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Chapter 12 DNA & RNA
Lesson 1 DNA
Transformation
Griffith called process transformation because one strain of bacteria (the harmless strain) had apparently been changed permanently into another (the disease-causing strain).
Avery & DNA
1) Key Point: Avery & other scientists discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next.
The Hershey-Chase Experiment
One of Virus that infects bacteria is known as a Bacteriophage (bak - TEER - ee -uh - fayj).
2) Key Point: Hershey and Chase concluded that the genetic material of the bacteriophage was DNA not protein.
The Components & Structure of DNA
DNA is a long molecule made up of units called nucleotides.
3) Key Point: Watson and Crick's model of DNA was a double helix, in which two strands were wound around each other.
Once they saw this, they realized that this principle, called base pairing, explained Chargaff's rules.
Lesson 2
Chromosomes & DNA Replication
DNA & Chromosomes
DNA is present in such large amount in Many tissues that its easy to extract and analyze.
Eukaryotic chromosomes contain both DNA and Protein, tightly packed together to form a substance called Chromatin.
Chromatin consists of DNA that is tightly coiled around proteins called histones. (as shown in Figure 12 - 10 Page 297 Biology Book)
DNA Replication
Before a cell divides, it duplicates its DNA in a copying process called replication.
4) Key Point: During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strands of the double helix of DNA serves as template, or model, for the new strands.
The principal enzyme involved in DNA replication is called DNA polymerase because it joins individual nucleotides to produce a DNA molecule, which is, of course, a polymer.
Lesson 3
RNA & Protein Synthesis
In molecular terms genes are coded DNA instructions that control the production of proteins within the cells.
5) There are three main types of RNA: messenger RNA, ribosomal RNA, & transfer RNA.
The RNA molecules that carry copies of these instructions are known as messenger RNA (mRNA) because they serve as messenger from DNA to the rest of the cell.
Ribosomes are made up of several dozen proteins, as well as a form of RNA known as ribosomal RNA (rRNA).
These RNA molecules are Known as Transfer RNA (tRNA)
Transcription
RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary sequence in RNA a process called transcription.
Transcription requires an enzyme known as RNA polymerase that is similar to DNA polymerase.
6) During transcription, RNA polymerase binds to DNA and separates the DNA the DNA as a template from which nucleotides are assembled into a strand of RNA.
The enzyme will bind only to regions of DNA known as Promoters, which have specific base sequences.
The DNA of eukaryotic genes contains sequence of nucleotides, called introns, that are not involved in coding for proteins.
The DNA sequence that code for proteins are called exons because they are " expressed in the sythesis of proteins.
The Genetic Code
1) UCGCACGGU 2) UCG-CAC-GGU 3) UCG-CAC-GGU
Translation
The decoding of an mRNA message into a polypeptide chain (Protein) is known as translation.
7) During translation, the cell uses information from messenger RNA to produce proteins.
These bases, called the anticoden, are complementary to one mRNA codon.
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