Biology Unit 3: DNA and Protein Synthesis
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Questions and Answers

What is the primary function of DNA helicase during DNA replication?

  • To connect Okazaki fragments in the lagging strand.
  • To seal breaks in the sugar-phosphate backbone.
  • To break the hydrogen bonds between bases in the DNA double helix. (correct)
  • To add nucleotides to the growing DNA chain.

Which of the following statements accurately describes the process of DNA replication?

  • DNA replication is a semi-conservative process, where each new DNA molecule contains one original and one newly synthesized strand. (correct)
  • DNA replication is a process that occurs only in eukaryotic cells.
  • DNA replication is a random process, where the new DNA molecules are not necessarily identical to the original molecule.
  • DNA replication is a conservative process, where both new DNA molecules contain only newly synthesized strands.

What is the role of DNA polymerase in DNA replication?

  • DNA polymerase is responsible for unwinding the DNA double helix.
  • DNA polymerase is responsible for connecting Okazaki fragments in the lagging strand.
  • DNA polymerase is responsible for adding nucleotides to the growing DNA chain. (correct)
  • DNA polymerase is responsible for breaking the hydrogen bonds between bases in the DNA double helix.

Why is the synthesis of the lagging strand in DNA replication discontinuous?

<p>Because DNA polymerase can only add nucleotides to one end of the growing chain. (D)</p> Signup and view all the answers

What is the difference between the leading and lagging strands in DNA replication?

<p>The leading strand is synthesized continuously, while the lagging strand is synthesized discontinuously. (C)</p> Signup and view all the answers

What is the name of the enzyme responsible for connecting Okazaki fragments in the lagging strand?

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

Which of the following is NOT a characteristic of DNA replication?

<p>DNA replication occurs in the cytoplasm of eukaryotic cells. (D)</p> Signup and view all the answers

What is the significance of the fact that DNA replication is semi-conservative?

<p>It ensures that each new DNA molecule retains one strand from the original molecule. (C)</p> Signup and view all the answers

What significant discovery did Hershey and Chase make about DNA?

<p>DNA serves as the hereditary material in organisms. (A)</p> Signup and view all the answers

What process allows DNA to make exact copies of itself?

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

Which of the following best describes one of DNA's major functions?

<p>DNA encodes genetic instructions for cellular activities. (D)</p> Signup and view all the answers

What was the outcome of Griffith's studies on bacteria?

<p>Nonlethal bacteria can become lethal through transformation. (A)</p> Signup and view all the answers

What role does DNA play in evolution, according to the content?

<p>DNA mutations and recombinations contribute to biodiversity. (C)</p> Signup and view all the answers

In the context of DNA, what does 'mutations' refer to?

<p>Permanent alterations in the DNA structure and sequence. (B)</p> Signup and view all the answers

How did Hershey and Chase differentiate between DNA and protein during their experiments?

<p>Through radioactive labeling of DNA and protein. (C)</p> Signup and view all the answers

What type of substance did Griffith identify as capable of transforming bacteria?

<p>A transforming substance. (B)</p> Signup and view all the answers

What are the two types of nucleic acids mentioned?

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

Which bases are classified as purines?

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

What kind of bond forms between complementary bases in DNA?

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

How long is the DNA contained in every human cell approximately?

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

What is the average number of base pairs in a gene?

<p>1000 base pairs (A)</p> Signup and view all the answers

What do genes control in an organism?

<p>Cellular chemical reactions (C)</p> Signup and view all the answers

How many genes compose the DNA molecule of a single human chromosome?

<p>175,000 genes (C)</p> Signup and view all the answers

How are genes inherited from parents?

<p>In pairs from both parents (A)</p> Signup and view all the answers

Flashcards

Griffith's Experiment

Frederick Griffith's experiments identified a transforming substance that could alter non-lethal bacteria into lethal bacteria.

Hershey-Chase Experiment

Hershey and Chase conclusively proved DNA as the genetic material using a virus (T phage) that infects bacteria.

DNA's Role in Cellular Activities

DNA carries the genetic code, dictating cellular activities, including reproduction.

DNA Replication

DNA replicates to create exact copies of itself, ensuring genetic information is passed to daughter cells.

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DNA Mutations

Changes (mutations) in DNA's structure or number of molecules are the source of life's diversity.

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Gene Expression

The process of converting DNA's genetic code into proteins.

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Genetic Code

The sequence of nucleotide bases (adenine, guanine, cytosine, thymine) within DNA.

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Transcription

The process of copying DNA into RNA.

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DNA

A long, twisted strand of nucleotides that carries genetic information in the form of a sequence of base pairs.

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Nucleotide

A molecule that is part of DNA and consists of a phosphate group, a deoxyribose sugar, and a nitrogen-containing base.

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Base

A nitrogen-containing molecule that is a component of DNA and RNA. There are four types: adenine (A), guanine (G), cytosine (C), and thymine (T).

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Complementary base pairing

The pairing of two DNA bases (A-T, G-C) held together by hydrogen bonds. This complementary pairing is essential for DNA replication.

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Gene

A segment of DNA that contains the genetic information for a specific trait.

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Chromosome

A thread-like structure found in the nucleus of cells that carries genes.

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DNA base sequence variations

Differences in the sequence of DNA bases between individuals.

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What is DNA replication?

The process of copying DNA to create two identical double helices, ensuring each new cell gets a complete copy of the genetic information.

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Describe the semi-conservative nature of DNA replication.

Each new double helix contains one original strand from the parent DNA and one newly synthesized strand. This ensures accurate copying.

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What is the role of DNA helicase in DNA replication?

An enzyme that unwinds the DNA double helix by breaking the hydrogen bonds between base pairs, creating a replication fork.

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What is the function of DNA polymerase in DNA replication?

An enzyme that adds new nucleotides to the growing DNA strand, following the base pairing rules (A with T, C with G).

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What is the leading strand in DNA replication?

The strand that is synthesized continuously in the direction of the replication fork.

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Explain the lagging strand in DNA replication.

The strand synthesized discontinuously in short fragments called Okazaki fragments.

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What role does DNA ligase play in DNA replication?

An enzyme that joins the Okazaki fragments together, creating a continuous strand of DNA.

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Summarize the coordinated process of enzymes in DNA replication.

Enzymes involved in DNA replication work together to accurately copy the DNA molecule. The process involves unwinding, base pairing, and sealing breaks in the sugar-phosphate backbone.

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Study Notes

Unit 3: DNA, Protein Synthesis, Metabolism, and Enzymes

  • DNA is the genetic material, controlling cellular activities, including reproduction.
  • DNA carries a code of genetic instructions encoded in the sequence of bases.
  • DNA from a male and female combine to form the genetic information of offspring during sexual reproduction

DNA Replication

  • DNA makes exact copies of itself to pass onto other cells
  • This process is called replication
  • DNA copies itself through a semi-conservative process, where each new double helix has one original strand and one new synthesized strand

DNA Mutations

  • Mutations and rearrangements in DNA structure and number are the source of diversity in living organisms
  • Evolution proceeds from the level of DNA, with different combinations of DNA sequences due to mutations and sexual reproduction contributing to the existence of species.
  • DNA is the source of life's unity

RNA

  • RNA is the genetic material in some viruses, necessary for protein synthesis in all organisms
  • RNA may have been the original nucleic acid when life first arose on Earth (around 3.8 billion years ago), as it can replicate

Differences Between DNA and RNA

  • Uracil replaces Thymine in RNA
  • RNA uses Ribose sugar, instead of Deoxyribose
  • RNA is single-stranded, unlike DNA's double-helix structure
  • RNA is generally shorter than DNA

DNA Replication at the Molecular Level

  • DNA helicase unwinds the DNA by breaking hydrogen bonds
  • DNA polymerase incorporates complementary nucleotides to form new DNA strands, on one strand a 'leading' strand forms directly and follows helicase movements, while the 'lagging' strand forms in fragments called Okazaki fragments
  • DNA ligase joins the gaps in the lagging strand

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Description

Explore the fundamental concepts of DNA structure, replication, mutations, and the role of RNA in genetics through this comprehensive quiz. Learn how genetic material influences cellular activities and drives evolution. Test your knowledge on the processes that sustain life at the molecular level.

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