Download AP Biology Discussion Notes

AP Biology Discussion
Notes
Tuesday 9/27/2016
Goals for Today:
• Be able to name the scientists that helped
build our knowledge of DNA and be able to
describe their contributions
• Be able to discuss how scientific
understanding is built
• Be able to list or understand the contributions
of less known scientists
• Be name the 3 basic components of DNA
9/27 Question of the Day:
Who (What) am I?
Characteristics of Nucleic Acids
CHON P
The Central Dogma
Genetic information is:
Encoded in DNA;
Transmitted by DNA Replication;
Transcribed into RNA;
Translated into Protein.
DNA codes for the sequence of
Amino Acids in Proteins, which
means DNA determines the
Structure AND ________ of
proteins built in an organism.
How long have we known what
was the genetic material? (What
molecules allow us to inherit
similarities and characteristics
from our parents?)
3 likely candidates
• DNA
• RNA
• Protein
Monomer = Nucleotide
Polymer = Polynucleotides
What do we know about the
relationship between DNA &
Protein?
• DNA
• RNA
• Protein
Griffith’s Experiments (1928 – publication)
Griffith discovered that harmless bacteria could turn
virulent when mixed with bacteria that cause disease.
A bacteria that is virulent is able to cause disease.
Griffith had discovered what is now called
transformation, a change in genotype
caused when cells take up foreign genetic
material.
Oswald Avery’s Experiments (1930 – 1944)
•Series of experiments showed that the activity of the material
responsible for transformation is not affected by proteindestroying enzymes.
•The activity is stopped, however, by a DNA-destroying
enzyme.
•Thus, almost 100 years after Mendel’s experiments,
Oswald Avery and his co-workers demonstrated that
DNA is the material responsible
for transformation NOT protein.
DNA or Proteins?
• Even after Avery’s experiments it
was not widely accepted that DNA
was the genetic material, but this
line of research did spark a race of
sorts to figure out more about the
physical structure of DNA
Avery’s Experiment
DNA or Proteins?
• Even after Avery’s experiments it was
not widely accepted that DNA was the
genetic material, but this line of
research did spark a race of sorts to
figure out more about the physical
structure of DNA
DNA’s Role Revealed
In 1952, Alfred Hershey and
Martha Chase used the bacteriophage
(__________) to prove that DNA carried
genetic material.
A bacteriophage is a virus that infects
bacteria.
Life Cycle of a virus (bacteriophage)
Hershey & Chase use viruses to
prove DNA is the genetic material
Hershey & Chase use viruses to
prove DNA is the genetic material
Nucleic Acids
What are monomers of Nucleic Acids?
Monomer = Nucleotide
Polymer = Polynucleotides
Erwin Chargaff
• Chargaff’s research
analyzed the amount of
each nitrogen base in
different organisms
• Humans Adenine=
30.4%
• E. coli Adenine = 24.7%
Erwin Chargaff
• Chargaff’s research
determined that in DNA
there were always equal
parts
• Adenine = Thymine
As well as equal parts
• Cytosine = Guanine
Erwin Chargaff
• Chargaff’s research
determined that in DNA
there were always equal
parts
• Humans Adenine = 30%
• Humans Thymine = ?
• Humans Guanine = ?
• Humans Cytosine = ?
One more for practice…
• If you have a species with 35% Cytosine
what percentage of the other base pairs
would there be?
–A–G–T-
Base Pairing
Purines:
Pyrimidines:
Purine - Pyrimidine
Base Pairing
Look
carefully—
Why can A only
pair with T and
C can only pair
with G???
Still needed to know the
structure!
• What is the structure of DNA?
• Who discovered the structure of DNA?
DNA is shaped like a double helix (a twisted
ladder)
This shape was discovered by two scientists:
James Watson & Francis Crick
Scientific Knowledge
• Scientific knowledge and discovery is
always built on what we already know,
past discovery & knowledge
What we Know Now:
Questions?
Chapter 8
Quiz Corrections
– Separate sheet of paper
- Separate Assignment!
● Re-write (you can summarize)
missed question.
o Write the correct answer & be sure to
EXPLAIN why it is correct!
o Check with Me before you turn it in!!
Quiz Corrections
● Retake – 1 week, corrections must be
completed 1 day before retake!
● Retakes may only be completed before or
after school. (Not during the school day)
9/27 Species of the Day
• Living Stones! Lithops
What controls/codes for the
sequence of Amino Acids in the
Proteins of this plant?