Basics of Molecular Biology

How many rounds of DNA Replication were needed to disprove the Conservative method?

1; After the first round Meselson and Stahl were able to see mixed strands of DNA, containing both N-15 and N-14 DNA.

How many basic types of nucleic acids exist? 1 2 3 4 Sugar

2

How many subunits make up the ribosome complex?

2; The ribosome is a special protein that is built to accept the mRNA strand. It actually has two different parts, with one part roughly twice as big as the other.

he sugar end of the DNA strand is referred to as the _____ end and the phosphate end is referred to as the _____ end. 3' ; 5' 5' ; 3' top ; bottom hydrogen ; polynucleotide Covalent

3' ; 5'

Lysis happens when: A bacteria swells with viruses and bursts. A bacteria lands on a virus. Viral DNA is integrated into bacterial DNA. A temperate bacteriophage infects a bacteria.

A bacteria swells with viruses and bursts.

What is the basic structure of a purine? A chain of nitrogenous bases A single ring of carbon, hydrogen and nitrogen A double ring formed from carbon, hydrogen and nitrogen A single ring formed from carbon, hydrogen, oxygen, and chlorine

A double ring formed from carbon, hydrogen and nitrogen

An example of a transversion mutation is _____. An adenine substituted for a guanine. A cytosine substituted for a thymine. A guanine substituted for a thymine. A thymine substituted a cytosine. any other nitrogenous base

A guanine substituted for a thymine.; A transversion is when you switch a purine with a pyrimidine, or vice-versa.

What kind of mutation causes sickle-cell anemia?

A missense mutation that switches one amino acid in the chain for another. A missense mutation is a point mutation that changes a codon to indicate a different amino acid. This usually changes the polypeptide and therefore can change the function of the overall protein.

A nucleic acid monomer is called: Ribose A nucleosome A nucleoside A nucleotide Deoxyribose

A nucleotide

Which type of mutation does NOT change the overall function of the protein?

A silent mutation; A point mutation that has no overall effect on a protein's function is called a silent mutation. Sometimes a silent mutation results in the same exact sequence of amino acids.

A phosphodiester bond links: A sugar to another sugar A nitrogenous base and another nitrogenous base A nitrogenous base and a phosphate group A sugar and a phosphate group A sugar and a nitrogenous base

A sugar and a phosphate group

What is a nonsense mutation?

A type of mutation results in an incomplete polypeptide because of an early stop signal. A point mutation that turns one codon into a stop codon. Nonsense mutations always result in the early termination of a polypeptide.

Which of the following modifications of this DNA sequence, ACTGAC, would be considered a frameshift mutation? ACTGAT ACAGAC AGTGAC ACCTGAC

ACCTGAC

Based on the original sequence, ACTTGAC, which of the following answer choices includes a transition mutation? ACTTGGC ACTTGTC ACTTTAC ACTTCAC base substitutions

ACTTGGC; Transitions are base substitutions that swap a purine for another purine or a pyrimidine for another pyrimidine.

Which of the following statements is true? Adenine forms hydrogen bonds with thymine. Adenine forms carbon bonds with thymine. Cytosine forms hydrogen bonds with adenine. Cytosine forms carbon bonds with guanine. Cytosine forms two hydrogen bonds with guanine.

Adenine forms hydrogen bonds with thymine.

Which is the correct base pairing in DNA? Adenine with guanine, cytosine with thymine Adenine with thymine, cytosine with guanine Adenine with uracil, cytosine with guanine Adenine with cytosine, guanine with thymine

Adenine with thymine, cytosine with guanine; Purines and pyrmidines always pair up. Since adenine and guanine are both purines, they would not pair up with each other. Adenine pairs up with the pyrimidine thymine, while cytosine pairs with guanine. Uracil is only found in RNA, so it would not pair with adenine in DNA molecules.

Which is the correct base pairing in RNA? Adenine with guanine, cytosine with thymine Adenine with thymine, cytosine with guanine Adenine with uracil, cytosine with guanine Adenine with cytosine, guanine with thymine

Adenine with uracil, cytosine with guanine

Plasmids can be found in hosts in the ______ domain(s). Bacteria Archaea Eukarya All of the above

All of the above

A type of point mutation that alters the length of the DNA strand is _____.

An insertion or deletion.

_____ is used to describe a mutation in which one nitrogenous base is replaced by another.

Base substitution

Which of the following DNA binding motifs attaches to E-box sequences in DNA? Basic helix loop helix Leucine zipper Positively charged amino acids Finger and thumb domains

Basic helix loop helix; Basic helix loop helix proteins contain two domains. The basic domain attaches to E-box sequences in DNA while the helix loop helix domain can attach to other transcription factors to form complexes.

Why do we call DNA an antiparallel molecule?

Because the 3' and 5' ends of each strand run in opposite directions.

How do mutagens cause mutations?

By increasing the likelihood of a replication error

Which of the following cells might have the most mitochondria? Bacterium Skin cell Cardiac muscle cell None of these cells have mitochondria

Cardiac muscle cell; A cell can have one to thousands of mitochondria depending on how much energy it needs. A muscle cell needs a lot more energy than a skin cell.

The combination of multiple histones and DNA is called what?

Chromatin

Through what process does a plasmid commonly use to transfer its DNA to another cell host?

Conjugation

Describe the structure of nucleic acids (nucleotides).

Contain N in rings; nucleotides are made of sugar, phosphate, and nitrogenous bases.

What is the enzyme that attaches daughter nucleotides to the parent strand during DNA replication?

DNA Polymerase; DNA polymerase is an enzyme that helps put together the small parts of the DNA molecule. Those small parts, of course, are the nucleotides.

What enzyme is in charge of unwinding the DNA double helix?

DNA helicase; The first step occurs when DNA helicase unwinds the double helix by breaking the hydrogen bonds between the parent strands of DNA. This splitting and unwinding process opens up the DNA molecule into a Y-shape, which we call the replication fork.

Which enzyme is responsible for binding Okazaki fragments together?

DNA ligase is the enzyme that binds adjacent Okazaki fragments on the lagging strand, resulting in a continuous daughter strand where DNA polymerase had worked in a discontinuous fashion.

Which enzyme checks DNA for errors?

DNA polymerase

Why can't DNA polymerase work continuously on both parent strands?

DNA polymerase only works in the 3' to 5' direction. The leading strand's free end is a 3' end, and the end that's nearest to the replication fork is the 5' end. So, DNA polymerase can simply start at the free end, working in the 5' to 3' direction, and run continuously toward the replication fork.

Which of the following forms the backbone of a DNA molecule? Ribose and a nitrogenous base Deoxyribose only Deoxyribose and a nitrogenous base Deoxyribose and a phosphate group Deoxyribose and ribose

Deoxyribose and a phosphate group

Which of the following bases are categorized as purines? Thymine and adenine Thymine, cytosine and uracil Guanine, adenine and uracil Guanine and cytosine Guanine and adenine

Guanine and adenine; The double-ring bases, adenine and guanine, are called purines.

_____ is a protein that plays a central role in DNA folding.

Histone

Which of the following DNA-binding proteins is used to store DNA? Histones NeuroD1 Helicase DNA polymerase I

Histones

Which of the following roles in the cell could non-coding DNA perform? I. Provide structural support at the end of chromosomes. II. Encode a protein that will play a significant role in cell division. III. Serve functional purposes.

I and III

Place the following terms in order building out from the most basic informational subunit to the entire genetic unit: I. Chromosome II. DNA III. Chromatin IV. Nucleosome

II, IV, III, I DNA → nucleosome → chromatin → chromosome. We start with DNA, which is organized into nucleosomes. These are the subunits of chromatin. This information is further organized into chromosomes.

Which of the following is a primary function of a nucleic acid? I. Structural support II. Storage of information III. Energy storage

II. Storage of information

Where are hydrogen bonds located within the DNA?

In the center of the molecule linking the nitrogen bases of both strands.

Bacteriophages successfully make bacteria replicate them because they: Inject their own DNA into the bacteria, brainwashing the bacteria Attack the bacteria and kill it Take the bacterial DNA out and use it themselves Always destroy their host

Inject their own DNA into the bacteria, brainwashing the bacteria

Which type of mutations can result in a frameshift?

Insertions and deletions

Why is it necessary that the DNA helicase unwinds the DNA?

It exposes the nitrogenous bases of the nucleic acid chain so that new nucleotides can be added to create the daughter strand. DNA helicase is an enzyme that unwinds the DNA double helix by breaking the hydrogen bonds between the complementary bases.

A bacteriophage infects a bacteria with the purpose of:

Reproduction

R plasmids contain genes that confer ______ to the host.

Resistance

Why do people try to protect their skin from ultraviolet radiation?

UV radiation is a mutagen. UV radiation is just one of many mutagens that exist in our environment. Other mutagens include X-rays, extreme heat, or chemicals that react with DNA molecules.

Which of the following is NOT one of the nitrogenous bases found in DNA? Guanine Thymine Adenine Cytosine Uracil

Uracil

Which type of bacteriophage destroys its host? Virulent Temperate Lysogenic Lambda

Virulent

Because hydrogen bonds are weak bonds, they create a perfect site for _____. separating nucleic acid strands attaching a helicase enzyme attaching a phosphodiester bond separating amino acid strands separating fatty acid strands.

separating nucleic acid strands; Hydrogen bonds are generally weaker than all the other bonds in the molecule, so this is a perfect spot to start separating the nucleic acid strands.

The Dispersive method of DNA Replication was disproved when the scientists observed... two separate bands of DNA of different densities. one band of DNA of intermediate density. three separate bands of DNA of different densities. one band of DNA of highest possible density. one band of DNA of lowest possible density.

two separate bands of DNA of different densities; The Dispersive method suggests that DNA would be copied in short chunks, resulting in half of the parent DNA being lost with each cycle. The parent strand did not get broken up with each cycle, disproving the theory.

How do different cells within our body do different jobs if they all have the same DNA? Different cells express different transcription factors. Different cells change their DNA as they differentiate. Different cells do express all of the same proteins, but some are destroyed later. Different cells express the same transcription factors but different variants of RNA polymerase.

Different cells express different transcription factors. All cells in our body have the same DNA. However, we have many types of cells in our body that express different proteins to do different jobs. The way the cell accomplishes this is through transcription factors. Transcription factors turn on or off certain genes, and thus if cells need to do different jobs they express different transcription factors and make different proteins.

What is the structure of plasmid DNA?

Double-stranded circular

What disease is caused by deletion of a nucleotide base from the dystrophin gene?

Duchenne Muscular Dystrophy

What is the cristae in a mitrochondria?

Folds created by the inner membrane

What are mutations that result in DNA sequences that are slightly too long or too short called?

Frameshift mutation; Frameshift mutation occurs when one base is added or removed.

point mutation

Gene mutation involving changes in one or a few nucleotides at a single location in a DNA sequence.

The process by which a bacteriophage integrates its own DNA with the bacterial DNA and passes it to future generations is called:

Lysogeny

Where is DNA located in the mitochondria?

Matrix; The matrix contains enzymes for cellular respiration as well as its own ribosomes and DNA needed to create some of the proteins important for this process.

Who performed the experiment that proved semi-conservative DNA replication was correct?

Matthew Meselson and Franklin Stahl

What kind of organism was used to investigate the method of DNA Replication?

Meselson and Stahl used E. coli bacteria that contained only N-15 DNA.

What is a mutagen?

Mutagens are any chemical or physical agents that cause a mutation in an organism's DNA. Mutagens are typically found in an organism's environment

In the Meselson-Stahl experiment, why does N-15 DNA sink to a lower level than N-14 in a centrifuge tube?

N-15 DNA has a higher density than N-14 DNA. The extra neutron in N-15 puts one extra piece to the DNA strand. That extra weighs more than the N-14, which does not contain it. The N-15 strands that paired with N-14 strands still sank lower than the N-14 only strands, but not as low as the N-15 only strands.

How is the N-15 isotope different from the N-14 atom?

N-15 has one extra neutron.

Which of the following is an example of a transcription factor? NeuroD1 DNA polymerase I Histones Topiosomerase

NeuroD1; NeuroD1 is a transcription factor that controls different genes depending on the cell it is expressed in. It is particularly important for development of the nervous system and insulin production by the pancreas during development.

What are the small components (monomers) that make up the large DNA polymer?

Nucleotides

Agrobacterium tumefaciens is unique bacteria in that it can transfer its plasmid DNA to ______

Plants

What is this molecule?

Pyrimidine

What is the enzyme that builds the RNA Primer?

RNA Primase

The deletion of a base in the DNA strand will _____. Not alter the mRNA strand but will result in a modification to the subsequent amino acid. Not alter the mRNA but will result in the removal of the subsequent amino acid. Result in the deletion of a base in the mRNA strand and a modification to the subsequent amino acid. Result in the deletion of a base in the mRNA strand and the removal of the subsequent amino acid.

Result in the deletion of a base in the mRNA strand and a modification to the subsequent amino acid.

Which does NOT describe the inner membrane of the mitochondria? Impermeable Selectively permeable Folds to create cristae Contains components for cellular respiration Interior to the outer membrane

Selectively permeable

Part of a normal DNA sequence is TACCGG. If this sequence undergoes a base substitution, out of the possibilities given identify the sequence that could be a possible result. TACCGG TACAGG TACGG TACCGGA None of the answers are correct.

TACAGG; A base substitution swaps one base for another one without changing the reading frame of a DNA sequence.

What disease can occur when a short nucleotide sequence is inserted into the hexosaminidase gene?

Tay Sachs

In which method of DNA Replication would all parent DNA be conserved in the original molecule?

The conservative model states that DNA didn't split open at all, but somehow kept the parent strands intact while creating an entirely new and separate copy.

In which method of DNA Replication would new DNA consist of alternating parent and daughter DNA?

The dispersive model, suggested that DNA only copied itself for short chunks at a time, producing new strands that alternated parent and daughter DNA.

Which of the parent DNA strands is replicated discontinuously?

The lagging strand is the parent strand which runs in the 5' to 3' direction toward the fork, and it's replicated discontinuously.

Which is the strand that replicates just as quickly as the replication fork opens up?

The leading strand

How does a frameshift mutation in the gene coding for the enzyme, hexosaminidase A, result in Tay-Sachs disease?

The mutation results in incorrect synthesis of the enzyme.

The location where the process of DNA replication begins is called the _____.

The origin of replication is the place where the process of DNA replication begins. As the helicase moves down the length of the strand, the replication fork moves along in its wake.

What happens to the RNA primer once DNA replication is begun by DNA polymerase?

The primer is removed. The RNA primer isn't needed anymore once DNA polymerase is doing its job. So, it actually gets removed, and later, DNA polymerase will come back around and make sure that spot is filled in with DNA.

How would a shift in the reading frame likely alter the resulting protein? The protein would be greatly altered because multiple amino acids would be miscoded. The protein would be only slightly altered because a single amino acid would be miscoded. The protein would be not be altered because the reading frame does not affect the resulting protein. Any alteration to the reading frame would prevent the protein from being formed. Frameshifts are less common than base substitutions.

The protein would be greatly altered because multiple amino acids would be miscoded.

Why do DNA strands need to be antiparallel? The strands need to run in opposite directions for hydrogen bonding to work. This is false; DNA strands need to be parallel. Both strands need to have sugars at the top and phosphates at the bottom. DNA needs to have sides. DNA is composed of two strands.

The strands need to run in opposite directions for hydrogen bonding to work. Complementary base pairing works like a lock and key, so there's only one orientation in which hydrogen bonding will work. If you try to orient the two strands parallel to each other, the sugar ends of the polynucleotides are both at one end and the phosphate groups are at the other end. However, the nitrogenous bases can't hydrogen-bond in this orientation.

Which word part is used to designate that a molecule is an enzyme?

The suffix '-ase'

The replication of DNA is a complex process; all of the following statements are correct, EXCEPT On the lagging strand, one RNA primer is required for the beginning of every Okazaki fragment. There is one replication fork in one replication bubble. DNA replication is considered to be a semiconservative process. In order to complete replication, the replication bubbles grow and merge together.

There is one replication fork in one replication bubble. While every replication fork consists of a leading and lagging strand, each fork is actually joined to another fork in the form of a replication bubble.

How does DNA polymerase bind DNA? Through three domains, the palm, fingers and thumb Through E-box sequences near promotor regions on DNA Using basic helix loop helix domains Through positively charged amino acids which attract the negatively charged sugar phosphate backbone on DNA

Through three domains, the palm, fingers and thumb

Which of the following BEST explains the role of DNA polymerase? To assemble daughter nucleotides on the parent strand. To unwind the DNA double helix. To build the RNA primer. To join the adjacent Okazaki fragments. To assemble strands of RNA nucleotides.

To assemble daughter nucleotides on the parent strand. DNA polymerase is the enzyme that matches and lays down nucleotides to build the daughter DNA strand along each parent DNA strand.

What is the purpose of the RNA primer?

To initiate the process of DNA replication. A RNA primer is a short polynucleotide segment that primes, or prepares, the way for DNA replication by helping DNA polymerase to get started in doing its job. The job of RNA primase is to make, or synthesize, a primer for replication to start.

What type of molecule is released during the formation of a peptide bond?

Water; When two amino acids are lined up side by side, one of them gives up a hydrogen molecule, and the other gives up an oxygen and a hydrogen. The two hydrogens and one oxygen form H2O, or water. The water molecule leaves, and the amino acids are stuck together.

When can a genetic mutation get passed down through successive generations?

When it doesn't cause significant harm to the organism's ability to survive and reproduce. If a mutation doesn't cause significant harm, then it may be passed down through successive generations. Over time, the mutation may become more and more common, until it becomes the 'new normal.

Using the given information, determine the correct order of the following events during the replication of the lagging strand. a. The DNA double helix unwinds. b. The Okazaki fragments are joined. c. The RNA primase builds an RNA primer on the parent strand. d. Nucleotides are added and matched to the parent strand.

a, c, d, b; The correct order is The DNA double helix unwinds, then the RNA primase builds an RNA primer on the parent strand. Next the Nucleotides are added and matched to the parent strand, and finally the Okazaki fragments are joined.

Which is NOT a component of a nucleotide? sugar phosphate base acid

acid

The nucleotide that is a major form of energy storage in the cell is: adenosine triphosphate (ATP) guanine DNA ribose

adenosine triphosphate (ATP)

The sugar in DNA's nucleotides is: ribose deoxyribose oxyribose pentose

deoxyribose

A discrete unit of DNA that produces a protein that provides the functionality a cell needs is _____.

gene; A gene is a distinct unit of DNA that can code for RNA, and in turn, that RNA can make protein.

Phosphate bonds are important because they are weak never broken high energy ionic

high energy

What part of the mitochondria creates more space for cellular respiration?

inner membrane

A mutation in DNA can affect the amino acid sequence because it affects the code found in _____. mRNA tRNA rRNA the nucleus the fatty acid chain

mRNA

Which two types of nucleic acids move into the ribosome during translation?

mRNA and tRNA

A molecule that contains nitrogen and has the chemical properties of a base is called a(n) _____. organic base nitrogenous base elemental base base

nitrogenous base

Adenine and thymine are examples of this component of a nucleotide: nitrogenous base sugar phosphate backbone

nitrogenous base

A polymer of nucleotides is known as a: nucleic acid hydrochloric acid protein deoxyribose

nucleic acid