Chapter 13
DNA vs RNA
DNA
A. Double Helix
B. Bases: AT GC
RNA
A. Ribo Nucleic Acid
B. Bases: AU GC
C. Travels outside of the Nucleus
D. Created in the nucleus and travels to cytoplasm
RNA’S Role
A. Genes contain coded DNA instructions that tell cells how to build proteins
1. Decoding these genetic instructions is to copy part of the base sequence
from DNA into RNA
2. RNS, like DNA is a nucleic acid that consists of a long chain nucleotides
3. RNA then uses the base sequence copied from DNA …
Types of RNA
A. MRNA
1
Messenger RNA
B. TRNA
1
Transfer RNA
C. RRNA
1
Ribosomal RNA
Comparing DNA and RNA
A. Each nucleotide in both DNA and RNA is made up of a 5-carbon sugar,
phosphate group, and nitrogenous base
B. There are three important differences between RNA and DNA
1
The sugar is RNA is ribose instead of deoxyribose
1. RNA is generally single-stranded and not double-stranded
2. RNA contains uracil in place of thymine
C. These chemical differences make it easy for the enzymes in the cell to tell the
DNA and RNA apart
Functions of RNA
A. A working copy of a SINGLE gene
B. Most RNA molecule are involved in protein synthesis only
C. Each type of RNA molecule specializes in a different aspect of this job
Types of RNA
D. MRNA
1. Messenger RNA
2. RNA molecules that carry copies of these instructions are known as Mrna
3. They carry information from DNA to other parts of the cell
E. tRNA
1. Transfer RNA
2. When a protein is built a transfer RNA molecule transfers each amino acid
to the ribosome as it is specified by the coded messenger RNA
F. rRNA
1. Ribosomal RNA
2. Proteins are assembled on ribosomes, small organelles composed of two
subunits
3. These ribosome subunits are made up of several ribosomal RNA molecules
and as many as 80 different proteins
RNA Synthesis
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DNA vs RNA Page 2 of 4
A. In transcription, segments of DNA serve as templates to produce
complementary RNA molecules
1. ACTTGGCGC
2. UGAACCGCG
Transcription
A. Transcription requires an enzyme known as RNA polymerase, that I similar to
DNA polymerase
B. Prokaryotes transcription is in cytoplasm
C. Eukaryotes transcription is in nucleus
D. RNA polymerase binds to DNA during transcription and separates the DNA
strands
E. RNA polymerase then uses one strand of DNA as a template from which to
assemble nucleotides into a complimentary strand
F. Promoters are signals in the DNA molecule that show RNA polymerase exactly
where to begin making RNA
G. Promoters is where the RNA polymerase binds to the DNA
RNA Editing
A. Introns-in between non coding segments (where there are no genes)
B. Exons-expressed or coding regions
C. RNA molecules sometimes require bits and pieces to be cut out of them
before they can go into action
D. The portions that are cut out and discarded are called introns
E. In Eukaryotes, introns are taken out of pre-mRNA molecules while they are
still in the nucleus
F. The remaining pieces, known a exons, are then spliced back together to form
the final mRNA
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DNA vs RNA Page 3 of 4
Ribosomes and Protein Synthesis
A. Translations
1. mRNA  protein
2. Nucleotides  amino acids
B. Codons= 3 bases
1. 1 codon 1 amino acid
2. 64 codons in the genetic code
Chapter 13
DNA vs RNA Page 4 of 4