DNA => RNA => ProteinCentral Dogma of Life

DNA• Name: Deoxyribonucleic Acid

• “Molecule of Life”• Stays in the nucleus of eukaryotes• Codes for RNA and ultimately

proteins

• Structure: Double stranded (double helix)

• Monomers: Nucleotides• Deoxyribose, phosphate group, nitrogenous base• N bases: Adenine, Guanine,

Cytosine, & Thymine

RNA• Name: Ribonucleic Acid• Disposable copy of DNA- moves to the cytoplasm to make proteins

• Structure: Single Stranded• Monomer: Nucleotides• Ribose, phosphate group, nitrogenous base• N base: Adenine, Guanine,

Cytosine, & Uracil• Three kinds

• mRNA - messenger• tRNA - transfer• rRNA - ribosomes

Nucleotide• Remember that a nucleotide is made up of three parts:

1. Phosphate group

2. 5 carbon sugar

3. Nitrogenous base • The nitrogenous base differs

• A, T, C or G in DNA• A, U, C or G in RNA

DNA Replication• DNA must be replicated

• When does this happen during the cell cycle?

• When does DNA get replicated?• When new cells need to be made

• To replace dead or damaged cells• To grow and develop• To form a new life- fertilization birth

• 2 strands of DNA run in opposite directions

DNA Replication• Enzymes involved

• DNA helicase- unwinds, unzips double stranded DNA, exposes nitrogenous bases so they can be based paired

• DNA polymerase- adds new DNA nucleotides

• DNA replication is semi-conservative, meaning that each new DNA strand is made of one old and one new strand

Protein

• Monomers: Amino Acids

• Functions: • Enzymes• Structural Proteins

• In the cell membrane• Give characteristics to cells

• They make you, YOU!

Genes

• Segments of DNA • The code on the DNA codes for a PROTEIN.

How to get from DNA to Proteins

• Transcription - The rewritten language of DNA nucleotides to RNA nucleotides

• Translation - The translation from the language of nucleotides to the language of amino acids.

Transcription: From DNA => mRNA• Rewriting the nucleotide

code• In the Nucleus• The DNA transcribed is

for a certain protein (from a gene)• DNA splits• 1 Strand is used as a

template• RNA polymerase is used

to build mRNA strand.• Once complete the mRNA

goes into the cytoplasm.

Codons

• Series of 3 nucleotides on the mRNA

• Each codon codes from only on specific Amino Acid

1 codon for 1 amino acid

Translation From mRNA => Proteins

• mRNA comes from the nucleus to the Ribosome

• At the Ribosome, the code of mRNA nucleotides is translated into the language of Protein amino acids using tRNA

tRNA• RNA molecules that

helps build proteins• One end has an amino

acid attached• One end has an

anitcodon• Series of 3 nucleotides on

the tRNA• Match with the mRNA

codons• The amino acid is

specific to the anticodon

Translation1. mRNA enters the ribosome

• Always starts with AUG on mRNA

2. tRNA from the cytoplasm attaches to the mRNA

3. Amino acid attached to tRNA is dropped off

4. The next tRNA with the matching anitcodon to the next codon enters the ribosome

5. The amino acid is dropped off and tied to the 1st amino acid…Until Stop Codon.

Amino AcidRibosome

tRNA

What is the Protein?

• The series of Amino Acids created in translation

• The order of amino acids determine the protein

• Change the amino acids, you change the protein

Transcription and Translation Ex.

• DNA Sequence• TACATACGCTTT

• Complementary RNA• AUGUAUGCGAAA

• Amino Acid Sequence• Met-Try-Ala-Lys

Transcription and Translation Ex.

• DNA Sequence• TACATACGCTTT

• Complementary RNA• AUG/UAU/GCG/AAA

• Amino Acid Sequence• Met-Try-Ala-Lys

Mutations

• Occur when DNA is replicated during the cell cycle• substitutions• deletions• insertions

Base Substitution

• One DNA nucleotide is changed• May or may not cause

a change in the protein• No change = silent

mutation• Could change amino

acid, and therefore the function of the protein

Silent Mutation

• Original DNA Sequence• TACATACGCTTT

• Complementary RNA• AUGUAUGCGAAA

• Amino Acid Sequence• Met-Try-Ala-Lys

• Mutated DNA Sequence• TACATGCGCTTT

• Complementary RNA• AUGUACGCGAAA

• Amino Acid Sequence• Met-Try-Ala-Lys

Silent Mutation

• Original DNA Sequence• TACATACGCTTT

• Complementary RNA• AUG/UAU/GCG/AAA

• Amino Acid Sequence• Met-Try-Ala-Lys

• Mutated DNA Sequence• TACATGCGCTTT

• Complementary RNA• AUG/UAC/GCG/AAA

• Amino Acid Sequence• Met-Try-Ala-Lys

Mutation: Change in Protein

• Original DNA Sequence• TACATACGCTTT

• Complementary RNA• AUGUAUGCGAAA

• Amino Acid Sequence• Met-Try-Ala-Lys

• Mutated DNA Sequence• TACACACGCTTT

• Complementary RNA• AUGUGUGCGAAA

• Amino Acid Sequence• Met-Cys-Ala-Lys

Mutation: Change in Protein

• Original DNA Sequence• TACATACGCTTT

• Complementary RNA• AUG/UAU/GCG/AAA

• Amino Acid Sequence• Met-Try-Ala-Lys

• Mutated DNA Sequence• TACACACGCTTT

• Complementary RNA• AUG/UGU/GCG/AAA

• Amino Acid Sequence• Met-Cys-Ala-Lys

Base Insertion & Deletion

• Adding or taking away of nucleotides

• Will change the overall order of the amino acids, and therefore the Protein will change

Mutation: Change in Protein

• Original DNA Sequence• TACATACGCTTT

• Complementary RNA• AUG/UAU/GCG/AAA

• Amino Acid Sequence• Met-Try-Ala-Lys

• Mutated DNA Sequence• TACAGTACGCTTT

• Complementary RNA• AUG/UCA/UGC/GAA/A

• Amino Acid Sequence• Met-Ser-Cys-Glu

Mutagens

• What causes mutation• UV light• X-rays• Chemicals

DNA => Protein