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: 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)

What are the names of these molecules?

Question from Paper 1

A = GlucoseB = Amino AcidC = GlycerolA = Ribose

Review!

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

macromolecule Organelle

Then, compare your answers with a partner!

Object SizeEukaryote 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 0.000000001 nm (theoretical)

4 processes needed for the spontaneous origin of life on Earth

1. The non-living synthesis of simple organic molecules (D.1.2)

What is a polymer?Review!

Monomer = CH2

Polymer = Lipid

What is a monomer?

These 3 pictures show the same molecule. What is the name of the polymer?What is the name of the monomer?

A polymer is a molecule made out of repeating parts.

The simple, repeating parts that make up a polymer are called monomers.

a. What kind of molecule is shown below?b. Name the monomer of this molecule, and how many

are present.c. If this molecule underwent hydrolysis, would water be

consumed or released? How many water molecules would do this?

a) protein, polypeptide or oligopeptideb) 7 amino acidsc) 6 H2O molecules would be consumed

Review!

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

Molecule Type Monomer Dimer Polymer

Polysaccharide

Amino Acids, Proteins Dipeptide

Lipids(aka fats) n/a lipid

Genetic Material n/a

Naming System of some biological MoleculesReview!

Molecule Type Monomer Dimer PolymerSugars,

Carbohydrates Monosaccharide Disaccharide Polysaccharide

Amino Acids, Proteins

Monopeptide(one amino acid) Dipeptide Polypeptide

Lipids(aka fats) CH2 n/a lipid

Genetic MaterialNucleotide, nucleic acid, nitrogenous

base…n/a DNA

Label each molecule (the pictures).Label the process that makes each molecule (the purple arrows).List the name of the enzymes / molecules that carry out each process.Identify the location where each of these molecules / processes are.

DNA

mRNA ProteinReplication

Transcription Translation

DNA helicaseDNA polymerase

DNA helicaseRNA polymerase

RibosometRNA

Happens in the nucleus Happens in the cytoplasm / at the ribosomes

Review!

What is a codon?Review!

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 accrued since the common origin of life on Earth.

What was around on Earth before life?

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.

https://www.youtube.com/watch?v=63IoOLXmzKg3 experiments that changed the world.

The first self-replicating molecules could have been RNA, not DNA!• Ribozymes is RNA that are also enzymes (hey you

told us that all enzymes are proteins! Liar!)

Which came first, DNA, RNA, or proteins?

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.”

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

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

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

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

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

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?

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!

https://www.youtube.com/watch?v=c6LaMwRZUjwVideo about the origin of life on earth. Computer graphics, with narration.

https://www.youtube.com/watch?v=9D05ej8u-gUThe most astounding fact, Neil Degrasse Tyson.

https://www.youtube.com/watch?v=KeJoVeKSsyANeil Degrasse Tyson, on alien intelligence.

https://www.youtube.com/watch?v=63IoOLXmzKgKid talking with graphics: 3 experiments that changed the world.