Transcription is the process by which RNA polymerase copies a strand of DNA into RNA. In DNA
Adenine normally pairs with Thymine, and Guanine pairs with Cytosine. This is based on the fact that
Purines must bind with Pyrimidines in order that the DNA molecule is 3 nitrogenous rings wide.
Additionally the base pairs are matched by the number of Hydrogen Bonds they share. In RNA transcription
Thymine is replaced by Uracil so that Adenine (in DNA) binds with Uracile as shown below.
____________________________
___________________________
After transcription takes place the newly formed RNA travels outside of the Nucleus and finds a
Ribosome an organelle that makes Protein. The RNA is read 3 nitrogenous bases at a time. This is because
there are 20 amino acids that make all proteins, and this is the minimum number of letters needed to reach the
20 amino acids. The amino acids are placed together in the correct sequence so that a resulting Protein is
made. This process is known as Translation.
To summarize up to this point
DNA 
RNA 
By means of Transcription
Protein
Translation
Proteins then go on to perform a wide variety of functions in the cell. From Digestion to Synthesis
(making things). Proteins are even responsible for Movement and Energy Production. A Geneis a piece of
DNA with a unique code, sequence, order that corresponds to a particular protein. This is called the Central
Dogma of biology.
All of our traits are controlled by genes. Each person inherits a set of genes from their
Mother and a set of genes from their Father, so each person has two sets of genes. (In the
diagram there are two boxes for each person).
Each gene has two different versions, called Alleles.
The two Alleles can be the same (e.g. ‘AA’ or ‘aa’) – calledHomozygous. Or the two alles
can be different (e.g. ‘Aa’ or ‘aA’) – called Heterzygous.
One allele can be dominant and the other recessive. If a person has at least one
Dominant allele then they will show the trait. If they have two recessive alleles then they will
show the alternate version of the trait (In the diagram ‘A’ is dominant and ‘a’ is recessive).
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
AMP
Nucleic Acids (AGTC) – DNA &
(AGUC )- RNA
Amino Acids
Proteins - Gene
Multiple proteins - Chromatid
Letters
Words
Sentences
Paragraph
Gene – A segment of DNA that codes for a particular protein (genetic material)
Chromatid – A collection of multiple genes
Allele - An alternate form of a gene
Chromosome – A collection of chromatid each containing different alleles
Genotype – The genetic information contained in a cell or organism on its chromosomes
Phenotype – The physical appearance or attributes of a cell or organism
Pedigree – A chart showing relatedness of family members
Heterozygous – A genotype containing different alleles
Homozygous – A genotype containing only one allele
Mitosis – Cellular Replication, the mechanism of how cells copy themselves
Meiosis - Sexual Reproduction, Halving the number of chromatids in a cell to make gametes sperm and
eggs
Punnet Square -