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?

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

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

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

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

Differences between RNA and DNA

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

Chapter 12 Molecular Genetics 12.3 DNA, RNA, and Protein

Protein Synthesis is 2 Steps

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)

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.

Watch It http://www.dnalc.org/resources/3d/13-transcription-advanced.html

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)

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)

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.

Kahoot Partner Challenge https://play.kahoot.it/#/?quizId=7037e59c-cff9-418b-a260-dc89334a5bc0

STEP 2 Translation

Watch It http://www.dnalc.org/resources/3d/16-translation-advanced.html

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.

QUIZIZZ Challenge http://quizizz.com/admin/quiz/start_new/566ed58d9c4cc5b65b004186

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

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

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.

Why mutations matter

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

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

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

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

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

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

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

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

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

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

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

Glencoe Biology Transparencies Chapter 12 Molecular Genetics Glencoe Biology Transparencies

Chapter 12 Molecular Genetics Image Bank

Chapter 12 Molecular Genetics Image Bank