Bio H – Molecular Biology
Molecular Biology Notes
I.
History: Groundbreaking discoveries leading to our discover of DNA as our genetic material
- after completing the article you have on these, summarize the experiments and the CONCLUSION drawn
by each of the following scientists/teams
A. Morgan (we’ll talk about him in class)
B. Griffith
C. Avery and McCleod
D. Hershey and Chase
E. Watson and Crick
Bio H – Molecular Biology
II.
DNA Structure – We’ve already done this!! What do we know about –
a. The overall shape of the DNA molecule?
b. The monomer?
What is the backbone made of? ______________________________________________________________________
The bases, for DNA consist of one of 4 types that fall into 2 categories:
_____________________________
___________________________
Difference?
Only certain bases can form hydrogen bonds with each other; _____________________. Why?
Therefore all A’s are bound to T’s and all G’s are bound to C’s
Chargaff’s Rule: _____________________________________________________________________________________
Bio H – Molecular Biology
- Example: A double stranded piece of DNA has 800 bases. 300 are A’s. How many of each of the others are there?
Heating DNA causes it to _______________________ ; meaning?
Which is harder to denature? Why?
III.
GCCGGCGCG
or
AATATTATAA
DNA Replication
When does it occur:
What happens to the DNA after replication?
What happens to the cell?
What does Semi-conservative replication mean:
Happens in the nucleus (of course!)
Ingredients:
a. ___________________________
c. ___________________________
b. ___________________________
d. ___________________________
- There are sevaral major steps. Summarize each one below in your OWN words from the animation (you may have
only three instead of four, but THIN about what steps are required for replication.
1.
2.
3.
4.
Bio H – Molecular Biology
Diagram: if you need to, sketch a diagram of this process.
Telomere problem:
- What are telomeres?
- What is the problem?
- What is the cell’s answer to this problem?
- What are the implications of this problem?
Bio H – Molecular Biology
PROTEIN SYNTHESIS (G0, G1, S, G2)
In order to create protein, we need not only DNA, and enzymes, but also several forms of RNA and amino acids (and
we ALWAYS need ATP if we are synthesizing or breaking down any molecule)
IV: Types of RNA and its structure
What is the purpose of RNA during protein synthesis?
In what ways is the structure of RNA different from DNA?
Types of RNA – summarize the job of each of the following
–
mRNA – messenger RNA; also called a “transcript”;__________________________________________
–
rRNA – Ribosomal RNA; _______________________________________________________________
–
tRNA – transfer RNA; __________________________________________________________________
TWO MAJOR STEPS OF PROTEIN SYNTHESIS: Transcription and Translation
IV.
Transcription: transfer of information from DNA to RNA in the nucleus
a. _____________________________________________________________________________________
b. The WHOLE strand of DNA doesn’t get turned into RNA at once
Bio H – Molecular Biology
Summarize what you saw in the animation in three simple steps
Step 1:
Step 2:
Step 3:
Transcription – Diagram
Step 4: In eukaryotes there is an additional modification step that occurs. The mRNA is altered slightly to improve
stability and enable the message to leave the nucleus. Why might this be necessary? How does it work?
Bio H – Molecular Biology
What is the difference between having a gene and expressing a gene?
V. Genetic Code:
How does it work?
AUG tells the cell to bring in the amino acid Methionine
AGG tells the cell to bring in a different amino acid, arginine
Codon chart – used to check which amino acid is coded for by each codon
Bio H – Molecular Biology
VI. Translation:
-
Using the mRNA code as the directions to make a particular sequence of amino acids (a protein!)
We need:
1. mRNA transcript from the nucleus
2. Ribosomes
3. tRNA’s
Bio H – Molecular Biology
Summarize the process of translation in a few simple steps.
Finally, put the steps of transcription and translation together. When do these steps occur,
where do they occur, why do they occur, what are the basic steps that happen, what is the
final outcome.
So, now that we have been through this summary document….
What do we mean by “the central dogma?” Why is it so important? What is the curious
question surrounding the central dogma?
Bio H – Molecular Biology
Mutations
Mutations are ___________________________________________________________________
Types of mutations
1. ________________________ - are often point mutations (a one base change)
a. Types:
i. ________________________
ii. ________________________
iii. ________________________
2. ______________________________________ - mutations involving loss or mislocation of a part or
all of a chromosome . Typically involves many genes.
3. Point mutations
Substitution
Can be silent or change an amino acid

THE FAT CAT ATE THE RAT

THE FAT HAT ATE THE RAT
Insertion

THE FAT CAT ATE THE RAT

THE FAT CAT HAT ETH ERA T
Deletions

THE FAT CAT ATE THE RAT

THE FAT CAA TET HER AT
Bio H – Molecular Biology
Frameshift mutations
Shifts the ______________________________
of the genetic message so that the
____________________ may not be able to
perform its function, or may not be made .
Point mutations causing frameshifts affect all amino acids after the mutation. Frameshift mutations are
much worse than substitutions (which change only one amino acid
Chromosome mutations - Changes in the number and structure of entire chromosomes
Can see these mutations in a karyotype