Biology Journal 9/21/ What does DNA have the instructions to make? 2.What fraction of DNA passes on to offspring? 3.What are the words for how prokaryotes and eukaryotes reproduce?

Biology Journal 9/22/2015 Think about the 3 key experiments from yesterday. How can we summarize these important contributions to biology? What did it show? What was the evidence? What previous hypothesis did it disprove? Pasteur Swan Neck Experiment Hershey-Chase radioactive viruses experiment Miller-Urey pre- biotic Earth experiment

What did it show? What was the evidence? What previous hypothesis did it disprove? Pasteur Swan Neck Experiment Bacteria cells only come from other cells Bacteria only grows if exposed to other bacteria Spontaneous generation (living things “pop-up” out of nothing) Hershey- Chase radioactive viruses experiment Miller-Urey pre-biotic Earth experiment

What did it show? What was the evidence? What previous hypothesis did it disprove? Pasteur Swan Neck Experiment Bacteria cells only come from other cells Bacteria only grows if exposed to other bacteria Spontaneous generation (living things “pop-up” out of nothing) Hershey- Chase radioactive viruses experiment DNA contains genes A virus’ DNA (not proteins) was found in infected bacteria Proteins contain genes Miller-Urey pre-biotic Earth experiment

What did it show? What was the evidence? What previous hypothesis did it disprove? Pasteur Swan Neck Experiment Bacteria cells only come from other cells Bacteria only grows if exposed to other bacteria Spontaneous generation (living things “pop-up” out of nothing) Hershey- Chase radioactive viruses experiment DNA contains genes A virus’ DNA (not proteins) was found in infected bacteria Proteins contain genes Miller-Urey pre-biotic Earth experiment Complex organic molecules can be made from small, inorganic molecules 13 amino acids were created from H 2 O, NH 3, H 2, CH 4, and N 2 (what we think made up pre-biotic atmosphere) None? Scientists didn’t have a good explanation for the origin of cells yet!

Biology Journal 11/6/2013 Describe Louis Pasteur's swan neck experiment. How was this experiment evidence for the cell theory? “I invented Pasteurized milk, so that ya’llz wouldn’t be dying like all the time.”

1.5 The Origin of Cells

1.5 The origin of cells: There is an unbroken chain of life from the first cells on Earth to all cells in organisms alive today. Nature of science: Testing the general principles that underlie the natural world—the principle that cells only come from pre-existing cells needs to be verified. Understandings:  Cells can only be formed by division of pre-existing cells.  The first cells must have arisen from non-living material.  The origin and evidence of eukaryotic cells can be explained by the endosymbiotic theory.  64 codons in the genetic code have the same meanings in nearly all organisms, but that there are some minor variations that are likely to have accrued since the common origin of life on Earth. Applications and skills: Application: Evidence from Pasteur’s experiments that spontaneous generation of cells and organisms does not now occur on Earth. Pasteur’s experiment can be repeated using modern apparatus. Theory of knowledge: Biology is the study of life, yet life is an emergent property. Under what circumstances is a systems approach productive in biology and under what circumstances is a reductionist approach more appropriate? How do scientists decide between competing approaches? Topic 1: Cell Biology (15 hours)

In your notebook, list these objects from what you think is smallest to what you think is largest. Virus Eukaryote Cell Electron Prokaryote Cell Thickness of cell membrane Atom Molecule macromoleculeOrganelle Then, compare your answers with a partner!

ObjectSize Eukaryote Cell 10 to 100 µm (varies greatly) Prokaryote Cell 1 to 10 µm (varies greatly) Organelle 10 nm (membranes) to 1 µm (mitochondria) Virus About 20 nm (varies greatly) Thickness of cell membrane 10 nm Macromolecule 1 to 100 nm (varies greatly) Molecule 1 nm (depends on size of molecule) Atom 0.1 nm (depends on type of element) Electron nm (theoretical)

3 Experiments greatly changed our understanding of cells: 1.Pasteur’s Swan Neck debunking of “spontaneous generation” 2.Miller-Urey showing where bio-molecules could have come from 3.Hershey-Chase’s demonstrating DNA contains genes

1. Louis Pasteur's swan neck experiment demonstrated that bacteria cells must come from other bacteria cells, disproving that all life originated “spontaneously.” “I invented Pasteurized milk, so that ya’llz wouldn’t be dying like all the time.” 3 experiments that changed the world.

Pasteur’s experiment corroborates The Cell Theory. What are the 3 parts of the cell theory? 1. Cells are the smallest units of life. 2.All living things are made out of cells. 3.Cells only come from other cells. Review! An early microscope

Don’t confuse Cell Theory with the Endosymbiotic Theory. What could be 3 pieces of evidence that support the endosymbiotic theory? Mitochondria / chloroplasts have… 1. a double membrane 2.Their own DNA and ribosomes 3.Are the same size and bacteria 4.Reproduce via binary fission when their cell divides Review!

What was around on Earth before life?

2. In 1953, Miller and Urey took the chemicals we believe were present on Earth before life, and electrified it. Two weeks later they found 13 out of the 20 amino acids This has been repeated many times, and with different “starting” conditions. 3 experiments that changed the world.

3. In 1952, Hershey and Chase confirmed that DNA was the genetic material in a cell using bacteria-infecting viruses (bacteriophages) and radioactivity. watch?v=63IoOLXmzKg 3 experiments that changed the world.

Label each molecule (the pictures). Label the process that makes each molecule (the purple arrows). DNA mRNA Protein Replication Transcription Translation Review!

What is a codon? Every 3 bases on mRNA is referred to as a codon. It indicates what amino acid is added to a protein. Every 3 bases on tRNA is referred to as an anti-codon.

 64 codons in the genetic code have the same meanings in nearly all organisms, but that there are some minor variations that are likely to have happened since the common origin of life on Earth.

The first self-replicating molecules could have been DNA, or… RNA! Ribozymes is RNA that are also enzymes (enzymes run chemical reactions in living things) Which came first, DNA, RNA, or proteins?

Video about the origin of life on earth. Computer graphics, with narration. The most astounding fact, Neil Degrasse Tyson. Neil Degrasse Tyson, on alien intelligence. Kid talking with graphics: 3 experiments that changed the world.

Where else could the molecules / energy / conditions to start these chemical reactions come from?

The first cell membrane could have come from microspheres, or coacervates! Different chemicals that arrange themselves into natural barriers.

Either way, the first prokaryotes developed photosynthesis. This created an oxygen-rich atmosphere, and an ozone layer that later organisms (like us) needed. Thanks, cyanobacteria!

Video about the origin of life on earth. Computer graphics, with narration. The most astounding fact, Neil Degrasse Tyson. Neil Degrasse Tyson, on alien intelligence. Kid talking with graphics: 3 experiments that changed the world.

Biology Journal 11/7/2013 Describe the Miller-Urey experiment. Which of the “4 processes needed for the spontaneous origin of life on Earth” did this provide evidence for? Why?