2A. Distinguish between DNA and RNA. DNA Structure (12.1) State Standards 2A. Distinguish between DNA and RNA. 2B. Explain the role of DNA in storing and transmitting cellular information.

Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material Genetics Genetics is the branch of biology that studies heredity, the passing of traits (characteristics) from parents to offspring. This passing of traits involves the 2 nucleic acids, DNA & RNA.

Nucleic Acid Structure Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material Nucleic Acid Structure Nucleotides are the building blocks of DNA & RNA Nucleotides consist of a five-carbon sugar, a phosphate group, and a nitrogen-containing base

The sugar found in DNA is called deoxyribose. Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material DNA Structure The sugar found in DNA is called deoxyribose.

The double helix shape of DNA is often compared to a twisted ladder. Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material DNA Structure Cont’d The double helix shape of DNA is often compared to a twisted ladder. The ladder is made of 2 very long chains of nucleotides.

Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material DNA Structure Cont’d The rails of the ladder are represented by the alternating deoxyribose and phosphate. The pairs of bases (cytosine–guanine or thymine–adenine) form the steps or rungs.

The bases in a nucleic acid always pair up in the same way. Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material Base Pairing The bases in a nucleic acid always pair up in the same way. This is called Chargaff’s rule.

Adenine always pairs with Thymine. Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material Base Pairing Cont’d Adenine always pairs with Thymine. Guanine always pairs with Cytosine. The 2 sides of the ladder are held together by hydrogen bonds.

DNA carries information in a triplet code. Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material The DNA Language DNA carries information in a triplet code. Each sequence of 3 nucleotides codes for a certain amino acid or for the beginning or end of a sequence. The genetic code is unique for each organism.

Chapter 12 Molecular Genetics 12.1 DNA: The Genetic Material Chromosome Structure DNA coils around histones to form nucleosomes, which coil to form chromatin fibers. The chromatin fibers supercoil to form chromosomes that are visible during cell division.

What is the base-pairing rule for purines Chapter 12 Molecular Genetics 12.1 Formative Questions What is the base-pairing rule for purines and pyrimidines in the DNA molecule? A—G and C—T A—T and C—G C—A and G—T C—U and A—G A B C D FQ 2

What are chromosomes composed of? Chapter 12 Molecular Genetics 12.1 Formative Questions What are chromosomes composed of? chromatin and histones DNA and protein DNA and lipids protein and centromeres A B C D FQ 3

chromatin fibers chromosomes histones nucleosome Chapter 12 Molecular Genetics Chapter Assessment Questions Look at the following figure. Identify the proteins that DNA first coils around. chromatin fibers chromosomes histones nucleosome A B C D CAQ 1

#14. Use the analogy of a staircase or a railroad track to describe the structure of DNA.