Biology 1001 Spring 2008 (B. Fall), Class notes, topics #7 and 8—Molecular genetics: DNA, RNA,
chromosomes, genes; from genes to proteins (transcription and translation).
complete the reading assignments in your text (Freeman, Biological Science, 2
Topic #7: pp.
56-59 (proteins); 74-85 (nucleic acids); 303-318 (DNA).
Topic #8: 325-336 (genes and genetic code),
(Please note that these readings go into a lot more detail than I expect you to master, especially Ch. 16. Focus
your reading on
and terms in the outline below.)
I strongly recommend that you work through the tutorials on the Freeman companion website that are
referenced below in the outline, part V., A.: (1. DNA structure; 2. DNA replication; 3. transcription; 4.
Understand the basic structure of nucleic acids, and similarities and differences between DNA
Outline basic events of DNA replication: how (and why) DNA makes copies of itself.
Understand the central dogma (the relationship among DNA, RNA, and protein)
Outline the basic events of transcription and translation, and distinguish the two processes.
Understand what the genetic code means, and how to read it.
Appreciate what genes are, where they occur, and what they do.
[deoxyribonucleic acid] and
(ribonucleic acid) are each polymers made up of
nucleotide monomers (repeating subunits).
are comprised of a 5-carbon sugar + phosphate + one of four kinds of nitrogenous
bases of two groups:
Adenine and guanine (purines);
Cytosine and thymine (pyrimidines); in RNA, uracil replaces thymine.
Nucleic acid arrangement: bases are side groups off sugar-phosphate “backbone.”
DNA consists of two complementary antiparallel [running in opposite directions] strands, held
together by hydrogen bonds between base side groups and forming a double helix.
Complementary base pairing
: hydrogen bonds between C and G or between A and T result
in each strand being the complement of the other. Thus, 5’-ACGTCT-3’ in one strand has as
its complement 3’-TGCAGA-5’ in the other [3’ and 5’ refer to specific carbon atoms in the
Important properties of DNA include: replication, information content, stability.
[ribonucleic acid] structure is like DNA
for three features: single-stranded instead of
double; ribose instead of deoxyribose as the 5-carbon sugar; the base uracil replaces thymine.