Biology DNA Replication and Transcription
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Questions and Answers

What is the process called where DNA is transcribed into mRNA?

  • Translocation
  • Translation
  • Transcription (correct)
  • Replication

Which base pairs with adenine according to Chargaff's data?

  • Uracil
  • Thymine (correct)
  • Guanine
  • Cytosine

What are the sides of the DNA ladder composed of?

  • Nitrogenous bases
  • Ribose and phosphate
  • Sugar-phosphate molecules (correct)
  • Amino acids

What does the term semiconservative refer to in molecular biology?

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

How do tRNAs recognize the correct codons in mRNA?

<p>By complementary base pairing (D)</p> Signup and view all the answers

Which enzyme is responsible for unwinding DNA during replication?

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

What type of molecule is mRNA after transcription?

<p>An RNA molecule (C)</p> Signup and view all the answers

Which of the following is NOT involved in the central dogma of molecular biology?

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

What percentage of DNA is composed of thymine nucleotides if it contains 18% adenine nucleotides?

<p>18% (C)</p> Signup and view all the answers

In DNA replication, what is the primary role of helicase?

<p>Unwind the DNA helix (C)</p> Signup and view all the answers

What is the result of a malfunction in RNA polymerase?

<p>Failure to form mRNA (A)</p> Signup and view all the answers

Which chemical bond must be disrupted for DNA strands to separate during transcription?

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

According to Chargaff's rules, if DNA is made up of 28% adenine, what percentage of guanine is present?

<p>22% (D)</p> Signup and view all the answers

Which of these statements about the central dogma of molecular biology is correct?

<p>DNA to RNA to protein (B)</p> Signup and view all the answers

What is the primary purpose of tRNA in protein synthesis?

<p>To carry amino acids to ribosomes (D)</p> Signup and view all the answers

During what process is mRNA synthesized?

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

What is the function of DNA ligase during DNA replication?

<p>Join Okazaki fragments together (D)</p> Signup and view all the answers

Which of the following processes occurs in the cytoplasm?

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

How does the mRNA sequence relate to the DNA template strand?

<p>It's complementary to the DNA template strand with thymine replaced by uracil (B)</p> Signup and view all the answers

What type of nucleic acid is produced during the process of transcription?

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

What is a key difference between RNA and DNA?

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

Flashcards

Central Dogma

The flow of genetic information from DNA to RNA to protein.

Transcription

The process of copying genetic information from DNA to RNA. This occurs in the nucleus.

Chargaff's Rule

Adenine (A) always pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C) in DNA.

DNA Structure

DNA is shaped like a twisted ladder. The rungs are made of nitrogenous bases, and the sides are made of sugar-phosphate molecules.

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Semiconservative Replication

The process of DNA replication where each new DNA molecule has one old and one new strand.

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tRNA recognition

tRNA molecules carrying the correct amino acid recognize their corresponding codons on mRNA through complementary base pairing between their anticodon and the mRNA codon.

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Unwinding enzyme in DNA replication

Helicase is the enzyme responsible for unwinding the DNA double helix during replication.

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DNA Replication Steps

DNA replication involves three steps: (1) unwinding, (2) base pairing, and (3) joining.

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What adds nucleotides in DNA replication?

DNA polymerase adds new nucleotides to the growing DNA strand, following base pairing rules (A-T, G-C).

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What's the difference between DNA and RNA?

DNA is double-stranded and contains thymine (T), while RNA is single-stranded and contains uracil (U).

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What does RNA polymerase do?

RNA polymerase makes a copy of a DNA sequence, creating an mRNA molecule.

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What is transcription?

Transcription is the process of converting DNA information into mRNA, which is a message for protein synthesis.

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What is translation?

Translation is the process of converting the mRNA message into a protein, using tRNA to bring amino acids.

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What is tRNA?

Transfer RNA (tRNA) brings specific amino acids to the ribosomes during protein synthesis.

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What is rRNA?

Ribosomal RNA (rRNA) is a major component of ribosomes, which are the sites of protein synthesis.

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Where does translation occur?

Translation takes place in the cytoplasm, on ribosomes.

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What is the central dogma of molecular biology?

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

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What must happen before transcription or replication?

The two DNA strands must be separated before transcription or replication can occur, to allow access to the base pairs.

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Study Notes

DNA Replication and Transcription

  • Central Dogma: Genetic information flows from DNA to RNA to protein.
  • Transcription: DNA is transcribed into mRNA in the nucleus.
  • RNA Types: mRNA carries the genetic code from DNA to ribosomes; rRNA forms part of ribosomes; tRNA carries amino acids. DNA -> mRNA-> Protein
  • DNA Structure: A twisted ladder; rungs made of nitrogenous bases (A-T, G-C); sides composed of sugar-phosphate molecules.
  • Semiconservative Replication: Each new DNA molecule consists of one old strand and one new strand.

Chargaff's Rules

  • Base Pairing: Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C).

DNA Replication

  • Unwinding: Helicase unwinds the DNA double helix.
  • Enzymes: DNA polymerase adds complementary nucleotides; DNA ligase joins DNA fragments.

Translation

  • tRNA and Codons: tRNA anticodons bind to mRNA codons (complementary base pairing) bringing the correct amino acid.

RNA vs. DNA

  • Structure: RNA is single-stranded; DNA is double-stranded.
  • Bases: RNA contains uracil (U) instead of thymine (T).

Processes and Locations

  • Transcription: Occurs in the nucleus.
  • Translation: Occurs in the cytoplasm.
  • DNA Replication: Occurs in the nucleus.
  • Intron removal: Occurs in the nucleus (part of mRNA processing)

Process Details

  • DNA Replication: Semiconservative process; each new DNA molecule has one old and one new strand.
  • Base Pair Ratios: If DNA has 18% adenine, it also has 18% thymine; that leaves 64% left over divided by 2 to get 32% guanine and 32% cytosine.
  • mRNA Formation: RNA polymerase creates mRNA from DNA template (complementary bases).

Enzyme Roles

  • Helicase: Separates DNA strands during replication.
  • RNA Polymerase: Creates mRNA during transcription.
  • DNA Polymerase: Adds nucleotides during replication.
  • DNA Ligase: Joins DNA fragments.

mRNA vs Other Types

  • mRNA: Carries genetic code for protein synthesis.
  • rRNA: Forms part of the ribosomes that read the mRNA.
  • tRNA: Carries amino acids to the ribosome.

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Description

Test your knowledge on the central dogma of molecular biology, focusing on DNA replication and transcription processes. This quiz covers key concepts such as the structure of DNA, the function of different types of RNA, and the roles of essential enzymes in replication and translation.

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