BSC 170 Test 2 Review - 9/30

How polymerization of nucleotides results in nucleic acids

By joining pentoses with phosphodiester bonds between carbon #3 of one nucleotide and carbon #5 of the subsequent nucleotide, nucleic acids are polymerized

How many hydrogen bonds are generated when complementary base pairs are present?

When coupled, cytosine and guanine will form three hydrogen bonds

When combined, adenine and thymine will form two hydrogen bonds

Structure differences between RNA and DNA

RNA: Pentose is ribose, the second pyrimidine is uracil, it is a lone stranded composition, and reduces its stability over time

DNA: Pentose is deoxyribose, the second pyrimidine is thymine, and double-stranded antiparallel strands are joined by base-to-base hydrogen bonds

What is the structure of DNA’s two strands?

The DNA strands are antiparallel to one another

One's 5' end and the other's 3' end are matched

What are three parts of a nucleotide?

A 5-carbon sugar in the middle, a nitrogenous base, and three phosphates arranged in a chain

Who are the researchers who delineated the composition of DNA?

Wilkins, Watson, and Crick

What is meant by DNA replication that is semiconservative?

During double helix replication, each daughter molecule has one freshly created strand and one old strand that is "conserved" from the parent molecule

How does DNA’s structure facilitate its own replication?

Specific base pairing raises the possibility that genetic material will be copied

Replication forks

Where helicase unwinds the double helix

Single strand DNA

Is bound to a single-strand binding protein, which stabilizes it so that it can be utilized as a template

Topoisomerase

Breaks, swivels, and rejoins DNA strands to relieve "unwinding" strain prior to replication forks

5' end of the leading strand and the Okazaki fragment to the lagging strand

Primase synthesizes an RNA primer

DNA polymerase III

Synthesizes new DNA strands by covalently appending nucleotides to the 3' end of pre-existing DNA strands or RNA primers, utilizing parental DNA as a template

DNA polymerase I

Substitutes DNA nucleotides for the primer's RNA nucleotides at the 5' end

DNA ligase

Connects Okazaki fragments of the lagging strand and the 3' end of DNA that replaces the primer to the remainder of the leading strand

The distinction between the strand synthesis of the leading and lagging strand

The leading strand of the response involves continuous replication

The lagging strand requires DNA polymerase to function in a direction away from the replication fork

DNA polymerase's primary enzymatic function

To catalyze the elongation of newly synthesized DNA at a replication fork

What do the majority of DNA polymerases need?

The majority of DNA polymerases need a DNA template strand and a primer

What are the replication origins?

The point at where the two DNA strands split apart, creating a replication "bubble"

Step 1 of transcription (initiation)

RNA polymerase binds to a specific sequence on the DNA, known as the promoter, which signals the start of transcription of a gene

The DNA double helix unwinds, allowing the RNA polymerase to access the DNA template strand

Step 2 of transcription (elongation)

RNA polymerase moves along the template strand of the DNA in the 3' to 5' direction

It reads the DNA sequence and synthesizes a complementary mRNA molecule by adding nucleotides that code for RNA

Step 3 of transcription (termination)

RNA polymerase continues to read the DNA until it reaches a specific DNA sequence called the terminator

Upon reaching the terminator sequence, the RNA polymerase detaches from the DNA, and the completed mRNA transcript is released

What function do promoters serve in transcription?

Promoters indicate that RNA synthesis has begun

Three stages of eukaryotic mRNA maturation or modification

A modified nucleotide 5' cap is applied to the 5' end

A poly-A tail is added to the 3' end

RNA splicing: introns are precisely removed, and the remaining exons are joined together to create a continuous coding sequence

Which DNA location will RNA Polymerase attach to for starting transcription?

The promoter region

Which of the following describes an abnormal process in eukaryotic RNA modification?

Stop codon addition

Regarding RNA splicing, which of the following propositions is true?

In the mRNA, exons are joined and introns are eliminated

What feature is common to DNA regions that will be split apart during transcription initiation?

An A-T-rich sequence is a common feature of promoter regions, the sites where transcription begins

In prokaryotes, the sequence has the consensus sequence TATAAT, and it is typically located about 10 base pairs upstream of the transcription start site 

RNA polymerase gets directly attached to sequences in the promoter region

In eukaryotes, the sequence is called the TATA box, and it is usually located 25 to 35 base pairs upstream of the transcription start site

The TATA-binding protein recognizes and binds to this site, which is the first step in assembling the transcription pre-initiation complex and recruiting RNA polymerase

Which of the following best describes the transcription-initiation mechanisms of prokaryotes and eukaryotes?

While eukaryotes form an initiation complex of many proteins that engages RNA Polymerase, prokaryotes drive initiation with particular DNA sequences in the promoter

How is the right amino acid transported to the ribosome's A site?

It is retained by a tRNA molecule with an anticodon corresponding to the mRNA's A site codon

Which of the following codons for methionine initiation is correct?

AUG

What's at the ribosome's P site for the great majority of the time during translation elongation?

A tRNA molecule that is part of an expanding protein chain

What is the name of the intricate structure found in cells that puts proteins together?

Ribosome

How does the translation process end?

A terminator protein reaches the A site and causes the ribosome to disintegrate when a stop codon is present (UAA, UAG, or UGA)

What is the name of the procedure that creates RNA from the information found in DNA?

Transcription

Which enzyme is responsible for transcription?

RNA polymerase

Given that the tRNA linked to this amino acid is used to initiate translation, which amino acid is found at the amino terminus of the great majority of proteins?

Methionine

Which of the following describes an RNA type that is NOT involved in protein assembly?

dRNA

What is the name of the mechanism that uses information from mRNA to assemble a particular protein?

Translation

If one strand of a brief, double-stranded DNA molecule has the following sequence: 5' CCCCAAAT 3'

What is the total number of hydrogen bonds that connect the two strands?

20 hydrogen bonds

If one strand of a brief, double-stranded DNA molecule has the following sequence: 5' ATTTCCGAAT 3'

What is the total number of hydrogen bonds that connect the two strands?

23 hydrogen bonds

Hydrogen bonds for cytosine (C) and guanine (G)

3 hydrogen bonds

Hydrogen bonds for adenine (A) and thymine (T)

2 hydrogen bonds

Of the following, which is true in terms of both DNA and RNA?

They are both made of nucleic acids

What unique location is the first nucleotide introduced to a nucleic acid?

Transcription initiation site

Which of the following claims about purines and pyrimidines is true?

Purines have two rings, whereas pyrimidines have one

Which of the following nucleotides DOESN'T often make up RNA?

Thymine

Which specific kind of link connects the nucleotides in a nucleic acid?

Connections between carbon 3 and carbon 5 through phosphodiester

DNA nucleotides

Deoxyribose (sugar), nitrogenous bases are adenine (A), guanine (G), cytosine (C), and thymine (T) in DNA

RNA nucleotides

Ribose (sugar), nitrogenous bases are adenine (A), guanine (G), cytosine (C), and uracil (U)

Which pentose carbon does the phosphate bond to in a nucleotide?

carbon 5

Because of their polarity, nucleic acids allow us to distinguish between their two ends. In terms of the polarity of nucleic acids, which of the following propositions is true?

The 5' end is always where the first nucleotide is inserted.

With regard to adenine and guanine, which of the following is true?

Both have a structure of 2 ring

What type of mechanism holds the two strands of DNA together?

The bases' hydrogen bonds

Regarding typical base pairing in double-stranded DNA, which of the following propositions is true?

Every base pair will be found between a pyrimidine and a purine base

When DNA replicates, which enzyme creates the majority of the new strand's DNA?

Third-generation DNA polymerase

Where might you anticipate discovering fragments of Okazaki?

On each replication fork's trailing strand

What kind of mutation results in an altered nucleotide but leaves the resulting protein's amino acid sequence unchanged?

Quiet/silent mutation

Skin cancer is associated with intense solar exposure because

DNA mutations are caused by UV exposure from sunshine

When two nucleotides are inserted into the sequence of a gene, what kind of mutation happens?

Frameshift mutation

What kind of point mutation causes a codon to change from being a stop codon to encoding an amino acid?

Nonsense mutation

In terms of the mutations brought about by DNA replication, which of the following propositions is true?

While DNA polymerase does occasionally make mistakes, it usually fixes them on its own

Which of the following, 5' GGGCAAT 3', would be the proper complementary sequence to this DNA strand?

3' CCCGTTA 5'

Which enzyme is in charge of dividing the two parent DNA strands during DNA replication?

Helicase

Which enzyme is in charge of removing RNA from RNA/DNA hybrid areas during DNA replication and substituting it with fresh DNA?

DNA Polymerase I

Which of the following sums up DNA synthesis's orientation the best?

While the new strand grows in a 5' to 3' direction, the DNA polymerase travels along the template strand in a 3' to 5' manner

What function does DNA ligase serve in replication?

Seals nicks and joins short fragments of DNA called Okazaki fragments on the lagging strand, creating a single, continuous DNA molecule

Which structure is usually formed to aid in the termination of transcription?

The stem-loop structure

What kind of single-nucleotide mutation causes a single amino acid in the resulting protein to change?

Missense mutation