Bio 212 Exam 2

repressor

(1) in bacteria, a protein that binds to an operator sequence in DNA to prevent transcription when an inducer is not present and that comes off DNA to allow transcription when an inducer binds to the repressor protein. (2) in eukaryotes, a protein that binds to a silencer sequence in DNA to prevent or reduce gene transcription

termination

(1) in enzyme-catalyzed reactions, the final stage in which the enzyme returns to its original conformation and products are released. (2) in transcription, the dissociation. of the RNA and RNA polymerase from DNA. (3) in translation, the release of the polypeptide and dissociation of a ribosome from mRNA when the ribosome reaches a stop codon

Central Dogma

-an organism's genotype is determined by the sequence of bases in its DNA -an organism's phenotype is a product of the proteins it produces alleles of the same gene differ in their DNA sequence proteins produced by different alleles of the same gene frequently differ in their amino acid sequence

RNA and self replication

1)a complementary copy of the RNA is made -free ribonucleotides form hydrogen bonds with complementary bases on the original template strand of RNA 2) their sugar-phosphate groups form phosphodiester linkages to produce a double-stranded RNA molecule 3) the hydrogen bonds between the double-stranded product must be broken by heating or by a catalyzed reaction the newly made complementary RNA molecule now exists independently of the original template strand if steps 1-3 were repeated with the new strand serving. as a template (steps4-6)

synthesis of lagging strand

1. primer added 2. first fragment synthesized 3. second fragment synthesized 4. primer replaced 5. gap closed

If a DNA strand has 24% T, what percent of A will be present?

24%

If this was your sequence of DNA...what would be the complementary DNA sequence that is base paired with it? 5' - A A T C G A C T A G A C T A G C - 3'

3' - T T A G C T G A T C T G A T C G - 3'

The following RNA strand was produced: 5′ AAA AUG AGU AAG 3′ . Which of the following DNA strands could have been the template for this RNA?

3' TTT TAC TCA TTC 5'

For double-stranded DNA, consider the following base ratios: 1. A/G 2. C/T 3. C/G 4. (A+C)/(G+T) 5. (A+G)/(C+T) 6. (A+T)/(G+C) Which of those ratios always equals 1?

3, 4, and 5

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

32

If a strand of DNA has 45% A, what percent will be C?

5%

At a specific area of a chromosome, the following sequence of nucleotides is present where the chain opens to form a replication fork:3' C C T A G G C T G C A A T C C 5'An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

5' ACGUUAGG 3'

If the sequence in the coding strand of DNA for a particular amino acid is 5'AGT3', then the anticodon on the corresponding tRNA would be ________.

5' ACU 3'

The sequence of one strand of DNA is shown below. Which of the following is the sequence of its complementary strand? 3′ ATTTGGCC 5′

5' TAAACCGG 3'

If the sequence of DNA is5'-CATGAATAGGGT-3' (coding strand)3'-GTACTTATCCCA-5' (template strand)then the mRNA sequence after transcription is:

5'-CAUGAAUAGGGU-3'

The sequence of one strand of a DNA segment is 5'-GACTCCATGC-3'. The sequence of the complementary strand is:

5'-GCATGGAGTC-3'

Which of the following sequences would result from replication of this DNA template strand? 3′-AAGTCAGT-5′

5'-TTCAGTCA- 3'

To build a protein that is 20 amino acids long, the coding region of the mRNA sequence must be at least ------- ribonucleotides long.

63

A deletion mutation occurs, leaving 23 bases in the nucleotide sequence. What is the maximum number of amino acids that could be coded for by this sequence?

7

Which statement is false? A phosphodiester bond links nucleic acids. A CO2 molecule is released when the phosphodiester bond is formed. A nucleotide contains either a ribose or deoxyribose sugar. A ribose has an -OH group on the 2' carbon.

A CO2 molecule is released when the phosphodiester bond is formed.

deoxyribonucleotides

A nucleotide consisting of a deoxyribose sugar, one or more phosphates, and one of four nitrogen-containing bases: adenine, guanine, cytosine, or thymine.

ribonucleotide

A nucleotide consisting of a ribose sugar, one or more phosphates, and one of four nitrogen-containing bases: adenine, guanine, cytosine, or uracil.

missense mutation

A point mutation (change in a single base pair) that changes one amino acid for another within a protein

nonsense mutation

A point mutation (change in a single base pair) that converts an amino-acid- specifying codon into a stop codon.

Single-strand DNA-binding proteins (SSBPs)

A protein that attaches to separated strands of DNA during replication or transcription, preventing them from re-forming a double helix.

TATA-binding protein (TBP)

A protein that binds to the TATA box in eukaryotic promoters and is a component of the basal transcription complex.

silencer

A regulatory sequence in eukaryotic DNA to which repressor proteins can bind, inhibiting gene transcription.

TATA-box

A short DNA sequence in many eukaryotic promoters that is important for assembling general transcription factors and RNA polymerase at the core promoter; located about 30 base pairs upstream from the transcription start site.

primer

A short, single-stranded RNA molecule that base-pairs with a DNA template strand and is elongated by DNA polymerase during DNA replication.

Each codon shown below specifies an amino acid. For which one is it possible that a change in a single base could create a stop codon?

AAA

_____ bind(s) to DNA enhancer regions.

Activators **Activators are a type of transcription factor that bind to enhancer regions.

Messenger RNA (mRNA)

An RNA molecule transcribed from DNA that carries information (in codons) that specifies the amino acid sequence of a polypeptide.

Topoisomerase

An enzyme that prevents the twisting of DNA ahead of the advancing replication fork by cutting the DNA, allowing it to unwind, and rejoining it.

primase

An enzyme that synthesizes a short stretch of RNA to use as a primer during DNA replication.

stop codon (termination codon)

Any of the three codons UAA, UAG, and UGA, that indicate the point at which mRNA translation is to be terminated.

Which could lead to uncontrolled growth in cancer? The overexpression of MPF activity The overexpression of G1 cyclin A nonfunctional E2F protein A nonfunctional Rb protein B and D B and C

B and D

What determines which base is to be added to an RNA strand during transcription?

Base pairing between the DNA template strand and the RNA nucleotides **Transcription involves the formation of an RNA strand that is complementary to the DNA template strand.

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG **in RNA uracil replaces thymine

What two types of defects does a cancerous cell possess?

Cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive.

phosphodiester linkage

Chemical linkage between adjacent nucleotide residues in DNA and RNA. Forms when the phosphate group of one nucleotide condenses with the hydroxyl group on the sugar of another nucleotide.

Which of the following sequences is the correct order for transcription initiation?

Chromatin remodeling → Exposure of promoter and regulatory sequences → Assembly of proteins → Proteins contact core promoter

DNA contains biological information

DNA can store and transmit biological information DNA carries the information required for the organism's growth and reproduction the language of nucleic acids is contained in the sequence of the bases DNA carries the information required for the growth and reproduction of all cells

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

DNA in both daughter cells would be radioactive

The Hershey-Chase experiment proved that

DNA is the hereditary material

Which of these would not be found on the leading strand?

DNA ligase no okazaki fragments on the leading strand

Which enzyme is incorrectly paired with its function?

DNA ligase—synthesize Okazaki fragments

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

DNA polyermase can assemble DNA only in the 5' to 3' direction **Since DNA polymerase can assemble DNA only in the 5' to 3' direction, the new strand complementary to the 3' to 5' strand must be assembled either in short 5' to 3' segments, which are later joined together by ligase, or be assembled continuously.

Which of the following is not a correct statement Primase is one type of RNA polymerase DNA ligase joins adjacent deoxynucleotides with a phosphodiester bond Okazaki fragments are linked together shortly after they are formed DNA polymerase I extends the leading strands and okazaki fragments

DNA polymerase I extends the leading strands and okazaki fragments

How is the leading strand replicated?

DNA polymerase requires a primer -a few nucleotides are bonded to the template strand -this provides a free 3' OH group that can combine with an incoming dNTP to form a phosphodiester bond Primase -a type of RNA polymerase -synthesizes a short RNA segment that serves as a primer -DNA polymerase III then adds bases to the 3' end of the primer the product is called the leading strand of continuous strand -it leads into the replication fork -it is synthesized continuously in the 5' to 3' direction

What happens when p53 is mutated?

DNA replication will be able to occur in mutated cells

Roles of DNA

DNA's stability makes it a reliable store for genetic information, it is less reactive than RNA, and it is more resistant to chemical degradation makes a poor catalyst Biologists think that the first life-form was made of RNA and not DNA

antiparallel

Describing the opposite orientation of the strands in a DNA double helix with one strand running in the 5' to 3' direction and the other in the 3' to 5' direction.

Which statement is correct concerning the relationship between chromosomes and either genes, chromatin, or sister chromatids?

Each replicated chromosome consists of two sister chromatids **Replication of a chromosome's single DNA double helix produces two identical dsDNA copies called sister chromatids

DNA polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule

_____ is a carcinogen that promotes colon cancer.

Fat (A diet high in fat increases the risk of both colon and breast cancer.)

What phase are non dividing cells stuck in?

G0

What checkpoint will halt the cell cycle if the DNA is damaged?

G2

Which answer correctly identifies a cell-cycle checkpoint with a criterion for passing it?

G2 checkpoint: Chromosomes have replicated successfully **G2 occurs after S and before M phase, so it is advantageous for the cell to have a checkpoint assessing chromosome replication here.

transcription factor

General term for a protein that binds to a DNA regulatory sequence to influence transcription. It includes both regulatory and basal transcription factors.

regulatory transcription factors (transcription factors)

General term for proteins that bind to DNA regulatory sequences (eukaryotic enhancers, silencers, and promoter-proximal elements), but not to the promoter itself, leading to an increase or decrease in transcription of specific genes

What histone is known as the linker histone?

H1

What triggers the cell to move from the G1 phase to the S phase?

High E2F levels

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

lagging strand (discontinuous strand)

In DNA replication, the new strand of DNA that is synthesized discontinuously (as a series of short pieces that are later joined) in a direction moving away from the replication fork.

ribosome binding site (Shine-Dalgarno sequence)

In a bacterial mRNA molecule, the sequence just upstream of the start codon to which a ribosome binds to initiate translation.

primary transcript

In eukaryotes, a newly transcribed RNA molecule that has not yet been processed to a mature RNA. Called pre-mRNA when the final product is a protein.

poly(A) tail

In eukaryotes, a sequence of 100-250 adenine nucleotides added to the 3' end of newly transcribed messenger RNA molecules

RNA processing

In eukaryotes, the changes that a primary RNA transcript undergoes to become a mature RNA molecule. For pre-mRNA it includes the addition of a 5' cap and 3' poly(A) tail and splicing to remove introns.

pre-mRNA

In eukaryotes, the primary transcript of protein-coding genes. Pre-mRNA is processed to form mRNA.

Basal transcription factors are proteins that bind to DNA. What is their function?

Initiate transcription by forming an initiation complex

Which of the following is not a property of DNA polymerase?

It can synthesize a new strand in the 3' → 5' direction.

RNA and proteins combine in cells to form structures called ribosomes. Ribosomes contain the active site for peptide bond formation. Based on their chemical structures, do you think protein or RNA molecules actually form the active site within the ribosome?

It could be either, because both molecules have catalytic properties

Important properties of the Code

It is redundant. All amino acids except two are encoded by more than one codon. It is unambiguous. One codon never codes for more than one amino acid. It is nearly universal. With a few minor exceptions, all codons specify the same amino acids in all organisms. It is conservative. The first two bases are usually identical when multiple codons specify the same amino acid.

How is the lagging strand replicated?

It is replicated discontinuously in the opposite direction that the replication fork moves is synthesized as short discontinuous fragments called Okazaki fragments DNA polymerase III then adds bases to the 3' end of the primer DNA polymerase moves away from the replication fork -helicase continues to open the replication fork -and expose single-stranded DNA on the lagging strand DNA polymerase I removes the RNA primer at the beginning of each Okazaki fragment and fills the gap The enzyme DNA ligase joins the Okazaki fragments to form a continuous DNA strand

What checkpoint would the cell cycle stop at if chromosomes have not attached to the spindle apparatus?

M

Once researchers identified DNA as the unit of inheritance, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. What is the mechanism of information transfer in eukaryotes?

Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place.

Which statement about the genetic code is false? All amino acids except two are encoded by more than one codon One codon always codes for more than one amino acid All codons specify the same amino acids in all organisms When multiple codons code for the same amino acid they usually have the same first two bases

One codon always codes for more than one amino acid

Which of the following statements about DNA and RNA are false? RNA strands pair adenine with uracil instead of thymine Only DNA has directionality Only DNA can self replicate RNA is catalytic while DNA is not

Only DNA has directionality Only DNA can self replicate

The initiator tRNA attaches at the ribosome's _____ site.

P ** the initiator tRNA attaches to the ribosome's P site

Where does the peptide bond form between amino acids?

P site of the ribosome

translation

Process by which a polypeptide is synthesized from information in codons of messenger RNA

Which of the following accurately compares tumor suppressor genes and proto-oncogenes?

Proto-oncogenes code for growth factors, while tumor suppressor genes inhibit cell division of damaged cells.

RNA's Versatility

RNA can function as a catalytic molecule Ribozymes are enzyme-like RNAs RNA has a degree of structural and chemical complexity folding brings widely spaced nucleotides together at the active site of this catalytic RNA

Which of the following events in transcription initiation likely occurs last?

RNA polymerase binds to the promoter of the gene **RNA polymerase is recruited only when other transcription factors, including TBP, are assembled at the promoter.

What name is given to the process in which pre-mRNA is edited into mRNA?

RNA processing **RNA processing edits the RNA transcript that has been assembled along a DNA template.

The synthesis of a new strand begins with the synthesis of a(n) _____.

RNa primer complementary to a preexisting DNA strand

What enforces the G1 checkpoint?

Rb

When are cyclin levels highest in the cell?

Right before M-phase begins

During what phase of the cell cycle does the DNA become replicated?

S

During which phase in the cell cycle could point mutations be introduced in DNA such that they are passed on to future generations of cells?

S

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have -------.

T4 protein and T4 DNA

Which of these statements are false? Wobble pairing allows one anticodon to read multiple codons. The area upstream of the start codon where a ribosome binds to initiate translation is called the Shine-Dalgarno sequence. The 5' and 3' untranslated regions need to be spliced out with the introns aminoacyl-tRNA-synthetases add an amino acid to a tRNA

The 5' and 3' untranslated regions need to be spliced out with the introns

Chromatin

The complex of DNA and proteins, mainly histones, that compose eukaryotic chromosomes. Can be highly compact (heterochromatin) or loosely coiled (euchromatin)

Deoxyribonucleotides link together to form a polymer after a phosphodiester bond is formed between

The hydroxyl group of one deoxyribonucleotide and the phosphate group of another deoxyribonucleotide

replisome

The macromolecular machine that copies DNA; includes DNA polymerase, helicase, primase, and other enzymes.

dispersive replication

The parent molecule is cut into sections The daughter molecules contain old DNA interspersed with newly synthesized DNA

M phase

The phase of the cell cycle during which cell division occurs. Includes mitosis or meiosis and often cytokinesis.

A phosphodiester linkage occurs between?

The phosphate group on the 5' carbon of one nucleotide and the -OH group on the 3' carbon of another

double helix

The secondary structure of DNA, consisting of two antiparallel DNA strands wound around each other.

non-template strand (coding strand)

The strand of DNA that is not transcribed during synthesis of RNA. Its sequence corresponds to that of the mRNA produced from the other strand.

How are RNA hairpin turns related to transcriptional termination in E. coli?

The turns are formed from complementary base pairing and cause separation of the RNA transcript and RNA polymerase.

If cells did not have a functional topoisomerase what would occur?

There would be two much torsional strain ahead of the polymerase and the DNA would not be able to be unwound.

Alternative splicing allows

Two different species with the same number of genes to produce different numbers of proteins

You want to engineer a eukaryotic gene into bacterial colony and have it expressed. What must be included in addition to the coding exons of the gene?

a bacterial promoter sequence

sigma

a bacterial protein that associates with the core RNA polymerase to allow recognition of promoters

purine

a class of double-ringed nitrogenous bases [adenine (A), guanine (G)] found in nucleotides

Pyrimidines

a class of single-ringed nitrogenous bases [cytosine (C), uracil (U), thymine (T)] found in nucleotides

transcriptional activators (activators)

a eukaryotic regulatory transcription factor that binds to regulatory DNA sequences in enhancers or promoter-proximal elements to promote the initiation of transcription

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene?

a frameshift deletion at the beginning of the gene **A frameshift mutation at the beginning of a gene would affect every codon after the point where the mutation occurred. During protein synthesis, incorrect amino acids would be inserted from the point where the frameshift mutation occurred on; the resulting protein would most probably be nonfunctional. For this reason, a frameshift mutation at the beginning of a gene is generally the most severe type of mutation.

Holoenzyme

a general term for any multipart enzyme consisting of a core enzyme (containing the active site for catalysis) along with other proteins required for full function

chromatin remodeling complexes

a group of proteins that use energy from ATP hydrolysis to shift nucleosomes on DNA so as to expose regulatory sequences to, or hide them from, transcription factors

What is needed to start transcription?

a holoenzyme forming

ribosome

a large macromolecular machine that synthesizes proteins by using the genetic information encoded in messenger RNA. Consists of two subunits, each composed in ribosomal RNA and proteins

nucleic acid

a macromolecule composed of nucleotide monomers. Generally used by cells to store or transmit hereditary. information

proofreading

a mechanism for error correction during DNA synthesis in which a DNA polymerase recognizes and removes a wrong deoxyribonucleotide added during DNA replication and then continues synthesis

histone

a member of a class of positively charged (basic) proteins associated with DNA in the chromatin of eukaryotic cells

5' cap

a modified form of a guanine (G) nucleotide added onto the 5' end of eukaryotic mRNAs. Helps protect the mRNA from being degraded and promotes initiation of translation

inversion

a mutation in which a DNA sequence or a segment of a chromosome is flipped into the reversed orientation

point mutation

a mutation that results in a change in or an insertion or deletion of a single base pair in DNA

Based on the genetic code chart above, which of the following would be the result of this single base-pair substitution?

a nonsense mutation resulting in early termination of translation

silent mutation

a point mutation that changes the sequence of a codon without changing the amino acid that is specified

tumor supressor

a protein (or gene) that prevents cell division when conditions are unfavorable, such as when the cell has DNA damage. Defects in the function of tumor suppressors, such as p53 or Rb, are associated with the uncontrolled cell replication in cancer

intron

a region of a gene that is transcribed into RNA but is later removed.

What causes translation termination?

a release factor moves into the A site

How does Replication get started?

a replication bubble forms in a chromosome that is actively being replicated and grows as DNA replication proceeds because synthesis is bidirectional -in bacteria, the replication process begins at a single location the origin of replication -in eukaryotes also have bidirectional replication

codon

a sequence of three nucleotides in DNA or RNA that codes for an amino acid or a stop signal for protein synthesis

Imagine that you are studying the control of β-globin gene expression in immature red blood cells. (Mature red blood cells contain β-globin protein but lack a nucleus and, therefore, the β-globin gene.) If you deleted a sequence of DNA outside the protein-coding region of the β-globin gene and found that this increased the rate of transcription, the deleted sequence likely functions as ________.

a silencer

complementary strand

a strand of RNA or DNA with a base sequence that forms via complementary base-pairing with the template strand

parental strand (template strand)

a strand of preexisting DNA. The parental strand is used as a template during DNA synthesis

aminoacyl tRNA

a transfer RNA molecule that is covalently bound to an amino acid

p53 protein

a tumor suppressor protein (molecular weight of 53 kilodaltons) that responds to DNA damage by stopping the cell cycle, turning on DNA repair machinery, and, if necessary, triggering apoptosis. Encoded by the p53 gene

Rb protein

a tumor suppressor protein that helps regulate progression of a cell from G1 phase to S phase of the cell. Defects in Rb protein are found in many types of cancer

RNA replicases (RNA-dependent RNA polymerases) for RNA viruses

a viral enzyme that can synthesize RNA from an RNA template

promoter

a. short nucleotide. sequence in DNA that binds a sigma factor (in bacteria) or general transcription factors (in eukaryotes) to enable RNA polymerase to begin transcription. In bacteria, several contiguous. genes are often transcribed from a single promoter. In eukaryotes, each gene generally has its own promoter

Which of the following regulatory elements is not composed of DNA sequences?

activators **activators are proteins that are involved in transcription initiation

acetylation

addition of an acetyl group (-COCH3) to a molecule. Acetylation of histone. proteins is important in controlling. chromatin condensation

Which of the following bases are purines? Adenine and guanine Thymine and cytosine Adenine and thymine Cytosine and guanine

adenine and guanine

In the semiconservative replication of DNA, progeny DNA molecules consist of:

all molecules with one parental and one new strand

If genes were not regulated, then All your proteins would be transcribed from the same gene All your genes would be translated at once All your cells would make the same proteins All of the above

all of the above

Which of these is NOT a carcinogen?

all of the above are carcinogens

Polypeptides are assembled from _____.

amino acids **Proteins are composed of amino acid monomers.

What enzyme catalyzes the attachment of an amino acid to tRNA?

aminoacyl-tRNA synthetase

Transfer RNA (tRNA)

an L-shaped RNA molecule that has an anticodon at one end and an amino acid attachment site at the other Each tRNA carries a specific amino acid and binds to the corresponding codon in messenger RNA during translation

Ribosomal RNA (rRNA)

an RNA molecule that forms part of the ribosome

DNA helicase

an enzyme that breaks hydrogen bonds between nucleotides of DNA, "unzipping" a double-stranded DNA molecule

reverse transcriptase

an enzyme that can synthesize DNA from an RNA template

aminoacyl-tRNA synthetase

an enzyme that catalyzes the addition of a particular amino acid to its corresponding tRNA molecule

RNA polymerase

an enzyme that catalyzes the synthesis of RNA from ribonucleotides using a DNA template

DNA ligase

an enzyme that joins pieces of DNA by catalyzing the formation of a phosphodiester bond between the pieces

During translation, _ in tRNAs base pair with _ in the mRNA.

anti-condons; codons

Histone deacetylases (HDACs)

any of a class of eukaryotic enzymes that condense chromatin by removing acetyl groups from histone proteins

histone acetyltransferase (HAT)

any of a class of eukaryotic enzymes that loosen chromatin structure by adding acetyl groups to histone proteins

release factor

any of a class of proteins that trigger termination of translation when a ribosome reaches a stop codon

general transcription factors (basal transcription factor)

any of a class of proteins, present in all eukaryotic cells, that assemble on promoters and help RNA polymerase initiate transcription.

mutation

any permanent change in the hereditary material of an organism (DNA in most organisms, RNA in some viruses). The only source of new alleles in populations

regulatory sequence

any segment of DNA or RNA that is involved in controlling the expression of a specific gene or process such as RNA splicing by binding regulatory transcription factor protein or other proteins

Which of the following statements is not true? Mutations can:

are always harmful to an organism's health

A mutation in CDK that works at the G1 checkpoint can affect its ability to:

bind cyclin or phosphorylate Rb

What is the role of transcriptional activators? Work to stimulate transcription Bring chromatin-remodeling proteins to the correct location Both None of the above

both

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

complementary **Because the template strand determines the nucleotides to be added to the RNA strand, using the same complementarity rules of the DNA, they will be complementary to each other.

Nucleotides polymerize to form nucleic acids via

condensation reactions

DNA polymerases are enzymes that build DNA. They catalyze ____ reactions leading to the formation of ____ bonds.

condensation; phosphodiester

DNA's secondary structure

consists of two antiparallel strands twisted into a double helix the molecule is stabilized by hydrophobic interactions in its interior By hydrogen bonding between the complementary base pairs A-T and G-C

The specific sequence where RNA polymerase binds is called the

core promoter

What part of the cell would have high concentration of ribosomes?

cytoplasm

RNA interference (RNAi)

degradation of an mRNA molecule or inhibition of its translation following its binding by a short RNA whose sequence is complementary to a portion of the mRNA

Identify three possible components of a DNA nucleotide.

deoxyribose, phosphate group, thymine DNA and RNA have similar structures: a pentose sugar with a nitrogenous base and a phosphate group. DNA and RNA differ in the type of pentose sugar each possesses (DNA has deoxyribose; RNA has ribose) and in one base (DNA has thymine; RNA has uracil)

Meselson and Stahl

designed an experiment to provide more information about whether one of these hypotheses was correct. Results supported semiconservative DNA replication as the mechanism and explained how the hereditary material is duplicated DNA polymerase is the enzyme that catalyzes DNA

After DNA replication is completed, _____.

each new DNA double helix consists of one old DNA strand and one new DNA strand DNA replication is semiconservative.

Tumor suppressor genes ________.

encode proteins that help prevent uncontrolled cell growth

Which of the following regulatory DNA sequences might be located thousands of nucleotides away from the transcription start site of a gene?

enhancer **Enhancers can function thousands of nucleotides away from the promoter and transcription start site.

Forms of the Ras protein found in tumors usually cause which of the following?

excessive cell division

True or false? One possible way to alter chromatin structure such that genes could be transcribed would be to make histone proteins more positively charged.

false **The positive charge on histone proteins allows them to interact tightly with negatively charged DNA, thus inhibiting transcription. To disrupt this interaction, the histone proteins would have to be made more negatively charged.

True or false? Regulatory and basal transcription factors regulate transcription by binding to the promoter.

false **Basal transcription factors do indeed bind to the promoter, but regulatory transcription factors bind to promoter-proximal elements and enhancers.

p53 is a transcription factor because it:

has a DNA-binding domain

RNA's structure

has a tertiary structure which forms when secondary structure fold into more complex shapes functions as an information-containing molecule capable of self-replication RNA is intermediate between the complexity of proteins and the simplicity of DNA

The enzyme that breaks hydrogen bonds between complementary nitrogenous bases is called

helicase

The first step in the replication of DNA is catalyzed by _____.

helicase

leading strand. (continuous strand)

in DNA replication, the new strand of DNA that is synthesized in one continuous piece in a direction that follows the replication fork

splicesome

in eukaryotes, a large, complex assembly of snRNPs (small nuclear ribonucleoproteins) and many proteins that catalyzes removal of introns from primary RNA transcripts

poly(A) signal

in eukaryotes, a short sequence of nucleotides near the 3' end of pre-mRNAs that signals cleavage of the RNA and addition of the poly(A) tail

alternative splicing

in eukaryotes, the splicing of primary RNA transcripts from a single gene in different ways to produce different mature mRNAs and thus different polypeptides

promoter-proximal elements

in eukaryotic DNA, a regulatory sequence that is close to a promoter and can bind regulatory transcription factors

How would gene expression be affected if a cell is grown with compounds that prevent DNA deacetylation?

increased transcriptional activity

The product of the p53 gene _____.

inhibits the cell cycle

______ are removed from the pre-mRNA sequence of __________.

introns; eukaryotes

During RNA splicing, ____ are removed from the primary transcript by the __.

introns; spliceosome

Part complete What happens to RNA polymerase II after it has completed transcription of a gene?

it is free to bind to another promoter and begin transcription

Which is not a property of the genetic code? It is redundant Is is universal It is semiconservative It is unambiguous

it is semiconservative correct statement it is conservative

Angiogenesis is important for metastasis of cancer cells because:

it provides a mode of transport for the spread of the cells

The defining characteristic of a malignant tumor is that _____.

its cells can spread to other parts of the body and procedure secondary tumors

Would primase have more activity on the leading or lagging strand?

lagging strand lagging has multiple

What would be the consequence(s) for DNA synthesis if DNA ligase were defective?

lagging strand synthesis would be incomplete; leading strand synthesis would be largely unaffected **Without DNA ligase activity, Okazaki fragments on the lagging strand would not be joined together; leading strand synthesis would be largely unaffected.

p53 is considered a tumor suppressor protein because the action of this protein:

leads to cell cycle arrest

Short segments of newly synthesized DNA are joined into a continuous strand by _____.

ligase

Codons are part of the molecular structure of _____.

mRNA

Which type of RNA is produced when RNA polymerase transcribes a protein-coding gene?

mRNA

RNA processing converts the RNA transcript into _____.

mRNA **the editing of the RNA transcript produces mRNA

What amino acid sequence will be generated, based on the following mRNA codon sequence?5' AUG-UCU-UCG-UUA-UCC-UUG 3'

met-ser-ser-leu-ser-leu

Which of the following terms describes the DNA-protein complexes that look like beads on a string?

nucleosome **The "beads on a string" appearance of nucleosomes comes from the wrapping of DNA around a core of eight histone proteins.

How do nucleotides polymerize to form nucleic acids?

nucleotides polymerize via condensation reactions between the hydroxyl on the sugar component of one nucleotide and the phosphate group of another nucleotide Phosophodiester linkage occurs between the phosphate group on the 5' carbon of one nucleotide and the -OH group on the 3' carbon of another joins ribonucleotides -RNA joins deoxyribonucleotides - DNA

The sugar-phosphate backbone is directional

one end has an unlinked 5' carbon the other end has an unlinked 3' carbon 5' to 3' direction since RNA and DNA are always synthesized in this direction and nucleotides are added only at the 3' end of a growing nucleic acid molecule reflects the order that nucleotides are added to a growing molecule the nucleic acid's primary structure is the nucleotide sequence

DNA does not store the information to synthesize which of the following?

organelles **synthesis of organelles is not directly coded in the DNA

If a cell has accumulated DNA damage, it is unlikely to _____.

pass the G2 checkpoint

DNA ligase links Okazaki fragments by creating a ________ bond between DNA fragments

phosphodiester

Which is not a major way to remodel chromatin?

phosphorylation

Which of the following helps to prevent degradation of the mRNA?

polyA tail

RNA structure and function

primary structure consisting of a sugar-phosphate backbone formed by phosphodiester linkages RNA contains uracil instead of thymine RNA contains ribose instead of deoxyribose - the presence of -OH group on ribose makes RNA much more reactive less stable than DNA

The cancer-causing forms of the Ras protein are involved in which of the following processes?

relaying a signal from a growth-factor receptor

The action of helicase creates _____.

replication forks and replication bubbles **A replication fork is the transition region between paired and unpaired DNA strands.

RNA secondary structure

results from complementary base pairing bases of RNA typically form hydrogen bonds with complementary bases. on the same strand the RNA strand folds over, forming a hairpin structure -the bases are on one side of the fold -the bases align with an antiparallel RNA segment on the other side of the fold

How does DNA replicate?

semi conservatively the primary structure serves as a mold or template for the synthesis of a complementary strand complementary base pairing 1) separation of the double helix 2) hydrogen bonding of deoxyribonucleotides with complementary bases on the original template strand 3) phosphodiester bond formation between the deoxynucleotides to form the complementary strand

The reason for differences in the sets of proteins expressed in a nerve and a pancreatic cell of the same individual is that nerve and pancreatic cells contain different _____.

sets of regulatory proteins

How is the helix opened and stabilized?

several proteins are responsible for opening and stabilizing the double helix: enzyme helicase catalyzes the breaking of hydrogen bonds between the two DNA strands to separate them -single stranded DNA-binding proteins attach to the separated strands to prevent them from closing unwinding the DNA helix creates tension farther down the helix Enzyme topoisomerase cuts and rejoins the DNA -downstream of the replication fork and relieving this tension in the helix

Okazaki fragments

short segment of DNA produced during replication of the lagging-strand template. The Okazaki fragments are eventually linked together to. produce the lagging strand in newly synthesized DNA

Which one of the following mutations that may result from inhaling Benzopyrene will not have a negative impact on cell division?

silent

Which point mutation can result in the same translation of the RNA sequence?

silent

Which of the following is not a point mutation? Silent Missense Nonsense Specific

specific

An old DNA strand is used as a _____ for the assembly of a new DNA strand.

template **an old DNA strand is used as a template for the synthesis of a complementary new. strand

What strand is bound to the RNA polymerase and participates in complementary base pairing?

template strand

start codon

the AUG triplet in mRNA where protein synthesis begins; codes for the amino acid methionine

replication fork

the Y-shaped site where a double-stranded molecule of DNA is separated into two single strands for replication and on which DNA synthesis occurs

frameshift mutation

the addition or deletion of one or a few base pairs in a coding sequence that shifts the reading frame of the mRNA

The tRNA shown above has its 3' end projecting beyond its 5' end. What will occur at this 3' end?

the amino acid binds covalently

A mutation occurs that reduces the effect of an enhancer for a gene. As a result, which of the following will be reduced?

the amount of protein produced at the end of translation

The leading and the lagging strands differ in that _____.

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

sister chromatids

the paired, double-stranded DNA copies of a recently replicated chromosome. They are connected most tightly at the centromere and eventually separate during anaphase of mitosis or meiosis !!

conservative replication

the parental molecule serves as a template for the synthesis of an entirely new molecule

S phase

the phase of the cell cycle during which DNA is synthesized for the replication of chromosomes

G1 phase

the phase of the cell cycle that constitutes the first part of interphase, before DNA synthesis (S phase)

G2 phase

the phase of the cell cycle. between. synthesis of DNA (S phase) and mitosis (M phase); the last part of interphase

interphase

the portion of the cell cycle one M phase and the next. Includes G1 phase, S phase, and G2 phase

splicing

the process by which introns are removed from primary RNA transcripts and the remaining exons are connected together

chromatin remodeling

the process by which the structure of chromatin is changed to allow or inhibit transcription. May involve chemical modification of histone proteins or reshaping of the chromatin by large multiprotein complexes in an ATP-requiring process

Transcription

the process that uses a DNA template to produce a complementary RNA

Which of the following statements best describes the promoter of a protein-coding gene?

the promoter is a non transcribed region of a gene **The promoter is the regulatory region of a protein-coding gene at which RNA polymerase must bind to initiate transcription—it is not transcribed into the RNA.

Which of the following is an example of post-transcriptional control of gene expression?

the removal of introns and alternative splicing of exons

anticodon

the sequence of three base (a triplet) in a transfer RNA molecule that can bind to an mRNA codon with a complementary sequence

genetic code

the set of all codons and their meanings

Transcription begins at a promoter. What is a promoter?

the site in the DNA that recruits the RNA polymerase

A frameshift mutation would have the worst effect at

the start of the nucleotide sequence

semiconservative replication

the way DNA replicates, with each strand of an existing DNA molecule serving as a template to create a new complementary DNA strand

BRCA1 and BRCA2 are considered to be tumor suppressor genes because ________.

their normal products participate in repair of DNA damage

What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?

their phosphate groups

Hereshy and chase

they grew the virus in the presence of one of two radioactive isotopes, 32P and 35S and were used to infect E. coli cells Hypothesized that if genes consists of DNA: then the radioactive DNA would be found inside the cells, while radioactive proteins would be found only in the ghosts outside of the cells. If genes consisted of proteins then only radioactive protein would be found inside of the cells Results: the radioactive protein was found in the ghosts, the radioactive DNA was found in the cells, supported that DNA and not protein has the genetic material

Different types of cells express different genes primarily because

they have different transcription factors

Characteristics of DNA polymerase

they work in one direction 5' to 3' direction DNA polymerases can add deoxyribonucleotides to only the 3' end of a growing DNA chain exergonic

When a cytosine base pairs with a guanine ____________________ are formed between the two bases.

three hydrogen bonds adenine and thymine have two hydrogen bonds

In E. coli, what is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

What is the function ubiquitin?

to destroy proteins and stop gene expression

What is the process called that converts the genetic information stored in DNA to an RNA copy?

transcription **DNA is transcribed to give an RNA copy.

What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?

transcription **Transcription is the process by which a DNA template is used for the manufacture of several different types of RNA.

The process of going from DNA to mRNA is called _________ while going from mRNA to protein is called ___________.

transcription; translation

What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?

translation **Translation is the process by which information encoded in RNA is used to manufacture a polypeptide.

Regulatory proteins that prevent a cell from entering the S phase under conditions of DNA damage are also known as _____.

tumor suppressors

Alleles are:

two versions of the same gene