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.”
Topic 1: Cell Biology (15 hours)
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?
Review!
What are the names of these molecules?
A = Glucose
B = Amino Acid
C = Glycerol
A = Ribose
Question from Paper 1
In your notebook, list these objects from what you think is smallest to
what you think is largest. Then, compare your answers with a partner!
Virus
Eukaryote Cell
Prokaryote Cell
Atom
Thickness of cell
membrane
Molecule
macromolecule
Electron
Organelle
Object
Size
Eukaryote Cell
Prokaryote Cell
10 to 100 µm (varies greatly)
Organelle
Virus
Thickness of cell membrane
Macromolecule
10 nm (membranes) to 1 µm (mitochondria)
Molecule
Atom
Electron
1 nm (depends on size of molecule)
1 to 10 µm (varies greatly)
About 20 nm (varies greatly)
10 nm
1 to 100 nm (varies greatly)
0.1 nm (depends on type of element)
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)
Review!
What is a polymer?
A polymer is a molecule
made out of repeating
parts.
What is a monomer?
The simple, repeating
parts that make up a
polymer are called
monomers.
These 3 pictures show the same molecule.
What is the name of the polymer?
What is the name of the monomer?
Monomer = CH2
Polymer = Lipid
Review!
a.
b.
c.
What kind of molecule is shown below?
Name the monomer of this molecule, and how many
are present.
If this molecule underwent hydrolysis, would water be
consumed or released? How many water molecules
would do this?
a) protein, polypeptide or oligopeptide
b) 7 amino acids
c) 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.
An early microscope
Review!
Naming System of some biological Molecules
Molecule
Molecule Type
Type
Monomer
Monomer
Dimer
Dimer
Polymer
Polymer
Sugars,
Carbohydrates
Monosaccharide
Disaccharide
Polysaccharide
Polysaccharide
Dipeptide
Dipeptide
n/a
n/a
Polypeptide
n/a
n/a
DNA
Amino Acids,
Proteins
Amino
Acids,
Proteins
Lipids
(aka
fats)
Lipids
(aka fats)
Genetic Material
Genetic Material
Monopeptide
(one amino acid)
CH2
Nucleotide, nucleic
acid, nitrogenous
base…
lipid
lipid
Review!
Transcription
DNA helicase
RNA polymerase
Replication
DNA helicase
DNA polymerase
mRNA
Translation
Ribosome
tRNA
Protein
DNA
Happens in the nucleus
Happens in the cytoplasm /
at the ribosomes
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.
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
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.
3 experiments that changed the world.
https://www.youtube.com/watch?v=63IoOLXmzKg
Which came first, DNA, RNA, or proteins?
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!)
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!
Video about the origin of life on earth. Computer graphics, with narration.
https://www.youtube.com/watch?v=c6LaMwRZUjw
The most astounding fact, Neil Degrasse Tyson.
https://www.youtube.com/watch?v=9D05ej8u-gU
Neil Degrasse Tyson, on alien intelligence.
https://www.youtube.com/watch?v=KeJoVeKSsyA
Kid talking with graphics: 3 experiments that changed the world.
https://www.youtube.com/watch?v=63IoOLXmzKg