DNA Structure and Replication

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Questions and Answers

Which of the following correctly describes the process of DNA replication?

During DNA replication, the two strands of the DNA molecule separate, and each strand serves as a template for the synthesis of a new complementary strand.

DNA replication is a process that occurs in the cytoplasm of a cell.

DNA replication is a process that creates two identical DNA molecules, each consisting of one original strand and one newly synthesized strand. (correct)

DNA replication is a process that creates an exact copy of a DNA molecule.

What is the role of DNA ligase in DNA replication?

DNA ligase joins the fragments of the newly synthesized DNA strand. (correct)

DNA ligase unwinds the DNA double helix.

DNA ligase separates the two strands of the DNA molecule.

DNA ligase adds nucleotides to the growing DNA strand.

Which of the following is NOT a component of a nucleotide?

Nitrogenous base

Ribose sugar

Amino acid (correct)

Phosphate group

What is the type of bond that holds together the two strands of a DNA molecule?

Hydrogen bonds (A) Signup and view all the answers

Which of the following nitrogenous bases is NOT found in DNA?

Uracil (A) Signup and view all the answers

Where are genes found?

Genes are found in the cell's nucleus, within chromosomes. (D) Signup and view all the answers

Which of these is NOT a function of genes?

They pass on information from one generation to the next. (D) Signup and view all the answers

What is the best way to describe what genes are?

Genes are segments of DNA that contain instructions for building proteins. (B) Signup and view all the answers

What is the name of the building block of DNA?

Nucleotide (B) Signup and view all the answers

Which of these is NOT a function of the cell's nucleus?

Providing energy for the cell. (A) Signup and view all the answers

What is the role of chromosomes in relation to genes?

Chromosomes package and protect genes. (A) Signup and view all the answers

What are the four nitrogenous bases found in DNA?

Adenine, Thymine, Guanine, Cytosine (D) Signup and view all the answers

Which scientist is credited with discovering the double helix structure of DNA?

Watson and Crick (A) Signup and view all the answers

How is information passed on from one generation to the next?

All of the above are correct. (D) Signup and view all the answers

What does “blueprint of life” refer to in the context of genes?

Genes contain the instructions for building and maintaining an organism. (B) Signup and view all the answers

What type of bond connects the nitrogenous bases in DNA?

Hydrogen Bond (C) Signup and view all the answers

Which of these is the most accurate description of how genes work?

Genes act as templates for creating proteins. (B) Signup and view all the answers

What is the significance of Chargaff's rule?

It explains the complementary base pairing in DNA (C) Signup and view all the answers

What is the role of Rosalind Franklin's X-ray diffraction studies in understanding DNA?

They provided evidence for the double helix structure of DNA (B) Signup and view all the answers

How many hydrogen bonds are formed between guanine (G) and cytosine (C) in DNA?

Three (B) Signup and view all the answers

What is the primary function of DNA?

Storing and transmitting genetic information (D) Signup and view all the answers

What is the process by which DNA is copied before cell division?

Replication (B) Signup and view all the answers

What is the role of the enzyme helicase in DNA replication?

Helicase unwinds the DNA double helix by breaking hydrogen bonds. (B) Signup and view all the answers

What is the purpose of the primer in DNA replication?

The primer provides a starting point for the DNA polymerase to bind to the template strand. (D) Signup and view all the answers

During DNA replication, DNA polymerase adds new nucleotides to the growing strand in what direction?

From the 5' end to the 3' end. (D) Signup and view all the answers

Which enzyme is primarily responsible for creating new DNA strands in DNA replication?

DNA polymerase. (A) Signup and view all the answers

What is the name of the small, complementary DNA fragment that is built by primase during replication?

Primer. (C) Signup and view all the answers

What is the function of the enzyme ligase in DNA replication?

Ligase joins together separate fragments of DNA, such as Okazaki fragments, on the lagging strand. (B) Signup and view all the answers

What is the name of the process that results in two identical DNA molecules from one original molecule?

Replication. (B) Signup and view all the answers

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

Leading strand is synthesized continuously, while lagging strand is synthesized discontinuously. (C) Signup and view all the answers

Study Notes

DNA Structure, Replication, and Scientists

Genes: Blueprints of life, easily copied and replicated, carry heritable information for protein production. Found in chromosomes within the nucleus.
DNA (Deoxyribonucleic Acid): A polymer made of nucleotides (phosphate, 5-carbon sugar deoxyribose, and a nitrogenous base). DNA structure resembles a twisted ladder (double helix).
Nucleotide Components: The three components of DNA nucleotides are phosphate, a 5-carbon sugar (deoxyribose), and a nitrogenous base.
DNA Structure: Looks like a twisted ladder (double helix). Base pairs (A-T, G-C) hold the two strands together via hydrogen bonds; A always pairs with T, and G always pairs with C.
DNA Replication: A process that occurs when a cell divides; the DNA molecule unzips, and each strand serves as a template to create a new complementary strand. This is a semi-conservative process (one original strand remains in each new DNA molecule).
Replication Enzymes: Helicase unzips the DNA, primase creates a primer to start replication, DNA polymerase builds new complementary strands, and ligase joins the gaps.
DNA Scientists:
- Watson and Crick: Discovered the double helix structure of DNA.
- Erwin Chargaff: Stated that the percentages of nitrogen bases in DNA are complementary (A=T, G=C).
- Rosalind Franklin: Used X-ray diffraction to confirm the structure and shape of DNA.

DNA Replication Steps

Step 1: Unzipping: Helicase breaks hydrogen bonds between base pairs, creating a replication fork.
Step 2: Creating Templates: Each strand of DNA becomes a template to build new strands.
Step 3: Building Primers: Primase builds a short complementary DNA segment ("primer") to mark the start of replication.
Step 4: Building Complementary Strands: DNA polymerase builds new complementary strands to the template strand, adding new nucleotides to the 3' end of the growing strand (5' to 3' direction).
Step 5: Base Pairing: New nucleotides pair with their complementary base on the template strand (A-T, G-C).
Step 6: Sealing the Strands: Ligase seals the gaps between the new segments of DNA.
Step 7: Product: The result of replication is two identical DNA molecules, each with one original and one new strand (semi-conservative replication).

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Description

Explore the fascinating world of DNA, its structure, and the process of replication. Learn about the building blocks of life, including nucleotides and the significance of base pairing. This quiz dives into the essential concepts surrounding genetic material and its replication process.