AP Biology Discussion Notes

Monday 1/25/2016

WELCOMEBACK!

You may choose your seat

Semester 2 AP BIOLOGY• DNA Structure & Function

– DNA replication, Protein synthesis• Gene Activity & Biotechnology

– (Genetics & Inheritance)• Diversity & Organisms• Ecology & Evolution

– Animal behavior, community & population Ecology

We’ll learn:• How to decode the code of all living things• How to bring extinct animals back from the dead

(and discuss whether we should)!• How to stop smugglers• Discuss why & how “3-person babies” are being

made & “1-person” babies – cloning.• Learn how to & then do DNA fingerprinting• Learn how to & then do genetic modification of

an organism to give an organism new traits• Basics & Applications of Individual & Population

Genetics & Genetic Disorders

Things to think about:1. Look over material before the next class

– Write down thoughts, connections or questions

2. Read the chapter – even when not “assigned”

3. Watch Videos about topics – even when not assigned

4. Start reviewing topics from last semester– Tie them to topics this semester and write

down connections or questions5. ASK QUESTIONS

PANIC now and avoid the rush!

AP BIO TEST

May 9th

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

QoD Reminders:• Each day in class I will put up a

question of the day. • Students will be responsible for writing

the question & their best answer.• After each student has answered the

question on their own we will discuss it as a class

• QODs will be collected before each test for points!!!

Question of the Day 1/25• What is DNA? Write your thoughts

down, and what you know about it, you don’t have to be sure you are correct!

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

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 protein-destroying 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 Nucleotide – a nucleotide is the three component parts together

PhosphateGroup N

Nitrogenous base(Adenine, Guanine, Cytosine, or Thymine)

Sugar(deoxyribose)

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???

Base Pairing

Which pairs would come apart more easily? (Take less _______ to pull apart)

Base Pairing Which DNA strand

would come apart at a lower temperature?

1.25% Adenine

2. 45% Adenine

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

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

• Were Watson & Crick the only ones responsible for discovering the structure of the DNA molecule?

Who is Rosalind Franklin?

Secret of Photo 51

Initial Thoughts & Questions• What is the climate like for women in

the 1940s?• Historical Treatment of Minorities• What was her first nickname? • Why was it so bad?

Discovery of DNA’s Structure

• Secret of Photo 51 Video

Secret of Photo 51Thoughts & Questions?• Time to reflect maybe on how we

“other people”• Are there people that you don’t treat

well?• What do you do when people around

you are not acting respectfully?

Discovery of DNA’s Structure

• Secret of Photo 51 Video

ASSIGNMENT DUE TOMORROW

Set 2 goals for the quarterList 3 ways you can help yourself

to achieve each goal