DNA Structure and Function Quiz
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Questions and Answers

What is the basic structural unit of DNA?

  • Nucleotide (correct)
  • Ribonucleic acid
  • Protein
  • Amino acid

Which pairs of nitrogenous bases are complementary in DNA?

  • Adenine with thymine and guanine with cytosine (correct)
  • Thymine with adenine and uracil with guanine
  • Adenine with cytosine and thymine with guanine
  • Guanine with adenine and cytosine with thymine

What is the approximate distance for one complete turn of the DNA helix?

  • 1.5 nm
  • 3.4 nm (correct)
  • 20 nm
  • 10 nm

What are the two strands of DNA held together by?

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

Which statement about the strands of DNA is true?

<p>Strands are oriented in opposite directions (A)</p> Signup and view all the answers

What are hereditary characteristics?

<p>Inherent traits passed down through generations (A)</p> Signup and view all the answers

Which statement about genes is correct?

<p>Each gene carries a set of instructions for amino acid production (C)</p> Signup and view all the answers

What portion of human DNA codes for proteins?

<p>Less than 2% (D)</p> Signup and view all the answers

What is the process of translating mRNA into proteins called?

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

Which sections of DNA do not code for amino acids?

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

What is the first step in creating a model of DNA according to the activity?

<p>Study the four kinds of nucleotides. (C)</p> Signup and view all the answers

Which component must be on the left side when arranging nucleotides for the DNA strand?

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

What rule must be followed when creating a complementary strand of DNA?

<p>Base-pairing rule (D)</p> Signup and view all the answers

During which phase does DNA replication occur?

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

What is the purpose of creating a model of DNA in the activity?

<p>To understand the structure of DNA (A)</p> Signup and view all the answers

What enzyme is responsible for unwinding the DNA during replication?

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

On which strand are fragments of single-stranded DNA formed during replication?

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

What percentage of human DNA is similar to that of chimpanzees?

<p>60% (A)</p> Signup and view all the answers

Which of the following represents a cause of mutations during DNA replication?

<p>Improper base pairing (A)</p> Signup and view all the answers

What is the composition of the newly formed DNA molecules after replication?

<p>One original and one newly synthesized strand (D)</p> Signup and view all the answers

What constitutes the complete set of genetic instructions for an organism?

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

How many genes does the human genome have approximately?

<p>20,000-25,000 (D)</p> Signup and view all the answers

What percentage of the human genome is made up of genes?

<p>10% (A)</p> Signup and view all the answers

Which organism is mentioned as sharing the highest percentage of DNA with humans?

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

What is the primary function of phylogenetics in relation to DNA sequences?

<p>To determine evolutionary relatedness (B)</p> Signup and view all the answers

Which primate has DNA that is more similar to humans than gorillas?

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

What are the building blocks of proteins?

<p>Amino acids (B)</p> Signup and view all the answers

What is the significance of codons in the genetic code?

<p>They are sequences of three nucleotides coding for amino acids. (A)</p> Signup and view all the answers

What does it mean that the genetic code is universal?

<p>All living organisms share the same genetic code. (C)</p> Signup and view all the answers

Which molecule carries the genetic code that determines how proteins are made?

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

What is the first step in the transcription process of DNA into RNA?

<p>The double-stranded DNA molecule unzips (D)</p> Signup and view all the answers

Which enzyme is responsible for creating the complementary mRNA strand during transcription?

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

Which strand of DNA acts as the template for producing mRNA?

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

What signifies the start and end of the gene code during the transcription process?

<p>RNA polymerase recognition (A)</p> Signup and view all the answers

How does RNA polymerase contribute to the transcription process?

<p>It adds complementary RNA nucleotides to the growing mRNA strand (B)</p> Signup and view all the answers

What sugar is found in RNA?

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

Which base is found in RNA instead of thymine?

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

What is the first step in the process of protein synthesis?

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

Where is most RNA found within a cell?

<p>In the ribosomes and cytoplasm (A)</p> Signup and view all the answers

What determines the type and order of amino acids in a protein?

<p>The genetic instructions coded in DNA (B)</p> Signup and view all the answers

What role do ribosomes play in the process of translation?

<p>They decode the sequence of nucleotides in mRNA. (B)</p> Signup and view all the answers

What is the structure formed when multiple ribosomes are attached to a single mRNA molecule?

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

How do tRNA molecules contribute to protein synthesis?

<p>They carry amino acids and match with mRNA codons. (B)</p> Signup and view all the answers

What determines the sequence of amino acids in a protein?

<p>The sequence of nucleotides in the mRNA (C)</p> Signup and view all the answers

What are codons?

<p>Three nucleotides that code for an amino acid (B)</p> Signup and view all the answers

What is the primary function of chromosomes?

<p>They carry genes within the nucleus. (D)</p> Signup and view all the answers

What forms when chromatin condenses during cell division?

<p>Sausage-like structures (A)</p> Signup and view all the answers

How many chromosomes do humans have in somatic cells?

<p>46 chromosomes in 23 pairs (B)</p> Signup and view all the answers

What is a karyotype?

<p>A complete set of chromosomes arranged by size. (B)</p> Signup and view all the answers

What unique characteristic do chromosomes have?

<p>They display a distinctive banding pattern. (B)</p> Signup and view all the answers

Flashcards

What are the base pairs in DNA?

DNA's structure is like a twisted ladder, where each rung is made of two connected nitrogenous bases: adenine (A) paired with thymine (T) and guanine (G) paired with cytosine (C).

What is a nucleotide?

A nucleotide is a building block of DNA, containing a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases.

How are the two strands of DNA connected?

The two strands of DNA are held together by weak bonds called hydrogen bonds, which form between complementary base pairs.

What is the size of a DNA double helix?

The double helix structure of DNA has a diameter of about 2 nanometers, and each complete turn of the helix spans about 3.4 nanometers.

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What are the two types of nitrogenous bases?

Adenine and guanine are purines, while thymine and cytosine are pyrimidines.

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Gene

A short section of DNA that carries instructions for a specific trait, such as eye color or hair texture.

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DNA Replication

The process of copying DNA to create a new, identical copy.

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Transcription

The process of converting the information stored in DNA into a messenger RNA (mRNA) strand.

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Translation

The process of using the mRNA strand to create proteins.

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Non-coding DNA

Sections of DNA that do not code for proteins, but may have other functions.

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What are nucleotides?

Four kinds of building blocks that make up DNA. Each nucleotide has three parts: a phosphate group, a sugar group, and a nitrogen base.

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What is DNA replication?

The process of making new copies of DNA, ensuring that the genetic information is passed on accurately to new cells and generations.

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What are the four nitrogen bases in DNA?

Adenine (A), guanine (G), cytosine (C), and thymine (T).

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What is the base pairing rule?

Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).

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What is the semi-conservative nature of DNA replication?

During DNA replication, each strand of the original DNA molecule acts as a template for the synthesis of a new complementary strand, ensuring that each new DNA molecule has one original strand and one newly synthesized strand.

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Codon

A three-nucleotide sequence in DNA that specifies a particular amino acid in protein synthesis.

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Genetic Code

The set of rules that determines how codons are translated into amino acids.

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Amino Acids

The building blocks of proteins, linked together in specific sequences determined by the genetic code.

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Helicase

The enzyme that unwinds the DNA double helix during replication, breaking the hydrogen bonds between the base pairs.

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DNA Polymerase

The enzyme complex that adds new nucleotides to the growing DNA strand during replication, ensuring the new strand is complementary to the template.

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Mutation

A permanent change in the nucleotide sequence of DNA, which can be caused by errors during replication or exposure to mutagens.

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What is transcription?

The process of creating a messenger RNA (mRNA) copy from a DNA template.

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What is RNA polymerase?

The enzyme that controls the process of transcription, building the mRNA strand using a DNA template.

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What is the difference between RNA and DNA?

RNA, a type of nucleic acid, uses ribose sugar instead of deoxyribose sugar, found in DNA. It also replaces thymine with uracil as a nitrogenous base.

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What is the template strand?

The DNA strand that serves as the template for mRNA synthesis during transcription.

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What is protein synthesis?

The process of protein synthesis is crucial for understanding how cells function; the genetic instructions in DNA are used as a blueprint for producing proteins.

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What is the coding strand?

The DNA strand that is complementary to the template strand, with the same sequence as the mRNA.

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What begins the transcription process?

The process that starts when a gene is activated, allowing the DNA code to be copied into RNA.

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Describe the two main stages of gene expression.

Transcription, the process where a DNA template is used to create RNA, and translation, where the RNA message is translated into a protein sequence.

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What is the function of Proteins in the cell?

Proteins are crucial for various cellular functions, including controlling biochemical reactions. They are made of amino acids, the building blocks of proteins. The sequence and type of these amino acids determine the protein's function.

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How are genes related to protein synthesis?

Genes within DNA provide the code for the order and type of amino acids needed to build a specific protein.

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DNA Sequencing

A process that identifies the order of nucleotide bases in a DNA sequence, revealing the genetic code.

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Phylogenetics

The study of evolutionary relationships between organisms, often using DNA sequences to determine how closely related they are.

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What is translation?

The process by which a protein molecule is produced from an mRNA molecule.

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What is a ribosome?

A structure made of RNA and proteins that reads the mRNA and assembles the amino acids into a polypeptide chain.

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What is a codon?

Three consecutive nucleotides on the mRNA, coding for a specific amino acid.

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What is a tRNA?

A special RNA molecule that carries amino acids to the ribosome based on its complementary anticodon.

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What is a polysome?

A group of ribosomes attached to a single mRNA molecule, simultaneously translating it into proteins.

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What are chromosomes?

The structures within the nucleus carrying genes; composed of DNA and protein; become visible during cell division when chromatin condenses into a compact form.

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What is the diploid number?

The number of chromosomes present in the somatic cells of an organism; humans have a diploid number of 46 chromosomes.

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What are chromatids?

Each chromosome has two identical parts called chromatids, joined at the centromere, a DNA region near the middle.

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What is a karyotype?

A visual representation of all chromosomes from a single cell arranged and numbered by size and banding pattern.

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What is the banding pattern on chromosomes?

A unique banding pattern formed by special staining techniques, providing a visual identifier for regions containing hundreds of genes. It is not tied to individual genes.

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