Central Dogma of Biology
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Questions and Answers

What is the first step of protein expression?

  • Transcription (correct)
  • Replication
  • Translation
  • Conjugation

Which type of RNA acts as the template for protein synthesis?

  • snRNA
  • rRNA
  • mRNA (correct)
  • tRNA

What is the sugar component of RNA nucleotides?

  • Ribose (correct)
  • Glucose
  • Fructose
  • Deoxy ribose

Which nitrogenous base is present in RNA instead of DNA?

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

Where does translation occur in the cell?

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

What brings amino acids to the ribosome during translation?

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

Which of the following statements is true regarding DNA and RNA?

<p>RNA is single-stranded while DNA is double-stranded. (D)</p> Signup and view all the answers

What constitutes the primary structural components of cells?

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

Which option correctly describes the central dogma of biology?

<p>DNA → RNA → Protein (C)</p> Signup and view all the answers

In how many steps does protein expression occur?

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

What is the first step in the central dogma of biology?

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

What role does RNA polymerase play in transcription?

<p>It synthesizes RNA from a DNA template (A)</p> Signup and view all the answers

During transcription, which base in DNA is replaced by which base in RNA?

<p>Thymine is replaced by Uracil (D)</p> Signup and view all the answers

What is a codon?

<p>Three nucleotides coding for one amino acid (D)</p> Signup and view all the answers

What signals the end of the transcription process?

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

Which of the following is NOT a type of RNA produced during transcription?

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

Where does translation occur in eukaryotic cells?

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

What is the function of transfer RNA (tRNA) in translation?

<p>To bring amino acids to the ribosome (A)</p> Signup and view all the answers

In prokaryotes, transcription and translation can occur simultaneously because:

<p>Prokaryotes do not have a nucleus (C)</p> Signup and view all the answers

What is the universal start codon for protein synthesis?

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

Protein expression only involves the process of translation.

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

During transcription, the DNA is copied into messenger RNA (mRNA).

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

DNA is made up of ribose sugar, while RNA contains deoxyribose sugar.

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

Uracil is found in RNA but is replaced by Thymine in DNA.

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

Translation occurs on ribosomes and requires the help of tRNA.

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

The central dogma of biology describes the flow of genetic information from RNA to DNA.

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

Both DNA and RNA are double-stranded molecules.

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

Adenine pairs with Uracil in RNA.

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

All proteins are enzymes, making protein expression vital for cellular function.

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

The sugar component in RNA nucleotides is called ribonucleic acid.

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

Transcription involves the process of synthesizing proteins directly from DNA.

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

In eukaryotes, transcription occurs in the nucleus while translation occurs in the cytoplasm.

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

The anticodon of tRNA pairs with the corresponding codon on mRNA during translation.

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

The start codon for translation is UAG.

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

RNA polymerase requires a primer to synthesize RNA during transcription.

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

During transcription, thymine in the DNA is replaced by uracil in the RNA.

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

Codons consist of three nucleotides and correspond to individual amino acids during translation.

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

Both prokaryotes and eukaryotes use ribosomes for the process of transcription.

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

Translation begins with the amino acid tyrosine as the first amino acid for all proteins.

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

The process of translation can occur simultaneously with transcription in prokaryotic cells.

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

Flashcards

Protein Expression

The process of creating proteins using DNA instructions.

Transcription

Making a complementary mRNA copy of a gene from DNA.

Translation

Using mRNA to build a protein on ribosomes.

RNA

RiboNucleic Acid; a nucleic acid involved in protein synthesis.

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mRNA

Messenger RNA; carries genetic instructions from DNA to ribosomes.

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tRNA

Transfer RNA; brings amino acids to the ribosome during translation.

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Nucleotide

The building block of both DNA and RNA.

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Uracil

Nitrogenous base found in RNA, replacing Thymine.

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Central Dogma

DNA -> RNA -> Protein; the fundamental flow of genetic information.

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Amino Acid

The building block of proteins.

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Central Dogma of Biology

How information in DNA is used to make proteins, which comprise cell structure and function.

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RNA Polymerase

Enzyme that synthesizes RNA from DNA.

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Promoter

DNA sequence where RNA polymerase binds to start transcription.

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Termination Sequence

DNA sequence that stops transcription.

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Codon

Three nucleotides that specify one amino acid.

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tRNA (transfer RNA)

RNA molecule that carries amino acids to the ribosome during translation.

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Ribosome

Cellular organelle where proteins are assembled from amino acids.

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Mutation

Change in the DNA sequence.

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Why is protein expression important?

Proteins are essential for cell structure and function, including enzymes, organelles, and structural elements.

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What are the two steps of protein expression?

Transcription and translation.

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What happens in transcription?

DNA's genetic information is copied into mRNA by RNA polymerase.

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What is the role of mRNA?

Messenger RNA carries the genetic code from DNA to the ribosome.

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What happens in translation?

mRNA is used to assemble amino acids into a protein on ribosomes.

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What are the building blocks of proteins?

Amino acids.

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How is RNA different from DNA?

RNA uses ribose sugar instead of deoxyribose, and uracil instead of thymine.

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What is the difference in structure between DNA and RNA?

DNA is double-stranded, forming a helix, while RNA is single-stranded.

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Which base pairs with adenine in RNA?

Uracil (U)

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What are the base pairing rules for RNA?

Cytosine pairs with Guanine (C-G) and Adenine pairs with Uracil (A-U).

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What is the central dogma of biology?

The central dogma of biology describes how genetic information flows from DNA to RNA and then to proteins, which are essential for cell structure and function.

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What is transcription?

Transcription is the process of creating a messenger RNA (mRNA) copy from a DNA template. It involves RNA polymerase recognizing a promoter, unwinding the DNA, and synthesizing a complementary mRNA strand.

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What is translation?

Translation is the process of translating the genetic code carried by mRNA into a protein. It involves ribosomes, transfer RNAs (tRNAs), and codons.

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What is an anticodon?

An anticodon is a three-nucleotide sequence on a tRNA molecule that complements a specific codon on mRNA.

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What is a codon?

A codon is a three-nucleotide sequence on mRNA that codes for a specific amino acid during translation.

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What is a missense mutation?

A missense mutation is a substitution mutation that changes one nucleotide, leading to a change in the amino acid sequence of a protein.

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What is a nonsense mutation?

A nonsense mutation is a substitution mutation that changes one nucleotide, resulting in a premature stop codon in the mRNA sequence, leading to an incomplete protein.

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What is a frame shift mutation?

A frame shift mutation is an insertion or deletion of a nucleotide in the DNA sequence, resulting in the misreading of the entire genetic code downstream of the mutation.

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What is excision repair?

Excision repair is a cellular mechanism that removes damaged or mutated DNA sequences, restoring the original sequence through DNA polymerase and ligase.

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Study Notes

DNA to Protein: The Central Dogma

  • Protein expression is crucial for cell structure and function.
  • All enzymes are proteins, and proteins form organelles, flagella, cilia, peptidoglycan, ribosomes, etc.
  • Protein expression (creation) is called the central dogma of biology.

Two Steps: Transcription and Translation

  • Transcription: RNA polymerase copies a gene from DNA into mRNA (messenger RNA).
  • Translation: mRNA, with the help of ribosomes and tRNAs (transfer RNAs), creates proteins. tRNAs read mRNA and bring amino acids (protein building blocks).

RNA vs. DNA

  • DNA: Double helix, made of nucleotides (deoxyribose sugar, phosphate, and a nitrogenous base - A, T, C, G)
  • RNA: Single stranded, made of nucleotides (ribose sugar, phosphate, and a nitrogenous base - A, U, C, G). Uracil replaces Thymine.

Transcription Details

  • RNA polymerase: Enzyme that reads DNA and creates a complementary RNA strand.
  • Promoter: DNA sequence where RNA polymerase binds to start transcription.
  • Termination sequence: DNA sequence that stops transcription.
  • RNA polymerase unwinds the DNA and synthesizes RNA in the 5' to 3' direction.
  • No helicase, primer, or other replication enzymes are necessary, unlike DNA replication.

Translation Details

  • Ribosomes: Sites of protein synthesis.
  • mRNA: Contains the genetic code for a protein.
  • tRNA (transfer RNA): Has an anticodon that matches mRNA codons, bringing in the correct amino acid for each codon.
  • Codon: Three nucleotides on mRNA that specify one amino acid.
  • Translation proceeds from the start codon (AUG) to the stop codons (UAA, UAG, UGA).
  • Universal Genetic Code: The same codons code for the same amino acids in all life forms. The code is redundant (multiple codons for an amino acid)

Ribosomes and Translation Process

  • Ribosomes have an A site, P site, E site (exit site) that facilitate the binding of tRNAs, creation of peptide bonds, and release of empty tRNAs.
  • The ribosome moves along the mRNA, one codon at a time, adding amino acids to form the polypeptide chain.
  • Translation stops when a stop codon is encountered.

Prokaryotes vs. Eukaryotes

  • Prokaryotes: Transcription and translation can occur simultaneously in the cytoplasm.
  • Eukaryotes: Transcription occurs in the nucleus, translation in the cytoplasm. Introns (noncoding regions) must be removed from the pre-mRNA before translation.
  • Operons are unique to prokaryotes.

Mutations

  • Mutations: Changes in the DNA sequence.
  • Spontaneous mutations: Happen continuously, at a low rate.
  • Mutagens: Environmental factors (chemicals, radiation) that increase mutation frequency.
  • Types of mutations:
    • Substitution mutations (point mutations): One nucleotide is changed.
      • Missense mutation: The changed nucleotide codes for a different amino acid.
      • Nonsense mutation: The changed nucleotide codes for a premature stop codon.
    • Frameshift mutations (insertion/deletion): One or more nucleotides are inserted or deleted, altering the reading frame, impacting all subsequent amino acids.
  • Excision repair: Process for fixing damaged DNA, crucial for maintaining genetic information.

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Description

Explore the essential process of protein expression through the central dogma of biology, which includes transcription and translation. Understand the differences between DNA and RNA, and the roles of RNA polymerase in synthesizing mRNA. This quiz will test your knowledge on these fundamental biological concepts.

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