Gene Expression and RNA Function Quiz : Biology Unit 3
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Questions and Answers

What is the primary function of messenger RNA (mRNA) in the process of gene expression?

  • To splice introns from pre-mRNA
  • To catalyze peptide bond formation between amino acids
  • To synthesize proteins directly from DNA
  • To carry genetic information from DNA to the ribosome (correct)

Which of the following describes the elongation phase of transcription?

  • RNA polymerase moves along the DNA and adds ribonucleotides complementary to the template strand (correct)
  • RNA synthesis begins with the formation of a hairpin structure
  • RNA polymerase binds to the promoter region of a gene
  • RNA polymerase synthesizes RNA in the 3’ to 5’ direction

What occurs during the initiation phase of transcription?

  • Ribonucleotides are added to the growing RNA strand
  • The sigma subunit helps RNA polymerase position at the transcription start site (correct)
  • RNA polymerase forms a hairpin structure
  • The DNA double helix is unwound

Which type of RNA forms the core structure of ribosomes?

<p>Ribosomal RNA (rRNA) (A)</p> Signup and view all the answers

What is the result of RNA polymerase reaching a terminator sequence during transcription?

<p>Synthesis of the mRNA ends (D)</p> Signup and view all the answers

How does transfer RNA (tRNA) function during translation?

<p>It reads mRNA and brings the correct amino acids to the ribosome (B)</p> Signup and view all the answers

What is the role of small nuclear RNA (snRNA) in eukaryotic cells?

<p>Splices pre-mRNA by removing introns (D)</p> Signup and view all the answers

Which of the following statements about RNA synthesis is true?

<p>Uracil replaces thymine in RNA during synthesis (B)</p> Signup and view all the answers

What is the function of codons in mRNA?

<p>They determine the sequence of amino acids during translation. (D)</p> Signup and view all the answers

How many possible codons exist, and what is their redundancy in relation to amino acids?

<p>64 codons are available, but only 20 amino acids result from them, indicating redundancy. (D)</p> Signup and view all the answers

What is the start codon, and what amino acid does it specify?

<p>AUG, specifying methionine. (B)</p> Signup and view all the answers

What type of molecule can recognize multiple codons due to wobble pairing?

<p>tRNA (A)</p> Signup and view all the answers

Which statement accurately describes the role of the small ribosomal subunit during the initiation of translation in eukaryotes?

<p>It binds directly to the 5’ cap of the mRNA to find the start codon. (C)</p> Signup and view all the answers

During the elongation phase of translation, how does the ribosome move along the mRNA?

<p>In the 5’ to 3’ direction, aligning codons with incoming tRNA. (B)</p> Signup and view all the answers

Which of the following codons are stop codons that signal the termination of translation?

<p>UAA, UAG, UGA (D)</p> Signup and view all the answers

What occurs during the initiation phase of translation in prokaryotes?

<p>The small ribosomal subunit binds to the ribosome-binding sequence. (C)</p> Signup and view all the answers

What happens during prometaphase of mitosis?

<p>The nuclear envelope fully breaks down. (D)</p> Signup and view all the answers

Which checkpoint assesses DNA damage and completion of DNA replication?

<p>G2/M checkpoint (B)</p> Signup and view all the answers

What is one role of the spindle checkpoint during mitosis?

<p>To ensure all chromosomes are aligned at the metaphase plate. (A)</p> Signup and view all the answers

Which phase of mitosis involves sister chromatids being pulled apart Toward opposite poles?

<p>Anaphase (A)</p> Signup and view all the answers

During which phase do chromosomes condense and the mitotic spindle form?

<p>Prophase (B)</p> Signup and view all the answers

What is a critical function of the G1/S checkpoint?

<p>To evaluate the availability of nutrients and growth factors. (B)</p> Signup and view all the answers

Which of the following occurs during telophase?

<p>The nuclear envelope reforms around separated chromosomes. (B)</p> Signup and view all the answers

What is the outcome of cytokinesis?

<p>The cytoplasm is divided between two daughter cells. (A)</p> Signup and view all the answers

What is the primary way gene expression is commonly controlled?

<p>Through transcriptional regulation (B)</p> Signup and view all the answers

Where does transcriptional regulation commonly occur in the DNA?

<p>At the promoter region (D)</p> Signup and view all the answers

What role do activators play in positive control of transcription?

<p>They enhance the binding of RNA polymerase to the promoter. (C)</p> Signup and view all the answers

In prokaryotes, how can multiple genes be controlled simultaneously?

<p>By having a single promoter regulate an operon (A)</p> Signup and view all the answers

What is the function of a repressor in negative control of transcription?

<p>To bind to the operator and prevent transcription (A)</p> Signup and view all the answers

Which protein serves as an activator in the lac operon?

<p>CAP protein (D)</p> Signup and view all the answers

What happens if the core promoter region is altered?

<p>RNA polymerase cannot bind and transcription halts (D)</p> Signup and view all the answers

Which scenario exemplifies negative control in the lac operon?

<p>Lac repressor binds in the absence of lactose (D)</p> Signup and view all the answers

What is one way that mutations can positively influence a species?

<p>By enhancing genetic variation necessary for evolution (B)</p> Signup and view all the answers

In eukaryotes, how many promoter sequences does each gene typically have?

<p>One promoter per gene (B)</p> Signup and view all the answers

What does genomic imprinting involve?

<p>Selective inactivation of genes based on whether they are inherited from the mother or father. (C)</p> Signup and view all the answers

What is the consequence of mitochondrial DNA being inherited only from the mother?

<p>All offspring of an affected mother will inherit the mitochondrial trait. (C)</p> Signup and view all the answers

In chloroplast DNA inheritance, which pattern is most commonly observed in plants?

<p>Maternal inheritance, receiving chloroplast traits from the mother. (A)</p> Signup and view all the answers

Which statement best describes maternal imprinting?

<p>The maternal copy of the gene is inactivated, allowing the paternal copy to be expressed. (A)</p> Signup and view all the answers

Why do males with mitochondrial traits not pass them on to their children?

<p>Mitochondria are inherited exclusively from the egg cell. (B)</p> Signup and view all the answers

What is the purpose of dosage compensation in genetics?

<p>To balance gene expression on the X chromosome between sexes. (A)</p> Signup and view all the answers

What is one potential variation in chloroplast inheritance among plant species?

<p>Chloroplasts may be inherited solely from the father in some species. (A)</p> Signup and view all the answers

What genetic condition is characterized by an extra Y chromosome in males?

<p>Jacob's Syndrome (D)</p> Signup and view all the answers

Which of the following is NOT an advantage of genetic testing?

<p>Risk of miscarriage during testing (B)</p> Signup and view all the answers

When can amniocentesis typically be performed during pregnancy?

<p>Around the fourth month (A)</p> Signup and view all the answers

What is a key disadvantage of Chorionic Villi Sampling (CVS)?

<p>Higher risk of miscarriage compared to other methods (C)</p> Signup and view all the answers

What ethical consideration may arise from the knowledge of carrying genetic mutations?

<p>Potential emotional and ethical dilemmas (C)</p> Signup and view all the answers

Which method of genetic testing allows for identification of fetal genetic abnormalities?

<p>Amniocentesis (C)</p> Signup and view all the answers

What is one potential risk associated with genetic testing?

<p>Risk of emotional distress and ethical decisions (A)</p> Signup and view all the answers

How can genetic testing be beneficial in the context of personalized medicine?

<p>It helps tailor treatment options for individuals based on genetic makeup (D)</p> Signup and view all the answers

Flashcards

Transcription

The process that reads DNA to create RNA. RNA polymerase binds to DNA, unwinds the helix, and synthesizes complementary RNA.

Translation

The process that uses RNA as a blueprint to build proteins. Ribosomes read mRNA and assemble amino acids into a protein chain.

Messenger RNA (mRNA)

A molecule that carries genetic information from DNA to the ribosome to direct protein synthesis.

Ribosomal RNA (rRNA)

RNA that forms the core of ribosomes and catalyzes the formation of peptide bonds during protein synthesis.

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Transfer RNA (tRNA)

RNA that reads the mRNA sequence and brings the correct amino acids to the ribosome for protein synthesis.

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Transcription Initiation

The initial step in transcription where RNA polymerase binds to the promoter region of a gene.

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Transcription Elongation

The middle phase of transcription where RNA polymerase moves along the DNA template, synthesizing RNA in the 5' to 3' direction.

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Transcription Termination

The final step in transcription where RNA polymerase reaches a terminator sequence in the DNA and ends the process.

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Codon

A sequence of three nucleotides in mRNA that codes for a specific amino acid or a stop signal during translation.

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Redundancy of the Genetic Code

The redundancy of the genetic code, meaning that multiple codons can specify the same amino acid.

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Start Codon: AUG

The codon AUG signals the start of translation.

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Stop Codons: UAA, UAG, UGA

The codons UAA, UAG, and UGA signal the termination of translation. They do not code for amino acids.

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Wobble Pairing

The ability of a tRNA molecule to recognize more than one codon due to less strict base-pairing rules at the third position of the codon.

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Reading Frame

The starting point for translation on mRNA, determining the sequence of amino acids in the resulting protein.

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Translation Initiation

The process where the ribosome binds to mRNA, initiates translation with the start codon, and then proceeds to translate codons into amino acids to build a protein chain.

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Translation Elongation

Ribosomes move along mRNA, adding amino acids to the growing polypeptide chain based on the codons. This step continues until a stop codon is reached.

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Translation Termination

The process where the ribosome reaches a stop codon, causing the release of the newly synthesized polypeptide chain and disassembly of the ribosome.

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Checkpoint

A regulatory point in the cell cycle that makes sure the cell is ready to proceed to the next stage.

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G1/S Checkpoint

A checkpoint in the cell cycle occurring before DNA replication, checking if the cell is large enough, has enough resources, and is ready to proceed to S phase.

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G2/M Checkpoint

A checkpoint in the cell cycle occurring after DNA replication, ensuring DNA has been copied correctly and is ready for cell division.

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Spindle Checkpoint

A checkpoint in the cell cycle during mitosis, where it's verified all chromosomes are correctly attached to spindle fibers and are aligned at the metaphase plate.

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Apoptosis

The process by which a cell undergoes a programmed sequence of events leading to its own destruction

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Interphase

The phase of the cell cycle where the cell grows and prepares for division.

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Mitosis

The phase of the cell cycle where the cell divides its nucleus into two daughter nuclei, which creates two new cells.

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Cytokinesis

The process where the cytoplasm of a cell divides, which completes the process of cell division.

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Genomic Imprinting

A process where one copy of a gene is inactivated based on its parental origin (mother or father). The offspring then expresses only the non-imprinted copy of the gene.

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Maternal Imprinting

Genomic imprinting where the maternal copy of the gene is inactivated.

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Paternal Imprinting

Genomic imprinting where the paternal copy of the gene is inactivated.

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Non-Mendelian Inheritance

The inheritance of DNA from mitochondria and chloroplasts doesn't follow the Mendelian patterns seen with nuclear DNA. Instead, offspring inherit these organelles mostly from the mother.

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Mitochondrial DNA Inheritance

Mitochondrial DNA is inherited from the mother because offspring receive their cytoplasm (including mitochondria) from the egg cell. All offspring of an affected mother will inherit the mitochondrial trait.

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Chloroplast DNA Inheritance

In plants, chloroplasts are typically inherited from the mother due to the egg cell providing most of the cytoplasm.

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Dosage Compensation

The mechanism that balances gene expression on the X chromosome between sexes.

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X-chromosome Inactivation

A process that happens in females to inactivate one of their two X chromosomes. This ensures that females don't express twice the amount of X-linked genes as males.

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Transcriptional Regulation

The primary point at which a cell controls the expression of a gene. It relies on whether RNA polymerase can bind to DNA and start transcription.

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Promoter Region

A specific segment of DNA located upstream of the transcription start site. It acts as a landing pad for RNA polymerase, initiating transcription.

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Operon

A set of genes that are controlled by a single promoter. These genes are often involved in a related process and are transcribed together as a unit.

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Positive Control

A type of transcriptional regulation where a protein binds to DNA to enhance or activate transcription. It helps RNA polymerase bind to the promoter and initiate transcription.

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Activator

A protein that binds to the promoter in positive control to promote transcription. It helps RNA polymerase bind and initiate the process.

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Negative Control

A type of transcriptional regulation where a protein binds to DNA to block or inhibit transcription.

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Repressor

A protein that binds to DNA in negative control to block transcription. It prevents RNA polymerase from accessing the promoter and initiating transcription.

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Operator

A region on DNA where the repressor protein binds in negative control. This binding blocks RNA polymerase from accessing the promoter and starting transcription.

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Lac Repressor

A regulatory protein that binds to the operator in the lac operon to block transcription of lactose metabolism genes in the absence of lactose.

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Transcription Factor

A protein that binds to a specific site on DNA to promote or enhance transcription. It assists RNA polymerase by helping it bind to the promoter region.

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Jacob's Syndrome (XYY)

A genetic condition in males caused by an extra Y chromosome, often leading to increased height and potential cognitive challenges.

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Genetic Testing

Testing that analyzes an individual's genes to identify genetic variations or mutations.

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Amniocentesis

A technique used to analyze a fetus's chromosomes for potential genetic abnormalities. This involves extracting amniotic fluid from the womb.

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Chorionic Villi Sampling (CVS)

A procedure to diagnose genetic disorders by examining fetal cells obtained from the placenta.

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Pedigree Analysis

A method of analyzing family history to identify genetic disorders and assess the risk of inheriting or passing them on.

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Personalized Medicine

The use of genetic information to personalize medical treatment based on an individual's unique DNA.

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Risk of Miscarriage

A potential consequence of genetic testing methods like amniocentesis and CVS.

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Ethical Considerations

Ethical concerns related to genetic testing, encompassing issues of informed consent, privacy, and how genetic information is used.

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Study Notes

Gene Expression Overview

  • Transcription is the process of synthesizing RNA from a DNA template strand; RNA polymerase is the enzyme.
  • Translation is the process of synthesizing proteins from an mRNA template; ribosomes and tRNA are involved.
  • Transcription occurs in the nucleus of eukaryotic cells and the cytoplasm of prokaryotic cells.
  • Messenger RNA (mRNA) carries the genetic code from DNA to ribosomes for protein synthesis.
  • Ribosomal RNA (rRNA) forms the core of ribosomes and catalyzes peptide bond formation during protein synthesis.
  • Transfer RNA (tRNA) reads mRNA and brings the correct amino acids to the ribosome.
  • Small nuclear RNA (snRNA) splices pre-mRNA in eukaryotic cells.
  • MicroRNA (miRNA) regulates gene expression by inhibiting translation or promoting mRNA degradation.

Transcription

  • Initiation: RNA polymerase binds to a promoter region. Sigma helps position RNA polymerase at the initiation site (+1). RNA polymerase unwinds the DNA double helix and starts synthesizing RNA with a complementary nucleotide.
  • Elongation: RNA polymerase moves along the template strand, synthesizing RNA in the 5' to 3' direction. It adds ribonucleotides complementary to the DNA template.
  • Termination: RNA polymerase reaches a terminator sequence. The RNA forms a hairpin structure, causing the RNA polymerase to pause. RNA polymerase dissociates from the DNA template, releasing the mRNA.

Eukaryotic vs. Prokaryotic Transcription

  • Eukaryotes have multiple types of RNA polymerase, while prokaryotes have only one.
  • Eukaryotic promoters are more complex than prokaryotic promoters, requiring transcription factors.
  • RNA polymerase can bind directly to promoter sequences in prokaryotes with the help of a sigma factor.
  • Eukaryotes modify their primary transcripts (pre-mRNA) before translation, including 5' capping and 3' polyadenylation, and intron removal.
  • Eukaryotic transcripts require processing (splicing) to remove introns before exporting it to the cytoplasm.

RNA Processing in Eukaryotes

  • Primary transcripts (pre-mRNA) undergo extensive processing.
  • Addition of a 5' cap protects mRNA from degradation and aids in ribosome binding.
  • Addition of a 3' poly(A) tail also protects the transcript from degradation.
  • Removal of non-coding sequences (introns) is accomplished by splicing.
  • Alternative splicing allows a single gene to produce multiple mRNA variants.

Translation

  • Initiation: Small ribosomal subunit binds to the ribosome-binding sequence (RBS) and the first initiator tRNA. The large subunit joins, forming the initiation complex.
  • Elongation: New tRNA molecules (carrying amino acids) enter the A-site. A peptide bond forms between the amino acids. The ribosome moves along the mRNA, shifting the tRNA from the A-site to the P-site, and the tRNA in the P-site to the E-site before exiting.
  • Termination: The ribosome encounters a stop codon. A release factor protein binds to the stop codon at the A-site. The polypeptide chain is released, and the ribosome disassembles.

Gene Expression, Phenotype & Mutations

  • Mutations are changes in the DNA sequence.
  • Point mutations (substitutions): A silent mutation has no effect. A missense mutation causes a different amino acid. A nonsense mutation introduces a premature stop codon.
  • Frameshift mutations (insertions/deletions): Cause a change in the reading frame of the gene.
  • Chromosomal mutations involve larger segments of the chromosome.
  • Genetic modifications alter gene expression without altering the DNA sequence itself.

Cell Reproduction (Mitosis & Meiosis)

  • Mitosis produces two genetically identical diploid daughter cells for growth, repair and asexual reproduction.
  • Meiosis produces four genetically diverse haploid daughter cells for sexual reproduction.

Cell Cycle

  • Interphase: G1 (growth), S (synthesis), G2 (growth).
  • M phase: Mitosis and cytokinesis.

Cell Cycle Checkpoints

  • G1/S checkpoint: Checks for sufficient nutrients and growth factors, and whether the cell has grown large enough.
  • G2/M checkpoint: Ensures DNA replication is complete and checks for DNA damage.
  • Spindle checkpoint: Ensures all chromosomes are properly aligned at the metaphase plate and attached to spindle fibers.

Non-Mendelian Inheritance

  • Multiple alleles, codominance, incomplete dominance, polygenic inheritance, pleiotropy, sex-linked traits, X-inactivation, genomic imprinting, and mitochondrial inheritance are examples of non-Mendelian inheritance patterns, in which patterns of inheritance do not follow simple dominant-recessive relationships based on traits like blood type (ABO, Rh), eye color.
  • Traits influenced by both genetics and the environment (phenotypes).

Genetic Disorders

  • Mutations can lead to genetic disorders.
  • Nondisjunction during meiosis leads to aneuploidy (abnormal chromosome number).
  • Examples include Down syndrome (trisomy 21), Turner syndrome (XO), and Klinefelter syndrome (XXY).

Genetic Testing

  • Early diagnosis and risk assessment for genetic diseases.
  • Amniocentesis and chorionic villus sampling (CVS) enable in-utero genetic testing.

Genetic Recombination and Linkage Analysis

  • Crossing over during meiosis leads to genetic recombination.
  • Linked genes are located close together on chromosomes and tend to be inherited together.

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BIOL 1105 Test 3-2 PDF

Description

Test your knowledge on the roles of different types of RNA in gene expression and translation. This quiz covers key concepts such as mRNA function, transcription phases, and the significance of codons. Perfect for students studying molecular biology or genetics.

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