Transcript Molecular Genetics - Ursuline High School

The Structure of RNA
RiboNucleic Acid
• RNA is a polymer composed of RNA Nucleotides.
Covalent Bonds
Each “Nucleotide” is made
up of 3 components:
1. A phosphate group
2. A sugar – the sugar in
RNA is Ribose.
3. A Nitrogenous Base
Held Together by
“Covalent Bonds.” These
bonds are strong…. You
wouldn’t want your DNA
falling apart
This is how I draw a Nucleotide
P
S
B
The Location of RNA
• RNA can be found in the Nucleus
and the Cytoplasm.
• RNA is made in the Nucleolus.
Comparing RNA and DNA
DNA
Double Helix
Found only in the Nucleus
DNA Nucleotides have Deoxyribose as the sugar
Adenine bonds to Thymine
RNA
Single Helix
Found in the Nucleus and the Cytoplasm
RNA Nucleotides have Ribose as the sugar
Replaces Thymine with Uracil (there’s no Thymine in RNA)
There’s 3 types of RNA?
• Ribosomal RNA (rRNA) – used to make the
ribosomes.
• Messenger RNA (mRNA) – carries the DNA
instructions from the Nucleus to the
Ribosomes.
• Transfer RNA (tRNA) – picks up amino acids
in the cytosol and carries them to the
Ribosomes to be assembled into Proteins.
Transcription
(The Process by which a Template of DNA is used to make mRNA)
Transcription takes place in the
3’ to 5’ direction
Transcription takes place in the
Nucleus
Step 1. DNA Unzips
Step 2. RNA Polymerase
attaches RNA nucleotides to
the single DNA strand.
Step 3. The newly formed
mRNA molecule breaks away
from the DNA and leaves the
nucleus.
Translation
• Once the DNA code has been Transcribed
onto a mRNA molecule, mRNA leaves the
nucleus and moves into the cytoplasm. In
the cytoplasm the mRNA combines with
the Ribosomes to make Enzymes/Proteins.
The Process of reading the mRNA code
and building a(n) Enzyme/Protein is called
Translation, or Protein Synthesis.
In order for Translation/Protein
Synthesis to occur a cell needs:
• 1. mRNA (carrying the DNA code)
• 2. Ribosomes
• 3. Amino Acids
• 4. tRNA (picks up amino acids in the cytosol
and carries them to the ribosomes where they
will be joined together to form a Protein)
The mRNA is made in the
Nucleus through the process
of Transcription. mRNA is
made up of RNA nucleotides.
Each group of 3 nucleotides is
called a Codon and codes for
one amino acid of the newly
forming Protein.
This Segment of a mRNA molecule is 7 codons long, 21
nucleotides, and will code for 7 amino acids
Ribosomes
(the ribosomes are the actual site of Translation /protein synthesis)
Made in the Nucleolus, made up of
Ribosomal RNA, rRNA
Transfer RNA (tRNA)
• tRNA is a small, folded RNA
chain (74-93 nucleotides) that
picks up and transfers specific
amino acids to a growing
polypeptide chain at the
ribosomal site of protein
synthesis during translation.
•
It has sites for Amino Acid
attachment and an Anticodon.
•
• The Anticodon is composed of
• complementary bases.
•
Each tRNA molecule binds to
only one type of amino acid.
• More than one tRNA exists for
each amino acid.
Animals and Plants get their amino acids the
same way they get their Nucleotides.