The Function of DNA
• The major functions of the cell are carried out in the organelles of the cell
• They are like the cell’s organs
• They process food, transport materials, help moves, etc.
• Organelles carry out these functions using proteins
Organelles and Proteins
Proteins
• Proteins are molecules
• Proteins carry out all of the functions inside the cell
• They are a type of molecule called a polymer
• Polymer – made up of the same, repeating part.
• The repeating parts that make up a protein are called amino
acids
• There are 20 amino acids in nature
Proteins
• Proteins are made of amino acids
• Amino Acids connect to each other making long chains
• The chain of amino acids is a protein
Proteins
• There are 20 amino acids
• The order they are connected
is what determines the type of
protein
• Each type of protein does a
different job inside of the cell.
DNA Sequence
• The DNA sequence is the order the
nitrogenous bases are attached
• DNA stores information by its sequence
• Much like a computer stores information
in a sequence of 1’s and 0’s
• This sequence determines how the cell
will function.
DNA Sequence
• This sequence is used to make proteins
• Proteins carry out all of the functions of the
cell
• DNA makes proteins so this is how it controls
the cell
Transcription
• DNA is first transcribed (rewritten) into RNA in
the nucleus
• RNA is Ribonucleic Acid
• RNA is single stranded and looks like DNA
• It replaces Thymine (T) with Uracil (U)
• This process is called Transcription
• The type of RNA in this process is called mRNA
• mRNA is Messenger RNA
Transcription
• The mRNA leaves the nucleus and
travels to the cytoplasm
• When in the cytoplasm it will go to
the Ribosomes
Translation
• The ribosome attaches to the mRNA
• It then “reads” the mRNA in 3 letter sections
called codons
• Each codon represents an amino acid
• Amino acids = building blocks of protein
• tRNA brings the correct amino acid to the
ribosome
Translation
• The ribosome will then read the next 3 letter
sequence (codon)
• This represents a new amino acid
• tRNA will bring this to the ribosome
• The ribosome will connect the amino acids
together
• BOOM – protein!
• This process is called Translation
Genes
• Genes are sections of DNA that code for a single protein
• These are the sections that are transcribed (turned into mRNA) and then
translated (read by ribosomes and made into proteins)
Genes to Proteins
• DNA makes genes
• Genes create proteins
• The types of proteins determine how the
cell will function
• This is how DNA controls the function of
the cell.
• DNA is a recipe for all of the proteins in
the cell
Genetic Code
• The genetic code is the translation of
DNA/RNA to Proteins.
• It shows us what codons are used for specific
amino acids
Genes
• These genes are passed down when a living thing reproduces
• This means the offspring (children) will make the same proteins as the parents
Mutations
• Sometimes a cell will make a mistake and
change a nucleotide in the DNA
• This change is called a mutation
• Mutations can be neutral, harmful, and rarely
beneficial
• This depends on the change to the protein made
Cancer
• Cancer is typically caused by a mutation in the DNA
• This make the cell function so differently that it will
only have the information to copy itself and reproduce
• This process happens more quickly and builds a large
mass of improperly functioning cells
Viruses
• Viruses hijack the processes of transcription and translation to do their work
• Viruses are a protein that contains DNA or RNA
• Viruses find a way to get their DNA or RNA into a cell
• The cell reads it and makes the protein it codes for
• That protein, is a new virus!
• This process continues and releases viruses which then infect more cells
Genetic Engineering
• Genetic engineering is changing the genome
(code) in a living thing.
• This is done by taking a section of DNA that
codes for a protein you want.
• It is then put into a new cell’s DNA.
• The organism made from this cell will have this
gene and make this protein.