Transcript DNA - hdueck

DNA and RNA
The Molecule of Life: DNA and RNA
DNA vs. RNA Summary
DNA
By comparison
they both have:
RNA
Sugar phosphate background
Nitrogenous bases
By contrast each
has:
Double strand,
double helix
Single strand and
various shapes (3)
Deoxyribose sugar Ribose sugar
A=T and C=G
A=U and C=G
Stay in the nucleus Nucleus and
cytoplasm
Different 5 – C sugar: Deoxyribose
(DNA) and Ribose (RNA)
Thymine (DNA) and Uracil (RNA)
 Thymine versus Uracil
 Thymine in DNA is replaced by Uracil
in RNA
RNA
vs
DNA
Ribonucleic Acid Types (p 288-295)
There are several types. We will focus
on the main 3 types:
rRNA: large, makes up structure of ribosomes.
- Large globular structure, forms structure
with proteins to form ribosome
tRNA: smaller, contains amino acid to match
code of mRNA. Compact 3-D structure
mRNA: single strand, provides complementary
code from DNA for protein
- Single strand may fold back on itself to form
H-bonds
rRNA
 rRNA: Ribosomal ribonucleic acid
 Located in ribosomes
 Provides the site on the ribosome where
the protein is assembled
rRNA Structure
 This big “globular”
structure is the
structure for the
ribosome all
spread out.
 A smaller “glob”
provides the
second part of the
ribosome
structure.
Ribosome: rRNA
tRNA
 tRNA: Transfer ribonucleic acid
 In humans, more than 40 different tRNA
float freely in the cytoplasm, float to
ribosome for protein synthesis
 Each tRNA is connected to a different
amino acid
 Function: to place the correct amino acid
in a protein sequence
tRNA Structure
 Specific regions:
 3’ end is AMINO
ACID site
 Anticodon is
complementary to
mRNA codon
(code)
tRNA detail
 Typically 75 nucleotides long, twisted
into a tertiary structure (3-D)
 Specific in function to translation of
mRNA into protein amino acid
sequencing
tRNA detail
 Anticodon: three nucleotide sequence
that correlates to a specific amino acid
that is attached to its 3’end (amazing
isn’t it!)
 Anticodon complements the mRNA
three nucleotide sequence called the
codon.
mRNA
 mRNA: Messenger ribonucleic acid
 Long single strand of RNA that has the
coded complement from the DNA.
 Can fold back to form H-bonds with itself
 Brings the code from the nucleus to the
cytoplasm, specifically to ribosomes.
mRNA from DNA – Transcription
 DNA molecule is opened at a specific
gene site
 mRNA is assembled complementary to
one DNA strand
 When coding is complete, it detaches
and floats to the ribosome
 DNA re-fits itself.
 Key enzyme: RNA Polymerase
mRNA formed at
TRANSCRIPTION
Summary: 3 Main RNA Forms