Cell Biology Final Exam Review

Given the sequence of one strand of a DNA helix: 5'-GCATTCGTGGGTAG-3' Give the sequence of the complementary strand and label the 5' and 3' ends.

5'-CTACCCACGAATGC-3'

Which organism should have the highest percentage of unsaturated phospholipids in the membrane? A. arctic salmon B. polar bears C. desert snake D. bacterium living in hot spring

A arctic salmon

What is NOT true for euchromatin and heterochromatin? A. All the euchromatin regions are highly opened and favor gene activation. B. Genes that are packaged into heterochromatin are generally silenced. C. Specific histone modification can trigger formation and spreading of heterochromatin. D. Both euchromatin and heterochromatin are packaged into highly condensed chromosomes during mitosis.

A. All the euchromatin regions are highly opened and favor gene activation.

Which of the following statements is TRUE? A. Covalent bonds can be established by condensation reactions, which release water molecules. B. Heat can unfold a protein molecule and break it into small peptides. C. The folding of a protein can only be mediated by noncovalent bonds. D. Covalent bonds help assemble large protein complexes from protein subunits.

A. Covalent bonds can be established by condensation reactions, which release water molecules.

Working in a company, you try to develop a drug to inhibit the activity of an enzyme that plays an important role in cancer. This enzyme is an allosteric protein. What would be the best strategies for drug designing? A. Designing a compound that can compete with the substrate binding to this enzyme. B. Designing a compound that mimics the structure of the ligand that binds to this enzyme. C. Designing a compound that can block the binding of both substrate and ligand to this enzyme. D. Designing a compound that can bind anywhere on the surface of this enzyme.

A. Designing a compound that can compete with the substrate binding to this enzyme. B. Designing a compound that mimics the structure of the ligand that binds to this enzyme.

To study a protein that controls the phosphorylation of RNA polymerase II, which of the following model organism can NOT be chosen? A. E. Coli B. Yeast C. Drosophila D. Arabidopsis

A. E. Coli

Which of the following statements is FALSE? A. Each cholesterol molecule contains a hydrophilic head and two hydrophobic tails. B. Incorporation of cholesterol decreases the fluidity of the membrane. C. Cholesterols are transported in blood in small packages called lipoproteins. D. Cells can obtain cholesterol through receptor-mediated endocytosis.

A. Each cholesterol molecule contains a hydrophilic head and two hydrophobic tails.

About the different between eukaryotic transcription and prokaryotic transcription, which of the following statements are CORRECT? A. Eukaryotic transcription occurs in the nucleus, prokaryotic transcription in the cytoplasm. B. Eukaryotic mRNAs have a 5' cap and a 3' polyA tail, prokaryotic mRNAs do not. C. Eukaryotic transcription initiation is much more complex than prokaryotic transcription. D. Eukaryotic transcription initiation requires specific sequences at the promoter, prokaryotic initiation initiation does not. E. Eukaryotic genes can be transcribed by many RNA polymerases at one time, prokaryotic genes cannot.

A. Eukaryotic transcription occurs in the nucleus, prokaryotic transcription in the cytoplasm. B. Eukaryotic mRNAs have a 5' cap and a 3' polyA tail, prokaryotic mRNAs do not. C. Eukaryotic transcription initiation is much more complex than prokaryotic transcription.

Mutation of a gene leads to a protein that does not function normally, which leads to human diseases. What level(s) of protein structure can be affected by this mutation? A. Primary B. Secondary C. Tertiary D. Quaternary

A. Primary B. Secondary C. Tertiary D. Quaternary

Which of the following is NOT an epigenetic mechanism? A. RNA splicing B. DNA methylation C. histone methylation D. siRNA

A. RNA splicing

Which of the following statements about translation are CORRECT? A. The genetic code is universal, with rare exceptions. B. Many amino acids are coded by redundant codes. C. Among the three sites (A, P, E) on ribosomes, the E site is the entrance of charged tRNA. D. The newly synthesized peptide always begins with methionine (Met). E. To ensure a smooth and faithful transition, the assembly of a ribosome on mRNA prevents the binding of other ribosome units to the same mRNA.

A. The genetic code is universal, with rare exceptions. B. Many amino acids are coded by redundant codes. D. The newly synthesized peptide always begins with methionine (Met).

The size of a ribosome is 30nm. Which microscope listed could be used to look at the subcellular localization of single ribosomes. A. Transmission electron microscope B. PALM C. Phase-contrast D. Confocal E. STED

A. Transmission electron microscope B. PALM E. STED

Which of the following histone modifications can be associated with gene activation? A. acetylation B. phosphorylation C. methylation D. demethylation

A. acetylation B. phosphorylation C. methylation D. demethylation

Which of the following are noncoding RNAs? A. siRNA B. snRNA C. intron D. mRNA E. miRNA

A. siRNA B. snRNA E. miRNA

Which of the following hydrocarbon tail would yield the most highly mobile phospholipid? A. 24 carbons with 1 double bond B. 15 carbons with 2 double bonds C. 20 carbons with 2 double bonds D. 16 carbons with no double bonds

B. 15 carbons with 2 double bonds

DNA isolated from mouse liver cells contains 26% A. What percent will be G? A. 26% B. 24% C. 74% D. 13%

B. 24%

Which of the following statements is FALSE? A. Chromatins are present in eukaryotic cells, but not in prokaryotic cells. B. A histone core contains two of each of the core histones (H1, H2, H3, H4). C. A nucleosome contains a core of histones with DNA wrapped around it approximately two times. D. The N-terminal tails of core histones can be covalently modified.

B. A histone core contains two of each of the core histones (H1, H2, H3, H4).

Which of the following statements about the difference between DNA and RNA are TRUE? A. DNA and RNA have the same backbone, only one of four bases is different. B. DNA can form long double helix while RNA cannot. C. Genetic code can be transferred from DNA to RNA, but cannot be transferred from RNA to DNA. D. RNA can fold into 3-D structures therefore is generally more stable than DNA. E. Unlike the unique function of DNA, RNAs can serve as messenger, structural, or regulatory molecules.

B. DNA can form long double helix while RNA cannot. E. Unlike the unique function of DNA, RNAs can serve as messenger, structural, or regulatory molecules.

Which group of enzymes control protein activate by adding phosphate groups to the protein? A. Phosphatase B. Kinase C. Ligase D. ATPase

B. Kinase

Which of the following statements about genomes are TRUE? A. Most of the human genome codes for proteins. B. Most of the human genes contain introns C. Many human genes are believed to undergo alternative splicing. D. Human genomes is distributed on 46 chromosomes in most normal cells.

B. Most of the human genes contain introns. C. Many human genes are believed to undergo alternative splicing. D. Human genomes are distributed on 46 chromosomes in most normal cells.

Which of the following is NOT a mechanism of gene repression? A. Recruitment of a chromatin remodeling complex to reposition nucleosomes. B. Recruitment of histone acetyltransferase to the promoter region. C. Repressor direct binds to an activator to keep the activator off. D. Repressor competitively blocks the DNA binding of activators.

B. Recruitment of histone acetyltransferase to the promoter region.

Which of the following statements is FALSE? A. A protein chain starts with an amino group and ends in a free carboxyl group. B. The sequence of the atoms in the polypeptide backbone varies between different proteins. C. In a higher temperature, more chaperons can be synthesized to guide the folding of proteins. D. Hydrogen bonds along the protein backbone allow for the formation of alpha helices and beta sheets.

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

Which of the following statements about enzymes is FALSE? A. Many enzymes speed reactions by creating and stabilizing a transition state. B. The interaction9 between enzymes and substrates is generally mediated by noncovalent bonds. C. Amino acid side chains at the active site can hold the substrate, but never directly reacts with the substrate. D. Enzymes generally remain unchanged after finishing catalyzing a reaction

C. Amino acid side chains at the active site can hold the substrate, but never directly reacts with the substrate.

Which of the following statements is TRUE? A. An alpha helix containing 20 amino acids must be a transmembrane structure. B. An alpha helix containing some hydrophilic amino acids can not be a transmembrane structure. C. Cross membrane alpha helix contains hydrogen bonds. D. Only single and multiple alpha helix structures can form transmembrane domain.

C. Cross membrane alpha helix contains hydrogen bonds.

In a protein gel electrophoresis experiment, SDS can do all these works except: A. Breaking membrane and solubilizing membrane-binding proteins. B. Unfolding proteins and disrupting protein interactions. C. Cross-link proteins with nucleic acids. D. Coat all proteins with negative charges so that they can migrate in one direction.

C. Cross-link proteins with nucleic acids.

In a muscle cell, which internal organelles would you expect to particularly abundant? A. Lysosome B. Rough Endoplasmic Reticulum C. Mitochondria D. Peroxisome

C. Mitochondria

Which of the following statements about fluorescence microscopy is FALSE? A. The resolution of a regular fluorescence microscopy cannot reach over 200nm. B. Confocal microscopy improves the resolution fluorescence microscopy by excluding out-of-focus lights. C. The excitation wavelength of GFP is longer than its emission wavelength. D. GFP protein can be used to track the expression of specific genes or proteins in living cells.

C. The excitation wavelength of GFP is longer than its emission wavelength.

Which of the following statements about hydrogen bonds is TRUE? A. They are weak covalent bonds that are easily disrupted by heat. B. They are weak bonds formed between hydrocarbons in water. C. They are weak bonds formed between highly polar groups. D. They are weak bonds formed only between polar O-H groups

C. They are weak bonds formed between highly polar groups.

Which type of RNA in the following controls RNA processing? A. rRNA B. mRNA C. snRNA D. tRNA

C. snRNA

Which of the following statements about antibodies is TRUE? A. Antibodies adapt different overall shapes so they can bind to different antigens. B. Each antibody is composed of two polypeptide chains. C. Alpha helices and beta sheets establish domains in the polypeptide chains. D. Disulfide bonds are formed both between and within the polypeptide chains.

D. Disulfide bonds are formed both between and within the polypeptide chains.

Which of the following statements is TRUE? A. Nucleosomes are present in both eukaryotic chromosomes and prokaryotic chromosomes. B. In living cells, chromatin usually adopts the extended "beads-on-a-string" form. C. Nucleosomes bind DNA so tightly that they cannot move from the position once assembled. D. Genes that are being transcribed are thought to be packaged in a less condensed type of chromatin.

D. Genes that are being transcribed are thought to be packaged in a less condensed type of chromatin.

Which of the following statements is TRUE? A. Water is a polar molecule and hence an excellent solvent for all substances. B. All hydrophilic molecules form hydrogen bonds with water molecules. C. Hydrophobic interactions are most likely to occur on the surface of a water-soluble molecule. D. Phospholipids have both hydrophilic and hydrophobic components.

D. Phospholipids have both hydrophilic and hydrophobic components.

Which of the following could be induced by an insertion of one base pair into a cDNA sequence? A. No change in the protein sequence as the insertion may be removed during mRNA splicing. B. No change in the protein sequence as it could be a nonsense mutation. C. Producing a protein with one amino acid changed. D. Producing a protein with many amino acids changed. E. Producing a much shorter peptide chain.

D. Producing a protein with many amino acids changed. E. Producing a much shorter peptide chain.

Which of the following is TRUE for membrane synthesis? A. New phospholipids are synthesized in the lumen of ER. B. Scramblases catalyze transfer of specific phospholipids from one monolayer to another. C. Special transferases catalyze adding of sugars to glycolipids at the cytosolic side of the membrane. D. The newly-synthesized membrane can be added to plasma membrane through vesicular transport.

D. The newly-synthesized membrane can be added to plasma membrane through vesicular transport.