Do Now Scientist Discovery Hershey and Chase A

Do Now Scientist Discovery Hershey and Chase A. Analyzed DNA by X-Ray crystallography Watson and Crick B. Proved that the nuclear material in a bacteriophage, not the protein coat infects a bacterium. Rosalind Franklin C. Suggested the DNA structure of the double helix Griffith D. Discovered transformation in bacteria 1. 2. Match above. A court reporter types out a transcript of the court proceedings. What does the underlined word mean?

RNA

Objectives • SWBAT describe the 3 types of DNA • SWBAT describe the central dogma of biology • SWBAT compare transcription in the prokaryote and eukaryote.

Children of the Night • Xeroderma pigmentosum • http: //www. youtube. com/watch? v=Wt. Lt. By. N 1 m. QA

I. RNA Structure • RNA= ribonucleic acid • RNA is the 2 nd type of nucleic acid– it is also made of millions of nucleotides

DNA RNA • Double stranded • Single stranded • Sugar: deoxyribose • Sugar: ribose • Adenine bonds to thymine • No thymine! Adenine bonds instead to uracil • Only one type of DNA per organism • 3 types of RNA

Types of RNA There are 3 types of RNA: • m. RNA: messenger RNA, carries the information for protein synthesis • r. RNA: ribosomal RNA, makes the ribosomes in the cells functional. If there is no r. RNA on the ribosomes, they won’t function • t. RNA: transfer RNA, takes amino acids from the cytoplasm to the ribosomes to make them into proteins

m. RNA

r. RNA

t. RNA

Practice 1 • Which type of RNA is responsible for helping bring amino acids to make proteins? • Which type of RNA makes up ribosomal subunits ? • What type of RNA is this and what is it’s function?

Function of RNA • What does RNA actually do in the cell? RNA helps make the proteins coded for by DNA • To make proteins, the cell takes DNA, copies the sequence into an RNA copy and then makes proteins. This idea is called the Central Dogma

Central Dogma

RNA Transcription • How is the RNA Strand Actually Made? Transcription • Transcription= when you make an RNA copy of a sequence of DNA • What enzyme is in charge of RNA transcription? RNA polymerase

• What nucleotide does RNA have instead of thymine? Uracil

RNA Transcription • RNA transcription is very similar to DNA replication • BUT! Instead of putting a Thymine (t) next to each Adenine (A), RNA Polymerase puts a Uracil (U) there

Practice • What will the RNA strand be? • DNA Strand: TAAGCGCTCG

Transcription: Initiation • Step 1: Initiation RNA polymerase binds to a certain site on the DNA called the promoter and DNA strands unwind. RNA polymerase starts to make RNA. The stretch of DNA that is transcribed is called the transcription unit.

Transcription: Elongation • Step 2: Elongation • RNA polymerase adds nucleotides to the 3’end of the RNA molecule. • *RNA polymerase can only add 5’ 3’ • The DNA double helix reforms as RNA polymerase moves away.

Transcription: Termination • Step 3: Termination A sequence eventually tells the RNA polymerase to stop. The RNA polymerase falls off, and the m. RNA transcript is created!

Animation • http: //www. stolaf. edu/people/giannini/flashani mat/molgenetics/transcription. swf

Practice • A DNA template strand has the following sequence: TACGGGATT. What is the m. RNA sequence transcribed from the DNA? • Arrange the flow of genetic information in the cell in order: 1. m. RNA, 2. DNA, 3. protein. • Come up with a way to remember the three steps of the transcription! (picture, saying, drawing) Be prepared to share out!

Where is this happening in the cell? • What’s the main difference between prokaryotic and eukaryotic cells?

Differences

Prokaryotic Transcription & Translation

Eukaryotic m. RNA modification • After transcription, pre-m. RNA in the nucleus is modified at BOTH ends. • 5’ cap: adds a modified Guanine molecule, then 20 -40 nucleotides • Poly-A Tail: 50 -250 Adenine nucleotides are added at the 3’ end

RNA Splicing • 8000 nucleotides 1200 nucleotides (average) • Introns: intervening sequences that are cut of the pre-m. RNA • Exons: regions left in pre-m. RNA to be made into proteins (eventually expressed)

Practice • Where does transcription happen in prokaryotic cells? • Where does transcription happen in eukaryotic cells? • Which are the introns and exons in the following picture?

MIT OCW • https: //www. youtube. com/watch? v=t. Mr 9 XH 64 rt. M

• Replicate: TTTT

• Replicate: ATCG

• Transcribe: CGC

• Transcribe: TAG

• Replicate: GCGCGCG

• Transcribe: GGTTAGC

• Replicate: TAATAAG

• Transcribe: AAA

• Transcribe: GGG

• Transcribe: ATGCG

• Replicate: CCGGTTAA

• Replicate: TATCGC

• Replicate: ACGGTA

• Replicate: TTACGA

• Replicate: TATAGGC

• Transcribe: GCGCGCG

• Transcribe: CCGTAT

• Transcribe: GTCGAG

• Transcribe: TACCAG

RNA Translation Objectives: (1)SWBAT understand describe the process of translation in the cells

Central Dogma • DNA RNA Proteins Transcription Translation

Translation • Translation: the process of decoding m. RNA into a polypeptide chain • In translation, the information in a nucleic acid is converted into amino acids • Which type of RNA is translated? m. RNA

Translation • Where does RNA Transcription happen? The same place as DNA replication the nucleus Where does translation occur? On the ribosomes

CGA Genetic Code A G U • Genetic Code: the information that the RNA carries that specifies the amino acids that will be made • Every 3 nucleotides code for an amino acid. These 3 letter codes are called a codon. • 1 codon = 3 nucleotides = 1 amino acid A A A

Practice • Using the genetic code in your guided notes, what is the amino acid for the codon AGU? SERINE

Practice 1 • Complete practice 1 on your worksheets • Total time: 5 minutes

t. RNA • Who Can Remember? ! What is the function of t. RNA? To transfer amino acids from the cytoplasm to the ribosome

t. RNA • t. RNA has a cloverleaf pattern • At one end of the t. RNA is the anticodon, it bonds with the codon in the m. RNA (it is a complementary sequence)

t. RNA • At the other end of the t. RNA is the amino acid that the m. RNA codes for

t. RNA • Example: the m. RNA codon is UUU (remember that RNA does not have thymine but has uracil instead) What will be the anticodon for this m. RNA? AAA What amino acid will be carried by this t. RNA molecule? phenylalanine

Steps of Translation • Step 1: m. RNA leaves the nucleus and attaches to the ribosome • Step 2: t. RNA brings specific amino acids to the RNA (according to the m. RNA codons) • Step 3: t. RNA bonds to the m. RNA and its amino acid attaches to the growing polypeptide chain

More Terms • The m. RNA sequence is very long. How does the cell know at which codon to start making the protein and which codon to stop? • “Start” codon: This codon tells the protein chain to start building. The start codon is AUG or the amino acid methionine. Methionine is therefore the first amino acid in all proteins • “STOP” codon: there are 3 stop codons: UAA, UGA and UAG

Transcription Game