosis, when does DNA replication take place?
During interphase.
During which phase of meiosis do homologous chromosomes exchange segments?
Exchange of chromosome segments occurs during prophase I (meiosis I).
True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase.
False.
True or false. When an egg and a sperm fuse, a haploid zygote is formed.
False.
If the tubular elements of the cytoskeleton were NOT disassembled prior to mitosis, which of the following would be affected?
Formation of the mitotic spindle.
If the nitrogen base sequence on a strand of DNA is CGATACT, then the mRNA strand that is transcribed from this DNA strand is ________.
GCUAUGA.
If the human genome were considered to be a large cookbook, which of the following would represent the individual recipes?
Genes.
Which of the following are listed in order from largest (most inclusive) to smallest?
Genome, chromosome, gene, nucleotide.
Which of the following statements is accurate when referring to a cell about to begin mitosis?
Identical sister chromatids have formed and each is a newly replicated DNA double helix.
What is the function of the promoter site in transcription?
It is the site where RNA polymerase binds to begin transcription.
When do homologous chromosomes pair up?
Meiosis I.
When does reduction division take place?
Meiosis I.
How does the production of sperm differ from the production of eggs?
Meiosis during sperm production produces four sperm cells, whereas meiosis during egg production produces only one functional egg cell.
During which stage of mitosis are chromosomes lined up in the center of the cell?
Metaphase.
The chromosomes line up in the center of the cell during which phase of mitosis?
Metaphase.
Once the egg and sperm have united, the zygote grows and develops into a new human being by which process?
Mitosis.
Which of the following cell types are most likely to remain in G0?
Neurons.
The first mRNA triplet discovered was a code for which amino acid?
Phenylalanine.
During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?
Prophase I.
Which of the following lists the phases of mitosis in the correct order?
Prophase, metaphase, anaphase, telophase.
The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
Prophase.
The synthesis of a new strand begins with the synthesis of a(n) _____.
RNA primer complementary to a preexisting DNA strand.
During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA?
T.
During which phase of mitosis do individual chromosomes arrive at opposite poles of the cell?
Telophase.
The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?
Telophase.
Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?
Telophase.
At which point in the cell cycle are cells the smallest?
The beginning of G1.
What must happen before a cell can begin mitosis?
The chromosomes must be duplicated.
What is the relationship between the codon and the anticodon?
The codon is a set of three nucleotides found in the mRNA sequence. The anticodon is the complementary triplet found as part of the tRNA molecule.
Which statement about DNA replication is CORRECT?
The leading strand is built continuously, and the lagging strand is built in pieces.
Which of the following events in transcription occurs last?
The mRNA is released from RNA polymerase.
Which is likely to be the shortest chain of nucleotides?
The mRNA.
Which of the following statements about meiosis and mitosis is MOST correct?
The products of mitosis are two diploid cells, whereas the products of meiosis are four haploid cells, mitosis and meiosis both begin with duplicated chromosomes, and in mitosis the daughter cells are genetically identical, but in meiosis the daughter cells are genetically varied.
When the tRNA releases its amino acid, what happens?
The tRNA is released and exits the ribosome.
Which of the following statements about eggs and sperm is true?
They are gametes formed by meiosis.
How do mutations affect an organism?
They may cause the development of a disease-causing allele, they may cause the development of a more beneficial allele, and they, in some cases, may have no noticeable affect.
Which of the following is a way in which replication and transcription differ?
Transcription copies only one side of the DNA molecule.
True or false. Of the two meiotic divisions, meiosis II is more similar to mitosis.
True.
A gene is expressed when __________.
a protein is produced.
Division of the cytoplasm occurs during __________.
cytokinesis.
After DNA replication is completed, _____.
each new DNA double helix consists of one old DNA strand and one new DNA strand.
Differentiation of cells beyond the 8-cell stage of development is due to __________.
exposure of the cells to different environments.
Meiosis starts with a single diploid cell and produces
four haploid cells.
The nucleotides for assembling mRNA are found ________.
free in the nucleus.
A short segment of DNA that represents the code for a specific protein is a __________.
gene.
The first step in the replication of DNA is catalyzed by _____.
helicase.
A female that is planning to become pregnant is concerned about her exposure to environmental mutagens which may have caused DNA mutations. In order for these mutations to become heritable, they must affect the:
her egg cells.
During prophase I of meiosis,
homologous chromosomes stick together in pairs.
Nirenberg and Matthaei are famous for ________.
identifying the first mRNA triplet.
A cell preparing to undergo meiosis duplicates its chromosomes during
interphase.
A mutation in the DNA of an organism is passed on to offspring only when __________.
it occurs in cells that give rise to an egg or a sperm.
__________ contains codons and __________ contains anticodons.
mRNA; tRNA
Gametes are formed by ________.
meiosis.
A clone is an exact copy of a(n) __________.
molecule, gene, cell, or organism.
Transcription occurs in/at the __________ and produces __________ from a(n) __________ template.
nucleus; RNA; DNA
The correct order of events during meiosis is
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.
The action of helicase creates _____.
replication forks and replication bubbles.
The amino acids are attached by ________.
ribosome.
DNA replication occurs at an unbelievably fast rate. Once replication is complete, we can expect to find a _____ number of mistakes.
small
In the process of translation (and thus protein synthesis), the amino acid is carried in the cytoplasm by the ________.
tRNA.
An old DNA strand is used as a _____ for the assembly of a new DNA strand.
template
In discussing the purpose for making mRNA, the most accurate statement below is that ________.
the mRNA is produced to carry the message from the DNA to the translation stage.
In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
thymine ... cytosine
The purpose of meiosis is ________.
to produce haploid gametes.
The difference between transcription and translation is that ________.
transcription is the process of producing the mRNA, and translation is the process of using the mRNA to assemble a sequence of amino acids that form a polypeptide.
During the elongation phase of translation, the mRNA passes between __________, catalyzing the binding of __________ to each other.
two ribosomal subunits; amino acids
When we say that the genetic code is "nearly universal," we mean that ________.
with very few exceptions, the same codon codes for the same amino acid throughout the living world.