Nucleic Acids & Protein Synthesis Quiz
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Questions and Answers

What is the primary function of DNA ligase in DNA synthesis?

  • To synthesize the leading strand continuously
  • To remove RNA primers from the lagging strand
  • To join Okazaki fragments together (correct)
  • To replicate the parental DNA strand

Which of the following nitrogenous bases is present in RNA but not in DNA?

  • Thymine
  • Uracil (correct)
  • Cytosine
  • Adenine

What is the unique structural characteristic of RNA compared to DNA?

  • RNA contains two strands
  • RNA contains ribose sugar (correct)
  • RNA has thymine as a base
  • RNA is more stable than DNA

What is represented by the triplet code in a gene?

<p>It specifies the start and stop of amino acid sequences (C)</p> Signup and view all the answers

Which of the following best defines a gene?

<p>A sequence of nucleotides that forms part of a DNA molecule (A)</p> Signup and view all the answers

How many different triplet codons can be formed with four bases?

<p>64 (B)</p> Signup and view all the answers

During which process does mRNA synthesis occur?

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

Which of the following accurately describes the shape of protein molecules?

<p>They depend on the exact sequence of amino acids (C)</p> Signup and view all the answers

Which component is NOT part of a nucleotide?

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

What type of sugar is found in RNA?

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

Which pairing of bases forms 3 hydrogen bonds?

<p>Guanine and Cytosine (D)</p> Signup and view all the answers

Which statement about ATP is incorrect?

<p>It is primarily a structural component of DNA. (A)</p> Signup and view all the answers

How many strands do DNA molecules consist of?

<p>Double-stranded (A)</p> Signup and view all the answers

Which of the following is true regarding the bases of nucleic acids?

<p>Uracil replaces Thymine in RNA. (A)</p> Signup and view all the answers

What distinguishes purines from pyrimidines?

<p>Purines have a double-ring structure. (A)</p> Signup and view all the answers

Which of the following correctly describes DNA strand orientation?

<p>Strands are antiparallel. (C)</p> Signup and view all the answers

What type of bonds connect the deoxyribose sugars and phosphate groups in a DNA polynucleotide strand?

<p>Phosphodiester bonds (D)</p> Signup and view all the answers

Which sequence correctly describes the directionality of DNA strands?

<p>One strand runs 5' to 3' and the other runs 3' to 5' (A)</p> Signup and view all the answers

What is the role of DNA helicase in DNA replication?

<p>To break hydrogen bonds between base pairs (B)</p> Signup and view all the answers

During DNA replication, which enzyme catalyzes the formation of phosphodiester bonds?

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

What is meant by complementary base pairing in DNA structure?

<p>Adenine pairs with thymine and guanine pairs with cytosine (B)</p> Signup and view all the answers

What occurs during the semi-conservative replication process of DNA?

<p>One strand is from the parental DNA and one is newly synthesized (C)</p> Signup and view all the answers

In DNA replication, which direction does DNA polymerase synthesize new strands?

<p>From 5' to 3' (C)</p> Signup and view all the answers

How many hydrogen bonds are formed between adenine and thymine?

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

What type of mutation results in a change of amino acid coding and affects subsequent triplet codons in the DNA sequence?

<p>Insertion mutation (D)</p> Signup and view all the answers

Which mutation type is characterized by the deletion of a nucleotide from the DNA sequence?

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

How does a substitution mutation differ from insertion and deletion mutations?

<p>It only changes the amino acid for the triplet it occurs in. (A)</p> Signup and view all the answers

What is the primary consequence of a nonsense mutation?

<p>It results in a premature stop codon. (C)</p> Signup and view all the answers

Which type of mutation results in no change to the amino acid sequence despite a change in the DNA?

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

What result do frameshift mutations typically have on the final protein structure?

<p>They may drastically alter the protein's shape and function. (D)</p> Signup and view all the answers

Which condition is commonly associated with a missense mutation?

<p>Sickle cell anemia (A)</p> Signup and view all the answers

What is the general outcome for most mutations in terms of polypeptide structure and function?

<p>They typically do not alter the polypeptide structure greatly. (B)</p> Signup and view all the answers

What occurs when a gene is transcribed into mRNA?

<p>A single-stranded RNA molecule is formed. (D)</p> Signup and view all the answers

What role does RNA polymerase play in the formation of mRNA?

<p>It forms the sugar-phosphate backbone of the mRNA. (D)</p> Signup and view all the answers

During splicing, what happens to the introns in the primary transcript?

<p>Introns are removed entirely from the molecule. (B)</p> Signup and view all the answers

What is the result of reaching a 'stop' codon during translation?

<p>The amino acid chain is released as a completed polypeptide. (C)</p> Signup and view all the answers

Which of the following statements about gene mutations is accurate?

<p>Gene mutations occur continuously and can alter protein structure. (A)</p> Signup and view all the answers

What is an insertion mutation?

<p>A new nucleotide with a different base is added to the DNA sequence. (A)</p> Signup and view all the answers

In translation, the role of tRNA is to:

<p>Transport amino acids to the ribosome based on the mRNA sequence. (A)</p> Signup and view all the answers

What structural feature distinguishes the template strand of DNA in transcription?

<p>It serves as a template for mRNA synthesis. (B)</p> Signup and view all the answers

Flashcards

What are nucleic acids?

Nucleic acids are polymers made up of monomers called nucleotides.

What are nucleotides made of?

A nucleotide is made up of three parts: a nitrogenous base, a pentose sugar, and a phosphate group.

What is the difference between DNA and RNA sugar?

DNA contains the sugar deoxyribose, while RNA contains the sugar ribose.

What are the nitrogenous bases in DNA and RNA?

DNA has the bases Adenine, Thymine, Cytosine, and Guanine. RNA has Adenine, Uracil, Cytosine, and Guanine.

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What are purines?

Purines are double-ringed nitrogenous bases, including Adenine and Guanine.

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What are pyrimidines?

Pyrimidines are single-ringed nitrogenous bases, including Cytosine, Thymine, and Uracil.

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Describe the structure of DNA.

DNA is a double-stranded helix, with strands running in opposite directions (antiparallel).

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What is ATP?

ATP (adenosine triphosphate) is a nucleotide with three phosphate groups. It is the primary energy carrier in cells.

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What is a phosphodiester bond?

The covalent bond that links the phosphate group of one nucleotide to the deoxyribose sugar of the next nucleotide in a DNA strand.

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How are the DNA strands oriented?

One strand runs from 5' to 3', while the other runs from 3' to 5'.

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What is complementary base pairing?

Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).

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What is DNA replication?

The process by which DNA is copied before cell division.

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Why is DNA replication called semi-conservative?

DNA replication is semi-conservative because each new DNA molecule contains one original strand and one newly synthesized strand.

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What does DNA helicase do?

An enzyme that unwinds the parental DNA double helix by breaking hydrogen bonds between the nitrogenous bases.

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What is DNA polymerase's role in replication?

An enzyme that adds free nucleotides to the template strand of the parental DNA to create the new strand.

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In what direction does DNA polymerase build new strands?

DNA polymerase can only add nucleotides in the 5' to 3' direction.

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Why is the lagging strand synthesized discontinuously?

The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments.

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How are Okazaki fragments joined?

DNA ligase joins these lagging strand segments together to form a continuous complementary DNA strand.

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What is the structure of RNA?

RNA is a single-stranded polynucleotide made up of ribose sugar, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, and uracil).

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What are some examples of RNA?

Messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) are examples of RNA molecules.

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What is a gene?

A gene is a sequence of nucleotides on a DNA molecule that codes for a specific polypeptide.

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How does the genetic code work?

Each triplet codon within a gene codes for a specific amino acid.

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What does it mean that the genetic code is degenerate?

The genetic code is degenerate - multiple codons can code for the same amino acid.

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What is transcription?

Transcription is the process of copying a gene's DNA sequence into mRNA. This happens in the nucleus of the cell.

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Insertion mutation

A mutation where one or more nucleotide bases are inserted into the existing DNA sequence.

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Frameshift mutation

A type of mutation that changes how a gene is read. It occurs when an insertion or deletion mutation disrupts the normal grouping of three bases (codons) that code for amino acids.

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Deletion mutation

A mutation where one nucleotide base is deleted from the existing DNA sequence.

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Substitution mutation

A mutation where a single base in the DNA sequence is replaced by a different base.

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Silent mutation

A substitution mutation that does not change the amino acid sequence of the protein.

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Missense mutation

A substitution mutation that changes a single amino acid in the protein sequence.

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Nonsense mutation

A substitution mutation that introduces a premature stop codon, leading to a shortened protein.

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Altered polypeptide

A change in the amino acid sequence of a protein that affects its shape and function.

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What is translation?

The process of making a protein from RNA. During this process, the mRNA molecule attaches to a ribosome in the cytoplasm and tRNA molecules bring specific amino acids to the ribosome, where they are linked together to form a polypeptide chain.

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What is a gene mutation?

A change in the sequence of bases in a DNA molecule that may result in an altered polypeptide. Mutations can occur continuously.

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What's an insertion mutation?

A mutation that happens when a single nucleotide is randomly inserted into the DNA sequence.

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What is RNA splicing?

The process of removing introns from a primary transcript to produce a mature mRNA molecule. Exons (coding sequences) are fused together to form the continuous RNA molecule.

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What are introns?

Sections of a gene that are transcribed into RNA but are not translated into protein. They are removed during RNA splicing.

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What are exons?

Sections of a gene that are transcribed into RNA and translated into protein. They are joined together after splicing to form the mature mRNA molecule.

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What is tRNA?

A form of RNA that brings specific amino acids to the ribosome during translation, where they are added to the polypeptide chain. Each tRNA molecule has a specific anticodon that binds to a complementary codon on the mRNA molecule.

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Study Notes

Nucleic Acids & Protein Synthesis

  • Nucleic acids, like DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are polynucleotides.
  • Nucleotides are the monomers of nucleic acids.
  • Nucleotides consist of three components: a nitrogenous base, a pentose sugar (5 carbon atoms), and a phosphate group.

Nucleotide Structure

  • Nitrogenous bases are categorized as purines (adenine, guanine), which have a double ring structure, or pyrimidines (cytosine, thymine, uracil), which have a single ring structure.
  • DNA bases: adenine (A), thymine (T), guanine (G), cytosine (C)
  • RNA bases: adenine (A), uracil (U), guanine (G), cytosine (C)
  • DNA has deoxyribose sugar, RNA has ribose sugar
  • The sugar-phosphate backbone is formed by phosphodiester bonds, linking the 5' carbon of one sugar to the 3' carbon of the next.

DNA Structure

  • DNA is a double-stranded helix.
  • The two strands are antiparallel (run in opposite directions).
  • The strands are held together by hydrogen bonds between complementary base pairs: adenine (A) with thymine (T), and guanine (G) with cytosine (C).
  • A-T has two hydrogen bonds, C-G has three hydrogen bonds.

DNA Replication

  • Replication is semi-conservative: each new DNA molecule contains one strand from the original (parental) DNA and one newly synthesized strand.
  • DNA helicase unwinds the DNA double helix.
  • DNA polymerase adds complementary nucleotides to the exposed template strands.
  • Leading strand synthesis is continuous, lagging strand synthesis is discontinuous (Okazaki fragments).
  • DNA ligase joins the Okazaki fragments.

RNA Structure

  • RNA is a single-stranded molecule.
  • The sugar is ribose.
  • The bases are adenine (A), uracil (U), guanine (G), and cytosine (C).

Protein Synthesis

  • Genes are segments of DNA that code for proteins.
  • Transcription is the process of creating mRNA from a DNA template strand in the nucleus.
  • mRNA carries the genetic code to the ribosomes in the cytoplasm.
  • Translation is the process of assembling amino acids into a polypeptide chain based on the mRNA sequence. It happens in the ribosome.

Gene Mutation

  • Mutations involve changes in the DNA sequence.
  • Types of mutations include insertions, deletions, and substitutions.
  • Insertions and deletions can cause frameshift mutations, significantly altering the protein sequence beyond the site of the mutation.
  • Substitutions may or may not change the amino acid sequence, leading to silent, missense, or nonsense mutations.
  • Mutations affect the final polypeptide's shape and function.

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Related Documents

Nucleic Acids & Protein Synthesis PDF

Description

Test your knowledge on nucleic acids, including DNA and RNA, and their roles in protein synthesis. This quiz covers nucleotide structure, types of nitrogenous bases, and the unique characteristics of DNA and RNA. Challenge yourself to understand the molecular foundations of genetics.

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