DNA Basics and Structure Quiz

Questions and Answers

The letters 'DNA' stand for __________.

Deoxyribonucleic acid

DNA is composed of smaller subunits known as __________.

Nucleotides

The three parts of a nucleotide are , , and __.

Sugar, phosphate, and a nitrogen base

The four nitrogen bases that are found in DNA are , , , and .

Adenine, cytosine, guanine, and thymine Signup and view all the answers

Two of the nitrogen bases are single ring structures known as . These two bases are and __.

Pyrimidines; thymine, cytosine Signup and view all the answers

The other two bases are double ring structures known as . These two bases are and __.

Purines; adenine, guanine Signup and view all the answers

and are the two scientists that discovered the structure of the DNA molecule.

Watson and Crick Signup and view all the answers

DNA looks like a ladder twisted into a shape known as a __________.

Double helix Signup and view all the answers

The two molecules that make up the sides of the ladder or the side portion of a DNA molecule are and .

Sugars and phosphates Signup and view all the answers

The molecules that meet across the middle, forming the steps of the 'ladder' are known as __________.

Nitrogen bases Signup and view all the answers

Which nitrogen bases always pair with one another?

Adenine pairs with thymine; Cytosine pairs with guanine Signup and view all the answers

According to Chargaff's rules, the percentages of are equal to those of thymine and the percentages of are equal to those of guanine in the DNA molecule.

Adenine, cytosine Signup and view all the answers

The nitrogen bases are held together in the center of the molecule by __________.

Hydrogen bonds Signup and view all the answers

According to the principle of base pairing, hydrogen bonds could form only between adenine and cytosine.

False Signup and view all the answers

The type of sugar found in DNA is __________.

Deoxyribose Signup and view all the answers

If the sequence on the right-hand side of the DNA molecule was TAGGCTCA, the complementary side would have a sequence of __________.

ATCCGAGT Signup and view all the answers

The process in which DNA builds an exact duplicate of itself is known as __________.

Replication Signup and view all the answers

What is the primary function of DNA?

The primary function of DNA is to store information that tells the cells which proteins to make. Signup and view all the answers

Why is it so important that the DNA molecule be able to make copies of itself?

Just prior to cell division, the DNA must replicate so that each new daughter cell receives an exact copy of the genome for that cell. All cells that divide to form new cells must pass exact copies of their DNA to offspring cells. Signup and view all the answers

During replication, the two nucleotide chains and each chain serves as a for a new nucleotide chain. The sites where DNA replication and separation occur are called __.

Separate, template, replication fork Signup and view all the answers

During replication, enzymes called untwist the double helix, separating the two parental strands. The point at which the two chains separate is known as the .

Helicase, replication fork Signup and view all the answers

Enzymes called __________ move along the separated strands assembling the new chains of DNA.

DNA polymerases Signup and view all the answers

The replication of DNA begins at one end of the molecule and proceeds to the other end.

False Signup and view all the answers

DNA replication occurs simultaneously at many sites along the molecule speeding up the process of replication.

True Signup and view all the answers

When replication is complete, two copies of the DNA molecule have been produced and the cell is ready to begin .

Exact, cell division Signup and view all the answers

Each DNA molecule resulting from replication has one original strand and one new strand.

True Signup and view all the answers

Study Notes

DNA Basics

DNA stands for Deoxyribonucleic acid.
DNA consists of nucleotides, which are the basic subunits.
Each nucleotide comprises a sugar, a phosphate group, and a nitrogen base.

Nitrogen Bases in DNA

DNA contains four nitrogen bases: adenine, cytosine, guanine, and thymine.
Pyrimidines are single-ring structures, including thymine and cytosine.
Purines are double-ring structures, comprising adenine and guanine.

Discovery and Structure of DNA

Watson and Crick are credited with discovering the structure of DNA.
DNA resembles a twisted ladder, known as a double helix.
The sides of the DNA ladder are formed by sugars and phosphates.

Base Pairing

Nitrogen bases bond in the center, forming the steps of the ladder.
Adenine pairs exclusively with thymine, while cytosine pairs with guanine.
Chargaff's rules state adenine percentage equals thymine, and cytosine equals guanine.

Molecular Composition

Hydrogen bonds hold the nitrogen bases together.
DNA contains the sugar deoxyribose.

DNA Replication

If one strand of DNA is TAGGCTCA, its complementary strand is ATCCGAGT.
DNA replication is the process where DNA duplicates itself.
DNA's primary role is to store information for protein synthesis.

Importance of Replication

DNA must replicate before cell division, ensuring daughter cells inherit the exact genome.
Each nucleotide chain separates during replication, serving as a template for new strands.
Replication occurs at specific sites called replication forks.

Enzymatic Actions in Replication

Helicase enzymes unwind the double helix and separate parental strands.
DNA polymerases assemble new DNA chains along the separated strands.

Replication Process Features

DNA replication does not start at one end; it occurs simultaneously at multiple sites, enhancing efficiency.
Upon replication completion, two exact DNA copies are generated, preparing the cell for division.
Each resulting DNA molecule consists of one original and one new strand.

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Description

Test your knowledge on the fundamentals of DNA, including its composition, nitrogen bases, and the historic discovery by Watson and Crick. This quiz explores the molecular structure and base pairing rules associated with DNA. Challenge yourself and strengthen your understanding of genetics!