in the diagram below, the gray unit represents _____.

# in the diagram below, the gray unit represents _____.

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Nucleoli are present during _____.interphase
Cytokinesis often, but not always, accompanies _____.telophase
Chromosomes become visible during _____.prophase
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.anaphase
Spindle fibers attach to kinetochores during _____.prometaphase
When the separate chromosomes are being pulled from one place to another? This animation illustrates the events of _____.Anaphase
When a cleavage furrow appears and eventually pinch into 2 cells. This animation illustrates the events of _____.cytokinesis as it occurs in animal cells
When the chromosomes become visible? This animation illustrates the events of _____.Prophase
When chromosomes align laterally (along the metaphase plate: imaginary line located midway between the poles of the duplicated chromosomes and the original chromosomes), before they separate. This animation illustrates the events of _____.Metaphase
When the chromosomes break the nuclear envelope, and attach to microtubules. This animation illustrates the events of _____.prometaphase
When a cell plate divides into 2 cells. This animation illustrates the events of _____.Cytokinesis as it occurs in Plant Cells
When the sister cells are completely divided through Cytokinesis. This animation illustrates the events of _____.telophase
During prophase a homologous pair of chromosomes consists of _____.two chromosomes and four chromatids
Which of these phases encompasses all of the stages of mitosis but no other events?E
During _____ both the contents of the nucleus and the cytoplasm are divided.the mitotic phase
During _____ the cell grows and replicates both its organelles and its chromosomes.interphase
DNA replication produces two identical DNA molecules, called _____, which separate during mitosis.sister chromatids
After chromosomes condense, the _____ is the region where the identical DNA molecules are most tightly attached to each other.centromeres
During mitosis, microtubules attach to chromosomes at the ______.kinetochores
In dividing cells, most of the cell's growth occurs during ______.interphase
The _____ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.mitotic spindles
During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called _____.chromatin
In most eukaryotes, division of the nucleus is followed by ______, when the rest of the cell divides.cytokinesis
The _____ are the organizing centers for microtubules involved in separating chromosomes during mitosis.centrosomes
The cell cycle represents the coordinated sequence of events in the life of a cell from its formation to its division into two daughter cells. Most of the key events of the cell cycle are restricted to a specific time within the cycle. In this exercise, you will identify when various events occur during the cell cycle. Recall that interphase consists of the G1, S, and G2 subphases, and that the M phase consists of mitosis and cytokinesis.A. Non dividing cells exit cell cycle B. At this point, cell commits to go through the cycle. C. DNA replicates D. Centrosome replicates E. Mitotic spindle begins to form. F. Cell divides, forming two daughter cells.
As the chromosomes of a parent cell are duplicated and distributed to the two daughter cells during cell division, the structure of the chromosomes changes.1. N Y Y Y N 2. N N N Y Y 3. N Y Y Y Y
What phase is this?Prophase
What phase is this?Prometaphase
What phase is this?Metaphase
What phase is this?Anaphase
What phase is this?Telophase
What phase is this?Cytokinesis
During prophase, the microtubules of the mitotic spindle ______.lengthen
During anaphase, the nonkinetochore microtubules ______ and move past each other, and the kinetochore microtubules ______.lengthen, shorten
During telophase, the non kinetochore microtubules ______.disassemble
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?92
Why is it difficult to observe individual chromosomes with a light microscope during interphase?They have uncoiled to form long, thin strands.
Which of the following is true of kinetochores? A. They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers. B. They interdigitate at the cell's equator and then move apart, causing the cell to elongate. C. They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis. D. They are sites at which microtubules attach to chromosomes. E. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow.They are sites at which microtubules attach to chromosomes.
Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?cleavage
In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?large cells containing many nuclei
Cells divide by constriction of a ring of proteinsbacteria: TRUE animals: TRUE plants: FALSE
The presence of a cell wall prevents the cell from dividing by constrictionbacteria: FALSE animals: FALSE plants: TRUE
Tubulin or tubulin-like molecules function in binary fission (in bacteria) or cytokinesis (in animals and plants).bacteria: TRUE animals: FALSE plants: TRUE
Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?G1
One difference between cancer cells and normal cells is that cancer cellscontinue to divide even when they are tightly packed together.
The decline of MPF activity at the end of mitosis is due tothe degradation of cyclin.
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related todisruption of mitotic spindle formation.
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?cleavage furrow formation and cytokinesis
How do cancer cells differ from normal cells?Cancer cells may be immortal.
What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?transcription
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?translation
What name is given to the process in which pre-mRNA is edited into mRNA?RNA processing
Polypeptides are assembled from _____.amino acids
RNA processing converts the RNA transcript into _____.mRNA
How would this molecule have to be altered, to be used in RNA transcription?(a) Add another OH to the sugar. (b) Remove a CH3 group from the base.
You can tell this diagram is showing transcription rather than replication because ...(b) only one strand is being used as template. (c) the product contains U.
A codon consists of _____ bases and specifies which _____ will be inserted into the polypeptide chain.three ... amino acid
The flow of information in a cell proceeds in what sequence?from DNA to RNA to protein
What is the process called that converts the genetic information stored in DNA to an RNA copy?Transcription
DNA does not store the information to synthesize which of the following?Organelles
Transcription begins at a promoter. What is a promoter?A site in DNA that recruits the RNA Polymerase
Which of the following statements best describes the promoter of a protein-coding gene?The promoter is a nontranscribed region of a gene.
What determines which base is to be added to an RNA strand during transcription?Base pairing between the DNA template strand and the RNA nucleotides
Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?Complementary
What happens to RNA polymerase II after it has completed transcription of a gene?It is free to bind to another promoter and begin transcription.
In the diagram below, the gray unit represents _____.RNA polymerase RNA polymerase untwists a portion of the DNA double helix.
In the diagram below, the green unit represents _____.the promoter The promoter is the region of DNA at which the process of transcription begins.
In the diagram below, the two blue strands represent _____.DNA
Which of these correctly illustrates the pairing of DNA and RNA nucleotides? a) GTTACG CAATCG b) GTTACG CAAUGC c) GTTACG GTTACG d) GTTACG ACCGTA e) GTTACG UAACAUb) GTTACG CAAUGC In RNA, uracil takes the place of thymine.
The direction of synthesis of an RNA transcript is _____. a) 1' > 5' b) 5' > 3' c) 1' > 3' d) 3' > 5' e) 2' > 4'b) 5' > 3' Nucleotides are added to the 3' end of RNA.
During RNA processing a(n) _____ is added to the 5' end of the RNA.modified guanine nucleotide The 5' cap consists of a modified guanine nucleotide.
During RNA processing a(n) _____ is added to the 3' end of the RNA.a long string of adenine nucleotides A poly-A tail is added to the 3' end of the RNA.
Spliceosomes are composed of _____.snRNPs and other proteins
The RNA segments joined to one another by spliceosomes are _____.exons
Translation occurs in the _____.cytoplasm Ribosomes, the sites of translation, are found in the cytoplasm.
Suppose that a portion of double-stranded DNA in the middle of a large gene is being transcribed by an RNA polymerase. As the polymerase moves through the sequence of six bases shown in the diagram below, what is the corresponding sequence of bases in the RNA that is produced?UGAGCC There are three principles to keep in mind when predicting the sequence of the mRNA produced by transcription of a particular DNA sequence. The RNA polymerase reads the sequence of DNA bases from only one of the two strands of DNA: the template strand. The RNA polymerase reads the code from the template strand in the 3' to 5' direction and thus produces the mRNA strand in the 5' to 3' direction. In RNA, the base uracil (U) replaces the DNA base thymine (T). Thus the base-pairing rules in transcription are AU, TA, CG, and GC, where the first base is the coding base in the template strand of the DNA and the second base is the base that is added to the growing mRNA strand.
During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand. For any given gene, what ultimately determines which DNA strand serves as the template strand?the base sequence of the gene's promoter In eukaryotes, binding of RNA polymerase II to DNA involves several other proteins known as transcription factors. Many of these transcription factors bind to the DNA in the promoter region (shown below in green), located at the 3' end of the sequence on the template strand. Although some transcription factors bind to both strands of the DNA, others bind specifically to only one of the strands. Transcription factors do not bind randomly to the DNA. Information about where each transcription factor binds originates in the base sequence to which each transcription factor binds. The positioning of the transcription factors in the promoter region determines how the RNA polymerase II binds to the DNA and in which direction transcription will occur.
After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes. Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus? Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus? A) A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA. B) A translation stop codon is added at the 3' end of the pre-mRNA. C) Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. D) Coding sequences called exons are spliced out by ribosomes. E) A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.A) A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA. C) Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. E) A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
Where does translation take place?Ribosome
Which nucleic acid is translated to make a protein?mRNA
Which of the following processes is an example of a post-translational modification?Phosphorylation Enzymes can phosphorylate proteins to alter their activity.
Which of the following steps occurs last in the initiation phase of translation?The large ribosomal subunit joins the complex.
At which site do new aminoacyl tRNAs enter the ribosome during elongation?A-site
What is meant by translocation?The ribosome slides one codon down the mRNA. Translocation is the process by which the ribosome slides down the mRNA so a new cycle of elongation can begin.
True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.False There are no tRNAs complementary to the three stop codons; termination occurs when release factors recognize the stop codon in the A-site and catalyze the release of the polypeptide from the tRNA in the P-site.
Which of these is a tRNA?B
What enzyme catalyzes the attachment of an amino acid to tRNA?aminoacyl-tRNA synthetase
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.CUG
What is the name of the process shown in the diagram?initiation (of translation)
The initiator tRNA attaches at the ribosome's _____ site.P
Amino acids are attached to tRNA by enzymes called _____.aminoacyl-tRNA synthetase
The RNA that has an amino acid attached to it, and that binds to the codon on the mRNA, is called a _____.tRNA
The process, performed by the ribosome, of reading mRNA and synthesizing a protein is called _____.translation
_____ of translation happens when the ribosome hits a stop codon on the mRNA.Termination
_____ of translation always happens at the start codon of the mRNA.Initiation
Which contains the anticodon and has amino acids covalently attached? A) tRNA B) mRNA C) rRNAtRNA
Which contains the exons and specifies the amino acids sequence for a protein? A) tRNA B) mRNA C) rRNAmRNA
Which is a component of ribosomes and is the most abundant form of RNA? A) tRNA B) mRNA C) rRNArRNA
How is translation initiated?a) The small ribosomal subunit binds to the mRNA. b) The tRNA bearing methionine binds to the start codon. c) The large ribosomal subunit binds to the small one. d) The start codon signals the start of translation.
After an RNA molecule is transcribed from a eukaryotic gene, what are removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence?introns ... exons Introns, intervening sequences, are removed and the exons, expressed sequences, are spliced together.
What is the function of RNA polymerase?It unwinds the double helix and adds nucleotides to a growing strand of RNA. RNA polymerase has several functions in transcription, including unwinding the DNA double helix and adding RNA nucleotides.
Where does RNA polymerase begin transcribing a gene into mRNA?It starts after a certain nucleotide sequence called a promoter. In both eukaryotes and prokaryotes, RNA polymerase binds to the gene's promoter and begins transcription at a nucleotide known as the start point, although in eukaryotes the binding of RNA polymerase to the promoter requires transcription factors.
In eukaryotic cells, the processes of protein synthesis occur in different cellular locations. Where does these occur? - formation of ribosomal subunits - attachment of an amino acid - translation of cytoplasmic - transcription and RNA processing - translation of secreted proteinsa - formation of ribosomal subunits b - attachment of an amino acid c - translation of cytoplasmic d -transcription and RNA processing e - translation of secreted proteins
Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation. Imagine that a prokaryote-like organism has been discovered in the polar ice on Mars. Interestingly, these Martian organisms use the same DNA RNA protein system as life on Earth, except that there are only 2 bases (A and T) in the Martian DNA, and there are only 17 amino acids found in Martian proteins. Based on this information, what is the minimum size of a codon for these hypothetical Martian life-forms?5 bases In the most general case of x bases and y bases per codon, the total number of possible codons is equal to xy . In the case of the hypothetical Martian life-forms, is the minimum codon length needed to specify 17 amino acids is 5 (25 equals 32), with some redundancy (meaning that more than one codon could code for the same amino acid). For life on Earth, x equals 4 and y equals 3, thus the number of codons is 43, or 64. Because there are only 20 amino acids, there is a lot of redundancy in the code (there are several codons for each amino acid). Which of these is a logical signal transduction pathway? A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP3, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response.
True or false? A codon is a group of three bases that can specify more than one amino acid.False
Which of the following statements about mutations is false? a) A deletion mutation results in the loss of a base in the DNA sequence. b) A knock-out mutation results in a total absence of the mutated protein. c) Addition and deletion mutations disrupt the primary structure of proteins. d) An addition mutation results in an added base in the DNA sequence.b) A knock-out mutation results in a total absence of the mutated protein.
If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?Deletion The original sequence has lost the base C.
Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)? a) One addition and two deletion mutations. b) One addition mutation. c) One deletion mutation. d) One addition and one deletion mutation.d) One addition and one deletion mutation.
If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?Two
If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred? a) An addition mutation and a deletion mutation. b) An addition mutation c) A deletion mutation. d) None.a) An addition mutation and a deletion mutation.
The four levels of protein structure are primary, secondary, tertiary, and quaternary structure. Review the levels of protein structure by clicking the image below. Drag each label into the appropriate bin depending on whether it applies to primary, secondary, tertiary, or quaternary structure.The four levels of protein structure are: Primary structure--the unique amino acid sequence of a polypeptide Secondary structure--aspects of structure that result from hydrogen bonding between the backbone constituents of the polypeptide (Examples: helix, pleated sheet) Tertiary structure--the overall shape of a polypeptide, resulting from interactions between the side chains (R groups) of amino acids (Examples: hydrophobic interactions, van der Waals interactions, disulfide bridges, hydrogen bonds, and ionic bonds) Quaternary structure--the aggregation of multiple polypeptide subunits to form a functional protein These levels of structure are shown below for hemoglobin, the oxygen-carrying protein found in red blood cells. (Note that a hemoglobin molecule is made up of two subunits and two subunits; these are polypeptides and should not be confused with the helix and pleated sheet.)
If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. 5'-ACTTACGTGA-3'frameshift mutation
If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. 5'-ACTCGTGA-3'frame shift mutation
If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. 5'-ACTACGTGT-3'base substitution mutation
If a segment of DNA were replicated without any errors, the replicated strand would have the following sequence of nucleotides: 5' - ACTACGTGA - 3' Sort the following replicated DNA sequences by the type of point mutation each contains (frameshift, base substitution, or neither), as compared to the correct sequence shown above. 5'-ACTAAGTGA-3'Base substitution mutation
Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene? a) a base substitution at the beginning of the gene b) a base substitution at the end of the gene c) a frameshift deletion at the beginning of the gene d) a frameshift deletion at the end of the genec) a frameshift deletion at the beginning of the gene
Which of these is currently considered the best definition of a gene?A gene codes for either a polypeptide or an RNA molecule. As our understanding of protein synthesis has expanded, we have seen that one gene may code for several polypeptides. We have also discovered many RNA molecules with diverse but important functions in the cell.
Which of the following is not true of a codon? A) It consists of three nucleotides. B) It may code for the same amino acid as another codon. C) It never codes for more than one amino acid. D) It extends from one end of a tRNA molecule. E) It is the basic unit of the genetic code.D) It extends from one end of a tRNA molecule.
Which component is not directly involved in translation? A) mRNA B) DNA C) tRNA D) ribosomes E) GTPB) DNA
Which of the following molecules are produced by transcription? - Ribosomal Proteins - Ribozymes - Messenger RNA (Check all that applies)- Ribozymes - Messenger RNA
The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact?Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated.
Biology 180

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