bellringer 9/10/19- theories vs. laws - weebly · 2019. 10. 4. · bellringer 9/10/19- theories vs....

Bellringer 9/10/19- Theories vs. Laws

1.  What is the difference between the casual use of theory and the scientific use of theory?

2.  What is one example of the theory? 3.  How is a law different from a theory? 4.  What is one example of a law? ⚫  https://www.youtube.com/watch?v=P30QlwSsUic

Bellringer 9/12/19 Characteristics of life Review

⚫  1. What are the 4 characteristics of life represent by the images?

⚫ Why is “eating food” NOT a characteristics of life?

Bellringer 9/13/19The Double Helix Discovery

1.  List names of scientists involved in DNA discovery and they did.

2.  What did Watson and Crick use to help them figure out the structure of DNA?

3.  What part of the DNA holds the information for traits? Is the code complicated?

https://www.youtube.com/watch?v=1vm3od_UmFg

Bellringer 9/16/19 – DNA Structure

⚫  Describe the structure of DNA. Use the coloring sheet. ⚪  Include as much information as

you can (ie the backbone, the nucleotides, pairing rules, etc.)

Bellringer 9/17/19 DNA Building Blocks

1.  What are the building blocks of DNA called?

2.  What are the 3 parts to those building blocks?

3.  How many of those building blocks does human DNA have?

Bellringer 9/25 – Replication Helpers

⚫  What are the three enzymes involved in DNA replication? What does each enzyme do? ⚪  Hint: Enzymes often end in –ase ⚪  Which enzyme is this Tshirt

promoting?

Bellringer 9/26 - Using the mRNA Decoder

Remember this? 1.  What amino acid

does AAG code for? 2.  What does CCG code

for? 3.  What is special

about the codon UGA?

Bellringer 10/1/19 – DNA vs. RNA

⚫ Name FOUR differences between DNA and RNA

Bellringer 10/3/19- Genetic Decoding

1.  What would the mRNA look like for amino acid Lysine?

2.  What would the tRNA look like that complements mRNA?

3.  What would the segment of DNA that codes for lysine look like?

Bellringer – 10/4/19 Translation

⚫ How many codons would be created using the following gene? ⚪  3’ TACGGGCTAACTATT

5’ ⚫ How many tRNAs

would you need to assemble a protein using the gene above.

A 5E EXPLORATION OF HOW EVERYTHING LIVING IS PUT TOGETHER.

Unit 1: Molecules to Organisms

Protein Synthesis Phenomenon

⚫ Fill in the following questions on Page 14. ⚫ What do you already know about proteins?

⚫ What do you already know about DNA?

⚫ What do you already know about the internal workings (i.e. processes) of cells?


⚫ Cells have a few structures that we will need to identify in the classroom.

⚫ Indicate how the cell structure is represented in the classroom. ⚪  Draw or describe the key features.


⚫ Set Design: ⚪  Cell Membrane (outer covering) – ⚪  Nucleus (membrane bound) - ⚪  Cytoplasm -


⚫ The Players: ⚪  Ribosome (Factory) - ⚪  Transfer RNA Anticodons (Delivery person)

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ  ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ  ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ 

⚪  Amino acids (supplies) - ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ  ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ  ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ 

⚪  Messenger RNA (copy of order) - ⚪  DNA (original order) -


⚫ How would you describe the chart you see on the board?


⚫ Can you figure out how to read this decoder if ⚪  GGU codes for Glycine ⚪  AAA codes for Lysine

Introduction

⚫ Introduction: ⚪  The Ribosome (with masking tape in hand) stands near the

board. Predict what the tape could be for.

⚪  9 different tRNA molecules move through the cytoplasm of the cell. Describe what the tRNA’s look like. How would you describe their movement? What color are they represented by?

⚪  The register tape stands in the center of the room, opposite the ribosome. The register tape represents DNA in the nucleus.

ACT 1

⚫ ACT 1: ⚪  DNA cannot leave the “nucleus” but contains vital information

that the ribosome needs to make proteins. ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ What could be done to get information out of the nucleus?

⚪  mRNA enters the stage. mRNA only knows 4 letters….A, C, G, and U. Use the following rules to figure out a way to get the code out of the nucleus.

DNA Bases mRNA Bases tRNA Bases

A U A T A U C G C G C G

,

ACT 1

⚫ Describe how the code was sent out of the nucleus.

⚫ What difficulties were encountered?

⚪  Did the final code read as follows? AUG UGU CGG AAA AAG GUC GAA CCC UAA

⚪  If not what did we do differently?

ACT 2

⚫ ACT 2: ⚪  mRNA brings the code to the ribosome.

⚪  Ribosome: Reads the code mRNA brings to it, 3 letters at a time.

3 mRNA bases: ____ ____ ____

⚪  All other Cast: Check the decoding chart to identify which amino acid should travel to the ribosome.

Amino Acid: __________

ACT 2

⚫ tRNA #1 (houses the complementary code to the mRNA code): Gets up and travels to pick up the correct amino acid.

tRNA anticodon: ___ ___ ___

⚫ Amino Acid #1: The amino acid that matches the tRNA anticodon links arms and travels to the ribosome.

Amino Acid ___________

mRNA base

tRNA base

A U

U A

C G

G C

ACT 2

⚫ All other Cast: Check the decoding chart to verify the correct tRNA and amino acid are linked up and traveling to the correct location.

ACT 2

⚫ Ribsome: Takes the amino acid from the tRNA and links it to the next amino acid. Use masking tape to attach the wrists of the amino acids together.

⚫ tRNA’s and Amino Acids: Continue the process till all 9 pairs have been made and traveled to the ribosome.

⚫ Stop card: Once you arrive at the board the process has concluded.

⚪  What was being TRANSLATED in Act 2?

ACT 3

⚫ ACT 3: ⚪  All Cast: Copy down the original DNA sequence that was

present in the nucleus of the cell.

⚪  DNA Sequence:

___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___

Act 3: Conflict #1

⚫  Conflict #1 ⚪  What would happen if the 15th base C were mistakenly

REPLACES during DNA replication by a G?

⚪  What would happen to the amino acid sequence?

Act 3: Conflict #2

⚫ Conflict #2 ⚪  What would happen if an A were ADDED to the beginning of

the DNA sequence.

⚪  What happens to the amino acid sequence now?

⚪  Which Conflict had the greater impact? Why?

DNA and the Language of Life

Why do we study DNA?

⚫ We study DNA for many reasons ⚪  its central importance to all

life on Earth ⚪  medical benefits such as

cures for diseases ⚪  better food crops

Where is DNA located?

⚫ DNA ⚪  contains all of an organisms

genes ⚪  is in every cell in your body ⚪  is located in the cell nucleus ⚪  condenses into

chromosomes.

DNA – DeoxyriboNucleicAcid ⚫ DNA is often called the blueprint of life. ⚫ In simple terms, DNA contains the instructions for making proteins

within the cell.

⚫ molecule that stores heritable genetic information of an organism

⚫ DNA is a kind of nucleic acid, a polymer built from monomers called nucleotides.

Nucleotide

⚫ Monomer for nucleic acids like DNA and RNA ⚫ Nucleotide structure ⚪  Each nucleotide has 3 parts:

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ A ring-shaped sugar called deoxyribose ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ A phosphate group ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ A nitrogenous base

Nitrogenous Bases

⚫ The four nucleotides found in DNA differ only in their nitrogenous bases, called bases for short

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ Pyrimidines �� single-ring structures

•  Thymine (T) •  Cytosine (C)

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ Purines �� larger, double-ring structures

•  Adenine (A) •  Guanine (G)

DNA Strands

⚫ DNA is DOUBLE STRANDED ⚫ Sugar-phosphate

"backbone" ⚪  Nucleotides are joined to one

another by covalent bonds that connect the sugar of one nucleotide to the phosphate group of the next.

⚪  The nitrogenous bases are lined up along this backbone

Nucleotide Sequences

⚫ Nucleotides of a nucleic acid polymer can combine in many different sequences. ⚪  DNA ! RNA ! Proteins ⚪  Nucleotides ! DNA ! genetic code

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ 9 nucleotide sequence variety…just a few �� CTGCTATCG TTATCTAGC ACCTCAGTT �� How many different configurations of 9 nucleotides is there?

Make up two now! �� ___ ___ ___ ___ ___ ___ ___ ___ ___

⚪  Nucleotide chains also vary in length ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ from only a few hundred nucleotides to billions of nucleotides ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ the number of possible nucleotide sequences is essentially

unlimited!

HHMI: The Double Helix

DNA's Structure- the race to find it!

⚫ 1950s, scientists Rosalind Franklin and Maurice Wilkins ⚪  X-ray crystallography

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ produced some intriguing photographs of DNA ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ technique provides clues to the shapes and dimensions of complex molecules ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ The photographs showed the basic shape of DNA to be a helix, and revealed

the basic dimensions of the helix.

DNA's Structure- the race to find it!

⚫ In the meantime… ⚪  James Watson and Francis

Crick ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ Saw Franklin’s work and were

able to come up with a new model in which two strands of nucleotides wound about each other. �� This formed a twisting shape

called a double helix

The Double Helix

⚫ Watson and Crick’s model placed the ⚪  sugar-phosphate backbones on

the outside of the double helix ⚪  nitrogenous bases on the inside ⚪  nitrogenous bases joining in

the middle joining by hydrogen bonds ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ This new model successfully

represented DNA's structure.

Complementary Base Pairs

⚫ Erwin Chargaff performed an experiment that showed that adenine and thymine show up in DNA in an equal amount as did cytosine and guanine. ⚪  Watson and Crick realized that the

individual structures of the nitrogenous bases determine very specific pairings between the nucleotides of the two strands of the double helix. ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ These pairings are due to the sizes of the

bases and their abilities to form hydrogen bonds with each other.

Chargaff’s Rule

⚫ The purine adenine pairs with the pyrimidine thymine ⚪  A pairs with T ⚪  A is said to be "complementary" to T ⚫ The purine guanine pairs with

the pyrimidine cytosine. ⚪  G pairs with C. ⚪  G is complementary to C

Complementary Base Pairing

⚫ The sequence of nucleotides along the length of one of the two DNA strands can vary in countless ways

⚫ The bases on the second strand of the double helix are determined by the sequence of the bases on the first strand. ⚪  Each base must pair up with its complementary base. ⚪  Base-pairing rules set the stage for understanding how the

information in DNA is passed through generations

Complementary Base Pairing

⚫ 3’-CTCAGAATCGT-5’

⚫ Remember:

⚫ A𐀌𐀧𐀻𐀾𐁎𐁏𐁞𐁟𐁠𐁡𐁢𐁣𐁤𐁥𐁦𐁧𐁨𐁩𐁪𐁫𐁬𐁭𐁮𐁯𐁰𐁱𐁲𐁳𐁴𐁵𐁶𐁷𐁸𐁹𐁺𐁻𐁼𐁽𐁾𐁿𐃻𐃼𐃽𐃾𐃿𐄃𐄄𐄅𐄆𐄴𐄵𐄶𐆋𐆌𐆍𐆎𐆏𐆜𐆝𐆞𐆟𐆠𐆡𐆢𐆣𐆤𐆥𐆦𐆧𐆨𐆩𐆪𐆫𐆬𐆭𐆮𐆯𐆰𐆱𐆲𐆳𐆴𐆵𐆶𐆷𐆸𐆹𐆺𐆻𐆼𐆽𐆾𐆿𐇀𐇁𐇂𐇃𐇄𐇅𐇆𐇇𐇈𐇉𐇊𐇋𐇌𐇍𐇎𐇏𐇾𐇿𐈀𐈁𐈂𐈃𐈄𐈅𐈆𐈇𐈈𐈉𐈊𐈋𐈌𐈍𐈎𐈏𐈐𐀌𐀧𐀻𐀾𐁎𐁏𐁞𐁟𐁠𐁡𐁢𐁣𐁤𐁥𐁦𐁧𐁨𐁩𐁪𐁫𐁬𐁭𐁮𐁯𐁰𐁱𐁲𐁳𐁴𐁵𐁶𐁷𐁸𐁹𐁺𐁻𐁼𐁽𐁾𐁿𐃻𐃼𐃽𐃾𐃿𐄃𐄄𐄅𐄆𐄴𐄵𐄶𐆋𐆌𐆍𐆎𐆏𐆜𐆝𐆞𐆟𐆠𐆡𐆢𐆣𐆤𐆥𐆦𐆧𐆨𐆩𐆪𐆫𐆬𐆭𐆮𐆯𐆰𐆱𐆲𐆳𐆴𐆵𐆶𐆷𐆸𐆹𐆺𐆻𐆼𐆽𐆾𐆿𐇀𐇁𐇂𐇃𐇄𐇅𐇆𐇇𐇈𐇉𐇊𐇋𐇌𐇍𐇎𐇏𐇾𐇿𐈀𐈁𐈂𐈃𐈄𐈅𐈆𐈇𐈈𐈉𐈊𐈋𐈌𐈍𐈎𐈏𐈐T

⚫ C𐀌𐀧𐀻𐀾𐁎𐁏𐁞𐁟𐁠𐁡𐁢𐁣𐁤𐁥𐁦𐁧𐁨𐁩𐁪𐁫𐁬𐁭𐁮𐁯𐁰𐁱𐁲𐁳𐁴𐁵𐁶𐁷𐁸𐁹𐁺𐁻𐁼𐁽𐁾𐁿𐃻𐃼𐃽𐃾𐃿𐄃𐄄𐄅𐄆𐄴𐄵𐄶𐆋𐆌𐆍𐆎𐆏𐆜𐆝𐆞𐆟𐆠𐆡𐆢𐆣𐆤𐆥𐆦𐆧𐆨𐆩𐆪𐆫𐆬𐆭𐆮𐆯𐆰𐆱𐆲𐆳𐆴𐆵𐆶𐆷𐆸𐆹𐆺𐆻𐆼𐆽𐆾𐆿𐇀𐇁𐇂𐇃𐇄𐇅𐇆𐇇𐇈𐇉𐇊𐇋𐇌𐇍𐇎𐇏𐇾𐇿𐈀𐈁𐈂𐈃𐈄𐈅𐈆𐈇𐈈𐈉𐈊𐈋𐈌𐈍𐈎𐈏𐈐𐀌𐀧𐀻𐀾𐁎𐁏𐁞𐁟𐁠𐁡𐁢𐁣𐁤𐁥𐁦𐁧𐁨𐁩𐁪𐁫𐁬𐁭𐁮𐁯𐁰𐁱𐁲𐁳𐁴𐁵𐁶𐁷𐁸𐁹𐁺𐁻𐁼𐁽𐁾𐁿𐃻𐃼𐃽𐃾𐃿𐄃𐄄𐄅𐄆𐄴𐄵𐄶𐆋𐆌𐆍𐆎𐆏𐆜𐆝𐆞𐆟𐆠𐆡𐆢𐆣𐆤𐆥𐆦𐆧𐆨𐆩𐆪𐆫𐆬𐆭𐆮𐆯𐆰𐆱𐆲𐆳𐆴𐆵𐆶𐆷𐆸𐆹𐆺𐆻𐆼𐆽𐆾𐆿𐇀𐇁𐇂𐇃𐇄𐇅𐇆𐇇𐇈𐇉𐇊𐇋𐇌𐇍𐇎𐇏𐇾𐇿𐈀𐈁𐈂𐈃𐈄𐈅𐈆𐈇𐈈𐈉𐈊𐈋𐈌𐈍𐈎𐈏𐈐G

⚫ 5’-GAGTCTTAGCA-3’

The Shape of the DNA Molecule

⚫ DNA is a very long polymer. ⚫ The basic shape is like a

twisted ladder or zipper. ⚪  This is called a double helix. ⚫ DNA is double stranded

DNA Structure

⚫ Backbone ⚪  alternating

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ phosphate ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ deoxyribose, a sugar

⚫ Rungs ⚪  nitrogenous bases

phosphate

deoxyribose

bases

One Strand of DNA

⚫ Nucleotide: DNA building block ⚫ 3 parts: ⚪  Deoxyribose sugar ⚪  Phosphate group ⚪  Nitrogenous base ⚫ One strand of DNA is a

polymer of nucleotides ⚫ One strand of DNA has many

millions of nucleotides.

nucleotide

Four nitrogenous bases

⚫  Cytosine C ⚫  Thymine T ⚫  Adenine A ⚫  Guanine G

DNA has four different bases:

Two Stranded DNA

⚫ Remember, DNA has two strands that fit together something like a zipper. ⚫ The teeth are the

nitrogenous bases but why do they stick together?

Hydrogen Bonds

⚫ When making hydrogen bonds, cytosine always pairs up with guanine, ⚫ And adenine always

pairs up with thymine. ⚫ (Adenine and

thymine are shown here.)

C

C

C

C

N

N

O

O

C

Important:

⚫  Adenine and Thymine always join together ⚫  Cytosine and Guanine always

join together

⚫ Remember:

⚫ A-T

⚫ C-G

DNA Replication – Happens during the S phase of Interphase

DNA Replication Animation

⚫ DNA Replication Animation

⚫ Describe what you see happening in each step. ⚪  Step1: ⚪  Step2: ⚪  Step 3: ⚪  Step 4: ⚪  Step 5:

DNA Replication

⚫ When a cell divides, forming new cells, a complete set of genetic instructions is generated for each new cell.

⚫ And when an organism reproduces, genetic instructions pass from one generation to the next

⚫ For this to occur, there must be a means of copying the instructions.

From Film Negative to Photo

⚫ Have you ever had additional copies of a favorite photo OLD made from a photo negative?

⚫ Even if you've lost your negative, a new negative can be made from your print, from which more prints can be made.

⚫ This same principle enables a cell to make a copy of its genetic material.

DNA Replication

⚫ Basic Concept = ⚪  Create a new strand by matching

nucleotides to an existing strand

⚫ Remember:

⚫ A --T

⚫ C--G

DNA Replication

⚫ Replication is semi-conservative ⚪  one strand is old, one strand new

DNA Replication

⚫ DNA must be copied ⚫ DNA strand is split in half ⚫ Enzymes begin pairing up

nucleotides with their compliments on the parent strand ⚫ Enzymes make these covalent

bonds according to base pairing rules ⚫ The 2 new strands are called

daughter strands

DNA Replication Role Play

1.  1. Build the original strand of DNA using base paring rules

2.  2.Use Helicase to unwind 3.  Use DNA Polymerase 3 to join new

bases 4.  DNA Polymerase 1 checks and

corrects 5.  Look at the two new strands "  How are they similar? "  What part of each strand is

“parent” DNA? Which is “daughter” DNA?

⚫ One Side of Original DNA

⚫ C ⚫ G ⚫  T ⚫ A ⚫ A

DNA Polymerase

⚫ Enzymes speed up reactions! ⚪  12 enzymes work in DNA

replication ⚫ Enzymes called

DNA polymerases make the covalent bonds between the nucleotides of the new DNA strand.

⚫ The process is fast and amazingly accurate—an error occurs in only about one in a hundred million nucleotides.

Replication Bubbles – Origins of Replication

⚫ Copying proceeds outward in both directions, creating replication "bubbles

⚫ Parent DNA strands open up as daughter strands grow on both sides of each bubble

⚫ Many replication bubbles can start at the same time. ⚪  shortens the total time to copy

all the DNA ⚫ All the bubbles merge ⚪  two double-stranded DNA

molecules ⚪  each with one new and one old

strand

Replication: 1st step

⚫ Unwind DNA ⚪  helicase enzyme

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ unwinds part of DNA helix ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ stabilized by single-stranded binding proteins

single-stranded binding proteins replication fork

helicase

DNA

Polymerase III

Replication: 2nd step

But… We’re missing something!

What?

Where’s the ENERGY for the bonding!

▪  Build daughter DNA strand

◆  add new complementary bases

◆  DNA polymerase III

DNA polymerases

⚫ DNA polymerase III ⚪  1000 bases/second! ⚪  main DNA builder ⚫ DNA polymerase I ⚪  20 bases/second ⚪  editing, repair & primer removal

DNA polymerase III enzyme

Arthur Kornberg 1959

Roger Kornberg 2006

Editing & proofreading DNA

⚫ 1000 bases/second = lots of typos! ⚫ DNA polymerase I ⚪  proofreads & corrects typos ⚪  repairs mismatched bases ⚪  removes abnormal bases

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ repairs damage throughout life

⚪  reduces error rate from 1 in 10,000 to 1 in 100 million bases

⚪  Replication Review Movie

Fast & accurate!

⚫ It takes E. coli <1 hour to copy 5 million base pairs in its single chromosome ⚪  divide to form 2 identical daughter

cells ⚫ Human cell copies its 6 billion

bases & divide into daughter cells in only few hours ⚪  remarkably accurate ⚪  only ~1 error per 100 million bases ⚪  ~30 errors per cell cycle

DNA Replication Diagram Your Job: Color!

Protein Synthesis

⚫ A gene provides the information for making a specific protein.

What do genes code for?

proteins cells bodies

■  How does DNA code for cells & bodies?

◆  how are cells and bodies made from the instructions in DNA

DNA

The “Central Dogma”

⚫ Flow of genetic information in a cell ⚪  How do we move information from DNA to proteins?

transcription translation

replication

protein RNA DNA trait

DNA gets all the glory, but proteins do all the work!

Central Dogma of Gene Expression

To get from the chemical language of DNA to the chemical language of proteins requires 2 major stages:

transcription and translation

Information Flow: DNA to RNA to Protein

⚫ DNA = Language ⚫ Bases = the language's letters ⚫ Gene =sentence. ⚪  Specific strings of bases make up each gene "sentence" on one

DNA strand.

RNA – RiboNucleic Acid)

⚫ RNA is any nucleic acid whose sugar is ribose rather than the deoxyribose of DNA.

⚫ Differences between RNA and DNA ⚪  Uracil (U) Replaces thymine

(T) ⚪  Uracil (U) pairs with

adenine(A) ⚪  Single stranded ⚪  Ribose sugar

⚫ The other components of RNA are the same as those for DNA.

mRNA

From Gene to Protein

DNA transcription

nucleus cytoplasm

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

protein translation

ribosome

trait

Transcription: From DNA to RNA

⚫ DNA is HUGE! ⚪  Codes for many genes and thus many proteins ⚪  Only one protein needs to be made

⚫ Make a copy of those instructions (gene) only ⚪  Less to carry

⚫ RNA is a copy of the gene for our instructions to make a protein

⚫ Transcription Movie

Transcription: From DNA to RNA

⚫ This "transcribed" message ⚪  leaves the nucleus (it’s nice and small) ⚪  directs the making of proteins in the cytoplasm ⚪  DNA (huge) remains in the nucleus

mRNA

From Gene to Protein

DNA transcription

nucleus cytoplasm

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

ribosome trait

protein translation

Translation

⚫ RNA (copy of a gene) ! Protein ⚫ The flow of information

from gene to protein is based on codons. ⚪  Codon

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ three-base "word" that codes for one amino acid.

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ several codons form a "sentence" that translates into a polypeptide.

The Triplet Code

⚫ 61 of the 64 triplets code for amino acids ⚫ Only 20 amino acids ⚪  some amino acids are

coded for by more than one codon

⚪  no codon represents more than one amino acid.

Start and Stop Codons

⚪  “Stop” codons - do not code for amino acids ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ come at the end of each

gene sequence. �� UAA �� UGA �� UAG

⚪  “Start” codon - begins amino acid sequence ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ Does code for an amino acid

�� AUG

How does mRNA code for proteins? ⚫ How can you code for 20 amino acids with only 4 nucleotide bases

(A,U,G,C)?

TACGCACATTTACGTACGCGGDNA

AUGCGUGUAAAUGCAUGCGCCmRNA

Met Arg Val Asn Ala Cys Alaprotein

?

4

4

20

ATCG

AUCG


mRNA codes for proteins in triplets

TACGCACATTTACGTACGCGGDNA


Met Arg Val Asn Ala Cys Alaprotein

?

codon

Cracking the code

⚫ Francis Crick - determined 3-letter (triplet) codon system

1960 | 1968 Nirenberg & Khorana

WHYDIDTHEREDBATEATTHEFATRAT WHYDIDTHEREDBATEATTHEFATRAT

The Code

⚫ Code for ALL life! ⚪  strongest support for a

common origin for all life

⚫ Code is redundant ⚪  several codons for each

amino acid

■  Start codon ◆  AUG

◆  methionine ■  Stop codons

◆  UGA, UAA, UAG

Gene to Protein

⚫ There are 2 main steps from Gene to Protien ⚪  Transcription ⚪  Translation

Quick Review

⚫ You have just learned how genetic information flows from DNA to RNA to protein. ⚫ A sequence of DNA base triplets is transcribed into

RNA codons, which are translated into a sequence of amino acids that form a polypeptide

Three types of RNA

⚫ There are three types of ribonucleic acids (RNAs) involved in making proteins from the instructions carried in genes. ⚪  mRNA (messenger RNA) ⚪  tRNA (transfer RNA) ⚪  rRNA (ribosomal RNA)

Transcription – DNA to RNA

⚪  Messenger RNA (mRNA) is transcribed from a DNA template ⚪  Similar to DNA replication ⚪  In transcription ONLY ONE of the DNA strands serves as a

template for the newly forming mRNA ⚪  2 Steps:

৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ 1. DNA unwinds �� The two DNA strands first separate at the place where

transcription will start. ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ 2. Base Pairing

�� Then RNA bases pair with complementary DNA bases

Figure 11-14 During transcription, RNA nucleotides base-pair one by one with DNA nucleotides on one of the DNA strands (called the template strand). RNA polymerase is a transcription enzyme that links the RNA nucleotides together.

Transcription Base-pairing

⚫ The base-pairing during transcription is the same as when DNA replicates ⚪  EXCEPT: RNA has uracil instead of thymine, SO the base U in

RNA pairs with A in DNA.

Translation: RNA to Protein

⚫ Translation: Translating the message on mRNA ⚫ The main players in the mRNA translation process

are ⚪  Ribosomes ⚪  Transfer RNA. ⚪  Messenger RNA

Transfer RNA (tRNA)

⚫ Transfer RNA (tRNA) translates the three-letter codons of mRNA to the amino acids that make up proteins ⚫  There is a different version of tRNA molecule that

matches each codon.

Anticodon

⚫ Anticodon- the specific triplet of bases at the end of a tRNA molecule. ⚫ The three bases of the

anticodon are complementary to a specific codon in the mRNA.

Anticodon

⚫ During translation, the anticodon on tRNA recognizes a particular codon on mRNA by using base-pairing rules.

⚫  At the other end of the tRNA molecule is a site where a particular amino acid can attach.

⚫  An enzyme specific for each amino acid recognizes both a tRNA and its amino acid partner and links the two together, using energy from ATP.

Ribosomal DNA (rRNA)

⚫ Ribosomes bring mRNA and tRNAs together during translation. Each ribosome has an attachment site for an mRNA transcript, and two sites for tRNAs.

Translation: The Process

⚫ The first step in translation brings together all the pieces needed during translation: ⚪  the mRNA ⚪  the first tRNA with its

attached amino acid ⚪  the two subunits of a

ribosome. ⚫ The start codon AUG

dictates where translation will begin

Translation: The Process

⚫ Next, amino acids are added one by one to the growing chain of amino acids. ⚫ Each addition occurs in a

three-step process ⚫ This lengthening process

continues until the ribosome reaches a stop codon—UAA, UAG, or UGA. ⚪  Remember that the three stop

codons do not code for amino acids.

⚫ Translation begins with the attachment of a ribosome and the first tRNA to a "start" (AUG) codon. The ribosome then moves along the mRNA transcript. The polypeptide elongates as an amino acid is added for each codon. When the ribosome arrives at a "stop" codon, the completed polypeptide is released.

Transcription Animation

Transcription and Translation Paper Model

⚫  Step 1: READ THE DIRECTIONS!!!

⚫  Step 2: Follow the directions

⚫ Complete an mRNA strand using the DNA template provided

⚫ Use the genetic code to create the protein sequence

⚫ Research your protein!

Codon Bingo

⚫ DNA base triplet __ __ ___ is transcribed into the mRNA codon __ __ ___ which is translated into the amino acid _________

Protein Synthesis Quick Practice

⚫ 1. Replicate the DNA 3’ strand ATGTAGGGTGGC

⚫ 2. Transcribe the DNA base triplet CAT

⚫ 3. Translate the mRNA codon CAG

⚫ 4. Translate the DNA base triplet GGC

⚫ 5. Translate the mRNA codon ACU

⚫ Bonus:How many codons would be in the gene in #1.

Mutations

⚫ A mutation is any change in the nucleotide sequence of DNA. ⚫ Mutations can involve large regions of a

chromosome or just a single nucleotide pair

2 Categories of Mutations

⚫ Mutations within a gene can be divided into two general categories: ⚪  base substitutions ⚪  base insertions or deletions

Base Subsitution

⚫ A base substitution is the replacement of one base or nucleotide with another

⚫ Can cause ⚪  no change to a protein ⚪  change that affects the function of a protein( sickle cell disease).

⚫ How can some base substitutions show no effect on the protein that is made? ⚪  Remember that in the genetic code, several amino acids have more

than one codon. ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ Ex. both GAA and GAG code for the same amino acid (Glu). ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ If a mutation to DNA causes the mRNA codon to change from GAA to

GAG, no change in the protein product would result. T ৽ৼঀॸׯ߾߿ࡠࡡࡢࡣࡤࡥࡦࡧࡨࡩࡪࢡࢭࢮࢯࢰࢱࢲࢳࢴࢶࢷࢸࢹࢺࢻࢼࢽ֎֍ֈՠԯԮԭԬԫԪԩԨͿ "silent mutation"

Base Subsitution or Deletion

⚫ more nucleotides in a gene is usually more disastrous than the effects of a base substitution. ⚫ Because mRNA is read as a series of triplets, adding

or subtracting nucleotides may alter the triplet groupings of the genetic message. ⚫ Therefore, all the nucleotides that are "downstream"

of the mutation will be regrouped into different codons ⚫ These new codons code for new amino acids. ⚫ The result will be a different, and probably

nonworking, protein.

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