Bio 1610 Quiz 2

The epithelial cells in the skin of an animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal?

12

Put the following DNA replication events in the correct order: Primase synthesizes an RNA primer. The initiator protein binds the origin. Ligase seals up the nicks in the lagging strands. DNA polymerase synthesizes the newly replicated strand in a 5' to 3' direction. Helicase unwinds the DNA. DNA exonuclease removes mispaired nucleotides in the newly replicated strand.

3 **

Below is an image of translation occurring, use it to answer the following questions. A. If the ribosome is moving from right to left, as indicated by the arrow, what is the polarity of the mRNA? The left side of the mRNA (where the ribosome is moving towards) is the ____end. B. On the ribosome, which site is where the tRNA is ejected? C. The new aminoacyl tRNA is entering at which site? D. On which RNA do we find the anti-codon?

3' 3 1 tRNA

The following statements list events that occur during translation, from initiation through termination. Arrange the order of events that occur during translation by numbering them 1 (the first event) to 6 (the last event to occur). Note, not all the events are listed. Each answer should be a number, e.g. "1", "2", etc. without the quote marks A peptide bond is formed between the new amino acid at the A site to the polypeptide at the P site The large ribosomal subunit binds to the small ribosomal subunit The first aminoacyl tRNA holding methionine base pairs to the start codon AUG A stop codon enters the A site A release factor enters the A site A new aminoacyl tRNA binds to the codon in the A site

4 2 1 5 6 3

What anticodon in tRNAMet would pair with the codon 5'-AUG-3'?

5'-CAU-3'

A template DNA strand contains the sequence 5'-ATGCTGAC-3'. The corresponding sequence in the RNA transcript is:____.

5'-GUCAGCAU-3' Remember: RNA has U instead of T. Base paired strands are antiparallel. New nucleotides are made in the 5' to 3' direction. When we write out a nucleotide sequence in text (like these answers), the 5' end is almost always on on the left.

Remember: 1) New nucleic acids are made 5' to 3'. 2) Base paired strands are antiparallel. Apply this knowledge and determine which areas on this replication fork will have new DNA made as leading strand. (hint: Start with primers at the ends of the open fork on the top and the bottom.) Practice this with 3' at top left too. Flip and draw with fork opening to left. Remember that replication bubbles like the question below are two forks going in opposite directions.

A

Remember: 1) New nucleic acids are made 5' to 3'. 2) Base paired strands are antiparallel. Apply this knowledge and determine which areas on this replication bubble will have new DNA made as leading strands. (hint: Start with primers at the origin on the top and the bottom of the replication bubble.)

A and D

Carefully examine the figure below. (This is the best one to practice drawing, labeling and describing out loud) What happens next? (hint: if you are having a hard time deciding between A and P sites look at the picture in the previous question)

A polypeptide bond is formed between the arginine and the valine, transferring the polypeptide to the A site.

Which of these statements is true?

An exon is considered a "coding sequence" of DNA, and its information is retained in the processed mRNA within a cell.

Application question tip. Practice flipping questions around. Repeat the question above, this time with 3' on top left. Remember: 1) New nucleic acids are made 5' to 3'. 2) Base paired strands are antiparallel. Apply this knowledge and determine which areas will have new DNA made as leading strands. (hint: Start with primers at the origin on the top and the bottom of the replication bubble.) The question could be changed to ask which parts will have lagging strands etc. Slow down, read carefully and apply what you know.

B and C

Protein polarity is described as having an N-terminus and a C-terminus. Consider a ribosome that is actively engaged in translation. As the ribosome moves along the mRNA, the protein grows at the ________ terminal end by addition of the amino acid that is bound to the tRNA at the _______ site. (Try drawing and labeling the previous picture before you answer this)

C-terminus, A site

There are two divisions in Meiosis, but only one ____[ Meiosis I separates the two ____ thereby a diploid (2n) cell is reduced to become ____ (1n). Meiosis II separates the ____.

DNA replication homologs haploid two sister chromatids

Assuming that transcription and translation both proceed from left to right, which is the correct orientation of the DNA template, the RNA transcript, and the protein product?

DNA template 3'- ......... -5' / RNA transcript 5'- ......... -3' / Protein product H2N- ......... -COOH RNA polymerase can synthesize RNA only in 5' to 3' direction. DNA template should be antiparallel to the RNA transcript. When the first peptide bond is formed, the carboxyl group of the first amino acid reacts with the amino group of the next in line amino acid creating two chemically distinct ends with the free amino group (N) on the first amino acid and the free carboxyl group (C) on the last one.

The correct sequence of steps in the eukaryotic cell cycle is:

G1→ S phase → G2→ mitosis → cytokinesis. Good morning Sarah Granny Misses Clayton

Why is DNA ligase important for a cell? Select all that apply.

It joins Okazaki fragments on the discontinuous lagging strand. It joins DNA together from different origins of replication.

If the RNA transcript 5'-AUGAUCGGAUCGAUCCAU-3' is present and translated codon by codon from one end to the other, which of the following polypeptides would correspond to this part of the mRNA? Use the table shown to answer this question.

NH2- Met-Ile-Gly-Ser-Ile-His -COOH

Application question tip. Practice flipping images around. Repeat these replication questions again, this time the replication bubble has been flattened out and only one strand is shown. What you need to remember stays the same: 1) New nucleic acids are made 5' to 3'. 2) Base paired strands are antiparallel. 3) Start with a primer at the origin. This image below represent just one DNA template in replication. the letters A-E represent possible placement of primers. Which of these represent the correct order of primer placement?

Q 8 Post Class 11 practice quiz

Which example correctly lists the components necessary for eukaryotic transcription?

RNA polymerase, general transcription factors, DNA, and RNA nucleotides

Which statement about RNA is correct?

RNA uses the same purine bases as DNA.

A student was studying cell growth using cells grown in laboratory cultures. The cultures were synchronized so that all of the cells passed through the same stage of the cell cycle at the same time. The cells were examined during five different periods of time, intervals (A-E). The amount of DNA present per cell was determined for each interval. The graph below shows the result of this study. a. Most of the cells examined during interval A have half as much DNA as those measured in interval C. Therefore, most of the cells at interval B must have been in: b. Most of the cells examined during interval D were in: c. Most of the cells examined during interval C were in: G2 phase.

S phase M phase (specifically telophase of Mitosis) G2 phase

A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely:

S phase.

Which of the following statements are true? (choose all that apply)

Some amino acids are specified by just one codon, whereas others are specified by multiple codons.

If you made a change in the promoter sequence in the DNA that inactivates the promoter, what would happen at the RNA level?

The RNA polymerase would not be able to recognize and bind the DNA, so no RNA would be made.

Indicate all of the phrases that accurately describe what happens in eukaryotes when a ribosome encounters a stop codon. (3 correct answers)

The protein is released from the tRNA. A release factor binds to the A site The ribosomal small subunit and ribosomal large subunit separate from the mRNA.

Which of the following statements describes translation initiation in Eukaryotes:

The ribosime's large subunit binds to the small subunit at the AUG initiation site.

Examine the figure below. What will happen when the ribosome shifts one codon further on the mRNA, assuming the next codon is not a stop codon? Select all that apply.

The tRNA carrying the polypeptide will be in the P site. The tRNA that is no longer carrying the polypeptide will be ejected from the ribosome. A new tRNA will bind to the ribosome.

In order to test the effects of a new drug, you isolate the messenger RNA molecules from both treated and untreated eukaryotic cells and separate them according to size, using gel electrophoresis. In each lane of the gel, the shorter RNA molecules migrate more quickly through the gel and end up near the bottom of the gel, whereas the longer RNAs migrate more slowly and remain near the top. The samples that were loaded into each of the four lanes are as follows: Lane 1: the primary RNA transcripts isolated from the nucleus of untreated cells Lane 2: the primary RNA transcripts isolated from the nucleus of cells treated with the drug being tested Lane 3: RNA isolated from the cytosol of untreated cells Lane 4: RNA isolated from the cytosol of cells treated with the drug being tested Which conclusion is most likely to be correct?

These results suggest that the drug affects RNA processing. The only difference observed in this experiment is between RNA isolated from cytosol of treated and untreated cells. The primary transcript is transported from nucleus to cytosol after being processed. Therefore, the drug must affect RNA processing.

Promoters of many genes have regions that are rich in adenines and thymines. What is the most likely reason for this?

This is the region where template and nontemplate strands separate, and A-T base pairs require less energy to separate than G-C base pairs. A/T base pairs have two hydrogen bonds, while G/C pairs have three.

Consider the stages of mitosis, depicted in the image below. In what order do the stages of mitosis occur?

V>II>IV>I>III In prophase, the mitotic spindle has not yet formed and chromosomes are still loosely arranged (image V). In prometaphase, the mitotic spindle is formed and chromosomes are starting to migrate toward the center of the cell (image II). In metaphase, the chromosomes are aligned in the middle of the cell (image IV). In anaphase, the mitotic spindle starts to pull the sister chromatids apart (image I). In telophase, sister chromatids have been fully separated, the mitotic spindle is starting to disassemble, and the cell is preparing to split in two (image III). Stages of mitosis occur in the order: prophase > prometaphase > metaphase > anaphase > telophase. This corresponds to answer choice "V > II > IV > I > III."

What cellular process(es) is/are responsible for the increase in protein content associated with the gap (G1 and G2) phases of the cell cycle?

both transcription and translation Increased protein content comes most directly from translation, but translation requires RNA produced from transcription, so both are required.

Some poisonous plants harm people and animals because they produce compounds that are structurally similar to amino acids. Possible reasons why these compounds are toxic include that they _______________ Select all correct phrases.

change the final folded shape of the protein. impair the function of proteins. are recognized by amino acyl tRNA synthetases, and are linked to a tRNA molecule.

Which of the following does NOT lead to genetic variability?

division of chromosomes during anaphase of mitosis Mitosis does not contribute to genetic diversity. It makes exact copies of a cell.

Meiosis...

halves the number of chromosomes in cells

Examine the figure shown, which depicts one stage in the process of translation in a eukaryote. Where will the tRNA be when the large subunit of the ribosome joins the complex?

in the P site of the ribosome

Which stages of mitosis are correctly matched with the events that occur in the stage? Select all that apply.

metaphase; chromosomes line up in the middle of the cell cytokinesis; a contractile ring of actin filaments forms at the cell equator

Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come?

the incoming nucleotide

A cell in prophase I of meiosis has _____ as many chromosomes as each of the daughter cells following cytokinesis of meiosis II.

twice

A skin cell in G2 of interphase has _____ as much DNA as it had in G1.

twice