DNA and RNA
Deborah J Brooks
Biochemistry (GRT1) Task 1
Western Governors University
DNA Replication at Biochemical Level
Role of Ligase
Role of mRNA
Role of RNA Polymerase Inhibition related to
the death cap mushroom
Nucleic acids are required for the storage and
expression of genetic information. There are
two chemically distinct types of nucleic acids.
(deoxyribonucleic acid). The repository
of genetic information.
RNA (ribonucleic acid). “The working
copies” of DNA. The copying or translation
process in DNA synthesis.
DNA replication at the biochemical level
involves the copying of doubled-stranded DNA
to produce a second double helix that is
identical to the first (“DNA Replication”).
The DNA being copied passes through several
proteins, and these unwind it and split into two
single strands; each of the two strands is copied
and become one-half of the new DNA doublehelix, in a process termed “semi-conservative” replication.
Each of the proteins in the replication process
performs a specific function. For example,
helicase unwinds the double helix into two
individual strands, while single-stranded binding
proteins coat the DNA strands to keep them
from adhering back together.
Primase synthesizes the primers that will begin
the replication process, and polymerase- in
conjunction with the DNA clamp-strings
nucleotides together to create a DNA strand.
DNA Replication Diagram
DNA BINDING PROTEINS
Name S AT THE
LEADING TO LOCAL
Name S TO
ALLOWING BINDING OF
ARE REMOVED BY
NEW DNA STRA
DS IN THE 5'-3'
OF THE DOUBLE
WHICH SERVES AS
A PROCESS CALLED
Ligase Enzyme in DNA
Ligase links shorter sections, known as
“Okazaki fragments,” together to create a
single long strand of DNA.
Since DNA polymerases are not able to seal up
nicks that occur when DNA replaces RNA
primers in the replication process, ligase comes
into the process to do that through the use of
phosphdiester bonds in ATP or NAD connecting
a free 3’ hydroxyl to the 5’ phosphate next to it.
Ligase in DNA Replication
Role of mRNA
Polymerase Inhibition and the
Death Cap Mushroom
knowledge of biochemistry of DNA can
help to explain how the death cap
mushroom poisons an individual who
poisonous effect of the death cap
mushroom is related to the biochemistry of
DNA and RNA and the process of RNA
Death cap mushroom/Amatoxins
death cap mushroom gives off
amatoxins that are toxic to the liver as well
as being absorbed from the gastrointestinal
main toxin given off by death cap
mushroom is ά- amanitine, and there are
also nine cyclic 900-Dalton molecular
weight octapeptide amatoxins.
Shortly after an individual ingest άamanitine, the nucleoli of his/her liver cells will disintegrate, which in turn interferes
with DNA transcription because it inhibits
RNA polymerase II.
The way ά-amanitine does this is to bind to
the 140,000-Dalton RNA polymerase ll
subunit, inhibiting it.
This inhibition effectively stops protein
synthesis in the body, so the organs that
are most dependent on protein synthesis
are the ones that...
References: Clancy, Suzanne; Brown, William. “Translation:
DNA to mRNA to Protein.” Nature Education, 1.1.
Richard, Harvey, Ferrier, Denise. (2010).
Biochemistry. Lippincott’s Illustrated Reviews 5th
ed. Baltimore, Maryland. Wolters Kluwer.
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