Answers to many of these questions can be found on the "Answers to End-of-Chapter Questions" page at the text website.

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1. Describe what is meant by the semi-conservative replication of DNA, and explain the roles of DNA, unattached DNA nucleotides, and enzymes in this process.

2. Draw a diagram, create a concept map, or write a paragraph that explains the relationships among these terms:

   chromosome	allele	gene expression
   trait	DNA	RNA polymerase
   messenger RNA	transfer RNA	ribosomal RNA
   codons	anticodons	ribosomes
   transcription	translation	RNA processing
   amino acids	polypeptide	protein
   primary stucture	secondary structure	tertiary structure
   quaternary structure	enzyme	active site

3. Explain how the sequence of DNA nucleotides for a specific allele is related to the production of a specific protein.

4. Explain transcription, RNA processing, and translation, and the roles of RNA polymerase, messenger RNA, transfer RNA, ribosomal RNA, and ribosomes in carrying out these processes.

5. Describe how enzymes catalyze reactions changing substrate molecules to products.

Caution: DNA replication is NOT part of protein synthesis!!

(from the University of Texas, Austin)

• Occurs in the nucleus.

• Transcription is the synthesis of RNA complementary to one side of a section of the DNA double helix.

• Enzymes unwind the DNA strand, and RNA polymerase builds the RNA chain using one strand of the DNA double helix as a template.

• A copy of the information in the gene is produced in the form of a messenger RNA molecule.

• Single stranded

• Shorter than DNA

• Ribose sugar instead of deoxyribose

• Made by complimentary base pairing with DNA: C & G and A &U instead of T

• Three types of RNA:
  • Messenger RNA (mRNA)
  • Transfer RNA (tRNA)
  • Ribosomal RNA (rRNA)

• RNA undergoes processing in the nucleus after transcription

• Introns (noncoding sections of DNA) are removed leaving Exons to be expressed.

• a "cap" is added to the 5' end and a "poly-A tail" is added to the 3' end of mRNA.

• Translation Movie(from the University of Virginia)

• mRNA is read in the ribosomes 3 bases at a time. Each group of 3 bases is called a codon.

• The Three Stages of Translation:
  • Initiation

  • Elongation

  • Termination

• Each codon codes for one amino acid. Where do amino acids come from?

• The codon AUG starts translation coding for methionine (MET), and the codons UGA, UAA, and UAG stop translation.

Protein Synthesis (from Access Excellence)

.

Review from last lecture

Some proteins are Enzymes which:

• Act as catalysts to reduce the energy needed to make or break chemical bonds in molecules.

• Have active sites with specific shapes and chemical properties into which specific substrate molecules fit.

• Work to break apart, join together, or rearrange molecules

• Are not broken down in the reaction process.

• May require the energy of ATP

• May require an organic helper molecule (a coenzyme) or inorganic helper molecules like Fe, Zn, Mg as cofactors

• Loose their activity if they are denatured

Take me home, right now!