We have. Learned the structure of DNA. Talked about DNA replication and all of the complicated vocabulary that goes with it

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1 Do Now 1. What enzyme inserts new DNA nucleotides during replication? 2. Name 2 other important players in DNA replication and their function. 3. In what direction can DNA polymerase add nucleotides? 4. Why do Okazaki fragments form during DNA replication?

2 We have Learned the structure of DNA Talked about DNA replication and all of the complicated vocabulary that goes with it

3 Now We will learn how DNA repairs itself and then gets turned into mrna through a process called TRANSCRIPTION.

4 Agenda 1. Do-now review 2. Graphic Organizer 3. Central Dogma and DNA v. RNA Notes 4. Exit Ticket 5. Transcription Notes 6. Group Practice 7. Independent Practice 8. Exit Ticket

5 coiled into DNA chromosomes sections are genes have 2 alleles code for proteins express traits

6 DNA made of units made of 2 strands chains of nucleotides 3 parts base can be sugar phosphate make up the A T G C backbone

7 Objective 1. SWBAT state the Central Dogma of biology: 2. SWBAT recall at least 3 differences between DNA and RNA 3. SWBAT write the correct complementary RNA strands for a given DNA sequence. 4. SWBAT explain what happens in the 3 phases of transcription.

8 The Central Dogma Key Point #1 Central Dogma of biology: DNA is transcribed into RNA which is translated into proteins. The central dogma tells us the PROCESS by which DNA s information is used to make proteins.

9 Central Dogma DNA Transcription RNA Translation Protein

10 Objective 1. SWBAT state the Central Dogma of biology: 2. SWBAT recall at least 3 differences between DNA and RNA 3. SWBAT write the correct complementary RNA strands for a given DNA sequence. 4. SWBAT explain what happens in the 3 phases of transcription.

11 RNA Key Point #2 mrna carries genetic information from the nucleus to the cytoplasm. DNA has instructions, but cannot take them to where proteins are made. It cannot leave the nucleus mrna is the messenger that can do this for DNA. It can be in the nucleus AND go out to the cytoplasm where proteins are made.

12 Structure of RNA Key Point #3 RNA is different from DNA because: (1) it is a single strand of nucleotides (2) it uses the sugar ribose while DNA uses deoxyribose (3) it uses uracil (U) instead of thymine (T) as a base. DNA has deoxyribose sugar RNA has ribose sugar.

13 Back to Making Proteins Key Point #4 Transcription stores the information in DNA as RNA messages. There are a few types of RNA, but messenger RNA (mrna) is used in transcription. *The information IS the bases.

14 Base Pairing RNA Yesterday we learned how DNA is made of complimentary base pairs. mrna follows similar rules. loves U

15 Guided Practice 1 One strand of DNA has the nitrogenous bases of TAGCCAG What is the complimentary strand of DNA? RNA? AUCGGUC ATCGGTC

16 Guided Practice 2 One strand of DNA has the nitrogenous bases of CCCATATTA What is the complimentary strand of DNA? RNA? GGGUAUAAU GGGTATAAT

17 DNA v. RNA: All the info in one place! DNA RNA # of strands Nitrogenous bases used TWO ATGC ONE AUGC Type of sugar in backbone Deoxyribose Ribose What does it do to genetic information? Stores it; holds it Takes messages Is it made of nucleotides? yes yes Found in nucleus? Cytoplasm? Complimentary strand to DNA of GATTACTACGA? Complimentary strand to DNA of TTTAGGGCCCAT Nucleus only- never leaves CTAATGATGCT AAATCCCGGGTA Nucleus, can move into cytoplasm CUAAUGAUGCU AAAUCCCGGGUA

18 Exit Ticket Review these objectives, we re about to take the first exit ticket: 1. SWBAT state the Central Dogma of biology: 2. SWBAT recall at least 3 differences between DNA and RNA

19 Exit Ticket 1. What is the central dogma of biology? 2. Give THREE differences between DNA and RNA. 3. Give ONE similarity between DNA and RNA.

20 Objective 1. SWBAT state the Central Dogma of biology: 2. SWBAT recall at least 3 differences between DNA and RNA 3. SWBAT write the correct complementary RNA strands for a given DNA sequence. 4. SWBAT explain what happens in the 3 phases of transcription.

21 Key Point #5 RNA polymerase only elongates from the 5 to 3 direction, so it reads DNA from a 3 to 5 direction Watch out for tricky AP problems where this rule comes into play: What would the complementary RNA sequence be for a DNA sequence: 5 - A C T G 3 A. 5 T G A C 3. B. 3 C A G T 5. C. 5 T C T G 3 D. 3 U G A C 5

22 Key Point #6 There are 3 steps to transcription 1. Initiation: RNA polymerase binds to a promoter 2. Elongation: RNA polymerase pairs up C and G as well as A and U 3. Termination: A special DNA sequence tells transcription to stop 4. RNA Processing: Junk nucleotides are cut out of the RNA transcript

23 Key Point #7 Initiation starts when RNA polymerase recognizes a special DNA sequence called the promoter. Special proteins called transcription factors recognize a key DNA sequence called the TATA box (repeating Ts and As)

24 Fig ʹ 3ʹ 5ʹ 3ʹ 1 A eukaryotic promoter includes a TATA box Promoter Template 3ʹ 5ʹ TATA box Start point Template DNA strand Transcription factors 2 Several transcription factors must bind to the DNA before RNA polymerase II can do so. 3ʹ 5ʹ RNA polymerase II 3 Additional transcription factors bind to the DNA along with RNA polymerase II, forming the transcription initiation complex. Transcription factors 5ʹ 3ʹ 5ʹ 3ʹ 5ʹ RNA transcript Transcription initiation complex

25 Key Point #8 Elongation is the continual pairing of RNA nucleotides across from their complementary DNA nucleotides in the 5 to 3 direction

26 Key Point #9 Termination occurs when RNA polymerase reaches the termination sequence, at which point: RNA polymerase detaches The new mrna trancript is cut off of the DNA The DNA goes back to a double helix

27 Post-translational Processing Key Point #10: Once mrna is transcribed, it is called premrna Pre-mRNA must be processed in 3 ways before it can leave the nucleus 1. Addition of the 5 cap 2. Addition of the poly-a tail 3. RNA splicing

28 Fig. 17-3b-3 Nuclear envelope TRANSCRIPTION DNA RNA PROCESSING Pre-mRNA mrna TRANSLATION Ribosome Polypeptide (b) Eukaryotic cell

29 5 Cap and poly-a Tail Key Point #11: The 5 end gets capped off and the 3 end receives a tail of many As, called a poly-a tail. These both 1. Help move mrna out of the nucleus 2. Protect mrna from harmful enzymes 3. Help the ribosomes attach to the 5 end 5ʹ (we ll see this in a second!) Protein-coding segment Polyadenylation signal G P P P AAUAAA AAA AAA 5ʹ Cap 5ʹ UTR Start codon Stop codon 3ʹ UTR Poly-A tail 3ʹ

30 Introns and Exons Key Point #12: Most genes have long noncoding sequences (sections of DNA that do not make it into mrna and protein). Noncoding sequences are called intervening sequences or introns The coding sequences, which will be expressed, are called exons RNA splicing removes introns and joins exons, making an mrna with a continuous coding sequence

31 Fig Pre-mRNA 5ʹ Cap 5ʹ Exon Intron Exon Intron Exon 146 3ʹ Poly-A tail Coding segment Introns cut out and exons spliced together mrna 5ʹ Cap ʹ UTR 3ʹ UTR Poly-A tail

32 n Alternative splicing means that one gene can make many different proteins Alternative Splicing Key Point #13: The same gene can make more than one polypeptide, depending on which segments are treated as exons during RNA splicing The creation of these variations is called alternative splicing

33 (Yesterday s) Key Point #9 DNA polymerase can perform mismatch repair and correct errors in base pairing DNA can be damaged by chemicals, radioactive emissions, X-rays, UV light, and certain molecules (in cigarette smoke for example) In nucleotide excision repair, a nuclease cuts out and replaces damaged stretches of DNA

34 Fig Nuclease DNA polymerase DNA ligase

35 Key Point #10 Telomeres are repeating nonsense sequences at the end of our genes Telomeres are created and maintained by the enzyme telomerase, which can lengthen telomeres Their function is unknown, but may be involved in aging and cancer

36 Exit Ticket 1. What is the complementary RNA sequence to this DNA: 3 ATCG 5? Your answer should be written in the 5 to 3 direction to be correct. 2. Name the 3 steps to transcription. 3. What is the area where RNA polymerase binds to the DNA called and what sequence does it look for there? 4. Once mrna is made, where does it go and why?