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Bell Work• Create a new Section titled RNA, Transcription• Copy the following questions in your notebook

in preparation for a video.• 1. What is Transcription and where does it

happen?• 2. What is mRNA?• 3. What is Translation and where does it

happen?• 4. What is tRNA?

RNA & Transcription

How is RNA different from DNA?What kinds of RNA are there?

Why do cells need both?

P

P

P

P

P

P

P

P

P

P

P

P

P

P

P

Key:= Phosphate= Sugar (deoxyribose)

= Sugar (ribose)

= Nitrogen Base= Hydrogen Bond= DNA Nucleotide= RNA Nucleotide

P

P

P

P

P

P

P

P

C

G

A

U

U

A

C

A

DNA RNA

T

C

G

A

T

T

A

C

A

G

C

T

A

A

T

G

Key RNA differences:

1. Single-stranded2. Ribose instead of

deoxyribose3. U replaces T

(Why RNA?)• DNA is exceptionally good at

long-term storage of information (in the ATCG sequence)…but sucks at doing anything else.

• RNA is a less stable (which is actually a good

thing in this situation) but more all-purpose molecule– Perfect for a temporary copy that

will head out of the nucleus

=

Types of RNA3 types of RNA (for our purposes):1. mRNA: messenger RNA– Disposable DNA “copy” that carries messages

to cytoplasm2. tRNA: transfer RNA– Transfers (carries) protein pieces (amino acids)

to ribosome3. rRNA: ribosomal RNA– Part of ribosome (protein-building) factory

Transcription

Where are we going with all this?What does transcription do?

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DNA RNA Protein• Information only • Instructions that make

assembling easier• USEFUL – actually does

something• The entire point of this.

CAD Drawing

Blueprint Finished Product

Transcription TranslationTranscription

• In transcription, the DNA is temporarily unzipped

• An RNA copy is made from the DNA template– RNA Polymerase adds RNA nucleotides

• Wherever you would normally have a T, RNA Polymerase puts a U (uracil)

DNA Sequence: ATG CGG CGT ACARNA copy: UAC GCC GCA UGU

Transcription

10

Transcription “bubble”

DNA

mRNA

RNA Polymerase

RNA Editing or “Splicing”• Before leaving the nucleus, the RNA copy needs

to be trimmed/edited

• Introns are removed– Think “intruder”

• Exons stay– Think “excellent”

abcdefGHijklmnOpqrSTuvwxyz

GHOST

IntronExon Exon

ExonExon

Reading & Questions

• In your Biology textbook Read pg 202-203Then answer these questions in your NB1. What direction does RNA polymerase add new nucleotides?2. How is transcription initiated?3. What are the finishing touches that must be done to

mRNA before it is ready for translation4. What is added to the beginning and end of the mRNA5. What are Two possible reasons for the existence of

introns?

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Bellwork: Study forDNA Structure/ Replication Quiz

• Make a 3x5 study card • All information you needed for your DNA

models: Directionality (for dna synthesis), base pairing, shapes and names of base pairs, hydrogen bonds

• Enzymes in DNA replication. Chargaffs Rule

RNA “Letters” & “Words”

The 4 “letters” of mRNA are G, U, A, & CA 3-letter “word” of mRNA is called a “codon”

Codons & Amino Acids

• With 4 different letters, how many 3-letter codons are possible?

• How many amino acids are there?

Codons & Amino Acids

• 64 possible codons• 20 amino acids

• This means more than one codon codes for the same amino acid.

• The genetic code is “Universal and Redundant”

Translation• Translation turns the mRNA’s message into a

functional protein– mRNAà protein– (Takes place in the cytoplasm)

Ribosome

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(Translation)• There are 4 nucleotides in mRNA’s language• There are 20 amino acids in protein’s language

• To get between two different languages, you need to TRANSLATE

tRNA Anatomy

tRNA

Anticodon:3 unpaired bases

A.A.

Detachable amino acid

tRNA• (tRNA has the job of translating between

mRNA and protein)• tRNA carries the specific amino acid to the

ribosome

tRNA

A.A.

Protein Synthesis• Each tRNA drops off its amino acid to the

growing protein chain• The tRNA leaves the ribosome and picks up a

new amino acid

• The process continues until a stop codon is reached

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The Genetic Code

Begin in the middle and work your way out

Example:

U A C

Tyrosine!

You Try!¡ CAG

¡ Glutamine¡ AAA

¡ Lysine¡ GGA

¡ Glycine¡ GGU

¡ Glycine¡ AUG

¡ Methionine¡ UGA

¡ STOP

Always at the start of every protein

Acts like the capital letter at the start of a

sentence

Always at the end of every protein

Acts like the period at the end of a sentence.

Bellwork!

• Transcribe and Translate the following on a whiteboard:

• 1. TAC-CAG-ACG-TTG-ATT

• 2. TAC-GCT-GTT-CGG-ACT

• 3. TAC-CGG-TCT-GCC-ATC

PRACTICE: KEY• Translate the following:

• 1. AUG-GUC-UGC-AAC-UAA• START-VAL-CYS-ASN-STOP

• 2. AUG-CGA-CAA-GCC-UGA• START-ARG-GLN-ALA-STOP

• 3. AUG-GCC-AGA-CGG-UAG• START-ALA-ARG-ARG-STOP

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Agenda today• we will take the Science ACT Test on school

city, Pin is 4008• Complete school quality survey• If you beat a score of 38 (Sanch’s score)• you get extra credit

• `Finish Protein synthesis worksheet• Complete ”Central Dogma Worksheet”

The Central Dogma

BELL WORK

• Field trip Departure has changed to 9:30. Still return @ 2:30.• 1. Turn in your Field Trip Form in your

Period folder in the basket

• 2. Grab a computer with your table partner and find today’s assignment on my website (Semester 2 assignments)

Todays agenda

• Finish Protein synthesis/gene expression• Complete Central Dogma Worksheet• Practice ACT for Science• On school city Pin code: 1112

FRIDAY BIOTECH AGENDA• 1. Today is the last in class time to complete –Central Dogma Worksheet–Gel Electrophoresis Webquest

• 2. We will have a TEST on DNA structure, Central Dogma and Protein Synthesis first thing on Monday/Tuesday. So make sure you are proficient with all of this material!