This week, we talked about DNA…
• T goes with…?
• G goes with…?
• What does DNA
look like?
• Ok, so now we’ll talk about RNA…
What’s RNA?
• RNA is short for
Ribose Nucleic Acid.
It helps our body
decode DNA and it
helps assemble
proteins.
What’s the difference
between DNA and RNA?
• RNA single-stranded while
DNA has two strands.
• RNA contains Ribose sugar
instead of Deoxyribose sugar.
• RNA uses uracil(U) instead
of thymine (T).
Three Types of RNA
• There are three types of RNA.
• Most RNA molecules have only one
job – protein synthesis.
Three Types of RNA
• Messenger (mRNA):
a messenger between
DNA in the nucleus
and ribosomes in the
cytoplasm
Three Types of RNA
• Transfer (tRNA): transfers amino acids to
the ribosomes to build proteins
Three Types of RNA
• Ribosomal (rRNA): makes up part of the
ribosome; clamps/hold onto mRNA and
hold it in place
Three Types of RNA
• Label the three types of RNA…
Messenger
RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA
(rRNA)
PROTEIN SYNTHESIS
Essential Idea:
DNA  RNA  Proteins
(This is important. That’s why it’s so BIG! Circle
it, put a big star by it. I wouldn’t be telling you
do this if it wasn’t an IMPORTANT IDEA.  )
PROTEIN SYNTHESIS
• What? Using info from DNA to make proteins
– The sequence of DNA bases is a code for how to
make proteins.
• Where? Takes place in the nucleus and
cytoplasm of a cell
• Why? So our cells can make the proteins need
for important processes all over our bodies
– Ex. in humans, how we make hair, fingernails,
hemoglobin, insulin, enzymes, etc…
PROTEIN SYNTHESIS
DNA  RNA  Proteins
• How?
–DNA  RNA by transcription
–RNA  proteins by translation
Transcriptalatiowhat?
• Don’t worry, by the end of this you will be
EXPERTS! (Pros, masters, geniuses, magicians,
super synthesizers --- trust me, you got this).
• First, we’ll talk about transcription.
TRANSCRIPTION
• What? Making mRNA molecules by using the
DNA sequence as a template
• Where? Takes place in the nucleus
• Why? So that a disposable copy of the
“protein instruction manual” stored in DNA
can be transferred to the ribosome and used
to make a protein
• How?
Steps in Transcription
Transcription is just like DNA replication (almost)
except that we are making messenger RNA
instead and U is put in place of T
Steps in Transcription: Separation of Strands
1. The enzyme RNA polymerase uses one DNA
strand as a template
Steps in Transcription: Separation of Strands
1. Only one gene is copied at a time; mRNA is
made at the start of a gene sequence
Steps in Transcription: Base Pairing
2. Free RNA nucleotides are matched
to exposed DNA nucleotides (A=U, C=G)
Steps in Transcription: Bonding of Bases
3. Sugars and phosphates bond to form a
new backbone
Steps in Transcription:
Termination/Stop Codon
4. Transcription stops when a
terminator/ stop codon (end of the
sequence) is reached
Steps in Transcription:
Results of Transcription
5. The mRNA molecule is a
complementary (opposite)
copy of the DNA sequence
Steps in Transcription
5. Each three-nucleotide set on the mRNA is
called a codon, which represents a different
amino acid
Let’s practice transcription:
DNA: ATC CGT AAG CTC GTC
mRNA: UAG GCA UUC GAG CAG
Let’s practice transcription:
DNA: GGC TAA TCG ACT GCA
mRNA: CCG AUU AGC UGA CGU
Let’s practice transcription:
DNA: ATC GAC GCT CAT CGA
mRNA: UAG CUG CGA GUA GCU