Protein SynthesisProtein Synthesis

Reading the DNA Reading the DNA molecule to make molecule to make

proteins.proteins.

Genes and ProteinsGenes and Proteins• Nucleotides contain Nucleotides contain

informationinformation which is put to which is put to work through the work through the production production of proteins.of proteins.

• ProteinsProteins are 3D shapes are 3D shapes composed ofcomposed of a long chain of a long chain of amino acidsamino acids (A.A.) (A.A.)

• Each human cell contains Each human cell contains about 80,000 genes.about 80,000 genes.

How DNA controls cell How DNA controls cell functionsfunctions

1.1. DNA instructs cell to make DNA instructs cell to make amino acids.amino acids.

2.2. Amino Acids link together to Amino Acids link together to form proteins.form proteins.

20 different amino acids.20 different amino acids.

3.3. Proteins control the cells Proteins control the cells chemistry and what a cell will do. chemistry and what a cell will do.

4.4. Proteins allow us to display our Proteins allow us to display our traits.traits.

What are the “players” in What are the “players” in making Proteins?making Proteins?

• DNADNA stores the code to make stores the code to make and build proteinsand build proteins

• RNARNA brings amino acids for brings amino acids for protein synthesis.protein synthesis.

• Amino acidAmino acid by amino acid, the by amino acid, the proteins are assembled.proteins are assembled.

DNA DNA Ribosomes Ribosomes Amino Acid Amino Acid Protein Protein

RNA is like DNA, but is RNA is like DNA, but is different in 3 key ways:different in 3 key ways:

1.1. RNA is RNA is single strandedsingle stranded

2.2. The sugar in RNA is The sugar in RNA is RIBOSERIBOSE

3.3. The four Nitrogen bases are:The four Nitrogen bases are:

1.1.CytosineCytosine

2.2.GuanineGuanine

3.3.AdenineAdenine

4.4.UracilUracil (replaces Thymine)(replaces Thymine)

Three Different kinds of Three Different kinds of RNARNA

1.1. Messenger RNA Messenger RNA (mRNA)(mRNA)

2.2. Ribosomal RNA (rRNA)Ribosomal RNA (rRNA)

3.3. Transfer RNA (tRNA)Transfer RNA (tRNA)

Messenger RNA (mRNA)Messenger RNA (mRNA)

1.1. Carries genetic Carries genetic information from information from DNA (in nucleus) to DNA (in nucleus) to ribosomes (in cytoplasm)ribosomes (in cytoplasm)

2.2. ““Bar Code”Bar Code”

Ribosomal RNA (rRNA)Ribosomal RNA (rRNA)

1.1. Clamp on to mRNA and reads its Clamp on to mRNA and reads its information to assemble amino information to assemble amino acids in the correct order.acids in the correct order.

2.2. Connects the amino acids Connects the amino acids together (Makes the protein)together (Makes the protein)

3.3. Makes up the Ribosome (with Makes up the Ribosome (with Proteins)Proteins)

4.4. ““Register/Scanner”Register/Scanner”

Transfer RNA (tRNA)Transfer RNA (tRNA)

1.1. Transports Amino Acids Transports Amino Acids to the ribosome to be to the ribosome to be assembled into a protein.assembled into a protein.

2.2. ““Conveyer Belt”Conveyer Belt”

Transcription: Transcription: Transfer of Transfer of information from DNA to information from DNA to

RibosomesRibosomes• Similar to DNA replication (4 Similar to DNA replication (4

step process)step process)

1.1. DNA Molecule DNA Molecule unzipsunzips, and , and unpaired bases are exposedunpaired bases are exposed

2.2. RNA NUCLEOTIDES base pairRNA NUCLEOTIDES base pair with complementary DNA with complementary DNA nucleotides on the Master nucleotides on the Master Strand.Strand.

DNA master strand sequence:DNA master strand sequence:

AGC TAA CCGAGC TAA CCG

mRNA base-pair strand mRNA base-pair strand sequence:sequence:

UCG AUU GGCUCG AUU GGC

3.3. When base pairing is When base pairing is completed RNA nucleotides completed RNA nucleotides combine (combine (develop backbonedevelop backbone) ) to form mRNA.to form mRNA.

4.4. DNA reconnects and mRNA DNA reconnects and mRNA leaves the nucleus to enter leaves the nucleus to enter the cytoplasm.the cytoplasm.

The Genetic CodeThe Genetic Code• mRNA is the genetic messenger, mRNA is the genetic messenger,

which carries the message on how which carries the message on how to build the proteins.to build the proteins.

• Proteins are built from chains of Proteins are built from chains of smaller molecules called Amino smaller molecules called Amino Acids.Acids.

• A code is needed to convert mRNA A code is needed to convert mRNA into proteins.into proteins.

• There are 20 different amino acids There are 20 different amino acids with only 4 types of bases: A, U, G, Cwith only 4 types of bases: A, U, G, C

How the bases form a code for How the bases form a code for Proteins:Proteins:

• CodonCodon is a is a 3 nucleotide sequence3 nucleotide sequence that that codes for an amino acid.codes for an amino acid.

• The The order of nitrogen basesorder of nitrogen bases in the in the mRNA will mRNA will determine the type and determine the type and order of amino acidsorder of amino acids in a protein. in a protein.

• There are many possible combos, There are many possible combos, and mRNA codons.and mRNA codons.

• AUGAUG = = start protein productionstart protein production• UAAUAA = = stop protein productionstop protein production

DNA and m-RNADNA and m-RNAA T G T C A G A C G (Master DNA)

U A C A G U C U G C (m-RNA Strand)

• 3 base sequence in m-RNA is called a codon

• DNA and m-RNA molecules separate and the m-RNA molecules travel to the ribosomes

Translation: Translation: from mRNA to from mRNA to ProteinProtein

• Translation = converting info Translation = converting info in a sequence of nitrogen bases in a sequence of nitrogen bases in mRNA into a sequence of in mRNA into a sequence of amino acids that make up a amino acids that make up a protein.protein.

• Occurs in the ribosomes (in Occurs in the ribosomes (in cell’s cytoplasm)cell’s cytoplasm)

Translation: Translation: from mRNA to from mRNA to ProteinProtein

1.1. The mRNA sequence (protein The mRNA sequence (protein blueprint) passes through the rRNA blueprint) passes through the rRNA which acts as a register/scannerwhich acts as a register/scanner

2.2. tRNA attaches to amino acids in tRNA attaches to amino acids in cytoplasm and brings them to the cytoplasm and brings them to the rRNArRNA

• One end of tRNA molecule is One end of tRNA molecule is attached to one of 20 different attached to one of 20 different A.A., the opposite end has a 3 A.A., the opposite end has a 3 base sequence called an base sequence called an anticodonanticodon

3.3. Anticodon of tRNA matches and Anticodon of tRNA matches and bonds to correct codon on bonds to correct codon on mRNA moleculemRNA molecule

4.4. tRNA molecules detach and tRNA molecules detach and leaves the amino acid behind leaves the amino acid behind for the rRNA to connect to the for the rRNA to connect to the AA sequence being formed.AA sequence being formed.

5.5. Process is repeated until the Process is repeated until the “STOP” codon is reached… the “STOP” codon is reached… the Amino Acid chain breaks off, Amino Acid chain breaks off, and a complete protein is made.and a complete protein is made.

Errors in Stored Errors in Stored InformationInformation

• Cells may make proteins that Cells may make proteins that have amino acids in the wrong have amino acids in the wrong orderorder

1.1. Errors are the result of change Errors are the result of change in base sequences in a DNA in base sequences in a DNA moleculemolecule

2.2. These These errorserrors are called are called MUTATIONSMUTATIONS

Mutations in Mutations in Reproductive CellsReproductive Cells

• Mutations affect the reproductive Mutations affect the reproductive cells of an organism by changing cells of an organism by changing the sequence of nucleotides in a the sequence of nucleotides in a gene in the gene in the eggegg or or spermsperm

• If these cells take part in If these cells take part in fertilizationfertilization, the changed gene , the changed gene would be part of the genetic would be part of the genetic makeup of the offspringmakeup of the offspring

• This mutation may produce This mutation may produce negative resultsnegative results ( death of embryo) ( death of embryo) or or positive resultspositive results in very few cases in very few cases ( faster or stronger individuals)( faster or stronger individuals)

Mutations in Body CellsMutations in Body Cells• If radiation hit a If radiation hit a body cellbody cell such as such as

your skin tissue, this would your skin tissue, this would not be not be passedpassed on to your on to your offspringoffspring. . However, severe effects may result However, severe effects may result for the individual such as cancer.for the individual such as cancer.

• Aging is the result of a buildup of Aging is the result of a buildup of cells that do not work properlycells that do not work properly

• Some mutations effect cell Some mutations effect cell division which results in cells division which results in cells either dividing rapidly or not either dividing rapidly or not dividing at all.dividing at all.

3 types of Mutations:3 types of Mutations:• Point Mutation Point Mutation – – A change in a single A change in a single

base pair Ex. CAT to CAR = base pair Ex. CAT to CAR = incorrect Amino Acid (replaced)incorrect Amino Acid (replaced)

• Frameshift Frameshift – – A single base is either A single base is either addedadded or or deleteddeleted. Results in an . Results in an entirely new amino acid sequence. entirely new amino acid sequence. (addition or deletion)(addition or deletion)

• Chromosomal Chromosomal –– Affect the distribution Affect the distribution of genes to gametes during meiosis. of genes to gametes during meiosis. They cause They cause non-disjunctionnon-disjunction: the : the failure of chromosomes to separatefailure of chromosomes to separate

All 3 mutations will All 3 mutations will cause cause defective proteinsdefective proteins

to be producedto be produced•Cells or organism with Cells or organism with

mutation will not work mutation will not work correctlycorrectly

•Cells or organism with Cells or organism with mutation may diemutation may die

Causes of MutationsCauses of Mutations

• Many occur Many occur naturallynaturally • Materials causing mutations are Materials causing mutations are

called called mutagensmutagens..• May be influenced by the May be influenced by the

environmentenvironment:: 1. Chemicals1. Chemicals 2. Ultraviolet light2. Ultraviolet light 3. Radiation ( large amt. of 3. Radiation ( large amt. of

energy = bursts DNA)energy = bursts DNA) 4. High temperatures4. High temperatures

AssignmentAssignment

• Mini Lab pg 306Mini Lab pg 306• Do a lab write up, answer the Do a lab write up, answer the

analysis ?’s 1-3 and write a analysis ?’s 1-3 and write a conclusion statement.conclusion statement.

• Problem Solving lab – pg 305Problem Solving lab – pg 305• Answer the Thinking Answer the Thinking

Critically Questions 1-4Critically Questions 1-4