Biology 107 Final Exam

Using Chargaff's rules, if the percent of T in a bacterial genome is 40%, then the percent of G is:

10%

If DNA from an organism is analyzed it is found that the thymidine nucleobases makes up 20% of the total. What % of the nucleobases are adenine?

20%

During prophase, how many chromosomes are in each human cell?

46

3'- AGGGTAAATCATG -5' 5'- TCCCATTTAGTAC -3' If a promoter is located on the RIGHT hand side of this small gene region, what will be the final product of transcription in a eukaryotic cell?

5'-(G cap)-GUACUAAAUGGGA-(poly A)-3'

If the sequence of an mRNA is 5'-CAA UUC CGG-3', then the sequence of the DNA coding strand for this gene must have been:

5'-CAA TTC CGG

When amino acids polymerize to form a protein:

A covalent bond forms between the amino group of one amino acid and the carboxylic acid of a second.

Viral genomes can have all of the following chemical structures EXCEPT

A duplex with one strand RNA and one strand DNA.

Which of the following descriptions best fits the class of molecules known as nucleotides?

A nitrogenous base, a phosphate group, and a sugar.

Which of the following is NOT part of the Watson and Crick model of DNA?

A phosphate group is at the 3' end of each strand.

What is one type of cell that CANNOT arise from the differentiation of a mesenchymal stem cell?

A sperm cell.

When does the termination of translation take place?

A stop codon is reached.

A cell needs to move magnesium (Mg2+) from the outside of the cell to the inside. The concentration of Mg2+ is higher inside than outside. Which transport mechanism would be most probable?

Active transport of Mg2+ through a carrier protein.

Which of the following statements about the genetic code is FALSE?

All combinations of 3 bases in mRNA encode for an amino acid

Which of the following statements about the genetic code is FALSE?

All combinations of 3 bases in mRNA encode for an amino acid.

The protein shell that surrounds a virus is known as a __________.

Capsid

Which of the following statements about carrier proteins is FALSE?

Carrier protein function requires ATP

The enzyme that helps polypeptide chains fold is called a _________.

Chaperonin.

The amount of ___________ in the cell stays the same throughout the cell cycle.

Cyclin dependent kinase (CDK)

If radioactive thymidine is added to cells, what macromolecules will be labeled?

DNA

In eukaryotic cells, chromosomes are composed of _____________.

DNA and proteins.

The lipid-based structure that surrounds some viruses is known as a(n):

Envelope.

Which of the following is most likely to cross a cell membrane without assistance?

Ethane (CH3-CH3)

Stages of Transcription

Initiation Elongation Termination

Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression?

Introns are spliced out of the mRNA.

If a cell does not get a signal to pass the G1 checkpoint, what happens?

It enters G0.

The ____________ life cycle of a bacteriophage is characterized by integration of the phage genome into the host chromosome.

Lysogenic.

All of the following proteins involved in eukaryotic gene expression bind directly to DNA EXCEPT:

Mediator proteins.

At what point in the cell cycle do sister chromatids align along a mid-line in the cell?

Metaphase

The change of a AAU codon (Asn) to a GAU codon (Asp) is an example of a:

Missense mutation

A neuron and a liver cell both contain the gene for the dopamine transporter, yet the protein is only found in neurons. The main reason for this is:

Only the neurons have the correct activator proteins for the dopamine transporter gene.

In elongation, the growing peptide chain is transferred from the _____ site in the ribosome to the ______ site as a new peptide bond is formed

P; A

The chemical linkage between two amino acids is known as a...

Peptide bond.

Transcription always begins at a:

Promoter

Which of the following would not be found in a mature mRNA in a eukaryotic cell?

Promoter.

General transcription factors for eukaryotic genes typically bind to sequences known as:

Promoters.

If you add radioactive alanine (Ala; A) to a cell, which macromolecules will become contain the radioactivity (i.e. become labeled)?

Proteins

Keratin is a protein that is made up of two compactly folded protein chains that contain alpha helices. What is the HIGHEST level of protein structure observed in Keratin?

Quaternary Structure.

During transcription, which of the following steps is not observed?

RNA polymerase reads the template strand in the 5' to 3' direction.

Which of the following does NOT occur during the initiation of transcription?

RNA polymerase recruits general transcription factors to the promoter.

Which of the following statements best describes the termination of transcription in prokaryotes?

RNA polymerase transcribes to the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

Which of the following catalyzes transcription?

RNA polymerase.

There are many similarities and differences between bacterial conjugation involving Hfr and F+ cells. Which of the following events does NOT happen during F+ cell conjugation?

Recombination of the F+ plasmid with the F- cell chromosome

Which of the following is NOT a stage in the cell cycle that has a checkpoint?

S

Misfiling of proteins is a serious problem in cells. Which of the following diseases is not associated with an accumulation of misfolded proteins?

Scoliosis

Which level of protein structure do the alpha-helix and beta-pleated sheet represent?

Secondary

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?

Sequence of Bases

SDS-PAGE gels are used to study changes in protein primary structure. Which of the following statements about SDS-PAGE gels is correct?

Shorter polypeptides move a longer distance in an SDS-PAGE gel than longer polypeptides.

One disease that arises from a known point mutation in a protein is:

Sickle cell anemia.

Repressors for eukaryotic genes typically bind to sequences known as:

Silencers

Lenski has observed that bacterial populations can adapt to new environments through evolution driven by DNA mutations. Which type of mutation would you least expect to be a driver of gene evolution?

Silent mutations

Antibiotics target all of the following EXCEPT:

Splicosome

Based upon the principle of signal amplification, which of the following situations is most likely NOT observed during stem cell renewal?

TK1 only phosphorylates a single TK2 protein before it shuts down.

Which of the following would not be found near the 3' end of a mature eukaryotic mRNA?

Terminator sequence

If you isolate a pancreatic cancer cell from a patient, which of the following would you be most likely to NOT discover?

The chromosomes in the cancer cell could have the exact same DNA sequence as those from a wild type pancreatic cell from the same patient

What component of amino acid structure varies among different amino acids?

The components of the R-group.

Which of the following does NOT occur in Anaphase during mitosis?

The cytoplasm is divided into the two daughter cells.

The second step in the splicing of an intron out of mRNA is:

The donor site of the upstream exon attacks the intron acceptor site.

Which of the following is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures?

The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

How do phospholipids interact with water molecules?

The hydrophillic heads interact with water; the hydrophobic tails avoid water

What does it mean when we say that a signal is transduced?

The physical form of the signal changes from one form to another.

Which of the following statements is consistent with the Watson and Crick model of DNA?

The pyrimidine and purine in each base pair come from opposite strands.

Proteolysis depends on all of the following steps to occur EXCEPT:

The target protein is exported from the cell

If potassium chloride is dissolved in water, how will the nearest water molecules be oriented around the potassium ions?

The water molecules will prefer to point their oxygen atoms towards the potassium ions

Why are lipids and proteins free to move laterally in a membrane?

There are only weak hydrophobic interactions in the interior of the membrane.

YOU WILL NEED YOUR STEM CELL HANDOUT FOR THIS QUESTION If a stem cell has a missense mutation in the phosphate receiving site of TK2, what will be the result for self renewal?

There would be no phosphorylation of TK2 by TK1 and therefore no self renewal

Which of the following statements is true about mesenchymal stem cells?

They need an external signal to differentiate into a muscle cell

In the life cycle of a double stranded DNA virus, viral mRNA is produced by:

Transcriptional protein encoded by the host cell.

A stop codon is involved in the regulation of _____________.

Translation

Which of the following nucleases is not used to encode information in the human genome?

Uracil (because uracil is not found in DNA)

When nucleotides are added to a growing nucleic acid chain:

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second.

Which of the following, if missing, would usually prevent translation from initiating in prokaryotes?

a ribosome binding sequence.

An insertion of two nucleotides into a gene:

alters the reading frame of the mRNA.

During which phase of mitosis do the chromatids become chromosomes?

anaphase

Alternate RNA splicing ________.

can allow the production of proteins of different sizes and functions from a single mRNA.

Alternative RNA splicing ______

can allow the production of proteins of different sizes and functions from a single mRNA.

A missense mutation in a gene:

changes an amino acid in the encoded sequence

A sex pilus is needed for bacterial ________________.

conjugation

Protein phosphatase is an enzyme that __________.

deactivated other protein molecules by removing a phosphate group from them.

An Asn tRNA has all of the following elements in its folded structure EXCEPT:

deoxyribose sugars

Phospholipids and triglycerides both:

have a glycerol backbone.

Which of the following statements is false? Saturated fats:

have many double bonds in the carbon chains of their fatty acids (they have no double bonds)

Which type of bond must be broken for a beta sheet to unfold?

hydrogen bonds.

During the removal of proteins from the cell, ________ reactions occur. However, during their synthesis _______ reactions occur.

hydrolysis; dehydration

Lipids do not dissolve in water. Therefore, fatty acids are known as _____________ substances.

hydrophobic.

The attachment of what macromolecule is critical for the proper segregation of sister chromatids?

microtubules

What are prions?

misfolded versions of normal proteins that can cause disease.

According to the central dogma of molecular biology, what molecule should go in the blank? DNA -> mRNA -> _______

protein

Proteins perform many roles in cells. Which of the following is a role you would NOT expect for proteins?

proteins can bind to DNA to regulate translation.

Insulin is a protein hormone formed from two different polypeptides called the A chain and the B chain. Zinc helps form an insulin hexamer composed of three A chains and three B chains. What type of protein structure does zinc help form?

quaternary structure

The bacteria in the family Panibacillus all have a _______ shape.

rod

Which of the following is NOT a stage of transcription?

synthesis

In the process of transcription:

the DNA template strand is being read

The second gap in the cell cycle (G2) corresponds to ________________.

the phase between DNA replication and the M phase.

A bacterial cell and a random piece of DNA on your skin come in contact with one another, and the bacterial cell takes in the DNA and incorporates it into its genome. This is an example of bacterial ___________.

tranformation

A bacterium picks up an antibiotic resistance gene by receiving it during a bacteriophage infection. This is an example of bacterial ________.

transduction

The phosphate added to a target protein by a protein kinase usually comes from the __________.

transfer of a phosphate group from ATP to the protein target.

A bacterium picks up an antibiotic resistance gene by taking up a random piece of DNA from its environment. This is an example of bacterial ________.

transformation.