Fund Cell Bio Quizzes

The variations in the physical and biological characteristics between different proteins are influenced by the overall amino acid compositions, but most important is the unique amino acid ______.

 orientation.

 reactivity.

 sequence.

 number.

polarity,

sequence

Which of the following monomeric building blocks is needed to build a permeability-limited boundary around the whole cell and in the partitioning of cell compartments? 

 amino acids

 nucleotides

 fatty acids

 salts

 sugars

 fatty acids

Which of the following statements regarding protein structure is CORRECT?

There is free rotation around all covalent bonds in the polypeptide backbone.

Peptide bonds are the only covalent bonds that can link together two amino acids in proteins.

 The natively folded structure of a protein is often necessary for its function.  

 The sequence of the atoms in the polypeptide backbone varies between different proteins.

 Nonpolar amino acids tend to be located on the surface of folded proteins.

 The natively folded structure of a protein is often necessary for its function.  

A cell is considered the fundamental unit of life because of the following reasons, EXCEPT:

  1. A cell can carry out all the vital functions required for life.

 2. A cell can perform all essential life processes – metabolism, growth, reproduction, and respond to stimuli. 

  3. A cell has all the structural and functional elements for independent existence.

  4. A cell is too small to exist independently.

5. There are many unicellular living organisms.   

  4. A cell is too small to exist independently.

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also constrain the geometry of the molecule because they

 

1. prevent additional bonds from forming with the bonded atoms.

 

2. create a denser and bulkier electron cloud.

 

3. change the reactivity of the bonded atoms.

 

4. create a new arrangement of electron shells.

 

5. limit the rotation of the bonded atoms.

5. limit the rotation of the bonded atoms.

Of the following description of cells, which statement is NOT correct?

1. Cells can vary enormously in appearance and function.

2. Different cells have different chemical makeups and carry out distinct and unique chemical reactions.

3. Cells are self-replicating units.

4. A cell can be a unicellular organism or part of a multicellular organism.

5. All cells are believed to have evolved from a common ancestral cell.

2. Different cells have different chemical makeups and carry out distinct and unique chemical reactions.

Biological recognition between macromolecules in cells mostly relies on:

 1. exclusively through pi-pi bond interaction.

2. all of the above.

3. non-covalent interactions including H-bonding, ionic-bond, hydrophobic interaction etc.

4. covalent bonding.

5. surface symmetry.

3. non-covalent interactions including H-bonding, ionic-bond, hydrophobic interaction etc.

Polypeptides are synthesized from amino acid building blocks. The condensation reaction between the growing polypeptide chain and the next amino acid to be added involves the loss of ___________________. 

a water molecule.

 a OH group.

 a carboxylic acid group.

 a carbon atom.

an amino group.

a water molecule.

In eukaryotic cell, the _________________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

1. plasma membrane

2. lysosome membrane

3. nuclear envelop

4. mitochondrial membrane

5. Golgi network membrane

3. nuclear envelop

Prokaryotic cells can evolve rapidly, which helps them to quickly adapt to new food sources and develop resistance to antibiotics. Which of the options below lists the three main characteristics that support the rapid evolution of prokaryotic populations?

1. large population, rapid growth, can exchange DNA.

2. microscopic size, motile, anaerobic. 

3. no organelles, cell wall, can exchange DNA. 

4. cell wall, motility, and capable of sporulation. 

5. aerobic, motile, rapid growth. 

1. large population, rapid growth, can exchange DNA.

DNA polymerases are highly processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the growing daughter strands. Which entity of the replication machinery accounts for this characteristic?

1. RNA polymerase.

2. DNA helicase.

3. Single strand DNA binding protein.

4. Primase.

5. Sliding clamp.

Sliding clamp.

When using a repeating trinucleotide sequence (such as 5′-AACAACAACAACAAC………..-3′) in a cell-free translation system, you are likely to obtain...

 

1. Peptides made up of three different amino acids, each alternating with each other in a repetitive fashion.

2. Three different types of peptides, each made up of a single amino acid.

3. No peptide product is produced.

4. Poly-asparagine, since the codon for asparagine is AAC.

5. Peptides made up of three different amino acids in random order.

2. Three different types of peptides, each made up of a single amino acid.

The reasons that DNA makes a better material than RNA for the storage of genetic information include all of the following EXCEPT:

 

1. The use of “T” in DNA instead of “U” (as in RNA) protects against the effect of deamination, a common form of damage. Deamination of C produces a U (uracil) which is an abnormal base in DNA and thus removed by the DNA repair mechanism. T on the other hand has a 5’methyl group.

 

2. DNA is double-stranded and therefore the complementary strand provides a template from which damage can be repaired accurately.

 

3. The deoxyribose of DNA is chemically more stable.

 

4. The deoxyribose of DNA is chemically MORE REACTIVE than the ribose of RNA and this helps to speed up DNA replication.

 

5. The deoxyribose sugar of DNA makes the molecule much less susceptible than RNA to breakage, because of the lack of the hydroxyl group on carbon 2 of the ribose sugar.

4. The deoxyribose of DNA is chemically MORE REACTIVE than the ribose of RNA and this helps to speed up DNA replication.

The DNA double helix structure as originally described by Watson and Crick is stabilized by the following chemical forces:

 

π–π interaction of the aromatic ring structure of the bases.

 

Complementary base pair hydrogen bonding of the 2 antiparallel strands.

 

Negation (i.e. canceling) of the -ve charge of the sugar-phosphate backbone by +ve charge counterions  (e.g. Na⁺) in surrounding medium.

 

Twisted sugar-phosphate backbone to shorten the vertical displacement of adjacent bases for optimal base stacking.

 

All statements are correct.

All statements are correct.

Sickle cell anemia (SCA) is a well-known and often used example of how DNA mutation can change protein structure and function for disease pathogenesis.  Identify the correct statement of this mutation.     

 

1. All answers are correct.

2. The replacement of a polar acidic amino acid residue (D) to a nonpolar/hydrophobic residue (V) changes the folded structure of the b-globin protein to become aggregation prone and drive disease process.  

3. The codon changes amino acid residue #6 of the beta-globin chain from Glutamic Acid (D) to Valine (V)

4. This is what is known as a transversion substitution.

5. Mutation changes the codon #6 of the beta-globin gene from GAG to GTG.

All answers are correct.

Sometimes, chemical damage to DNA can occur just before DNA replication begins, not giving the repair system enough time to correct the error before the DNA is duplicated. This gives rise to mutation. If the cytosine in the sequence TCAT is deaminated and not repaired, which of the following is the point mutation you would observe after this segment has undergone two rounds of DNA replication?

 

TGAT

 

TTAT

 

Cannot be determined.  

 

TUAT

 

TAAT

TTAT

The mode of DNA replication is said to be semiconservative because......

 

Each daughter DNA molecule consists of one strand from the parent DNA molecule and one newly synthesized strand.

 

New DNA strands must be copied from a DNA template that is why it is conservative.

 

The original DNA is conserved and linked in segments with the newly synthesized pieces of DNA. 

 

Each daughter DNA molecule consists of two new strands copied from the parent DNA template.

 

After many rounds of DNA replication, the original DNA double helix is conserved and remains intact.

Each daughter DNA molecule consists of one strand from the parent DNA molecule and one newly synthesized strand.

In general terms, mutation rate of our DNA genetic material is kept at a very low frequency for all the following factors, EXCEPT

 

DNA polymerase is a high-fidelity enzyme that replicates DNA with absolute efficiency and accuracy.

 

The double stranded complementary base-pairing structure of DNA is ideally suited for repair.

 

“Abnormal bases” in DNA are checked and repaired by the genome “surveillance/QC” mechanisms in cells.

 

Various DNA repair mechanisms ensure the integrity of the genomic DNA sequence both during and after DNA replication.  

 

The transition of purines (e.g. A to G) or pyrimidines (e.g. C to T) involves more than 1 chemical step.

DNA polymerase is a high-fidelity enzyme that replicates DNA with absolute efficiency and accuracy.

Several members across three generations of the same family  were diagnosed with the same kind of cancer when they were unusually young. Which one of the following is the most likely explanation for this phenomenon? It is possible that the individuals with the cancer have inherited  ________ (fill in the blank). 

 

a mutation in a gene required for the synthesis of purine nucleotides.

 

a mutation in a gene required for DNA synthesis.

 

a mutation in a gene required for mismatch repair.

 

a mutation of the DNA polymerase that replicates DNA.

 

a “turn-on” mutation of a proto-oncogene (cancer causing gene) in the somatic cell of a first generation individual (e.g. grandpa or grandma).

a mutation in a gene required for mismatch repair.

You have discovered an “Exo^–” mutant form of DNA polymerase in which the 5′-to-3′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged. Which of the following properties do you expect the mutant polymerase to have?

 

It will be unable to remove the RNA primer in  DNA replication.

 

It will polymerize more slowly than the normal Exo+ polymerase.

 

It will polymerize in both the 5′-to-3′ direction and the 3′-to-5′ direction.

 

It will fall off the template more frequently than the normal Exo+ polymerase.

 

It will be less likely to "erase" mis-incorporated bases and the newly synthesized DNA is more likely to retain mismatched bases to result in mutation.

It will be unable to remove the RNA primer in  DNA replication.