DNA Flashcards: Nucleotides and Bases

Questions and Answers

What are the three parts of the nucleotide?

sugar, phosphate, and nitrogen containing base

What kind of sugar is found in a nucleotide?

deoxyribose

Which nucleotide component contains nitrogen?

base

Name the four nitrogen bases shown in Model 1.

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

Circle a single nucleotide on each side of the ladder model of DNA.

Two complete nucleotides should be circled, each containing the base, sugar, and phosphate groups. Signup and view all the answers

What parts of the nucleotides make up the rungs of the ladder?

nitrogen bases Signup and view all the answers

What part of the nucleotides make up the sides (backbone) of the ladder?

sugar and phosphate Signup and view all the answers

Are the rungs of the ladder parallel or antiparallel?

False Signup and view all the answers

On the ladder model, label each of the bases with the letter A, T, C, G.

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

When one nucleotide contains adenine, what type of base is attached?

thymine Signup and view all the answers

How many hydrogen bonds connect the two bases when one nucleotide contains adenine?

2 Signup and view all the answers

When one nucleotide contains cytosine, what type of base is the cytosine attached to on the opposite nucleotide strand?

guanine Signup and view all the answers

How many hydrogen bonds connect the two bases when one nucleotide contains cytosine?

3 Signup and view all the answers

What is the rule for how the bases are arranged in the ladder model of DNA?

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

Fill in the complementary bases on the strand below according to the base-pair rule: A T C C A G

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

Describe the shape of the double helix.

A double helix has two strands coiled around each other. Signup and view all the answers

Number the steps to describe the replication of DNA in a cell.

<ol> <li>Hydrogen bonds between nucleotides break; 2. Strands of DNA separate; 3. Free nucleotides are attracted to exposed bases on the loose strands of DNA; 4. Hydrogen bonds between nucleotides form.</li> </ol> Signup and view all the answers

What type of biological molecule is DNA helicase?

enzyme Signup and view all the answers

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

Its role is to separate the DNA strands. Signup and view all the answers

What rule is used to join the free nucleotides to the exposed bases of the DNA?

The complementary base pairing of A-T and C-G. Signup and view all the answers

What is semi-conservative replication?

2 DNA strands unzip; 1 old strand is copied to form 1 full DNA molecule that contains 1 old strand and 1 new strand. Signup and view all the answers

What are mistakes in DNA replication called?

mutations Signup and view all the answers

Using the base pair rules, complete the table to show the percentage of each type of base in the 5 different organisms.

Human 16%-G, 31%-T; Cow 22%-C, 28%-T; Salmon 29%-A, 21%-G; Wheat 23%-G, 23%-C, 27%-T; Yeast 19%-C, 31%-C Signup and view all the answers

Study Notes

Nucleotide Structure

Nucleotides consist of three parts: sugar, phosphate, and nitrogen-containing base.
The sugar found in nucleotides is deoxyribose.
The nitrogen-containing base is responsible for incorporating nitrogen into the nucleotide.

Nitrogen Bases

Four nitrogen bases in DNA: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
The bases form the rungs of the DNA ladder, creating base pairs: A pairs with T, G pairs with C.

DNA Ladder Model

A complete nucleotide includes a base, sugar, and phosphate group.
The sugar and phosphate form the backbone of the DNA ladder.
DNA strands are anti-parallel, meaning the ends of the strands are opposite in orientation.

Base Pairing and Bonds

Adenine is paired with Thymine, while Cytosine pairs with Guanine in complementary base pairing.
Hydrogen bonds connect base pairs: two bonds between A and T, and three bonds between C and G.

DNA Replication Process

Steps of DNA replication involve:
- Breaking hydrogen bonds between nucleotides.
- Separating DNA strands.
- Attracting free nucleotides to exposed bases.
- Forming new hydrogen bonds between nucleotides.
DNA helicase is an enzyme that separates DNA strands during replication.

Semiconservative Replication

DNA replication is semiconservative; one old strand pairs with one new strand, resulting in one old and one new DNA molecule.
Mutations can occur during replication, but the semiconservative method helps reduce errors.

Base Composition in Organisms

Percentage of bases in various organisms:
- Humans: 16% G, 31% T
- Cows: 22% C, 28% T
- Salmon: 29% A, 21% G
- Wheat: 23% G, 23% C, 27% T
- Yeast: 19% C, 31% C

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Description

This quiz covers essential concepts related to nucleotides, the building blocks of DNA. It includes details about the components of nucleotides, including sugars and nitrogen bases. Perfect for students looking to reinforce their understanding of DNA structure.