DNA Structure - Free Printable
Educational worksheet: DNA Structure. Download and print for classroom or home learning activities.
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Step-by-step solution for: DNA Structure
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Show Answer Key & Explanations
Step-by-step solution for: DNA Structure
Let's go through each question on the DNA Structure: Summary Notes worksheet and provide the correct answers with explanations.
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Answer: *Nucleotides*
Explanation:
Nucleic acids (like DNA and RNA) are polymers composed of repeating units called nucleotides. Each nucleotide is a monomer that links together to form the long chain of DNA or RNA.
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Answer:
- Phosphate group
- Five-carbon sugar (deoxyribose in DNA)
- Nitrogenous base
Explanation:
Each nucleotide has three components:
1. A phosphate group – forms the backbone of the DNA strand.
2. A five-carbon sugar – in DNA, this is deoxyribose.
3. A nitrogenous base – which can be adenine, thymine, cytosine, or guanine in DNA.
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Answer: *Deoxyribose*
Explanation:
The sugar in DNA is deoxyribose, which differs from ribose (found in RNA) by lacking one oxygen atom (hence "deoxy").
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Answer: *Phosphate groups* and *Deoxyribose sugars*
Explanation:
The backbone of DNA is formed by alternating phosphate groups and deoxyribose sugars. These link together to form the two strands of the double helix.
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Answer: *Nitrogenous bases*
Explanation:
In the classic “ladder” model of DNA, the sides (backbone) are made of sugar-phosphate chains, and the rungs are formed by pairs of nitrogenous bases connecting the two strands.
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Answer:
- Adenine (A)
- Thymine (T)
- Cytosine (C)
- Guanine (G)
Explanation:
These are the four nitrogenous bases in DNA. Adenine and Guanine are purines (double-ring structures), while Thymine and Cytosine are pyrimidines (single-ring structures).
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Answer:
- Adenine pairs with Thymine
- Cytosine pairs with Guanine
Explanation:
Base pairing follows Chargaff’s rules:
- A pairs with T via two hydrogen bonds
- C pairs with G via three hydrogen bonds
This complementary base pairing is essential for DNA replication and stability.
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1. Nucleotides
2.
- Phosphate group
- Five-carbon sugar
- Nitrogenous base
3. Deoxyribose
4. Phosphate groups and Deoxyribose sugars
5. Nitrogenous bases
6.
- Adenine
- Thymine
- Cytosine
- Guanine
7.
- Adenine pairs with Thymine
- Cytosine pairs with Guanine
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This summary reflects the fundamental structure of DNA as discovered by Watson and Crick — a double helix with sugar-phosphate backbones and complementary base pairs forming the interior rungs.
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1) All nucleic acids are made of building blocks called
Answer: *Nucleotides*
Explanation:
Nucleic acids (like DNA and RNA) are polymers composed of repeating units called nucleotides. Each nucleotide is a monomer that links together to form the long chain of DNA or RNA.
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2) A nucleotide is made of three sub-units. List those below:
Answer:
- Phosphate group
- Five-carbon sugar (deoxyribose in DNA)
- Nitrogenous base
Explanation:
Each nucleotide has three components:
1. A phosphate group – forms the backbone of the DNA strand.
2. A five-carbon sugar – in DNA, this is deoxyribose.
3. A nitrogenous base – which can be adenine, thymine, cytosine, or guanine in DNA.
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3) The name of the sugar in DNA is called
Answer: *Deoxyribose*
Explanation:
The sugar in DNA is deoxyribose, which differs from ribose (found in RNA) by lacking one oxygen atom (hence "deoxy").
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4) The backbone of DNA is made of ________ and ________
Answer: *Phosphate groups* and *Deoxyribose sugars*
Explanation:
The backbone of DNA is formed by alternating phosphate groups and deoxyribose sugars. These link together to form the two strands of the double helix.
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5) The rungs of the DNA ladder are made of ________
Answer: *Nitrogenous bases*
Explanation:
In the classic “ladder” model of DNA, the sides (backbone) are made of sugar-phosphate chains, and the rungs are formed by pairs of nitrogenous bases connecting the two strands.
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6) List the 4 nitrogen bases found in DNA
Answer:
- Adenine (A)
- Thymine (T)
- Cytosine (C)
- Guanine (G)
Explanation:
These are the four nitrogenous bases in DNA. Adenine and Guanine are purines (double-ring structures), while Thymine and Cytosine are pyrimidines (single-ring structures).
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7) In DNA the nitrogen bases form pairs. List the pairings below:
Answer:
- Adenine pairs with Thymine
- Cytosine pairs with Guanine
Explanation:
Base pairing follows Chargaff’s rules:
- A pairs with T via two hydrogen bonds
- C pairs with G via three hydrogen bonds
This complementary base pairing is essential for DNA replication and stability.
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✔ Final Answer Key:
1. Nucleotides
2.
- Phosphate group
- Five-carbon sugar
- Nitrogenous base
3. Deoxyribose
4. Phosphate groups and Deoxyribose sugars
5. Nitrogenous bases
6.
- Adenine
- Thymine
- Cytosine
- Guanine
7.
- Adenine pairs with Thymine
- Cytosine pairs with Guanine
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This summary reflects the fundamental structure of DNA as discovered by Watson and Crick — a double helix with sugar-phosphate backbones and complementary base pairs forming the interior rungs.
Parent Tip: Review the logic above to help your child master the concept of dna model worksheet.
