DNA Structure and Function Quiz

Questions and Answers

What is a nucleotide composed of?

A sugar, a base, and a phosphate (correct)

A sugar, a base, and a glycoprotein

A sugar, an amino acid, and a phosphate

A sugar, a lipid, and a phosphate

Which of the following bases is NOT found in DNA?

Thymine

Adenine

Cytosine

Uracil (correct)

What kind of bond joins nucleotides in a single strand of DNA?

Phosphodiester bond (correct)

Ionic bond

Hydrogen bond

Peptide bond

What is the orientation of the two strands in double-stranded DNA?

Antiparallel orientation Signup and view all the answers

What type of bond forms between the bases of nucleotides on opposite strands of DNA?

Hydrogen bond Signup and view all the answers

Which sugar is found in DNA nucleotides?

Deoxyribose Signup and view all the answers

What is the main structural feature that nucleotides share in DNA?

They have the same sugar Signup and view all the answers

How are the nucleotide bases typically represented in DNA?

By their first letters Signup and view all the answers

What type of cell division produces gametes with half the number of chromosomes of the parent cells?

Meiosis Signup and view all the answers

What term describes chromosomes that have genes for specific characteristics at the same locus?

Homologous chromosomes Signup and view all the answers

Which term best defines the outward appearance resulting from a dominant allele?

Phenotype Signup and view all the answers

Which of the following describes the genetic makeup of an individual?

Genotype Signup and view all the answers

What is the process of creating identical copies of DNA called?

Replication Signup and view all the answers

Which chromosomes determine the sex of an individual?

Sex chromosomes Signup and view all the answers

What type of allele is expressed in the phenotype of an organism when present?

Dominant allele Signup and view all the answers

What is the haploid number in gametes represented by?

N Signup and view all the answers

What is the primary role of hydrogen bonds in the structure of DNA?

They facilitate the separation of DNA strands during replication. Signup and view all the answers

Which pairs of bases follow the base-pairing rules in DNA?

A pairs with T and G pairs with C Signup and view all the answers

What structural formation does DNA adopt?

A double helix resembling a twisted ladder Signup and view all the answers

What is DNA replication?

The process of making an identical copy of DNA Signup and view all the answers

What enzyme is responsible for unwinding the DNA double helix during replication?

DNA helicase Signup and view all the answers

What defines the genetic code in DNA?

The specific order of nucleotides Signup and view all the answers

Why is DNA considered the universal code?

It codes for cell production and reproduction in all organisms. Signup and view all the answers

What is the function of DNA polymerase during DNA replication?

To add complementary nucleotides to exposed bases Signup and view all the answers

Study Notes

DNA Structure and Function

DNA is located in the nuclei of cells, organized into chromosomes that store genetic information.
Composed of nucleotides, DNA contains three components: deoxyribose sugar, a phosphate group, and a nitrogenous base.
Four nitrogenous bases exist in DNA: adenine (A), thymine (T), guanine (G), and cytosine (C).
Single-stranded DNA forms through covalent phosphodiester bonds between the sugar and phosphate groups of adjacent nucleotides.
Double-stranded DNA is formed via hydrogen bonds between complementary bases on opposite strands, following specific pairing rules (A with T and G with C).
The two DNA strands run in opposite directions (antiparallel orientation), crucial for replication and gene expression.

DNA Replication

DNA replication begins with unwinding the double helix by the enzyme DNA helicase, exposing the bases.
DNA polymerase adds complementary nucleotides to exposed bases, resulting in two DNA molecules containing one original and one new strand.
DNA replication results in the formation of a double helix structure, essential for genetic continuity.

Genetic Code and Variability

The sequence of nucleotides in DNA determines the genetic makeup of organisms, analogous to letters forming words in language.
DNA's universal code underpins cellular processes across all living organisms, indicating common evolutionary origins.

Chromosomal Information

Chromosomes, made of DNA and proteins, house genes, which are segments of DNA coding for specific traits.
Autosomes are all chromosomes excluding sex chromosomes, while sex chromosomes determine an individual's gender.

Key Genetic Terms

Diploid number refers to body cells containing two sets of chromosomes (2N), while haploid number indicates gametes with one set (N).
Homologous chromosomes possess genes for the same traits at identical locations.
Mitosis yields two genetically identical daughter cells, whereas meiosis produces gametes with half the number of chromosomes.
Alleles are varying forms of the same gene on homologous chromosomes, with dominant alleles expressed in phenotype.

Important Processes

Gene expression and DNA replication rely on the specific pairing of nucleotides and the unique structure of DNA.
Understanding these concepts forms the foundation of genetics, cell biology, and evolutionary theory.

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Description

This quiz explores the essential components of DNA, including its structure and the types of nucleotides that make up its molecules. You'll learn about how genetic information is encoded and the role of chromosomes. Test your understanding of this fundamental biological concept!