BIOL 302 Exam 3

The AAUAAA sequence found near the 3' end of a eukaryotic mRNA is required for generating the 3' end of the transcript AND for polyadenylation

True

A 5-2' phosphodiester bond is never seen in nucleic acids, the bonds are always 5-3

False

Certain conserved nucleotide sequences found in exons and introns are required for correct RNA splicing

True

The major role of the 5' UTR of a mRNA is to control mRNA stability

False

Spliceosomes are the complexes that add the poly-A tail to mRNA

False

The poly A tail of a mRNA is encoded by 100s of Ts found in the DNA at the 3' end of the gene

False

A polyribosome is a single mRNA that is being translated by many ribosomes at one 1

True

Acetylation of certain histone proteins cause the proteins to be more positively charged leading to decreased gene expression

False

Nuclear pores control the highly regulated passage of molecules into and out of the nucleus

True

Translation is terminated by special tRNA molecules that recognize stop codons

False

The mRNA is translated in the 5' to 3' direction

True

The C terminus of the protein is synthesized last

True

Translational regulatory proteins often bind to the 5' UTR of certain mRNAs to regulate their translation

True

The enzyme that catalyzes peptide bond formation (peptidyl transferase) is part of one of the ribosomal proteins S7

False

Exons are parts of genes that
a- are present in mature mRNA
b- contain protein coding sequences of a gene
c-sometimes can be spliced out of a primary transcript
d- often encode entire protein domains
e- all of the above

All of the above

The enzyme that links the 5-methylguanosine (the 5' cap) through a 5' to a 5' triphosphate linkage to the ends of the RNA transcripts is called

guanultransferase

The addition of the poly A tail to a eukaryotic mRNA requires

a 3'-OH group on the RNA

Tamoxifen is a targeted anti-cancer drug used to treated ER+ breast because

it binds to and blocks the activity of the estrogen receptor

Why is telomerase referred to as a 'reverse transcriptase'?
a- because it makes telomeres in the reverse orientation
b- because it chemically transforms the RNA primer into DNA primer
c- because it is able to synthesize telomeres without any template
d- because it uses an internal RNA molecule as a template to synthesize DNA
e- none of the above

because it uses an internal RNA molecule as a template to synthesize DNA

The part of the tryptophan operon called the operator is needed for

the binding of a transcriptional repressor to the promoter

Enhancer elements are DNA sequence elements that

are regions that bind transcriptional proteins

When estrogen binds to the estrogen receptor the following occurs

the bound estrogen receptor binds to DNA that contains a specific sequence

The total N.A are extracted with small beads attached to oligonucleotides with the sequence 5'-TTTTTTTTTTTTTTTTTT-3'. After mixing, the beads are washed to remove the unbound material. The analysis of the nucleic acids that have remained bound with the beads would demonstrate that they were composed of mostly:

mRNA

Small snRNA molecules such as U1 and U2 are directly required in the cell for

proper functioning of the spliceosome

Transcriptional termination in E. coli occurs when

a stem-loop structure on the RNA transcript that binds a protein and signals the polymerase stop and to come off the DNA

The poly A tail that is found on most eukaryotic mRNAs appear to be important for

the stability of the RNA and transport from the nucleus

Dr. Barbara McClintock was awarded the Nobel Prize for her discovery of

movable genetic elements in the genome

Huntington's disease is in inherited disease due to

unstable tri-nucleotide DNA repeats

A LINE element is a region of DNA in the genome and
a- is approximately 5000bp in length
b- is present in as many as 500,000 copies or more
c- is found in apparently random places in the genome
d- has genetic and structural similarities to some type of viruses

All of above

The --------- refers to the structure resulting from a phosphodiester bond involving the 5'-end of an intron and the 2'-OH of an A nucleotide intron that occurs during splicing

lariat

During the elongation phase of protein synthesis, an antibiotic inhibitor blocks protein synthesis by inhibiting the peptidyl transferase reaction (the reaction does not occur). At the inhibited ribosome, the A site is occupied by

Aminoacyl tRNA

During the middle of the elongation phase of protein synthesis, a chemical inhibitor is added that blocks protein synthesis by inhibiting the translocation reaction (translocation does not occur). At the inhibited ribosome, the A site is occupied by

peptidyl tRNA

The initiator tRNA for protein synthesis interacts with AUG codon and carries the amino acid

methionine

The amount of histone mRNA in the cell is reduced after DNA synthesis is completed by

Increasing the rate of degradation of histone mRNA

Regulation of the amount of protein that exists in the cell regulating the translation of the mRNA is also called post- BLANK regulation

transcriptional

In Drosophila, there are over 38,000 distinct acon guidance receptor proteins encoded by the DSCAM gene. This occurs through

alternative splicing of a large number of exons exon

Regulation of translation of the ribosomal protein S7 and sigma 32 protein have the following
a- the amplification of the number of Dscam
b-alternative splicing of a large number of exons exon
c- translation is required only under very specific conditons
d- the mRNA can be present in the cell without being translation

all of the above

Which of the following does not occur while a eukaryotic mRNA is in the nucleus, before it enters the cytoplasm?

The ribosome binds to the mRNA

Many currently used antibiotics specifically kill bacterial cells and not eukaryotic cells because
a- they are not absorbed by eukaryotic cells, only bacterial cells
b- eukaryotic cells have mechanisms that repair the damaged caused by antibiotics
c-they are degraded by eukaryotic cells that have enzymes that deactivate the antibiotics
d- they specifically de-acetylate bacterial proteins but not eukaryotic proteins
e- they take advantage of structural differences between bacterial and eukaryotic ribosomes

they take advantage of structural differences between bacterial and eukaryotic ribosomes

Kozak sequences, present in the 5'-UTR of mRNA molecules participate in

a- correct positioning of the ribosome during initiation and translation

A protein known to bind to the 5'-UTR of a mRNA

ribosomal protein S7

A protein that controls that activity of the translation factor of EIF2

heme-controlled inhibitor

A RNA polymerase

poly A polymerase

The role of acetylation of histones in transcription

Acetylation effectively loosens the 30nm fiber by chargers of histones (H3 & H4). This opens the DNA up so that the transcription complex can identify and bind to the promoter regions on the acetylated genes in order to begin transcription. Acetylation increases gene transcription generally

Kozak sequences present on the mRNA participate in

correct positioning of the ribosome during initiation of translation

Transcriptional factors called TAFs bind directly to

The TATA binding protein

The polyA tail of a mRNA is encoded by 100s of Ts found in the DNA at the 3' end of the gene (T/F)

F

Conserved nucleotide sequences found in exons are required for correct RNA splicing to occur (T/F)

T

A protein complex called ___ acts as a clamp to hold the DNA polymerase onto the DNA during DNA replication.

Sliding clamp or PCNA

During discontinuous DNA synthesis on the lagging strand, Okazaki fragments are entirely removed by RNAse H. (T/F)

F

Most cells have mechanisms that allow protein primary sequences to be translated back into the RNA sequence (T/F)

F

There are five different nucleotides that usually become incorporated into a DNA strand (T/F)

F

The Tm of a double stranded DNA molecule is a direct result of the percent of purines in the DNA (T/F)

F

Enzymes can increase the rates of chemical reactions by bringing substrates together to effectively increase their local concentration (T/F)

T

Protein, double strand DNA, and rRNA can all be denatured by heat (T/F)

T

The observation that the moles of G= moles of C in double strand DNA is referred to as one of _____ rules

Chargaff's

Enzymes can increase the rates of chemical reactions by binding to transition states of the reaction thereby making the reaction more likely to occur. (T/F)

T

Ribozymes are enzymes that are made from

RNA

In order to use the table of the genetic code to identify an amino acid sequence, the sequence that is used to translate the code is read directly from the template strand (T/F)

F

The multiple sites of DNA replication observed along a eukaryotic chromosome are known as

Replication bubbles

Which of the enzymes listed below synthesize RNA?

DNA primase

In the analysis of enzyme kinetics and reaction rates, the Km value refers to

the amount of substrate that results in the 1/2 Vmax

The reactivity of RNA is due to the presence of a ____ sugar

Ribose

The classic “beads-on-a-string” structure is the most decondensed chromatin possible and is produced experimentally. Which chromatin component is removed in order to decondense chromatin to this form?

Histone H1

The estrogen receptor is an example of a

Protein that can function as a transcription factor

The term UTR when applied to the structure of a mRNA is an abbreviation for untranslated region (T/F)

T

The enzyme that links the methyl guanosine (5’ cap) to the end of the RNA transcript is called

Guanyl transferase

The process of synthesis of a specific protein by translating the nucleotide sequence of a mRNA is called transcription (T/F)

F

Acetylation of histones helps activate gene expression by changing the overall charges on some histone protein (T/F)

T

Transcriptional enhancer elements can be located downstream of the actual transcribed region (T/F)

T

Nuclear pores control the highly regulated passage of molecules into and out of the nucleus (T/F)

T

Transcriptional termination in E. coli occurs when a stem-loop structure forms on the DNA and creates a physical barrier (T/F)

F

An amino acyl tRNA usually has

A single amino acid linked to it through its 3' OH

Which of the following is not a true statement regarding exons:a)they usually contain multiple stop codons b)are present in the mature mRNA c) contain protein coding sequences d)often encode entire protein domains d)they can sometimes be spliced out of the primary transcript and still yield a functional mRNA

They usually contain multiple stop codons

A large multi-protein and RNA complex that binds to the primary RNA transcript and participate in splicing out of introns is called the ribosome (T/F)

F

The promoter specific transcription factors, such as Sp1, NF1 or p53, bind to very specific DNA sequences (T/F)

T

The enzyme that links the amino acids together during protein synthesis is a heat stable ribosomal protein (T/F)

F

A polyribosome is a single ribosome that is translating many mRNAs (T/F)

F

Translation is terminated by special tRNA molecules that recognize stop codons (T/F)

F

Genes called homeobox genes that can be considered master developmental regulators were discovered in the fruit fly, Drosophila.(T/F)

T

A large protein complex called F1-ATPase uses ATP to pump H+ ions across membranes during electron transport(T/F)

F

Embryonic stem cells are derived from the placenta of a developing embryo(T/F)

F

The proton gradient generated by electron transport actually consists of both an ion concentration gradient and a voltage gradient (an electrochemical gradient) (T/F)

T

Electron Transport occurs in both the mitochondria and the chloroplast (T/F)

T

In the carbon fixation process in chloroplast CO2 is initially added to acetyl-CoA (T/F)

F

There are more mitochondria in a sperm cell that has to swim long distances to reach the egg than even a heart cell (T/F)

F

The compound CH3CH2CH2OH is considered to be non-polar. This is because we can tell by the structure that it will not dissolve in water (T/F)

F

Ionic bonds between acidic and basic amino acids are often important in generating a fully formed correct protein structure (T/F)

T

Denaturation of a protein can occur without breaking any of the peptide bonds (T/F)

T

Essential amino acids are those that we cannot produce ourselves and we need to get from our diet (T/F)

T

Covalent bonds are the most common types of bonds involved in holding the quaternary structure of a protein together (T/F)

F

At neutral pH (7.4) both the acidic and basic amino acids are uncharged because it is below their pKs, respectively and under these conditions they lose charges (T/F)

F

In contrast to a small protein such as RNase (124 amino acids), on a very large protein of over 1,000 amino acids, a single amino acid change would not be expected to have that much of an impact on the overall structure (T/F)

F

The SV40 virus is a virus that can cause cancer when introduced into human or mouse cells. A number of years ago it was found to be a contaminant in

poliovirus vaccine preperations

Which of the model organism can transition from a single cell form into a multicellular form?

Dictostelium

What model organism is currently used for drug testing before clinical trials can be performed with people?

Lab mouse

In order to grow most mammalian cells in culture the cells need to be placed in a culture media that contains nutrients and sugars as well as 10%

Cow serum

Which part of the cell cycle is the period when the proteins and materials required for DNA synthesis are being generated in the cell?

G1

One of the reasons that chemotherapy treatments often result in patients having low red blood cell counts and low platelets is because

The treatment kills stem cells in the bone marrow

Amphipathic molecules, such as a fatty acid, have the following properties

They have distinct hydrophilic and distinct hydrophobic regions