Download Unit Three “Cell Proliferation and Genetics”

Unit Three
“Cell Proliferation and Genetics”
“Protein Synthesis”
From Gene to Protein
• The way in which the “Control Center” of the cell,
which is the DNA in the nucleus, enables the
efficient operation of the remainder of the cell is
via Protein Synthesis
• Recall that proteins maintain the proper function
of the cell by acting as enzyme that regulate the
vital chemical reactions of the cell
• In essence, DNA makes RNA makes Protein so
that the protein can maintain homeostasis
(equilibrium)
RNA Structure
• RNA has a very similar
structure to DNA
• It also has a Sugar,
Phosphate Group, and
Nitrogenous Bases
• It is different in that it is
single stranded i.e. it is
one side of a ladder
RNA Structure
• RNA’s nitrogenous bases are the same as in
DNA except Thymine (Pyrimidine) is replaced
by Uracil
• There is no Thymine in RNA
• Since it is single stranded it is less complex
compared to DNA
• RNA serves as the genetic material in viruses,
and it is also found in other organisms but
with a different role in the cells
Categories of RNA
• Ribosomal RNA (rRNA) – DNA serves as template
for production of rRNA; formed in the nucleus of
a cell; moves into the cytoplasm to bond with
proteins; rRNA + proteins make up Ribosomes
(site of protein synthesis)
• Messenger RNA (mRNA) – DNA serves as
template for production of mRNA; mRNA
contains code for protein synthesis; it takes code
out of nucleus to ribosomes for subsequent
protein synthesis
Categories of RNA
• Transfer RNA (tRNA) – DNA serves as template
for production of tRNA; once produced in
nucleus moves out into cytoplasm; locates
ribosomes and delivers its amino acids for
assembly by ribosomes using the already
delivered code by mRNA
• rRNA = factory
• mRNA = operational system
• tRNA = building materials
Protein Synthesis
• There are two stages of Protein Synthesis:
– 1. Transcription – the copying of the Nucleic Acid
instructional code (DNA to RNA)
– 2. Translation – the translating of the Nucleic Acid
code into Amino Acid code that results in the
building of proteins
Transcription
• Transcription is the synthesis of RNA from a
DNA template
– 1. DNA unwinds and separates
– 2. RNA Polymerase makes mRNA from DNA
– 3. Newly completed mRNA moves into the
cytoplasm for Translation
Translation
• Translation is the making of proteins using the
three types of RNA that came from the
nucleus
– 1. rRNA joins to the Ribosome
– 2. Protein Synthesis begins using the code of the
mRNA and the amino acid building materials the
tRNA’s have brought to the Ribosome
Transcription
Translation
Transcription & Translation
Overview
Controlling Protein Synthesis
• Controlling Transcription
– A protein called a “Repressor” can attach to the DNA
making it impossible for the RNA Polymerase to attach
to the DNA
– In order for RNA Polymerase to attach properly to one
strand of the DNA double helix, the DNA must be
unzipped with the assistance of a protein called an
“Activator”
– RNA Polymerase is guided to its transcription start
point, the “Promoter”, by proteins called “Enhancers”
Protein Synthesis Summary
• https://www.youtube.com/watch?v=itsb2SqRR0
• https://www.youtube.com/watch?v=NJxobgkP
EAo