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BIOL150 > Chapter 12.1 Transcription > Flashcards

Chapter 12.1 Transcription Flashcards

1
Q

Provide a molecular definition of the term gene

A

The entire nucleic acid sequence that is necessary for the synthesis of a functional gene product, which may be a polypeptide or any type of RNA
It’s an extremely specific sequence of nucleotide monomers that has the ability to control the expression of one or more traits in every type of living organism
Genes are made up of DNA (found in the cell nucleus of eukaryotes)
Two types of molecular genes: protein-coding genes and non-coding genes

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2
Q

Define the central dogma

A

The central dogma is a theory in genetics and molecular biology that describes the flow of genetic information in cells
The genetic information flows only in one direction, from DNA to RNA to protein

  1. Transcription: the process of transferring information from DNA to RNA
  2. Translation: the process of using RNA as a template for protein synthesis

proposed by Francis Crick

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3
Q

Discuss the three stages of transcription

A

Initiation: The beginning of transcription. It occurs when the enzyme RNA polymerase binds to a region of a gene called the promoter. This signals the DNA to unwind so the enzyme can “read” the bases in one of the DNA strands. The enzyme is now ready to make a strand of mRNA with a complementary sequence of bases
Elongation: This is the addition of nucleotides to the mRNA strand. RNA polymerase reads the unwound DNA strand and builds the mRNA molecule, using complementary base pairs. During this process, and adenine (A) in the DNA binds to a uracil (U) in the RNA
Termination: This is the ending of transcription, and occurs when RNA polymerase crosses a stop (termination) sequence in the gene. The mRNA strand is complete, and it detaches from DNA

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4
Q

Compare and contrast transcription in bacteria and eukaryotes

A

It’s fundamentally the same process, but there are some key differences:
1. Location: Bacteria and archaea perform transcription in the cytoplasm, while eukaryotes perform transcription in the nucleus
2. RNA processing: RNA transcripts can act as mRNAs right away in bacteria, while in eukaryotes, the transcript of a protein-coding gene is called a pre-mRNA and must go through extra processing before it can direct translation
3. RNA polymerases: eukaryotes use three different polymerases, RNA polymerases I, II, and III, all structurally distinct from the bacterial RNA polymerase
4. Simultaneity of Transcription and Translation: Transcription and translation occur at the same time in prokaryotes, while in eukaryotes, the RNA is the first transcribed in the nucleus and then translated in the cytoplasm
5. Post-transcriptional Modifications: RNAs from eukaryotes undergo post-transcriptional modifications including: capping, polyadenylation, and splicing

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5
Q

Describe transcription regulation in eukaryotes

A

A complex process that controls gene expression. It involves the combined effects of structural properties of DNA and the interactions of transcription factors

Eukaryotic DNA is packaged into chromatin, which affects the accessibility of genes to transcription machinery. Transcription factors are proteins that bind to specific DNA sequences and either activate or repress translation. Most eukaryotic genes require general transcription factors and RNA polymerase, as well as other regulatory factors, for high levels of transcription

Gene expression in eukaryotic cells is also regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription. In some cases, eukaryotic repressors simply interfere with the binding of other transcription factors to DNA

In eukaryotes, additional regulatory sequences called enhancers and the proteins that bind to enhancers are needed to achieve high levels of transcription. Enhancers are DNA sequences that regulate the transcription of genes.

Lastly, even after a gene has been transcribed, gene expression can still be regulated at various stages. Some transcripts can undergo alternative splicing, making different mRNAs and proteins from the same RNAs and proteins from the same RNA transcript. Some mRNAs are targeted by microRNAs, small regulator RNAs that can cause an mRNA to be chopped up or block translation. A protein’s activity may be regulated after translation, for example, through removal of amino acids or addition of chemical groups

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6
Q

Explain how genes within the same chromosomes vary in their direction of transcription

A

The transcription of a gene is controlled by a region of DNA called the promoter, which is located at the start of the gene. The promoter region determines the direction of the transcription.

The RNA polymerase enzyme, which carries out transcription, binds to the promoter region and separates the DNA strands. It then uses one of the strands as a template to synthesize a complementary strand of RNA. The strand that is used as a template to synthesize a complementary strand of RNA. The strand that’s used as a template is called the template strand and determines the direction of transcription

If the promoter is located at the left end of the gene, the gene is transcribed from left to right. If the promoter is at the right end of the gene, the gene is transcribed from right to left.

The two DNA strands are antiparallel, meaning they run in opposite directions. This allows the genes on the two strands to be transcribed in opposite directions

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7
Q

Transcribe an mRNA sequence from a DNA strand:
5’ -ATGCGTACGT- 3’

A

5’ -AUGCGUACGU- 3’

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8
Q

Discuss the three mRNA modification in eukaryotes

A

These modifications are necessary to turn pre-mRNA into a mature mRNA molecule that can leave the nucleus and be translated

Splicing: the removal of introns, or “junk” sequences, and the pasting together of the remaining, good sequences - exons. Introns are non-coding sequences that must be spliced out of mRNA so that its translation leads to a functional protein

5’ Capping: A 5’ cap is added to the beginning of the RNA. This cap is a modified guanine (G) nucleotide, and it facilitates binding of the ribosome to the mRNA, increases mRNA stability, and improves intron splicing

3’ Poly(A) tail: a poly-A tail, which is a tail of adenine (A) nucleotides, is added to the end of the RNA. This tail protects the mRNA from degradation, assists in the export of the mature mRNA to the cytoplasm, and aids in translation

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9
Q

DNA

A
  1. Information storage: DNA stores the genetic information of an organism. This information is used to construct functional products such as proteins
  2. template for transcription: during transcription, the DNA sequence of a gene is copied to make an RNA molecule. This process is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand using a DNA strand as a template
  3. Regulation of Gene expression: the DNA contains promoter sequences near the beginning of a gene. These promoters control the binding of RNA polymerase and the initiation of transcription. So, DNA plays a key role in regulation gene expression
  4. Coding for proteins: the transcribed DNA message, or RNA transcript, is used to produce proteins. The information in DNA is not directly converted into proteins, but must first be copied into RNA
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10
Q

Double helix

A
  1. The unwinding of DNA: the double helix must unwind to allow an enzyme called RNA polymerase to transcribe the DNA. This unwinding separated the DNA strands, enabling one strand to serve as a template for transcription
  2. Directionally: The antiparallel nature of the double helix allows transcription to occur in a specific direction, from 5’ to 3’. This directionality is essential for the correct sequence of the resulting mRNA
  3. Regulation of transcription: Certain proteins can bind to specific areas of the double helix, influencing the rate and timing of transcription. These regulatory proteins can either promote or inhibit the binding of RNA polymerase to the DNA
  4. Protection of Genetic information: the double helix structure helps protect the genetic information from damage. This is crucial because any errors in the DNA sequence could lead to the production of faulty proteins
  5. Role of helicase: the enzyme helicase plays a key role in unwinding the double helix by breaking the hydrogen bonds between the paired nucleotides. This is important during both DNA repair and the process of transcription
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11
Q

Genes

A
  1. Information storage: genes are segments of DNA that store the genetic information of an organism. This information is used to construct functional products such as proteins
  2. Template for transcription: During transcription, the DNA sequence of a gene is copied to make an RNA molecule. This process is performed by enzymes called RNA polymerase, which link nucleotides to form an RNA strand using a DNA strand as a template
  3. Regulation of gene expression: the DNA contains promoter sequences near the beginning of a gene. These promoters control the binding of RNA polymerase and the initiation of transcription. DNA plays a key role in regulating gene expression
  4. Coding for proteins: the transcribed DNA message, or RNA transcript, is used to produce proteins. The information in DNA is not directly converted into proteins, but must first be copied into RNA
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12
Q

Gene expression and regulation

A
  1. Information Transfer: Transcription is the first step in gene expression, where the information from a gene is used to construct a functional product such as a protein. The DNA sequence of a gene is transcribed to make an RNA molecule
  2. Control of Protein Synthesis: By controlling the level of transcription, gene expression and regulation can determine when and how much protein product is made by a gene. This is crucial because the types and amounts of proteins synthesized in a cell determine its structure and function
  3. Response to Environmental Signals: Signals from the environment or from other cells can activate proteins called transcription factors. These proteins bind to regulatory regions of a gene and increase or decrease the level of transcription. This allows the cell to respond to changes in its environment
  4. Regulation of Cell Identity: The genes that a cell turns on largely determine its identity and properties. For instance, a photoreceptor cell in your eye can detect light because it expresses genes for light-sensitive proteins
  5. Post-Transcriptional Regulation: Even after a gene has been transcribed, gene expression can still be regulated at various stages. Some transcripts can undergo alternative splicing, making different mRNAs and proteins from the same RNA transcript. Some mRNAs are targeted by microRNAs, small regulator RNAs that can cause an mRNA to be chopped up or block translation. A protein’s activity may be regulated after translation, for example, through removal of amino acids or addition of chemical groups
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13
Q

Central Dogma

A

The Central Dogma of molecular biology, which states that information flows from DNA to RNA to protein, is fundamental to the process of transcription. Here’s why:

  1. Information Transfer: Transcription is the first step in the Central Dogma, where the information from a gene (DNA) is used to construct a functional product such as a protein. The DNA sequence of a gene is transcribed to make an RNA molecule
  2. Template for Transcription: During transcription, the DNA sequence of a gene is copied to make an RNA molecule. This process is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand using a DNA strand as a template
  3. Regulation of Gene Expression: The Central Dogma provides the basic framework for understanding how genetic information flows from a DNA sequence to a protein product inside cells. This flow of information is followed through three different processes: replication (DNA is duplicated), transcription (a DNA segment is read and transcribed into RNA), and translation (the RNA sequence is translated into a sequence of amino acids as the protein is formed)
  4. Coding for Proteins: The transcribed DNA message, or RNA transcript, is used to produce proteins. The information in DNA is not directly converted into proteins, but must first be copied into RNA

Summary: It describes the normal flow of biological information: DNA can be copied to DNA (DNA replication, DNA information can be copied into mRNA (transcription), and proteins can be synthesized using the information in the mRNA as a template (translation)

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14
Q

Transcription and RNA transcript

A

Transcription is the process in which a gene’s DNA sequence is copied to make an RNA molecule. This process is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand using a DNA strand as a template. The RNA molecule produced can be messenger RNA (mRNA) or non-coding RNA (ncRNA)

The major steps of transcription are initiation, promoter clearance, elongation, and termination. RNA polymerase binds to a promoter sequence near the beginning of a gene to initiate transcription. Transcription is the first part of the central dogma of molecular biology

The RNA transcript is the product of transcription. It carries the genetic instructions of a gene from the nucleus to the ribosome in the cytoplasm. If the gene that’s transcribed encodes a protein (which many genes do), the RNA molecule will be read to make a protein in a process called translation.

In eukaryotes, RNA molecules must be processed after transcription: they are spliced and have a 5’ cap and poly-A tail put on their ends. Transcription is controlled separately for each gene in your genome

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15
Q

RNA polymerase

A

RNA polymerase binds to the promoter sequence of DNA near the beginning of the gene and unzips the two DNA strands. This marks initiation

It then synthesizes a complementary RNA strand in the 5 to 3 direction on the template strand. The RNA strand is called the primary transcript and needs to be processed before it can be functional

It interacts with many proteins, in which the proteins help in enhancing the binding specificity of the enzyme, aid in unwinding the double helix, modulate the activity of the enzyme based on the requirements of the cell, and alters the speed of transcription

RNA polymerase is involved in the production of molecules that have a wide range of roles, one of its main functions is to regulate the number and kind of RNA transcripts formed in response to the cell’s requirements

The key enzyme involved in creating an equivalent RNA copy of a DNA sequence. This transcription is the first step leading to gene expression

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16
Q

Elongation and termination

A

Elongation: the stage where the RNA polymerase moves along the DNA template and synthesizes a complementary RNA strand. In eukaryotes, RNA polymerase II transcribes the major share of genes. During the elongation, the transcription machinery needs to move histones out of the way every time it encounters a nucleosome. Transcription elongation occurs in a bubble of unwound DNA, where the RNA polymerase uses one strand of DNA as a template to catalyze the synthesis of a new RNA strand in the 5 to 3 direction

Termination: the stage where the RNA polymerase reaches the end of the gene and releases the newly synthesized RNA molecule. In eukaryotes, RNA polymerases I and II terminate transcription in response to specific termination sequences in either the DNA being transcribed (RNA polymerase I) or in the newly-synthesized RNA (RNA polymerase III). RNA polymerase II terminates transcription at random locations past the end of the gene being transcribed. The newly-synthesized RNA is cleaved at a sequence-specified location and released before transcription terminates

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17
Q

Promoters

A

A DNA sequence that controls the initiation of transcription of a gene by binding transcription factors and RNA polymerase. The promoter is usually located upstream of the gene and its specific sequence determines how often and under what conditions the gene is transcribed. Promoters are essential for regulating gene expression in response to environmental stimuli or cellular needs

Binds transcription factors that control the initiation of transcription. The promoter region can be short or quite long; the longer it is, the more available space for proteins to bind. To initiate transcription, a transcription factor binds to the TATA box, which causes other transcription factors to subsequently bind to the TATA box

Promoters control the binding of RNA polymerase to DNA

Each gene has its own promoter, and a promoter contains DNA sequences that let RNA polymerase or its helper proteins attach to the DNA

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18
Q

TATA box

A

a DNA sequence that helps initiate transcription. It’s a type of promoter sequence that specifies to other molecules where transcription begins. The TATA box is the binding site of the TATA-binding protein (TBP) and other transcription factors in some eukaryotic genes

It’s recognized by one of the general transcription factors, allowing other transcription factors and eventually RNA polymerase to bind

Found in the core promoter region of genes in archaea and eukaryotes

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19
Q

Terminator

A

A section of nucleic acid sequence that marks the end of a gene during transcription.
These processes include the direct interaction of the mRNA secondary structure with the complex and/or the indirect activities of recruited termination factors. Release of the transcriptional complex frees RNA polymerase and related transcriptional machinery to begin transcription of new mRNAs

20
Q

Sigma factor

A

A protein needed for initiation of transcription in bacteria. It’s a bacterial transcription initiation factor that enables specific binding of RNA polymerase (RNAP) to gene promoters. The specific sigma factor used to initiate transcription of a given gene will vary, depending on the gene and on the environmental signals needed to initiate transcription of that gene

Sigma factors provide promoter recognition specificity to the RNA polymerase (RNAP) and contribute to DNA strand separation, then dissociating from the RNA polymerase core enzyme following transcription initiation

The regulation of expression of sigma factors occurs at transcriptional, translational, and post-translational levels as dictated by the cellular environment and the presence or absence of numerous cofactors. Sigma factor synthesis is controlled at the levels of both transcription and translation. Often times, sigma factor expression or activity is dependent on specific growth phase transitions of the organism

21
Q

General transcription factors

A

GTFs are a class of protein transcription factors that bind to specific sites on DNA to activate transcription of genetic information from DNA to mRNA. They’re necessary for transcription to occur in eukaryotes. They’re part of the transcription preinitiation complex that interacts with RNA polymerase

Transcription factors help ensure that the right genes are expressed in the right cells of the body, at the right time
General transcription factors are different from other transcription factors that regulate gene expression by acting as activators or repressors. General, or basal, transcription factors simply assist in the binding of RNA polymerase to the promoter. Other types of transcription factors include activators and repressors. These transcription factors affect transcription in different ways; activators assist in the binding of RNA polymerase and repressors stop transcription

22
Q

Primary transcript

A

The single-stranded RNA product synthesized by transcription of DNA. It’s processed to yield different various mature RNA products such as mRNAs, tRNAs, and rRNAs. The primary transcripts designated to be mRNAs are modified in preparation for translation

Transcription produces primary transcripts that are further modified by several processes. These processes include the 5’ cap, poly-A tail, and alternative splicing. In particular, alternative splicing directly contributes to the diversity of mRNA found in cells

23
Q

mRNA (messenger RNA)

A

A type of primary transcript that becomes a messenger RNA after processing. Pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription. Once pre-mRNA has been completely processed, it’s mRNA

carries protein information from the DNA in a cell’s nucleus to the cell’s cytoplasm where the protein-making machinery reads the mRNA sequence and translated each three-base codon into its corresponding amino acid in a growing protein chain

This molecule consists of just one strand and serves as a temporary copy of the gene. Immediately after transcription, what we get is pre-mRNA. This molecule contains two parts: exons and introns

24
Q

Polycistronic mRNA vs Monocistronic mRNA

A

Polycistronic mRNA:
- refers to prokaryotic mRNA consisting of two or more cistrons
- In prokaryotes, functionally-related genes assemble in groups in such a way that all proteins can be transcribed at once when needed
- Polycistron mRNA refers to mRNA with two or more cistrons, found in prokaryotes, composed of multiple open reading frames, and can produce multiple proteins
- transcription of operons produces polycistron mRNA

Monocistronic mRNA:
- Refers to eukaryotic mRNA that consists of a single cistron
- can produce a single protein
- each gene contains a separate promoter region
- most mRNAs are monocistronic
- monocistron mRNA is composed of a single open reading frame
- transcription of genes produces monocistronic mRNA

25
Q

RNA processing

A

Transcription: the process of copying a DNA sequence into an RNA sequence. This is done by RNA polymerase, which binds to a promoter sequence near the beginning of a gene. The DNA strand used as a template is the template strand.

RNA splicing: in eukaryotes, the primary transcript (pre-mRNA) undergoes splicing to remove introns (non-coding regions) and join exons (coding regions) together

5’ capping: the 5’ end of the pre-mRNA molecule is modified by the addition of a cap, which is a modified guanine nucleotide. This cap protects the mRNA from degradation and assists in translation initiation

3’ polyadenylation: when a sequence called a polyadenylation signal shows up in an RNA molecule during transcription, an enzyme chops the RNA in two at that site. Another enzyme adds about 100-200 adenine nucleotides to the cut end, forming a poly-A tail. The tail makes the transcript more stable and helps it get exported from the nucleus to the cytosol

Export to the cytoplasm: the mature mRNA is then exported from the nucleus to the cytoplasm for translation

26
Q

5’cap and Poly(A) tail

A

5’ cap: the 5’ end of the pre-mRNA molecule is modified by the addition of a cap, which is a modified guanine nucleotide. This cap protects the mRNA from degradation and assists in translation initiation

Poly-A tail: An enzyme adds about 100-200 adenine nucleotides to the cut end (3’), forming a poly-A tail, which makes the transcript more stable and helps it get exported from the nucleus to the cytosol

27
Q

Polyadenylation

A

On the 3’ end

when a sequence called a polyadenylation signal shows up in an RNA molecule during transcription, an enzyme chops the RNA in two at that site. Another enzyme adds about 100-200 adenine nucleotides to the cut end, forming a poly-A tail. The tail makes the transcript more stable and helps it get exported from the nucleus to the cytosol

28
Q

Exons and Introns

A

Coding regions (exons) are interrupted by noncoding regions (introns). During transcription, the entire gene is copied into a pre-mRNA, which includes exons and introns

Exons are the sections of DNA (or RNA) that code for proteins

Introns are noncoding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein

During the process of transcription, both exons (coding regions) and introns (non-coding regions) are transcribed from the DNA into pre-mRNA. Then during RNA splicing, the introns are removed and the exons are joined together to form the final mRNA molecule that will be translated into a protein

29
Q

RNA splicing

A

the introns are removed and the exons are joined together to form the final mRNA molecule that will be translated into a protein

30
Q

Spliceosome

A

A large complex made up of proteins and RNA molecules known as small nuclear RNAs. These snRNAs combine with specific proteins to form small nuclear ribonucleoproteins, which then come together to form the spliceosome

The spliceosome recognizes the intron-exon boundaries of the pre-mRNA, cuts at these boundaries, and joins the exons together while discarding the introns. This process, known as splicing, results in a mature mRNA molecule that contains a continuous coding sequence and can be translated into a protein

31
Q

Alternative splicing

A

In alternative splicing, interactions between different proteins, the cell, and the environment can cause different segments of the original DNA to be omitted from the mRNA. When this happens, the alternate mRNA is translated into an entirely different protein

Before a primary mRNA is translated into a protein, it has to be modified and edited. In normal splicing, a special protein and RNA complex called the spliceosome attaches itself to the primary mRNA. The primary mRNA has various regions, called introns and exons. These regions are mixed together and the introns must be removed to create a functional protein. The spliceosome is specially equipped to remove the introns

Alternative splicing can also take place; a signal may be given to exclude an exon, or even multiple exons from the final mRNA. Other signals and pathways can cause the spliceosome to leave introns intact or skip large sections of the protein

32
Q

Briefly discuss the stages of transcription

A
  1. Initiation: Transcription begins when RNA polymerase binds to a promoter sequence near the beginning of a gene (directly or through helper proteins). The DNA double helix must unwind near the gene that is getting transcribed. The region of opened-up DNA is called a transcription bubble
  2. Elongation: RNA polymerase uses one of the DNA strands (the template strand) as a template to make a new, complementary RNA molecule. The RNA is synthesized in the 5’ -> 3’ direction (as seen from the growing RNA transcript)
  3. Termination: Transcription ends in a process called termination. Termination depends on sequences in the RNA, which signal that the transcript is finished
33
Q

A segment of the template strand of a double-stranded molecule has the sequences 5’-
ACTTTCAGCGAT-3’. What is the sequence of an RNA molecules synthesized from this DNA
template written 5’-3’?

A

5’ -UGAAAGUCGCUA_ 3’

34
Q

What are three mechanisms of RNA processing in eukaryotes?

A

In eukaryotes, RNA processing involves several key mechanisms:

  1. 5’ Capping: The 5’ end of the pre-mRNA molecule is modified by the addition of a cap, which is a modified guanine nucleotide. This cap protects the mRNA from degradation and assists in translation initiation.
  2. RNA Splicing: In eukaryotes, the primary transcript (also known as pre-mRNA) undergoes splicing to remove introns (non-coding regions) and join exons (coding regions) together. This process is carried out by a complex known as the spliceosome.
  3. 3’ Polyadenylation: When a sequence called a polyadenylation signal shows up in an RNA molecule during transcription, an enzyme chops the RNA in two at that site. Another enzyme adds about 100 - 200 adenine (A) nucleotides to the cut end, forming a poly-A tail. The tail makes the transcript more stable and helps it get exported from the nucleus to the cytosol.
35
Q

Explain how alternative splicing leads to the vast number of different mRNAs found in eukaryotic cells

A

Alternative splicing is a process that allows a single gene to code for multiple proteins. In eukaryotic cells, genes are composed of exons, which are coding sequences, and introns, which are non-coding sequences. During the process of transcription, both exons and introns are copied into a pre-mRNA molecule.

In the subsequent process of RNA splicing, introns are typically removed and exons are joined together to form a mature mRNA molecule. However, in alternative splicing, different combinations of exons, and sometimes even introns, are joined together, resulting in multiple unique mRNA molecules from a single gene.

This means that even though humans have about 20,000 genes, thanks to alternative splicing, we can make many times more than 20,000 different proteins. This contributes to the complexity and diversity of proteins in eukaryotic cells, allowing for a wide range of cellular functions and responses to environmental changes.

It’s also worth noting that errors in alternative splicing can lead to the production of incorrect proteins, which can contribute to various diseases, including many types of cancer.

36
Q

Describe 2 of the main differences between prokaryotic and eukaryotic gene expression

A
  1. Location of transcription and translation: in prokaryotic cells, which lack a nucleus, the processes of transcription and translation occur almost simultaneously in the cytoplasm. In contrast, eukaryotic cells have a nucleus where transcription occurs. The newly synthesized mRNA is then transported out of the nucleus into the cytoplasm, where translation takes place
  2. Regulation of gene expression: in prokaryotic cells, the control of gene expression is almost entirely at the transcriptional level. When more protein is required, more transcription occurs. On the other hand, eukaryotic gene expression can be regulated at many levels, including the epigenetic level, transcriptional level, post-transcriptional level (such as splicing and transport out of the nucleus), translational level, and post-translational level
37
Q
  1. mRNA complementary to DNA is produced via __________.
    a. Replication
    b. Transcription
    c. Translation
    d. protein synthesis
    e. Duplication
A

b. transcription

38
Q
  1. What is the promoter region?
    a. It is a region of RNA that binds to the RNA polymerase and initiates transcription.
    b. It is a component of each type of RNA.
    c. It is responsible for the selective nature of transcription.
    d. It is a region of a parent DNA strand that binds to the RNA polymerase and initiates transcription
A

d. It is a region of a parent DNA strand that binds to the RNA polymerase and initiates transcription

39
Q
  1. A gene—
    a. is synonymous with a chromosome
    b. is composed of mRNA
    c. is a specific segment of nucleotides in DNA
    d. contains only those nucleotides required to synthesize a protein
    e. specifies the sequence of nutrients required by the body
A

C. is a specific segment of nucleotides in DNA

40
Q
  1. Which of the following is a single-stranded molecule that contains the information for assembly of a
    specific protein?
    a. transfer RNA
    b. messenger RNA
    c. exon DNA
    d. intron DNA
    e. ribosomal RNA
A

b. messenger RNA

41
Q
  1. A transcription factor is—
    a. An activated gene
    b. A hormone
    c. A protein that binds DNA and regulates synthesis of mRNA
    d. An activated mRNA
    e. An intercellular communication molecule
A

c. A protein that binds DNA and regulates synthesis of mRNA

42
Q
  1. Introns are usually present in bacteria.
    a. This is true
    b. This is false
A

False mf

43
Q
  1. The central dogma of molecular biology states that information flows from—
    a. DNA to RNA to proteins
    b. Proteins to RNA to DNA
    c. RNA to DNA to proteins
    d. DNA to proteins to RNA
    e. RNA to proteins to DNA
A

A. DNA to RNA to proteins

44
Q
  1. What is the function of the 5 ́ cap and the 3 ́ poly-A-tail?
    a. Initiates transcription
    b. Forms bonds between amino acids
    c. Protects mRNA from degradation
    d. Splices out the intron sequences
    e. Acts as a stop codon in some polypeptides
A

c. Protects mRNA from degradation

45
Q
  1. Where does eukaryotic transcription take place?
    a. In the nucleus
    b. In the nucleolus
    c. In the cytoplasm
    d. On the ribosome
    e. On the rough ER
A

A. In the nucleus

46
Q
  1. If RNA polymerase reads the sequence ATCTTA, which of the following sequences will it make?
    RNA?
    a. GACUUA
    b. UAGAAU
    c. TAGAAU
    d. CAGTTC
    e. TUGUUG
A

b. UAGAAU

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