Chapter 1 - Introduction: Exploring Life

Chapter 1 - Introduction: Exploring Life
Textbook Summer Assn

GNS AP Biology Website

What is Science Chapter 1 - Introduction: Exploring Life
NEW AIM: What is Science? What is Science Science is something that you do. It is a verb. It’s the process we use to try and know something. Remember…its all about making observations and using them to build models, which are in turn used to make predicts/decisions.

? How do we do science Chapter 1 - Introduction: Exploring Life
AIM: What is Science? ? How do we do science

It’s all about making observations...
Chapter 1 - Introduction: Exploring Life AIM: What is Science? It’s all about making observations... Ex. The structure of DNA (What is the function of DNA?)

The observations: Chapter 1 - Introduction: Exploring Life
AIM: What is Science? The observations: Phoebus Levene Russian Organic Chemist Rockefeller University 1928 He characterized the different forms of nucleic acid, DNA from RNA, and found that DNA contained adenine, guanine, thymine, cytosine, deoxyribose, and a phosphate group. One of the first to figure out how to use polarized light to observe molecular configuration… One of the first models of DNA (the tetranucleotide)

AIM: What is Science? The observations: Phoebus Levene Russian Organic Chemist Rockefeller University 1928 He characterized the different forms of nucleic acid, DNA from RNA, and found that DNA contained adenine, guanine, thymine, cytosine, deoxyribose, and a phosphate group. One of the first to figure out how to use polarized light to observe molecular configuration… Levene observed the behavior of polarized light passing through molecular structures in order to determine the four nucleotides of DNA and how they covalently bind to each other. One of the first models of DNA (the tetranucleotide)

AIM: What is Science? The observations: Erwin Chargaff Austrian Biochemist Columbia University 1952

AIM: What is Science? The observations: Chargaff took DNA from many different species, hydrolyzed it down to nucleotides, and performed chromatography to separate them from each other and compare concentrations. He observed an A:T ratio of 1:1 and a C:G ratio of 1:1, but the (A/T):(C/G) ratio varied, which refuted the tetranucleotide model. He did not observe or predict base pairing (That A hydrogen bonds to T, etc…)

AIM: What is Science? The observations: Rosalind Franklin British Chemist/Physicist King’s College 1953

AIM: What is Science? The observations: Dr. Franklin used X-rays as a means of making observations. She purified DNA is a very special way and then hit the DNA with Xrays to produce the image to the right (photo 51)

AIM: What is Science? The observations: Photo 51 has a particular pattern that indicates the molecule is a double helix. Controversy ensued after James Watson got his eyes on the photo before being published, which can be read about here:

AIM: What is Science? The observations: Rosalind Franklin British Chemist/Physicist King’s College 1953 Map showing England and the distance between Franklin and Watson (Cavendish Labs)

The current DNA model: Chapter 1 - Introduction: Exploring Life
AIM: What is Science? The current DNA model: James Watson (mol. biologist) Francis Crick (biophysicist) University of Cambridge 1953

AIM: What is Science? The current DNA model: Watson and Crick using the following observation without ever doing a single experiment to build the current model of DNA: Polarized light observations indicating the four nucleotides and how they are connected Chargaffs chromatography observation that A:T is 1:1 and C:G is 1:1, but vary in ratio to each other. The unpublished photo 51 indicating a double helix

AIM: What is Science? The current DNA model: James Watson (mol. biologist) Francis Crick (biophysicist) University of Cambridge 1953 Where are the control groups in all this science?

How were the foundations of genetics unraveled?
Chapter 1 - Introduction: Exploring Life AIM: What is Science? How were the foundations of genetics unraveled? Through careful observations of pea plant matings!

How were the foundations of genetics unraveled?
Chapter 1 - Introduction: Exploring Life AIM: What is Science? How were the foundations of genetics unraveled?

Chapter 1 - Introduction: Exploring Life AIM: What is Science?
It is all about careful observation (data collection)… Followed by building models that fit the data…

Have people figured out better ways to observe DNA? YES! There are a number of techniques, but none as amazing as X-ray crystallography to view the molecular world!!!

Fancy math Data (Observation) of where electrons are located in crystal… Modern day diffraction image data (observation) off a crystallized molecule… Model of the molecule within the electron density data….

The most sophisticated scientific instrument?

All you do is collect and process data…build and refine models…and use these models to make predictions constantly…

Come up with your own example of you doing science today… and write it up

We are always doing science!
Chapter 1 - Introduction: Exploring Life AIM: What is Science? We are always doing science! Because you are always making observations, predictions, etc… When you walk down the hall you are collected data (visual data with your eyes, auditory data with your ears, etc…). With this data you generate questions and make predictions. For example, you observe someone running at you. Hypothesis: The person will run into me. Prediction: If I do not move then I will get hit. Experiment: Stay put. Results: The person hit me supporting my hypothesis.

We are always doing science. In fact, what you see, the image in front of you right now, is a scientific model. Explain.

AIM: What is Science? How does the scientific enterprise actually work? What is the goal of this enterprise?

What do scientists do with their findings?
Chapter 1 - Introduction: Exploring Life AIM: What is Science? What do scientists do with their findings? They publish them in scientific journals like Science, Nature, Cell, EMBO, PLOS One, etc…

Tentative and Fallible
Chapter 1 - Introduction: Exploring Life AIM: What is Science? Tentative and Fallible The findings of science are based on observation, but the observations could be misleading. For example, the Earth appears to be flat… Likewise, people thought Newton’s law of gravity was correct, but Einstein came along and revised it. This type of thing happens all the time. In addition, it was originally thought that water was HO. All of the observations pointed to HO at the time… The more reliable observations you make, the closer one gets to knowing the truth…

Why is it that we can never be 100% certain of anything no matter how many observations we make…?

How is science like doing a jigsaw puzzle? …sort of What does each piece represent? Are we certain about the shape and color of the piece or how they connect? Are we able to get all the pieces? Relate this to solving the structure of DNA.

How is science like doing a jigsaw puzzle? …sort of

Theory Law Chapter 1 - Introduction: Exploring Life
AIM: What is Science? Theory 1. Very broad in nature (describe many, many different phenomenon). 2. Supported by enormous numbers of observations 3. Examples: Theory of Evolution Cell Theory Law 1. Very concise in nature (describes a very specific phenomenon). 2. Supported by enormous numbers of observations 3. Examples: Law of Gravity Laws of thermodynamics Laws of motion

Science GOD and Chapter 1 - Introduction: Exploring Life
AIM: What is Science? GOD and Science

? So is this class really about science
Chapter 1 - Introduction: Exploring Life AIM: What is Science? ? So is this class really about science

? science Chapter 1 - Introduction: Exploring Life
AIM: What is Science? The Course Outline: ? The hierarchy of life, emergent properties, and the structure -function relationship science Library / Book Analogy – MSG analogy (store information and life as emergent properties)

General Phylogenetic Tree of Life (Drawn in Class) A few single celled eukaryotes lack mitochondria…either from the originals or lost them...all parasites Amphibians – 370 Mya Modern birds – 60Mya right after K/T extinction Modern humans – 200,000 years ago Time, kingdoms, phyla, cell types, common ancestor, speciation, heterotroph hypothesis and oil analogy, the beginning was anaerobic.

(Drawn in Class)

Phylogenetic tree overview A and B will be most similar to each other C and D will be most similar to each other, A/B will be equally similar to C/D, E will be the most dissimilar You can switch A and B, it doesn’t change anything. Same for C and D. Most recent common ancestors don’t change. Branch points indicate the common ancestral population and the occurrence of speciation.

AIM: What is Science? Be able to build a phylogenetic tree from data:

History of the World in 18 Minutes (watch and take notes…hmmm, I wonder why)

Know all the remaining bold words and figures in chapter 1 like… The properties of life (Figure 1.2) The hierarchy of life (Figure 1.3) Producers vs consumers Energy flow through ecosystems (Figure 1.4) Reductionism Negative vs positive feedback Classification (Figure 1.14) Domains of life (Figure 1.15) Darwin and Natural Selection Controlled Experiments: Independent Variable, Dependent Variable, control group, experimental group, ways to improve experiments, placebo

Chapter 1 - Introduction: The Scientific Study of Life Chapter 3 - The Molecules of Cells AIM: What are the major characteristics of life? AIM: How is all life united? AIM: How do organisms build/break macromolecules? Period 5/6

Chapter 1 - Introduction: Exploring Life

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