Slide 1 of 39 Copyright Pearson Prentice Hall 12-3 RNA and Protein Synthesis 12–3 RNA and Protein...

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Copyright Pearson Prentice Hall

12-3 RNA and Protein Synthesis12–3 RNA and Protein Synthesis

12–3 RNA and Protein Synthesis

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DNA is located in the nucleus.

DNA is impermeable to the nuclear envelope.

Genes are segments of DNA which code for the production of proteins.

Ribosomes outside the nucleus make the proteins.

RNA contains coded information for making proteins.


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Do you see a problem with this scenario?


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RNA is the solution to this problem.

RNA is DNA’s main man.RNA is DNA’s “go to guy”.RNA is DNA’s number one

“get it done person”.

One of RNA’s jobs is to copy DNA’s instructions and take those instructions

out of the nucleus to the ribosomes.


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The Structure of RNA


1. RNA is a type of nucleic acid which is made up of a long chain of nucleotides.

2. Each nucleotide, like DNA, is made up of a:

1. 5-carbon sugar,

2. phosphate group

3. nitrogenous base.

(Sounds familiar..........just like DNA’s nucleotides)


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There are three main differences between RNA and DNA:

• 1. The sugar in RNA is ribose instead of deoxyribose.

• 2. RNA is a single-strand of nucleotides.

• 3. RNA contains uracil in place of thymine.

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Types of RNA

There are three types of RNA•1. messenger RNA ~ mRNA

•2. ribosomal RNA ~ rRNA

•3. transfer RNA ~ tRNA


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Types of RNA

Messenger RNA (mRNA) copies DNA’s code for making proteins and takes it’s copy to the ribosomes.


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Types of RNA

Ribosomal RNA (rRNA) is the main component of a ribosome. rRNA is bound into two “round” units by proteins to form the large and small subunits which make up a ribosome.

Ribosome

Ribosomal RNA


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Types of RNA

Transfer RNA (tRNA) transfers specific amino acids to the ribosome for the making of the proteins.

Amino acid

Transfer RNA


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Transcription

What is transcription?


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Transcription

Transcription

RNA copies DNA’s code in its own language and take the code to the ribosomes to make proteins.

Transcription requires the enzyme RNA polymerase.

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1.During transcription, RNA polymerase attaches to DNA and separates the DNA strands.

Steps to Transcription:

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2. RNA polymerase then adds RNA nucleotides to one side of the DNA molecule/the sense side of DNA.

-DNA is a double strand of nucleotides BUT only one side of the DNA molecule actually codes for making proteins.


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2 strands of DNA

1. Sense side:Has code for makingproteins.

2. Antisense side:Has no code~ makes

no sense.

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3. RNA nucleotides are added to the sense side of DNA following the base pair rule:

Guinine bonds to Cytosine and

Uracil bonds to Adenine

A T G G C

GCA CT

Sense side of DNA

U A C C G


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4. This single strand of RNA is now known as messenger RNA or mRNA and it now has a copy of DNA’s code for making proteins.

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5. Since mRNA is single stranded it can now take a copy of DNA’s code out of the nucleus to the ribosomes.


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Transcription

RNA

RNA polymerase

DNA

Hyperlink


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The Genetic Code

Protein Synthesis:

The process of using mRNA’s copy of DNA’s code to make all necessary proteins.

Takes place where?

-at the ribosomes

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Proteins are made up of:-long chains of amino acids

Total number of different amino acids that make up all proteins:

-20

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These 20 different amino acids bond in various orders (like the letters of the alphabet) to create all proteins.


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The Genetic Code

A codon consists of three RNA nucleotides in a row on mRNA that code for a particular amino acid.

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Start codon:Three nitrogen bases in a row on mRNA

that starts EVERY protein…..AUG

Amino acid Methionine starts every

protein

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Stop codon:Three nitrogen bases in a row on mRNA

that ends every protein.Three different codons: UAA, UAG, UGA

Stop codon do not code for any amino acid


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Translation

What is translation?

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Translation

Translation:

-Process by which the ribosome reads mRNA’s code and makes a protein.

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Translation

Steps of translation:

1. mRNA leaves the nucleus and take its code to the ribosomes.

Nucleus

mRNA

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2. Ribosome attaches to mRNA and moves along it looking for a start codon/AUG.

3. Transfer RNA/tRNA travels through the cytoplasm locating the appropriate amino acid.

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Anticodon:anti =

opposite

An anticodon is three nitrogen bases on the end of tRNA .

Its code is opposite of mRNA’s codon.


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Translation

LysinetRNAPhenylalanine

Methionine

Ribosome

mRNAStart codon

4. As the ribosome reads one codon at a time, tRNA brings down the appropriate amino acid.


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Translation

5. Amino acids bind together with peptide bonds forming a long chain.

tRNA

Ribosome

mRNA

Lysine

Translation direction

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Translation

6. After a tRNA delivers its amino acid, it breaks away and goes out to find a new amino acid.

7. The process continues until the ribosome reads a stop codon.

Polypeptide

Ribosome

tRNA

mRNA

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8. The long chain of amino acids-now a polypeptide/protein-breaks away and goes where?

-to the golgi-Why to the golgi?

-to be processes and to be given its 3-D shape

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The sequence of bases in DNA is used as a template for mRNA.

The codons of mRNA specify the sequence of amino acids in a protein.

CodonCodon Codon

Codon Codon Codon

mRNA

Alanine Arginine Leucine

Amino acids within a polypeptide

Single strand of DNA

Review:

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Hyperlink of translation

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Sense Strand of DNA:

CCAGTATACCCGAGTACCCCGCAGGAGCACCAGGAATTCCGCCATACACGCCCATCCCCACTCGAAAAAAAAAA

TATA Box

Poly-a-tail Promoter Region

Termination Region Site where transcription begins

Site where transcription ends. Start of a gene

End of gene

Primary mRNA:

Intron Exon Intron Exon Intron I------------------I------------------------------------------------I------------I-----------------------I-------------------------------------I

AUAUGGGCUCAUGGGGCGUCCUCGUGGUCCUUAAGGCGGUAUGUGCGGGUAGGGGUGAGCUUUUUUUUUU

Start codon Stop codon Start codon Stop codon Tells ribosome to Tells ribosome to

start making protein stop making protein

Mature mRNA:

Exon ExonI-----------------------------------------------I-----------------------I

AUGGGGCGUCCUCGUGGUCCUUAAAUGUGCGGGUAG

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DNA Codon mRNA codon

tRNA anticodon

Amino Acid

AAA UUU AAA PHENYL

GTC

GGA GLYCINE

METH/START

GAT

GUG VALINE

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CHNOPS LABDNA: TAC AGG GCG ATT

mRNA:____________________tRNA:______________________

Amino Acid sequence: ____________________________________Trait: _____________________

AMINO ACID SEQUENCE TRAIT

Methionine-threonine-glycine-tyrosine- Hairless

Methionine- threonine-glycine-glycine Hairy

Methionine- threonine-proline-proline Plump

Methionine- tyrosine-glycine-lysine Skinny

Methionine-serine-arginine Four-eyed

Methionine-serine-tyrosine Two-eyed

Methionine-glycine-arginine-lysine-proline Long nose

Methionine- proline-arginine-lysine-proline Short nose

Methionine-phenylalanine-lysine No freckles

Methionine- phenylalanine-asparagine Freckles

Methionine- glycine-arginine-arginine Blue skin

Methionine- glycine-arginine-phenylalanine Orange skin

Methionine-isoleucine-isoleucine-leucine Male

Methionine-isoleucine-isoleucine-glycine Female

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Processing pre-mRMA into mature mRNA:


Section 1 C G T A G A T A T A A A A G C T T A C A T G A C A T G A A T T CG C A T C T A T A T T T T C G A A T G T A C T G T A C T T A A G

Section 2T A T C C G A A T T C T A C A A C T G A A T T C C G G T T T G T AA T A G G C T T A A G A T G T T G A C T T A A G G C C A A A C A T Section 3A A A A A A T G T T T T T T A C

1. Cut out sections 1-3 of DNA and tape together in order.

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2. Locate the beginning of the gene on the sense side of DNA (Top line) and underline it.

How?TATA Box

3.Locate the end of the gene on the sense side of DNA and underline it.

How?poly-A-tail

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4. Act like RNA polymerase…..How?

Use your scissors to cut apart the sense and antisense sides of DNA beginning at the end of the TATA and going to the beginning of the poly-A-tail.

Section 1 C G T A G A T A T A A A A G C T T A C A T G A C A T G A A T T C

G C A T C T A T A T

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

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5. Number the DNA nucleotides 1-54 (start at end of TATA and to the beginning of the poly-a-tail.

6. Put in slashes, dividing it into 3’s or codons.

Section 1 C G T A G A T A T A A A A G C T T A C A T G A C A T G A A T T C

G C A T C T A T A T

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

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7. Cut out the two sections of pre-RNA and tape together. Put in slashes, dividing it into 3’s or codons.

8.Complete the process of transcription. How?

You now have just made pre-mRNA

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9. Locate the beginning of a protein.How?

Start codonAUG

10.Locate the end of a protein. How?

Stop codonUAAUAGUGA

11. Locate the next set of start and stop codons.

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12.Label the introns and exons.Introns:

Non codingExons:

Express……codes for a protein

13.Cut out the introns.14.Tape together the exons.15.Add a protective 5’ cap to the front and

a protective poly-A-tail tail to the end. These protect the mature mRNA from harmful enzymes in the cytoplasm.

Slide 1 of 39 Copyright Pearson Prentice Hall 12-3 RNA and Protein Synthesis 12–3 RNA and Protein...

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