1. Next, we have to learn how proteins are made….but why?
So far, you’ve learned about the cell, how it divides, DNA and how it is copied, and how we make sex cells…
Next, we have to learn how proteins are made….but why?

2. We are heading toward GENETICS and to understand why genes matter, you must know how they relate to anything.

3. Change ONE nucleotide, and in this case, you change how much protein is made = blue eyes instead of brown

6. SOME IMPORTANT QUESTIONS FIRST!
Which organelle makes proteins and where are those in the cell?
Where is the code that guides the production of proteins?
Seems like we have a problem

7. Chapter 12
12.3 PROTEIN SYNTHESIS
Central Dogma = DNA is converted to RNA which is then used to make protein.
DNA RNA Protein
RNA
Ribose Nucleic Acid (or ribonucleic acid)
Differences
Usually is single stranded
Contains Ribose instead of Deoxyribose
Contains Uracil instead of Thymine

8. Differences between RNA and DNA

9. Associates with proteins to form ribosomes in the cytoplasm
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
Messenger RNA (mRNA)
Long, single strands of RNA nucleotides that are formed complementary to one strand of DNA
Ribosomal RNA (rRNA)
Associates with proteins to form ribosomes in the cytoplasm
Transfer RNA (tRNA)
Smaller segments of RNA nucleotides that transport amino acids to the ribosome

10. Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein

11. Protein Synthesis is 2 Steps

12. 2 Steps to make a protein:
1. Transcription: make a copy of the DNA script and serve as a messenger that delivers the code to the ribosome in the cytoplasm. (this overcomes the problem of DNA in nucleus and ribosome in cytoplasm)
2. Translation: to translate means to make some code into a useful form. This translation turns codons into a chain of amino acids…a protein.
Transcription must come before translation (in alpha too)

13. DNA is unzipped in the nucleus by RNA
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
Transcription
Through transcription, the DNA code is transferred to mRNA in the nucleus.
DNA is unzipped in the nucleus by RNA
polymerase which binds to a specific section where an mRNA will be synthesized.

14. Watch It

15. Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
RNA Processing
The code on the DNA is interrupted periodically by sequences that are not in the final mRNA.
Intervening sequences which are removed are called introns. (stay IN the nucleus)
Remaining pieces of DNA that serve as the coding sequences are called exons. (Exit the nucleus)

17. Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
The Code
Experiments during the 1960s demonstrated that the DNA code was a three-base code.
The three-base code in DNA or mRNA is called a codon. (yes, they are called the same thing whether on DNA or on mRNA…not sure you needed to write this down…are you still writing….gosh, this is embarassing)

20. Each anticodon is complementary to a codon on the mRNA.
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
Translation
In translation, tRNA molecules act as the interpreters of the mRNA codon sequence.
At the middle of the folded strand, there is a three-base coding sequence called the anticodon.
Each anticodon is complementary to a codon on the mRNA.

22. Kahoot Partner Challenge

23. STEP 2
Translation

25. Watch It

26. Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
One Gene—One Enzyme
The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene codes for one polypeptide.

27. QUIZIZZ Challenge

28. A permanent change that occurs in a cell’s DNA is called a mutation.
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
Mutations
A permanent change that occurs in a cell’s DNA is called a mutation.
Types of mutations
Point mutation
Insertion
Deletion

29. 12.4 Gene Regulation and Mutation
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation

30. Can occur spontaneously
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
Causes of Mutation
Can occur spontaneously
Chemicals and radiation also can damage DNA.
High-energy forms of radiation, such as X rays and gamma rays, are highly mutagenic.

31. Why mutations matter

32. 3 Possible Outcomes of Mutation
“Negative” – loss of protein function (blue eyes)
“Positive” – gain of protein function (lactose tolerance)
No Change – coded for same amino acid so protein didn’t change

33. What is the base-pairing rule for purines
Chapter 12
Molecular Genetics
12.1 Formative Questions
What is the base-pairing rule for purines
and pyrimidines in the DNA molecule?
A—G and C—T
A—T and C—G
C—A and G—T
C—U and A—G A B C D
FQ 2

34. What are chromosomes composed of?
Chapter 12
Molecular Genetics
12.1 Formative Questions
What are chromosomes composed of?
chromatin and histones
DNA and protein
DNA and lipids
protein and centromeres A B C D
FQ 3

35. Which shows the basic chain of events
Chapter 12
Molecular Genetics
12.3 Formative Questions
Which shows the basic chain of events
in all organisms for reading and expressing
genes?
DNA  RNA  protein
RNA  DNA  protein
mRNA  rRNA  tRNA
RNA processing  transcription  translation A B C D
FQ 6

36. In the RNA molecule, uracil replaces _______.
Chapter 12
Molecular Genetics
12.3 Formative Questions
In the RNA molecule, uracil replaces
_______.
adenine
cytosine
purine
thymine A B C D
FQ 7

37. Which diagram shows messenger RNA (mRNA)?
Chapter 12
Molecular Genetics
12.3 Formative Questions
Which diagram shows messenger
RNA (mRNA)? A. C. B. D. A B C D
FQ 8

38. chromatin fibers chromosomes histones nucleosome
Chapter 12
Molecular Genetics
Chapter Assessment Questions
Look at the following figure. Identify the proteins that DNA first coils around.
chromatin fibers
chromosomes
histones
nucleosome A B C D
CAQ 1

39. Explain the difference between body-cell and sex-cell mutation.
Chapter 12
Molecular Genetics
Chapter Assessment Questions
Explain the difference between body-cell and sex-cell mutation.
Answer: A mutagen in a body cell becomes
part of the of the genetic sequence
in that cell and in future daughter
cells. The cell may die or simply not
perform its normal function. These
mutations are not passed on to the
next generation. When mutations
occur in sex cells, they will be
present in every cell of the offspring.
CAQ 3

40. Standardized Test Practice
Chapter 12
Molecular Genetics
Standardized Test Practice
What does this diagram show about the replication of DNA in eukaryotic cells?
DNA is replicated only at certain places along the chromosome.
DNA replication is both semicontinuous and conservative.
Multiple areas of replication occur along the chromosome at the same time.
The leading DNA strand is synthesized discontinuously. A B C D
STP 1

41. What is this process called?
Chapter 12
Molecular Genetics
Standardized Test Practice
What is this process called?
mRNA processing
protein synthesis
transcription
translation A B C D
STP 2

42. TTCAGG TTCTGG What type of mutation results in this change
Chapter 12
Molecular Genetics
Standardized Test Practice
What type of mutation results in this change
in the DNA sequence?
TTCAGG TTCTGG
deletion
frameshift
insertion
substitution A B C D
STP 3

43. Glencoe Biology Transparencies
Chapter 12
Molecular Genetics
Glencoe Biology Transparencies

44. Chapter 12
Molecular Genetics
Image Bank

45. Chapter 12
Molecular Genetics
Image Bank