DNA Structure Essentials

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Questions and Answers

What are the basic units of DNA called?

Lipids

Amino acids

Proteins

Nucleotides (correct)

Which pairing of nitrogenous bases follows Chargaff's Rule?

G - T

A - T (correct)

C - A

A - C

How many hydrogen bonds are there between the bases adenine (A) and thymine (T)?

2 hydrogen bonds (correct)

3 hydrogen bonds

4 hydrogen bonds

1 hydrogen bond

What are purines in the context of DNA structure?

Nitrogenous bases with 2 ring structure Signup and view all the answers

What constitutes the sugar-phosphate backbone of DNA?

Phosphate group and pentose sugar Signup and view all the answers

What is the relationship between the two DNA strands?

They run antiparallel to each other. Signup and view all the answers

Which component of DNA is responsible for creating the sugar-phosphate backbone?

Phosphodiester bonds between nucleotides. Signup and view all the answers

How many base pairs are typically present in one full turn of the DNA helix?

19 to 20 base pairs. Signup and view all the answers

What distinguishes purines from pyrimidines in DNA structure?

Purines have double ring structures, while pyrimidines have a single ring. Signup and view all the answers

What is the role of the hydrogen bonds in DNA?

They hold the two strands of DNA together. Signup and view all the answers

Which function of proteins is primarily responsible for speeding up biological reactions?

Enzymes Signup and view all the answers

How does DNA relate to protein synthesis?

DNA codes for proteins through a gene sequence. Signup and view all the answers

What role do proteins play in the transport of substances in the body?

They facilitate the movement of molecules throughout the body. Signup and view all the answers

Which of the following is NOT a general function of proteins?

Act as genetic material Signup and view all the answers

In what way do proteins contribute to cellular structure?

By providing structural support Signup and view all the answers

What role do histones play in the structure of chromatin?

They condense DNA by forming octamer structures. Signup and view all the answers

Which histone proteins make up the core histones?

H2A, H2B, H3, H4 Signup and view all the answers

What is the role of histone H1 in chromatin?

It serves as a linker protein, but is less tightly bound than others. Signup and view all the answers

Which statement about non-histone proteins is true?

They can affect chromosome compaction. Signup and view all the answers

Which of the following best describes the interactions between DNA and histones?

They are maintained by electrostatic interactions. Signup and view all the answers

Study Notes

DNA Structure

DNA consists of two complementary strands.
The basic units of DNA are nucleotides.
Nucleotides are composed of a phosphate group, a pentose sugar (deoxyribose), and a nitrogenous base.
There are two types of nitrogenous bases: purines (A and G) and pyrimidines (T and C).
Base pairs form through hydrogen bonds: A pairs with T (2 hydrogen bonds), and G pairs with C (3 hydrogen bonds).
Chargaff's Rule states that the percentage of adenine (A) equals the percentage of thymine (T), and the percentage of guanine (G) equals the percentage of cytosine (C).
The sugar-phosphate backbone forms the structural framework of the DNA molecule.
The nucleotides are connected by phosphodiester bonds.
The two strands are connected by hydrogen bonds between the bases.
The DNA strands run antiparallel, meaning they run in opposite directions (5' to 3' and 3' to 5').
The sugar-phosphate backbone has a double ring (purine) and a single ring (pyrimidine).
Each turn of the DNA helix has approximately 5 base pairs.
The DNA helix has a major groove and a minor groove.
The DNA helix makes a right-hand turn, with approximately 19 to 20 base pairs per turn.

Chromatin

Chromatin is a complex of DNA and histone proteins.
Histones are proteins that help package DNA into chromosomes.
Histones form histone octamers, which are composed of two copies each of H2A, H2B, H3, and H4.
DNA wraps around the histone octamer, forming a nucleosome.
Histones contain a high percentage of arginine and lysine, which are positively charged amino acids that attract the negatively charged DNA.
Non-histone proteins also play a role in chromosome compaction and gene expression.
Histone H1, a linker protein, helps to condense DNA further.

Protein Functions

Proteins have a wide range of functions.
They form structural components, such as collagen.
They act as enzymes, which are biological catalysts.
They function as hormones.
They act as transport molecules.
DNA encodes for proteins.
The sequence of DNA determines the amino acid sequence of the protein.
Proteins speed up biological reactions.
Proteins carry messages and hormones throughout the body.
Proteins provide structural support to cells and tissues.
Proteins transport substances throughout the body.

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Description

Explore the fundamental components of DNA in this quiz. Learn about nucleotides, base pairing, and the rules that govern DNA structure. Test your understanding of how the double helix forms and the significance of its antiparallel strands.