This "central dogma" of
today's molecular biology explains the inheritance
of evolutionary adaptations at the most basic
level we can imagine today. Once
Watson and Crick figured out the molecular
structure of DNA, the rest of the "secret of
life" unraveled. Biologists could
"see" ---
- replication: how the
double helix could separate so that each
strand could direct the synthesis of a new
"partner." Replication
explains genetic inheritance and how
chromosomes duplicate themselves before
mitosis and meiosis.
- transcription: how
DNA can direct the synthesis of RNA, which
then can carry the genetic instructions from
the nucleus to the rest of the cell while
leaving the DNA in the nucleus, protected for
future replications and transcriptions.
- translation: how the
sequence of bases in RNA can be
"translated" into a new
language--the amino acid sequence of protein. (And
you already can explain how the amino acid
sequence determines a protein's quartenary
structure and thus its ability to catalyze
other chemical reactions or to move
things.) Translation
explains how the genotype makes the phenotype
and how a mutation will sometimes result in a
new adaptation.
- Central Dogma overview:
-
| DNA
->more DNA -->
RNA -> protein |
These chapters are mostly about replication;
the next chapter is about transcription and
translation. This overview is to make
sure you know where we're going. |
MAIN
POINTS FROM THE TEXTBOOK
for Monday
- DNA STRUCTURE>
You need to be able to
explain the structure of
DNA.:
Study carefully pages 59-62 from
old chapter 3, especially the figures (
fig. 3.17a, 3.17b,
3.18,
box
3.4),. Be able to point out these parts of the
structure: chromosomes,
base, sugar (deoxyribose), phosphate, paired
(complementary) bases, nucleotide.
You do not need to be able to tell the differerences
between purines and pyrimidines or to distinguish among
the bases like GATTACA.
- GENETIC CODE> (pp. 223-227). The
most important point is to understand how to use fig.
11.10. You should put a tab or permanent
bookmark on p. 226 and customize your codon code to
include the single-letter amino acid abbreviations
from p. 45, like this
(or you could print this version and
carry it in your wallet at all times). You will be using this figure for
the rest of the semester to translate DNA messages.
- CENTRAL DOGMA> Review the dogma
above, and carefully read pp. 227-228, especially the
last two paragraphs. Then review pp. 223-227 to
develop better understanding of how a very tentative
hypothesis became "dogma."
-
| DNA
->more DNA -->
RNA -> protein |
- HISTORY>
In Lab 6 you will see a video which covers pp. 61-62,
with minor characters including some of the pre-dogma
historical figures from pages 217-223a. The only
history which will be on tests is explained on
the lab 6
web page.
- You may want to defer reading these optional pages
until after the video. The lab 6
web page has more information about the history of DNA
structure theory; knowing more history is optional
(pp. 217-227 historical content).
- OPTIONAL REPLACEMENT QUIZZES: do experiment
summaries for any of the classic experiments
described on pp. 217-227. limit: two
quizzes for two summaries.
- CD
activity 11.1 is optional (specifically
the Beadle
& Tatum experiment), but could help
with a replacement quiz
- CD
activity 11.2 is optional but recommended
for understanding the triplet codon and
mutation. You could write an experiment
summary of the last (or the next-tolast)
experiment for a replacement quiz. You
should feel proud if you know why the first
experiments do not provide convincing evidence
for the triplet hypothesis.
- CHECKLIST> monosaccharide, hydroxy
functional group, ribose, deoxyribose, nucleotide,
nitrogenous base, adenine, guanine, cytosine, thymine,
uracil, purine, pyrimidine, ribonucleotide,
deoxyribonucleotide, phosphodiester bond,
sugar-phosphate backbone, 5' and 3', complementary
base pairs, Watson-Crick pairing, Chargaff's rules,
ribonucleic acid (RNA), deoxyribonucleic acid (DNA),
double helix, metabolic pathway, metabolism, messenger
RNA (mRNA), genetic code, codon, stop codon, start
codon, reading frame, central dogma, transcription,
translation
- PREVIEW of test and quiz questions
- From Chapter 11
- Content Review #1
- Conceptual Review #3
- Applying Ideas #1
- Figure Review #3
- From Old Chapter 3 (pp. 67 ff)
- Content Review #3, 4, 7
- Conceptual Review #3, 4
- Figure Review #8
- And
these:
-
Complementary
base pairing in DNA happens between
[a] adenine & guanine. [b] adenine &
thymine.
[c] cytosine & adenine. [c] thymine &
guanine.
-
A
strand of DNA serves as a __?__ because it can
guide the generation of a new __?__ strand.
[a] base pair; identical. [b] biological strand;
different helical.
[c] helix; exact. [d] template; complementary.
- A
nucleotide consists of a sugar, phosphate, and a(n)
[a] base. [b] enzyme. [c]
helix. [d] primer.
- What
base sequence is complementary to this?
GTATGACTC
- What amino acids are coded by this base
sequence? AUGGCUUUUUGA
(answers)
need
help?
For Wednesday
- REPLICATION>
Be able to explain
replication:
fig. 12.3 plus all the figures especially but
also words on pp. 237b - 240a and The
DNA Synthesis Reaction part of CD activity 12.1 (it's optional
to know the names of the featured enzymes except for DNA polymerase); show in words or
diagrams how these are involved: DNA
polymerase, primer, nucleotide, unwinding, original strands (templates),
complementary new strands, 5' end and 3' end.
Be able to predict the base sequence
(abbreviations) of each new strand after DNA replicates
itself. Fig. 12.7b,
12.8, 12.9 .
The second part (An
Overview of DNA Synthesis) of CD activity 12.1
shows processes which are very important to understand; however,
you do not have to memorize the names and functions of the many
enzymes involved, except for DNA polymerase.
-
| DNA
->more DNA -->
RNA -> protein |
-
- ANALYZING DNA> There are three particularly
important procedures to understand because we will be referring to
them for the rest of the semester:
- PCR DNA copy-making: study pp. 240b-242a
(especially fig. 12.11a,
12.11b,
12.11b
continued ) and CD Activity
12.2 Polymerase Chain Reaction..
- DNA base sequence determination: The Sanger (dideoxy)
procedure is still used in some professional laboratories
today, even though there are machines which determine the base
sequence faster. The newer procedures are based on the
same principles as dideoxy sequencing described on p.
242. Study fig 12.12. Part
"c" involves the next procedure:
- Electrophoresis and autoradiography (Fig.12.12c) are
explained on p. 50 (Box
3.2).
- MUTATION>
- Types> Descriptions of
different types of mutations are on pp. 244b-246.Be
sure you are thoroughly prepared to explain in detail
fig. 12.16 and 12.17. CD
activity 11.1. (the
Crick triplet experiments from the previous chapter)
contains some mutation illustrations; it might help
you explain fig. 12.17 especially.
- REPAIR of mutations>
- pp. 243-4 describe DNA
polymerase's activity in the proofreading and
repair of potential "copying-error"
mutations during replication.
- there are other repair mechanisms
you will learn when you take Biol 402.
- Causes of mutations> Carefully read p.
246b! Also read the rest of the chapter.
- Mutations and Cancer> Review the cancer
checkpoint connection from the mitosis chapter, and
now try to apply that knowledge to your understanding
of the end of this DNA chapter.
- HISTORY> optional. The beginning of the
chapter (pp. 232-237a) is optional. For extra credit or
replacement quizzes, turn in one or two experiment
summaries of the experiments in this chapter:
- Meselson & Stahl
- Kornberg
- di Lucia & Cairns
- Cairns (fig. 12.6)
- Okazaki (discontinuous replication hypothesis)
-
RNA primer hypothesis
- Paabo's Neanderthal experiments
- CHECKLIST: antiparallel strands, replication fork, leading (or
continuous) strand, lagging (discontinous) strand, 5' to
3' direction, 3' to 5' direction, Okazaki fragments,
RNA primers, dideoxy
sequencing, polymerase chain reaction (PCR), mutation,
insertion mutation, deletion mutation, chromosome
inversion, point mutation, frameshift, mismatch error,
silent mutation, X-rays,
gamma rays, UV radiation, DNA proofreading, denaturation, primer
binding, primer extension, Taq polymerase, Thermus
aquaticus, Neanderthal (Homo neandertalensis),
dideoxynucleosides (ddNTP), exonuclease, mismatch
repair, excision repair system, DNA methylation,
hemoglobin, sickle-cell anemia, malaria parasite, colorectal cancer (HNPCC), xeroderma
pigmentosum (XP), cell culture, hydroxyl radicals need
help?
- PREVIEW OF TEST AND QUIZ QUESTIONS
Monday's answers:
1b.2d.3a.4 CATACTGAG 5 MAP
|
