Nucleic Acids & Protein Synthesis
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Questions and Answers

What are the three components that make up a nucleotide?

  • Nitrogenous base, glucose, phosphate group
  • Nitrogenous base, pentose sugar, phosphate group (correct)
  • Fatty acid, deoxyribose sugar, nitrogenous base
  • Amino acid, ribose sugar, phosphate group

Which sugar is found in RNA?

  • Glucose
  • Deoxyribose
  • Fructose
  • Ribose (correct)

How many hydrogen bonds are present between adenine and thymine in DNA?

  • 1 hydrogen bond
  • 2 hydrogen bonds (correct)
  • No hydrogen bonds
  • 3 hydrogen bonds

What type of structure do purines have?

<p>Double ring structure (A)</p> Signup and view all the answers

Which of the following is NOT a nitrogenous base found in RNA?

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

What is the primary function of ATP in cells?

<p>To provide energy for cellular processes (B)</p> Signup and view all the answers

What structural feature distinguishes DNA from RNA?

<p>Number of strands (D)</p> Signup and view all the answers

Which of the following nitrogenous bases is a pyrimidine?

<p>Cytosine (B), Thymine (C)</p> Signup and view all the answers

What type of bond links the deoxyribose sugars and phosphate groups in a DNA strand?

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

How are the two strands of DNA oriented relative to each other?

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

What is the role of DNA polymerase in DNA replication?

<p>To catalyze the bonding of nucleotides (A)</p> Signup and view all the answers

What are the base pairs in DNA held together by?

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

Which statement about complementary base pairing is correct?

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

During semi-conservative DNA replication, what happens to the parental DNA strands?

<p>They act as templates for new strands (C)</p> Signup and view all the answers

Which direction does DNA polymerase build the new strand during replication?

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

What is the function of DNA helicase during DNA replication?

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

What is the role of RNA polymerase during transcription?

<p>To bond the sugar-phosphate groups of RNA nucleotides (C)</p> Signup and view all the answers

What happens to introns during the processing of mRNA?

<p>They are spliced out and removed (C)</p> Signup and view all the answers

Where does translation of mRNA into a polypeptide chain occur?

<p>At the ribosome in the cytoplasm (A)</p> Signup and view all the answers

What is formed as a result of the translation process?

<p>A completed amino acid chain (polypeptide) (D)</p> Signup and view all the answers

What defines a gene mutation?

<p>A change in the sequence of base pairs in DNA (A)</p> Signup and view all the answers

Which of the following describes an insertion mutation?

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

What part of the tRNA molecule recognizes codons on the mRNA?

<p>Triplet anticodon (D)</p> Signup and view all the answers

What is the function of the stop codon during translation?

<p>It signals for the termination of the polypeptide chain (D)</p> Signup and view all the answers

What distinguishes the synthesis of the leading strand from the lagging strand during DNA replication?

<p>The leading strand is synthesized continuously, while the lagging strand is synthesized in fragments called Okazaki fragments. (A)</p> Signup and view all the answers

Which of the following correctly defines a gene?

<p>A segment of DNA that codes for a specific polypeptide. (B)</p> Signup and view all the answers

What is the role of DNA ligase during DNA replication?

<p>It joins Okazaki fragments together. (A)</p> Signup and view all the answers

Which feature is unique to RNA compared to DNA?

<p>Contains uracil instead of thymine. (D)</p> Signup and view all the answers

How do codons within a gene relate to amino acids?

<p>Each codon codes for a single specific amino acid. (C)</p> Signup and view all the answers

What is the primary role of messenger RNA (mRNA) in protein synthesis?

<p>To transport genetic information from DNA to the ribosome. (B)</p> Signup and view all the answers

Why is the genetic code considered degenerate?

<p>Due to the presence of multiple codons coding for the same amino acid. (C)</p> Signup and view all the answers

What type of bond links nucleotides together within a single RNA strand?

<p>Covalent phosphodiester bonds. (A)</p> Signup and view all the answers

What is the consequence of an insertion mutation on a DNA sequence?

<p>It alters the grouping of triplet codons downstream. (D)</p> Signup and view all the answers

Which type of mutation can result in a complete loss of function for a polypeptide?

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

What is a characteristic of substitution mutations?

<p>They involve swapping a base in the DNA sequence. (A)</p> Signup and view all the answers

How do frameshift mutations generally affect protein synthesis?

<p>They can alter the translation of all downstream codons. (A)</p> Signup and view all the answers

Which of the following mutations typically has the least impact on the final polypeptide?

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

What type of mutation is exemplified by sickle cell anaemia?

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

Which statement about deletion mutations is accurate?

<p>They can lead to frameshift mutations like insertions. (B)</p> Signup and view all the answers

Which of the following can be a potential outcome of mutations in genes?

<p>Some mutations result in altered polypeptides that do not function properly. (C)</p> Signup and view all the answers

Flashcards

What is a phosphodiester bond?

The chemical bond that connects two nucleotides in a DNA strand.

What does antiparallel mean in DNA?

The two strands of DNA run in opposite directions. One '5' to '3' and the other '3' to '5'.

What is DNA replication?

The process where a DNA molecule is copied by breaking its strands and using each as a template for a new strand.

What does DNA polymerase do?

The enzyme that adds complementary nucleotides to the template strand, building the new DNA strand.

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Explain base pairing in DNA.

The two strands of DNA are held together by weak bonds between the nitrogenous bases: Adenine (A) pairs with Thymine (T) and Guanine (G) pairs with Cytosine (C)-

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What is the replication fork?

The region where the DNA double helix is unwinding and new strands are being synthesized.

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What is a leading strand?

This strand is synthesized continuously in the direction of the replication fork.

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What is a lagging strand?

This strand is synthesized discontinuously in the opposite direction to the replication fork. This is because DNA polymerase can only build in one direction.

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What are nucleotides?

Nucleic acids are made up of smaller units called nucleotides, similar to how proteins are made up of amino acids.

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What are the components of a nucleotide?

A nucleotide consists of three components: a nitrogen-containing base, a pentose sugar (a 5-carbon sugar), and a phosphate group.

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What are purines and pyrimidines?

Adenine and guanine are purines, with a double-ring structure. Cytosine, thymine, and uracil are pyrimidines, with a single-ring structure.

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What is the difference between deoxyribose and ribose?

The sugar in DNA is called deoxyribose, while the sugar in RNA is called ribose. This small difference in the sugar molecule leads to different properties of DNA and RNA.

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What is the difference in structure between DNA and RNA?

DNA is a double-stranded helix, meaning it has two strands of nucleotides that are twisted around each other. RNA is single-stranded.

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What is the difference in bases between DNA and RNA?

DNA uses thymine (T) while RNA uses uracil (U). Both use adenine (A), cytosine (C), and guanine (G).

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What is ATP and what is it made of?

ATP is a nucleic acid that serves as the primary energy currency in cells. It is made up of adenine, ribose, and three phosphate groups.

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What does it mean that DNA strands are antiparallel?

The two strands of DNA run in opposite directions, like a highway with two lanes going in opposite directions. This is called antiparallel.

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DNA Replication

The process of building a new DNA strand from a template strand using enzymes like DNA polymerase, helicase, and ligase.

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Semi-Conservative Replication

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

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Leading Strand Synthesis

The continuous synthesis of a new DNA strand by DNA polymerase in the same direction as the unwinding of the double helix.

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Lagging Strand Synthesis

The synthesis of the lagging strand is discontinuous because DNA polymerase can only elongate the new strand in the 5'-3' direction, opposite to the unwinding of the double helix.

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Okazaki Fragments

Short, newly synthesized DNA fragments on the lagging strand.

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DNA Ligase

An enzyme that joins DNA fragments together, forming a continuous strand.

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RNA

A polynucleotide consisting of a single strand with alternating ribose sugars and phosphate groups.

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Genetic Code

The sequence of nucleotides within a gene that codes for a specific amino acid.

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Transcription

The process of copying the genetic code from DNA to mRNA.

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mRNA (messenger RNA)

A single-stranded nucleic acid molecule, carrying the genetic code from DNA to ribosomes for protein synthesis.

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Codon

A sequence of three bases on mRNA that codes for a specific amino acid during translation.

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RNA polymerase

The enzyme that reads DNA and builds the mRNA molecule during transcription.

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Translation

The process of translating the mRNA code into an amino acid sequence to build a polypeptide.

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tRNA (transfer RNA)

A type of RNA that carries specific amino acids to the ribosome during translation.

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Gene mutation

A change in the DNA base sequence that can alter the protein produced.

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Insertion mutation

A mutation that occurs when a nucleotide is added to the DNA sequence.

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Substitution mutation

A change in the DNA sequence where a single base is swapped for another. This can have various effects on the protein, depending on the specific change.

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Silent mutation

A substitution mutation that doesn't alter the amino acid sequence of the protein. It's a silent change.

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Missense mutation

A substitution mutation that changes a single amino acid in the protein, potentially altering its function.

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Nonsense mutation

A substitution mutation that creates a premature stop codon within the DNA sequence, resulting in a shorter and potentially non-functional protein.

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Deletion mutation

A mutation where a nucleotide is removed from the DNA sequence, changing the reading frame and potentially altering the amino acid sequence.

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Effect of gene mutations on polypeptides

The effect of mutations on the amino acid sequence of a protein, which can lead to changes in its structure and function.

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Frameshift mutation

A mutation that changes the reading frame of the DNA sequence by inserting or deleting nucleotides that are not multiples of three. This shifts the way the codons are read, often resulting in a drastically different protein.

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Study Notes

Nucleic Acids & Protein Synthesis

  • Nucleic acids include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
  • Nucleotides are the monomers of nucleic acids.
  • A nucleotide has three components: a nitrogenous base, a pentose sugar, and a phosphate group.
  • Nitrogenous bases are either purines (adenine, guanine) or pyrimidines (cytosine, thymine, uracil).
  • Purines have a double-ring structure, while pyrimidines have a single-ring structure.
  • Deoxyribose is the sugar in DNA.
  • Ribose is the sugar in RNA.
  • DNA is double-stranded, forming a double helix. RNA is single-stranded..
  • Adenine (A) pairs with thymine (T) in DNA, and with uracil (U) in RNA.
  • Guanine (G) pairs with cytosine (C) in both DNA and RNA.
  • In DNA, A-T bonds form two hydrogen bonds, and G-C bonds form three hydrogen bonds
  • ATP (adenosine triphosphate) is an energy-carrying molecule used in many cellular processes.

DNA Structure

  • DNA molecules consist of two antiparallel polynucleotide strands.
  • The strands are held together by hydrogen bonds between complementary base pairs (A-T and G-C).
  • The sugar-phosphate backbone forms the structural framework of the DNA strand.
  • The strands run in opposite directions (antiparallel). One strand is 5' to 3', and the other is 3' to 5'.
  • Phosphodiester bonds connect the sugar of one nucleotide to the phosphate of the next.

DNA Replication

  • DNA replication is semi-conservative.
  • DNA helicase unwinds the double helix.
  • Free-floating nucleotides pair with complementary bases on the template strands.
  • DNA polymerase catalyses the formation of phosphodiester bonds between nucleotides, creating new strands.
  • DNA polymerase works in the 5' to 3' direction.
  • Leading strand replication is continuous; lagging strand replication is discontinuous (Okazaki fragments).
  • DNA ligase joins the Okazaki fragments.

RNA Structure

  • RNA is a single-stranded polynucleotide.
  • RNA contains the sugar ribose.
  • RNA bases include adenine (A), guanine (G), cytosine (C), and uracil (U).
  • RNA is involved in protein synthesis.

Protein Synthesis

  • Protein synthesis involves two main stages: transcription and translation.
  • Transcription occurs in the nucleus. DNA is transcribed into mRNA.
  • mRNA carries the genetic code from the DNA to the ribosome.
  • Translation occurs in the cytoplasm. rRNA and tRNA work together to translate the mRNA code into a protein.

Gene Mutations

  • Mutations are changes in the DNA sequence.
  • Insertions, deletions, and substitutions are types of mutations.
  • Mutations can affect the amino acid sequence of a protein, leading to changes in the protein's structure and function.

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Nucleic Acids & Protein Synthesis PDF

Description

This quiz covers the structure and function of nucleic acids, specifically DNA and RNA. It details the components of nucleotides, base pairing, and the significance of ATP in cellular processes. Test your understanding of the molecular basis of genetics and protein synthesis.

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