Transcript DNA to Proteins

DNA to Proteins
Unraveling DNA
* The structure of DNA allows
it to hold information
* The order of the bases is the
code that carries the
information
* A gene is a string or group of
nucleotides that give the cell
information on how to make
a protein.
* Humans have over 30,000
genes
Genes Make Proteins
• DNA code is read like a book – from one end to the other
and in one direction.
• Bases form the alphabet of the code
• Groups of 3 bases code for an amino acid
• A long string of amino acids makes a protein
• Each gene is a set of instructions for making a protein
Proteins Make YOU!
• Proteins are all through cells and make the differences
you see in organisms.
• Proteins are chemical triggers and messengers for cell
processes.
• An organism may have thousands for genes that code
for thousands of proteins
Help from RNA
• RNA (ribonucleic acid) is
a molecule in all living
things and helps make
proteins
• RNA helps change DNA
code into a protein
• RNA has one strand.
DNA has 2 strands
• RNA does not have
thymine. It has uracil (U)
instead.
How to make a Protein
• Step 1 – DNA unzips.
• Step 2 – RNA makes a
copy of one side of the
DNA where a gene is
located.
• This mirror copy of DNA is
called messenger RNA or
mRNA
• This is called transcription
What Does the Code Say?
• Step 3 – RNA leaves the
nucleus and goes to the
cytoplasm. It is fed through
a ribosome The bases on
the mRNA strand are
matched by another type of
RNA called transfer RNA or
tRNA.
• Every group of 3 bases on
mRNA codes for 1 amino
acid
A Chain of Amino Acids = Protein
• Molecules of tRNA
deliver amino acids
from the cytoplasm to
the ribosome and add
them to a growing
protein.
• Usually one protein is
produced for each
gene
Changes in Genes
• A mutation is a change in
the base code of a gene.
• A base can be deleted
(left out), inserted (stuck
in) or substituted
(changed place).
• Mutations happen often
and can either make no
change, an improved trait
or a harmful trait.
Mutation Examples
How Mutations Happen
• Mutagens are any
substance that can cause
a mutation like UV
radiation, x rays, or
cigarette smoke
• Examples of mutations
are cystic fibrosis, sickle
cell anemia, & hemophilia
• If mutations happen in
sex cells, then the
mutation can be passed
on to the next generation.