Transcript Protein Synthesis

Protein Synthesis:
DNA Transcription & Translation
By Jessi Jones
Table of Contents
Slide Title
•
•
•
•
•
•
•
•
•
•
•
•
What is Protein Synthesis
The Site of Construction
The Workers
Transcription
How this works
DNA vs mRNA
tRNA
Codons and Their Amino Acids
Ribosomes
Translation
Completion
References
Slide #
3
4
5
6
7
8
9
10
11
12
13
14
What is Protein Synthesis?
• Protein Synthesis actually
means the ‘construction’
of proteins.
• We need proteins for our
body to grow and to work.
• Your body makes the
proteins it needs everyday
with the amino acids from
the foods that you eat.
The Site of Construction
Every cell in your body make proteins.
There are 2 parts to protein
synthesis;
1. Transcription:
copying the plans
2. Translation:
reading and
constructing
Each cell has millions of
construction sites
The Workers
The Nucleus
the head office where all the original blue prints and important
instructions are held safe as DNA.
The Ribosomes
the actual sites of construction, they are found throughout
the cytoplasm in the cell.
mRNA (messengerRNA)
go into the nucleus and copy parts of the DNA and take the
instructions to a ribosome.
tRNA (translatorRNA)
translate the instructions on the mRNA. They carry amino acids
(the building blocks), and 3 codons.
Transcription
DNA are the ‘blue prints’ for our body’s.
DNA never leaves the nucleus!
So, the pieces of information needed for each
project has to be copied and taken to the
construction sites.
That’s where mRNA comes in!
Messenger RNA go into the nucleus and
copy the parts it needs then go out and find
a ribosome.
How This Works
1. The DNA unwinds itself in one spot
2. mRNA attaches itself for a second and makes
a copy of that part of the instructions.
a. mRNA will replace the T codon
for U
b. It will also copy a start and end
code.
3. When complete, the mRNA leaves the
nucleus to find a ribosome.
1
a
4. The DNA strand then winds itself
back up.
2
DNA vs mRNA
This is a DNA double Helix.
It’s called that because it is
two rows twisted together.
mRNA is just one row.
tRNA
It has an Amino Acid
This is a tRNA
ready for
attachment
Amino acid
tRNA
And the 3 letter codon
3 letter codon
Codons and Their Amino Acids
The 3 letter codons on tRNAs are specific to the amino acid
they carry.
Below is a table of the 3 letter codons and the amino acids
associated with them.
Ribosomes
tRNA
Ribosome
mRNA
During Protein Synthesis mRNA is used by many ribosomes at once.
Space for
mRNA
Ribosomes are made up of 2 parts.
When joined there is a small space
between them where the mRNA
attaches and slides through.
This is also the area where the tRNAs
attach and for the polypeptide chain.
Translation
1. tRNAs 3 letter codon
matches the available
space on the mRNA and
attaches itself.
2. Amino acid attaches to
previous amino acid;
releasing the previous
tRNA continuing the
polypeptide chain.
3. Repeats until end
code on mRNA
is reached.
-The polypeptide is then released to coil upon
itself creating a protein.
- tRNA and mRNA are also released
- Ribosomes break apart
Completion
The polypeptide created coils upon
itself, creating a protein.
tRNAs seek specific amino acids that
match its 3 letter codon.
mRNAs return to the nucleus to repeat
the transcription process.
Ribosome’s float around the
cytoplasm waiting for the next job.
Protein synthesis begins again!
Proteins
References
• J. Creager, J. Black, & V. Davison. 1990. Microbiology:
Principles and Practice. Prentice-Hall, Inc. 839 pp.
• P. Raven & G. Johnson. 1999. Biology. WCB?McGraw
Hill Publishing. 1284pp.
• W. Purves, D. Sadava, G. Orians, H. Heller. 2001. Life:
The Science of Biology. WH Freeman & COmpany. 1044
pp.
• S. Mader. 1987. Biology: Evolution, Diversity amd the
Environment. William C. Brown Publishers. 772pp.