Stephen Taylor
i-Biology.net
Photo credit: Firefly with glow, by Terry Priest on Flickr (Creative Commons)http://flic.kr/p/h1KAJ
http://learn.genetics.utah.edu/content/molecules/firefly/
3.5.1
• Compare the structure of RNA and DNA
– (with respect to the type of sugar, the bases and
the number of strands)
3.5.2
• Outline DNA transcription in terms of the
formation of an RNA strand complimentary to
the DNA strand by RNA polymerase
Transcription animation:
http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf
Translation animation:
http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf
3.5.3
• Describe the genetic code in terms of codons
composed of triplets of bases
3.5.4
• Explain the process of translation, leading to
polypeptide formation
– Include the roles of mRNA, tRNA, codons,
anticodons and amino acids
DNA and Protein Synthesis
• DNA contains the genetic information to
make amino acids
• Amino acids combine to make proteins
• These proteins determine the physical traits
of an organism and control cellular functions.
• Proteins do everything,
and DNA gets all the
credit!
• Think of them as tiny minions
who do all the work
DNA and Protein Synthesis
FROM DNA TO PROTEIN…
•Think of DNA as a blueprint for your body
•A lot of the blueprint has to do with protein building, but not all of it
•To create a protein from the blueprint involves two main processes
•1.
TRANSCRIPTION
•The essential parts of the blueprint (DNA) for
protein building are copied (transcribed) by an
architect (mRNA) and transported to the
construction site
•2. TRANSLATION
•The protein blueprint (mRNA) is given to the
builders (ribosomes) who translate the DNA code
into the PROTEIN CODE to build proteins
RNA - the messenger
*single strand
*ribose sugar
*contains no thymine, uracil instead
*follows base pair rule
DNA: A T A G C G
RNA: U A U C G C
RNA carries the
"message" to the
ribosomes, where
proteins are made
CODES
•
DNA code:
–
4 possible bases (ATCG)
–
Nucleotides in various combinations connect together and pair forming a DNA double helix (double
stranded)
•
•
RNA code:
–
4 letters (AUCG)
•
–
–
•
Are connected to deoxyribose and phosphate forming nucleotides
Are connected to ribose and phosphate forming nucleotides
Nucleotides in various combinations connect together forming a RNA chain (SINGLE stranded)
Groups of 3 nucleotides (CODONS) make an RNA word
PROTEIN CODE–
–
–
–
–
EACH CODON CODES FOR AN AMINO ACID
All protein words are 3 letters long (ie: ATT, CAG, GGC)
Each 3 letter word (codon) codes for a specific amino acid
There are 20 possible amino acids
» THEY ARE THE SUBUNIT OF PROTEINS
Chains of amino acids make a PROTEIN
DNA and Protein Synthesis
• Codon: three bases code for a specific amino acid:
ex: AAA = Lysine
• The codons code for 20 amino acids
• Just like the alphabet has 26 letters to make all
the words we know, the 20 amino acids that, when combined in
different ways, make all the different proteins found in living
organisms
• The codons are the template for protein synthesis,
which takes place on the ribosomes (rRNA) in the
cytoplasm
DNA and Protein Synthesis – Codons and amino acids
ile
Name the
Amino Acid:
Start
UAU
Tyrosine
CCG
Proline
AGU
Serine
GCA
Alanine
•
•
•
•
Protein synthesis- Youtube
http://www.youtube.com/watch?v=NJxobgkPEAo
Protein synthesis 2 – Youtube
http://www.youtube.com/watch?v=1fiJupfbSpg
•
•
•
Cow dna - http://www.biologycorner.com/worksheets/DNAcontrols.html
Genetics bio corner:
http://www.biologycorner.com/lesson-plans/genetics/
DNA and Protein Synthesis – Codons and amino acids
Name the
Amino Acid:
UAU
CCG
Tyrosine
AGU
Proline
GCA
Serine
ile
Alanine
DNA and Protein Synthesis
But… How does the information
get from the DNA to the
cytoplasm?
mRNA
DNA and Protein Synthesis - Transcription
Transcription:
1)
DNA unzips
2)
mRNA (messenger ribonucleic acid) copies info from DNA using base
pairings
•
3)
RNA is different from DNA
a)
Single stranded, not double stranded
b)
Instead of deoxyribose, it has ribose
c)
instead of Thymine, it uses Uracil
mRNA carries the genetic code from the nucleus to the
ribosome in the cytoplasm
DNA and Protein Synthesis - Translation
Translation:
1)
rRNA (ribosomal RNA) attaches to mRNA and starts reading the
codons
2)
tRNA (transfer RNA) – carries no acids and attaches them to the
growing protein chain by matching its complementary anticodon with
the mRNA codon
3)
When protein production is complete, the ribosome releases the
protein chain
DNA and Protein Synthesis - Summary
DNA and Protein Synthesis
Practice making mRNA using the DNA template
A T T A C A
C U A A U G U
mRNA
DNA and Protein Synthesis
• Amino acids are linked together in the same
order as the codons , creating a protein chain
• Just like linking letters to make words, linking
amino acids makes proteins
mRNA
CUA AUG UGC
Amino
Acid
Amino
Acid
Amino
Acid
Go To This Website
• http://learn.genetics.utah.edu/content/molec
ules/transcribe/
http://learn.genetics.utah.edu/content/begin/dna/firefly/
Fill in the blanks on the following
slide
3.5.5
• Discuss the relationship between one gene
and one polypeptide
For more resources & links.
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