bio final exam

which is not an example of a protein with quaternary structure?

myoglobin, an oxygen-binding protein in muscle, consists of single subunit

Which of the following globular proteins is used to form filaments as an intermediate step to assembly into hollow tubes?

tubulin

Find the incorrect definition regarding protein structure:

primary structure- amino acid composition and concentration

Which of the following statements is true?

Nonpolar amino acids tend to be found in the interior of proteins.

The correct folding of proteins is necessary to maintain healthy cells and tissues. Unfolded proteins are responsible for such neurodegenerative disorders as Alzheimer's, Huntington's, and Creutzfeld-Jacob disease (the specific faulty protein is different for each disease). What si the ultimate fate of these disease-causing, unfolded proteins?

they are degraded

fill in the blank: the protein ___ is involved in vision in higher organisms; its prokaryotic cognate, ___ is a light-activated proton pump involved in ATP production. the cofactor of these proteins is ___

rhodopsin; bacteriorhodopsin, retinal/retionl

the following statement is incorrect regarding the peptide bond

none of the above

• the C-N bond cannot rotate

• the peptide bond is a special type of amide

• the peptide bond links consecutive two consecutive a-amino acids from C1 of one a-amino acid and the N2 of another

• all of the above

which of the following is not a feature commonly observed in B pleats

coiled-coil patterns

Recall the definition of an antigen as a molecule (or particle that can induce the formation of specific antibodies in an animal organism. Find the incorrect statement.

Generally speaking, lipids and nucleic acidsare a seffective antigens as proteins and carbohydrates.

Drawn below are segments of B pleats B( sheets). Which structure is parallel and which one is antiparallel?

b- structure i is parallel and ii is antiparallel

fill in the blanks: the a helices and B sheets are examples of protein ___ structure. A protein such as hemoglobin, which is composed of more than one protein ___, has ___ structure. A molecule such as an enzymatic substrate, a hormone, or a growth factor, is called a ____

secondary, subunit, quaternary, ligand

which of the following statements is incorrect

none of the above

-We only need to consume vitamins in small amounts

-Vitamins are precursors to some coenzymes

-Some vitamins are fat-soluble whereas others are soluble in water

- All of the above

DNA in Eubacteria is not contained in a nucleus. How is it organized?

it is associated to proteins but not as organized as the eukaryotic chromosomes

Which of the following statements is incorrect?

none of the above

-Between mitotic divisions, cells are in interphase.

-During meiosis, recombination takes place ni prophase I.

-in the human female, ova are arrested in prophase I until one ovum continues meiosis each month or so.

-All of the above

Fred Griffith studied two strains of Streptococcus pneumonia, one that causes a lethal infection when injected into mice, and a second that is harmless. He observed that pathogenic bacteria that have been killed by heating can no longer cause an infection. But when these heat-killed bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a mouse. What did Griffith conclude from this experiment?

The heat-killed pathogenic bacteria "transformed" the harmless strain into a lethal one.

Genetic mutations originate from changes in DNA sequence. in eukaryotic cells, they may also occur when the number of chromosome is affected. What is the term that describes an incorrect number of chromosomes in the cells of an organism?

aneuploidy

DNA replication si considered semiconservative because

each daughter DNA molecule consistsof one strand from the parent DNA molecule and one new strand

Which of the following statements regarding DNA replication is false?

on a DNA strand that is being synthesized, the 5' end is growing

DNA poylmerase catalyzes the joining of a nucleotide to a growing DNA strand. What prevents this catalyzing the reverse reaction?

loss of ATP as an energy source

letter A indicates

the guanine-cytosine base pair

the letters B and C point to a ____ base pair forming ___ hydrogen bonds

guanine-cytosine/3

the letter E indicates

the adenine-thymine base pair

the exception to the “central dogma of molecular biology” consists in the synthesis of DNA based on an RNA template. ____ catalyze the reaction

reverse transcriptases

the ___ arrow points to the major DNA groove whereas the __ arrow points to the minor groove

blue, red

if the genome of the bacterium Escherichia coli requires about 20 minutes to replicate itself, how can the genome of the fruit fly drosophila be replicated in only 3 minutes

Drosophila DNA contains more origins of replication than E. coli DNA.

Although the chromatin structure of interphase and mitotic chromosomes si very compact, DNA-bnidnig and protein complexes must be able to gain access ot the DNA molecule. Chromatin-remodeling provide this access by

using the energy of ATP hydrolysis to move nucleosomes

The nucleosome histone core is composed of four different histone proteins, assembled in a stepwise manner. Once the core octamer has been formed, DNA wraps around it to form a nucleosome core particle. Which of the following is the correct formula of the histones in the nucleosome?

H2A+H2B+H3+H4+H1

nI the DNA of a certain bacterial species, 13% of the nitrogenous bases are adenine (A). What are the percentages of the other bases?

13% G, 37% C, 37% T

Methylation and acetylation are common changes made ot histone H3, and the specific combination of these changes issometimes referred to as

the histone code

which of the following statements is not an accurate statement about thymine dimers

thymine dimers are covalent links between thymines on opposite DNA strands

the classic "beads-on-a-string" structure is the most decondensed chromatin structure possible and can be produced experimentally. Which chromatin components are not retained when this structure is generated?

linker histones

Telomeres serve as caps at the ends of linear chromosomes. Which of the following is not true regarding hte replication fo telomeric sequences?

the leading strand doubles back on itself to form a primer for the lagging strand

Human beings with the inherited disease xeroderma pigmentosum have serious problems with lesions on their skin and often develop skin cancer with repeated exposure to sunlight. What type of DNA damage is not being recognized in the cells of these individuals?

ultraviolet irradiation damage

in some individuals with Down Syndrome, the characteristic symptoms are less severe, and they are said ot have Familial Down Syndrome, Find the incorrect statement regarding Familial Down Syndrome.

the age of the parents is not an important contributing factor

which of the following statements is false?

RNA polymerase is responsible for both unwinding the DNA helix and for catalyzing the formation of the phosphodiester bonds between nucleotides.

The figure above clearly depicts the nucleolus, a nuclear structure that looks like a large dark region when stained. The other dark-speckled regions in this image, indicated with a question mark, are the locations of compact chromosomal segments called heterochromatin. What is the nucleolus?

nuclear regions of rRNA synthesis

Which one of the following isthe main reason that a typical eukaryotic geneis able to respondto a far greater variety of regulatory signals than a typical prokaryotic gene or operon?

the transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter

Hershey and Chase used radiolabeled macromolecules to identify the material that contains heritable information. What isotopes were used totrack protein andDNA, respectively, during this experiment?

35^S and 32^P

You have a piece of DNA thatincludes thefollowing sequence:

5'-ATAGGCATTCGATCCGGATAGCAT-3'

3'-TATCCGTAAGCTAGGCCTATCGTA-5'

Which of the following RNA molecules could be transcribed from this piece of DNA?

5'-UAUCCGUAAGCUAGGCCUAUGCUA-3

find the incorrect statement regarding RNA polymerases in eukaryotes

miRNA genes are transcribed by RNA polymerase (mtRNAP)

which of the following antibiotics targets RNA polymerase

rifampin

which of the following statements about RNA splicing is false ?

in order for a gene to function properly, exons must be removed from the primary transcript.

Transcription in bacteria differs from transcription in a eukaryotic cell in that

RNA polymerase (along with its sigma subunit) can initiate transcription on its own.

which is the anticodon in tRNA^Trp?

5’-ACC-3’

which amino acid would you expect a tRNA with the anticodon 5’-AAA-3’ to carry?

5’-ACC-3’

which of the following statements about the genetic code is correct

the genetic code is redundant

A mutation in the tRNA for the amino acid lysine results in the anticodon sequence 5-'UAU-3' (instead of 5'-UUU-3'). Which of the following aberrations in protein synthesis might this tRNA cause?

substitution of lysine for isoleucine

the process of ____ is catalyzed by ribozymes

RNA splicing

Which of the following does not occur before a eukaryotic mRNA is exported from the nucleus?

the ribosome binds to the mRNA

The piece of RNA below includes the region that codes for the binding site for the initiator tRNA needed in translation.

5-'GUUUCCCGUAUACAUGCGUGCCGGGGGC-3'

Which amino acid will be on the tRNA that is the first to bind tot h e A site of the ribosome?

arginine

Total nucleic acids are extracted from a culture of yeast cells and are then mixed with resin beads to which the polynucleotide 5-TTTT ITTTTTTTTITTITITTTTIT-3' has been covalently attached. After a short incubation, the beads are then extracted from the mixture. When you analyze the cellular nucleic acids that have stuck to the beads, which of the following is most abundant?

mRNA

Below is the sequence from the 3' end of an mRNA. 5'-CCGUUACCAGGCCUCAUUAUUGGUAACGGAAAAAAAAAAAAAA-3'

if you were told that this sequence contains the stop codon for the protein encoded by this mRNA, what is the anticodon on the tRNA in the P site of the ribosome when release factor binds to the A site?

5’-UUA-3’

You have a segment of DNA that contains the following sequence:

5-'GGACTAGACAATAGGGACCTAGAGATTCCGAAA-3'

3'-CCTGATCTTTATCCCTGATCTCTAAGGCTTT-5'

if you know that the RNA transcribed from this segment contains the following sequence:

5'-GGACUAGACAAUAGGGACCUAGAGAUUCCGAAA-3'

which of the following choices best describes how transcription occurs?

the bottom strand is the template strand; RNA polymerase moves along this strand from 3’ to 5’

find the mismatched pair regarding broad spectrum antibiotics

none of the above

-Chloramphenicol--prevents protein chain elongation by inhibiting the peptidyl transferase activity

-tetracyclines - bind 30S ribosomal subunit, inhibiting the binding of incoming aminoacyl-tRNAs C)

- Streptomycin--disrupts the initiation and elongation steps in protein synthesis.

-all of the above

Shown above is a tRNA for tryptophan. What is the anticodon and its the correct way to write it on a database?

5’-CCA-3’