RNA and Protein Synthesis

BIOLOGYChapter 10-2 and 10-3 (pgs 190-

197)

BIG IDEAS• The information needed to make

proteins in located in the nucleus in the form of DNA

• The enzymes and amino acid building blocks of proteins are located outside the nucleus in the cytosol

• RNA (ribonucleic acid) is responsible for getting the genetic information to the site of protein synthesis (ribosomes)

Review of DNA & Proteins:DNA-• Organic molecule (nucleic acid)

that is composed of repeating subunits - nucleotides

• Stores and transmits the genetic information in the form of ‘genes’

• Controls the production of protein

PROTEIN-• Organic molecule made up of

repeating subunits – amino acids• Important in all cell functions:

repair, energy, hormones, enzymes, transportation and storage and immunity.

FYI…

• Each ‘gene’, or section of DNA, is made up of a sequence of nucleotides arranged in a specific order according to our genetic ancestry.

• The order of these base units makes up the genetic information or “code” for the SYNTHESIS of PROTEINS in the body.

Protein SynthesisIn all cells, except for bacteria, DNA is stored in the nucleus and protein synthesis takes place in the ribosome in the cytoplasm..

? QUESTION ?So, how do cells use the genetic information, or ‘code’ stored in DNA to make millions of different proteins the body needs?

This is how we do it….

• The DNA (deoxyribonucleic acid) that contains the genetic code to make all of your proteins is trapped in the nucleus of the cell

• The ribosomes, enzymes, and amino acid building blocks of protein are out in the cytoplasm

• RNA (ribonucleic acid) is responsible for getting the ‘code’ from the nucleus to the cytoplasm

• RNA Copies DNA and then moves outside the nucleus to synthesize proteins in the ribosome

RNA – Ribonucleic Acid

Like DNA , RNA is a nucleic acid made up of repeating nucleotides

Differs in structure:1. Sugar (ribose)2. *Phosphate (same in both)

3. 1 of the fourNitrogenous Bases

(A, G, C, T in DNA U in RNA)4.Single strand – RNA Double strand - DNA

FYI - RNARNA differs from DNA in several ways.

–An RNA molecule has only one side of the ladder shape. –RNA has the bases A, G, and C. However, it has a base U or Uracil, instead of base T or thyamine.–So when forming base pairs, base A pairs with base U.

Comparison of DNA and RNA:Nucleotide Components Function Form/Structure

Sugar Nitrogen Base

DNA Deoxyribose Adenine, Guanine, Cytosine,Thymine

Store and transmit genetic info. that tells cells which proteins to make and when.

2 strands of nucleotides.

Double Helix

RNA Ribose Adenine, Guanine, Cytosine, Uracil

Move genetic info. from DNA to ribosomes; assemble polypeptide chains (proteins)

Single strand of nucleotides.

Single Helix

3 Types of RNA:

RNA: ribonucleic acid. Use information from DNA to make proteins.

1. mRNA – messenger RNA2. tRNA – Transfer RNA3. rRNA – Ribosomal RNA

Messenger RNA (mRNA)• Single, uncoiled

chain of RNA that transcribes DNA’s information from nucleus to cytoplasm

Transfer RNA (tRNA)

• Single chain of about 80 RNA nucleotides folded into a hairpin shape that bind to

specific amino acids

• There are 45different varieties

Ribosomal RNA (rRNA)

• Consists of RNA nucleotides in globular form – most abundant RNA type

• Along with proteins, rRNA makes up the ribosomes where proteins are made

PROTEIN SYNTHESIS

TRANSCRITION &

TRANSLATION

http://glencoe.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::550::400::/sites/dl/free/0078802849/383936/Vis_transcription_translation.swf::Visualizing%20Transcription%20and%20Translation

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2 Parts of Protein Synthesis

• 1. TRANSCRIPTION-mRNA is produced from DNA in the nucleus.

• 2. TRANSLATION-Takes place in the ribosome. mRNA is ‘read’ and amino acids are transferred into the growing chain of the protein by tRNA.

Transcription• Part 1 of Protein Synthesis• Process by which genetic

information is copied from DNA to mRNA• An enzyme, RNA polymerase

initiates transcription by binding to promoter regions on DNA

• DNA molecule separates• Only one of the DNA strands

acts as a template

Transcription• RNA polymerase connects RNA bases to the growing RNA strand

• The same as when DNA is replicated but uracil is used instead of thymine

• It continues until it reaches a termination signal

• PROMOTER-beginning of the gene being transcribed.

• TERMINATION SEQUENCE-end of the gene being transcribed. Tells the RNA polymerase “let go”.

Transcription

Do Now• How is RNA different from DNA?

• What are the three types of RNA?

• What is the purpose of Transcription?

Translation Part 2 of Protein Synthesis

• WHAT ARE PROTEINS?• Proteins are polymers of amino

acids• There are 20 different amino acids• The sequence of amino acids

determines the structure of the protein

• The function of the protein depends on its structure

Proteins:

Translation Part 2 of Protein Synthesis

•The sequence of nucleotides in an mRNA strand is translated into a sequence of amino acids to make a protein•A series of 3 nucleotides (bases) on mRNA make a codon. A codon codes for one amino acid.

Codons

Translation Part 2 of Protein Synthesis

•There are 64 codons and only 20 amino acids, so several codons can code for the same amino acid

•There are also a start codon (AUG) and stop codons (UAA, UAG, UGA

Check for Understanding:

• 3 mRNA bases = code for 1 amino acid

• If you have 450 mRNA bases, how many amino acids would you code for?

• How many codons would you have?

•mRNA goes to ribosome and begins translation from start codon•As the ribosome reads each codon, the corresponding tRNA will come and match its anticodon to the correct codon.•The anticodon is complementary to and pairs up with a corresponding mRNA codon.

TranslationPart 2 of Protein Synthesis

•The amino acid carried by the tRNA will be linked to the prior amino acid in the chain. Ribosome reads the stop codon and the process stops.

TranslationPart 2 of Protein Synthesis

TranslationPart 2 of Protein Synthesis

Summary:

• Let’s watch protein synthesis in ACTION!

• Or here…

• Now Play “Drag and Drop Protein Syntheisis”

Gene Expression

BIOLOGYChapter 11 (pgs 202 - 219)

BIG IDEAS

• Cells use information in genes to build hundreds of different proteins, each with a unique function.

• Not all proteins are required by the cell at one time.

• By regulating gene expression, cells can control when a specific protein is made.

Gene Expression

• Genome is the complete genetic material contained in an organism.

• Gene expression is the activation of a gene that results in the formation of a protein.

• A protein is produced only when it is needed.

Gene Expression

• For example:• When you drink cow’s milk, the

presence of lactose stimulates the cells that line the small intestines to produce the enzyme lactase to help digest this disaccharide.

Gene Expression

• For example:• When you drink cow’s milk, the

presence of lactose stimulates the cells that line the small intestines to produce the enzyme lactase to help digest this disaccharide.

Gene Expression