1. Central Dogma Protein Synthesis
4. Genes are a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism. As a basis for understanding this concept: a. Students know the general pathway by which ribosomes synthesize proteins, using tRNAs to translate genetic information in mRNA. DNA does not leave the cell nucleus, but messenger RNA (mRNA), complementary to DNA, carries encoded information from DNA to the ribosomes (transcription) in the cytoplasm. (The ribosomes translate mRNAs to make protein.) Freely floating amino acids within the cytoplasm are bonded to specific transfer RNAs (tRNAs) that then transport the amino acid to the mRNA now located on the ribosome. As a ribosome moves along the mRNA strand, each mRNA codon, or sequence of three nucleotides specifying the insertion of a particular amino acid, is paired in sequence with the anticodon of the tRNA that recognizes the sequence. Each amino acid is added, in turn, to the growing polypeptide at the specified position.
After learning about transcription and translation through careful study of expository texts, students can simulate the processes on paper or with representative models. Computer software and commercial videos are available that illustrate animated sequences of transcription and translation.
4. b. Students know how to apply the genetic coding rules to predict the sequence of amino acids from a sequence of codons in RNA.
The sequence of amino acids in protein is provided by the genetic information found in DNA. In prokaryotes, mRNA transcripts of a coding sequence are copied from the DNA as a single contiguous sequence. In eukaryotes, the initial RNA transcript, while in the nucleus, is composed of exons, sequences of nucleotides that carry useful information for protein synthesis, and introns, sequences that do not. Before leaving the nucleus, the initial transcript is processed to remove introns and splice exons together. The processed transcript, then properly called mRNA and carrying the appropriate codon sequence for a protein, is transported from the nucleus to the ribosome for translation.
Each mRNA has sequences, called codons, that are decoded three nucleotides at a time. Each codon specifies the addition of a single amino acid to a growing polypeptide chain. A start codon signals the beginning of the sequence of codons to be translated, and a stop codon ends the sequence to be translated into protein. Students can write out mRNA sequences with start and stop codons from a given DNA sequence and use a table of the genetic code to predict the primary sequences of proteins.
4. c. Students know how mutations in the DNA sequence of a gene may or may not affect the expression of the gene or the sequence of amino acids in the encoded protein.
Mutations are permanent changes in the sequence of nitrogen-containing bases in DNA (see Standard 5.a in this section for details on DNA structure and nitrogen bases). Mutations occur when base pairs are incorrectly matched (e.g., A bonded to C rather than A bonded to T) and can, but usually do not, improve the product coded by the gene. Inserting or deleting base pairs in an existing gene can cause a mutation by changing the codon reading frame used by a ribosome. Mutations that occur in somatic, or nongerm, cells are often not detected because they cannot be passed on to offspring. They may, however, give rise to cancer or other undesirable cellular changes. Mutations in the germline can produce functionally different proteins that cause such genetic diseases as Tay-Sachs, sickle cell anemia, and Duchenne muscular dystrophy.

2. Two types of nucleic acids
# of strands
kind of sugar
TRANSCRIPTION DIFFERS FROM REPLICATION IN THAT ONLY 1 STRAND OF THE DNA MOLEUCLE IS TRANSCRIBED AND THAT MEANS THAT THE RESULTING RNA MOLECULE IS SS
ALSO MRNA IS SHORT COMPARED TO A LARGE CHROMOSOME
bases used

3. The Importance of Protein Synthesis
Specific Roles:
Enzyme action
Transport
Motion
Protection
Support
Communication
Regulation
Examples:
Protein antibodies for immune system
Hair, nails, skin
Hemoglobin in blood
Insulin to regulate blood sugar levels

4. Central Dogma DNA is the genetic material within the nucleus.
Cytoplasm
Nucleus
DNA
DNA is the genetic material
within the nucleus.
Replication
The process of replication
creates new copies of DNA.
Transcription
The process of transcription
creates an mRNA using
DNA information.
RNA
The sequence of amino acids in protein is provided by the genetic information found in DNA. In prokaryotes, mRNA transcripts of a coding sequence are copied from the DNA as a single contiguous sequence. In eukaryotes, the initial RNA transcript, while in the nucleus, is composed of exons, sequences of nucleotides that carry useful information for protein synthesis, and introns, sequences that do not. Before leaving the nucleus, the initial transcript is processed to remove introns and splice exons together. The processed transcript, then properly called mRNA and carrying the appropriate codon sequence for a protein, is transported from the nucleus to the ribosome for translation. Each mRNA has sequences, called codons, that are decoded three nucleotides at a time.
Each codon specifies the addition of a single amino acid to a growing polypeptide chain. A start codon signals the beginning of the sequence of codons to be translated, and a stop codon ends the sequence to be translated into protein. Students can write out mRNA sequences with start and stop codons from a given DNA sequence and use a table of the genetic code to predict the primary sequences of proteins.
Translation
The process of translation
creates a protein using
mRNA information.
Protein

5. Protein Synthesis
Transcription
Translation

6. Transcription
The new RNA molecule is formed by incorporating nucleotides that are complementary to the template strand.
DNA
DNA coding strand 5’ G T C A T T C G G 3’ G
RNA 5’ U C A 3’ 3’
CALLED TRANSCRIPTION BECAUSE THE NUCLEIC ACID LANGUAGE OF DNA HAS TO BE REWRITTEN AS A SEQUENCE OF BASES ON RNA
ACTIVATED GENES DO NOT LEAVE THE NUCLEUS BECAUSE THE CYTOPLASM IS TOO HOSTIL
INSTEAD A MESSAGE IS CARRIED ON A STRAND OF MRNA
THE PROCESS OF MRNA FORMATION IS CALLED TRANSCRIPTION BECAUSE IN THE NUCLEUS THE MRNA IS TRANSCRIBED FROM THE DNA TEMPLATE C A G T A A G C C 5’
DNA template strand

7. Where to Begin

8. Production of mRNA copy of the DNA gene
Transcription
Production of mRNA copy of the DNA gene

9. Translation
The process of reading the RNA sequence of an mRNA and creating the amino acid sequence of a protein is called translation.
DNA T C A G
template
strand
Transcription
mRNA A G U C
Messenger
RNA
Codon
Translation
THE GENETIC INSTRUCTIONS FOR THE AA SEQUENCE OF A POLYPEPTIDE CHAIN ARE WRITTEN IN DNA
AND TRANSCRIBED TO RNA AS A SERIES OF 3 BASE WORDS CALLED CODONS
TRIPLETS IN THE DNA ARE TRANSCRIBED INTO COMPLEMENTARY 3 BASE CODONS IN THE MRNA
AND THEN THE MRNA CODONS ARE TRANSLATED INTO AA THAT WILL MAKE UP A POPYPEPTIDE
Protein
Lysine
Serine
Valine
Polypeptide
(amino acid
sequence)

10. INITIATION OF TRANSLATION BRINGS TOGETHER A SMALL RIBOSOMAL SUBUNIT, MRNA AND AN INITIATIOR T RNA AND ALIGNS THEM IN THE PROPER ORIENTATION TO BEGIN TRANSLATION

11. Codon
Translation will always begin with a start codon “AUG” (Start) and end with the “TAG” (end)

13. Translation Termination
Stop codon
Ribosome reaches stop codon
mRNA 5’ U C G A U A C U G
Arg C U
A PROTEIN RELEASE FACTOR BONDS TO THE STOP CODON
AND RELEASES THE COMPLETED PROTEIN FROM THE TRNA
Release
factor P
Met
Gly
Cys
Lys A

14. Translation Termination
Once stop codon is reached,
elements disassemble. U C G A C U G
Release
factor P
THE COMPLETED PP IS FREEDED FROM THE RIBOSOME
THE RIBOSOMAL SUBUNITS DETACH AND THE MRNA MAY MOVE ON TO START THE PROCESS ALL OVER AGAIN
THE ENTIRE PROCESS OF TRANSLATION TAKES ABOUT 20 SECONDS
Met
Gly
Cys
Lys
Arg A

15. EACH POLYRIBOSOME CONSISTS OF ONE STRAND OF MRNA THAT IS BEING READ SIMULTANEOUSLY BY A NUMBER OF RIBOSOMES
POLYRIBOSOMES GREATLY INCREASE THE RATE OF PROTEIN SYNTHESIS
BECAUSE A SINGLE STRAND OF MRNA CAN PRODUCE MANY PROTEIN MOLEUCLES IN A SHORT TIME
THIS IS HOW THE GENOTYPE PRODUCES THE PHENOTYPE
CHAPERONE PROTEIN HELP FOLD THE PP INTO ITS 3 D FORM
GO OVER PICTURE

16. Who am I? Messenger RNA a.k.a. mRNA
Copied from DNA, conveys information from chromosomes to ribosomes. Every three nucleotides is a codon.

17. Transports amino acids to ribosomes.
Who am I?
Transfer RNA
a.k.a. tRNA
Transports amino acids to ribosomes.

18. Subunits where the protein is assembled
Who am I?
Ribosomal RNA
a.k.a. rRNA
Subunits where the protein is assembled

19. Synthesis of proteins by ribosomes
Translation
Synthesis of proteins by ribosomes

21. Genes
Genes: a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism.
In eukaryotes, many general are interrupted by introns and exons.
Introns – long segments of nucleotides that have no coding information.
Exons – are the portions of a gene that are translated (expressed) into proteins.

22. Protein Synthesis General Pathway

23. Prokaryotes vs Eukaryotes Protein Synthesis
In prokaryotes, mRNA transcripts of a coding sequence are copied from the DNA as a single contiguous sequence.
Eukaryotes
The initial RNA transcript, while in the nucleus, is composed of exons, and introns.
Before leaving the nucleus, introns are removed and splice exons together.
The processed transcript, then properly called mRNA and carrying the appropriate codon sequence for a protein, is transported from the nucleus to the ribosome for translation.

25. Tay-Sachs
A baby with Tay-Sachs disease appears healthy at birth. Symptoms usually first appear 3 to 6 months after birth, beginning with mild motor weakness and occasional twitches of the eye (myoclonic jerks). By 6 to 10 months of age, the baby's motor skills may be lost. After this, the diseases progresses rapidly to seizures, blindness, paralysis, and death at age 4 to 5.

26. Mutations
Mutations are permanent changes in the sequence of nitrogen-containing bases in DNA.
Mutations occur when base pairs are incorrectly matched (e.g., A bonded to C rather than A bonded to T) and can, but usually do not, improve the product coded by the gene.
Inserting or deleting base pairs in an existing gene can cause a mutation by changing the codon reading frame used by a ribosome.

27. Mutations that occur in somatic, or nongerm, cells are often not detected because they cannot be passed on to offspring. They may, however, give rise to cancer or other undesirable cellular changes.
Mutations in the germline can produce functionally different proteins that cause such genetic diseases as Tay-Sachs, sickle cell anemia, and Duchenne muscular dystrophy.
Tay-Sachs picture
Sickle Cell Anemia
Duchenne muscular dystrophy

28. Duchenne muscular dystrophy
In individuals with the disorder, initial findings may include an unusual, waddling manner of walking (gait); difficulty climbing stairs or rising from a sitting position; and repeated falling.

29. Duchenne muscular dystrophy
If it gets worse more problems can occur like
Progressive curvature of the spine
Wasting of thigh muscles and abnormal enlargement of the calves
Abnormal fixation of certain joints (joint contractures) due to muscle weakness
Prolonged immobility
Shortening of muscle fibers
By approximately age 10 to 12, most affected individuals require the use of a wheelchair.

30. Warm-Up
The DNA in each of your cells are exactly alike. How come so many of your cells look completely different?
Now talk to the person sitting next to you and see what they came up with.
What does trans mean?
What does scribe mean?
What would transcribe mean?
Look for example of genetic mutations
Adaptations

31. Structure of DNA
DNA Base Pairing Rules
A T
C G