Evidence 1 –
DAPI is a fluorescent dye used by scientists to highlight DNA in cells. DAPI is blue under fluorescent
light. Below are some pictures taken of DAPI stained cells.
Human endothelial cells
Bovine Pulmonary Artery Wall Cells
Unidentified Bacterial Cells
Human Blood Cells
Conclusion - The nucleus is not the control center of the cell because bacteria can function with out a nucleus.
DNA is the ‘controlling factor’ in the cell
DNA is only found inside the nucleus in Eukaryotic organisms
Mutation Percentage ( in decimal form)
formdecemimal
Evidence 2 –
Number
1
2
3
4
5
6
7
8
9
10
Organism
Bacteriophage λ
Bacteriophage M13
Bacteriophage T2, T4
Escherichia coli
Drosophila melanogaster
Caenorhabditis elegans
Saccaromyces cervisiae
Mus Musculus
Neurospora crassa
Homo Sapiens
Name
Virus
Virus
Virus
Prokaryotic
Eukaryotic
Eukaryotic
Prokaryotic
Eukaryotic
Eukaryotic
Eukaryotic
Mutations percentage
77,000,000%
72,000,000%
2,400%
54%
34%
23%
22%
18%
7.2%
5%
Conclusion – The function of the nucleus is to protect DNA
Evidence 3 These results are based off an experiment in which scientists sampled the inside of the nucleus to
determine the components of the macromolecules that make up the nucleus.
Chemical Name
Adenine
Cytosine
Guanine
Phosphate
Ribose
Thymine
Description
The A in ATP
Nucleic Acid
Purine
Can form 2 Hydrogen Bonds
Nucleic Acid
Pyrimidine
Can form 3 Hydrogen Bonds
The G in GTP (A molecule related
to ATP)
Nucleic Acid
Purine
Can form 3 Hydrogen Bonds
A component of ATP
(Attached to Ribose in ATP)
A 5 carbon sugar
A component of ATP and related
molecules
Nucleic Acid
Pyrimidine
Can form 2 Hydrogen Bonds
Conclusion – See vocabulary section for DNA structure
Amount Collected (μm)
26
14
14
40
40
26
Evidence 4
Scientists were experimenting with different DNA stains other than DAPI. They found that when they used Pyronin
Y they stained another substance called RNA. The picture below shows a group of cells that were stained with
both DAPI (blue) and Pyronin Y (Red in high concentrations, orange in low concentrations)
Conclusion: The location of RNA in the cell is _____________________________________________________
The location of DNA in the cell is _____________________________________________________
Evidence 5
In 1953 Watson and Crick discovered the structure of DNA. (We did this as a class, the results are
summarized on the vocabulary page. In addition to figuring out the structure of DNA these two
scientists also noticed that DNA is like a zipper – in it can be split into a two single strands by separating
the hydrogen bonds between the base pairs. Check out this video
http://www.youtube.com/watch?v=0CMIgZQakHY
Evidence 6
The nuclear membrane is similar to the cell membrane. Materials that cannot diffuse or squeeze through
the membrane must use proteins to move in and out of the nucleus. The proteins of the nuclear
membrane only allow a single strand of genetic information through.
Bonus Evidence 7
Proteins are large molecules that are made from smaller molecules called amino acids. There are twenty
amino acids that make up all proteins. Large proteins such as hemoglobin contain as many as 574 amino
acids.
Vocabulary
DNA – Deoxyribose Nucleic Acid, doubled stranded genetic material
Purine – A double ring Nitrogenous base
Pyrimidine – A single ring nitrogenous base
Prokaryote – Bacteria, singled cell organisms that lack a nucleus
Eukaryote – single or multi celled organism that contains a membrane bound organelles
Virus – A non living macromolecule that is made of a protein coat surrounding DNA.
Hydrogen Bond – An attraction between two molecules (or parts of molecules). This is weaker than a
chemical bond
Base Pair – Two nucleic acids that interact in DNA
A–T
G–C
Sugar phosphate backbone – The repeating ribose – phosphate – ribose – phosphate pattern that
connects nucleic acids ( nitrogenous bases) together
RNA – Ribose Nucleic Acid a single stranded piece of genetic material
Structure of RNA
Structure of DNA
AMP