DNA and Protein Synthesis

• DNA contains the genetic information to make amino acids

• Amino acids combine to make proteins

• These proteins determine the physical traits of an organism and control cellular functions.

• Proteins do everything, and DNA gets all the credit!

• Think of them as tiny minions who do all the work

DNA and Protein Synthesis

DNA and Protein Synthesis

• Codon: three bases code for a specific protein:ex: AAA = Lysine

• The codons code for 20 amino acids

• Just like the alphabet has 26 letters to make all the words we know, the 20 amino acids make all the different proteins found in living organisms

• The codons are the template for protein synthesis, which takes place on the ribosomes (rRNA) in the cytoplasm

DNA and Protein Synthesis – Codons and amino acids

Name the Amino Acid:

UAU

CCG

AGU

GCA

Tyrosine

Proline

Serine

Alanine

DNA and Protein Synthesis

But… How does the information get from the DNA to the cytoplasm?

mRNA

DNA and Protein Synthesis - Transcription

Transcription:

1) DNA unzips

2) mRNA (messenger ribonucleic acid) copies info from DNA using base pairings

• RNA is different from DNAa) Single stranded, not double strandedb) Instead of deoxyribose, it has ribosec) instead of Thymine, it uses Uracil

3) Carries the genetic code from the nucleus to the ribosome in the cytoplasm

DNA and Protein Synthesis - Translation

Translation:

1) rRNA (ribosomal RNA) attaches to mRNA and starts reading the codons

2) tRNA (transfer RNA) – carries amino acids and attaches them to the growing protein chain

3) When protein production is complete, the ribosome releases the protein chain

DNA and Protein Synthesis - Summary

DNA and Protein Synthesis

Practice making mRNA using the DNA template

DNA and Protein Synthesis

• Amino acids are linked together in the same order as the codons , creating a protein chain

• Just like linking letters to make words, linking amino acids makes proteins

Amino Acid

Amino Acid

Amino Acid

DNA and Mutations

Mutations are any changes that take place in DNA:

• Can be spontaneous or caused by mutagens• ex: Chemicals, high temperatures, UV light, radiation

• Can change the genetic code, and be replicated when forming new body cells.

• In sex cells, can be passed on to offspring.

• Mutations can be neutral, beneficial, or harmful• ex: Blue eyes – a mutation that occurred 6-10,000 years ago, can be traced back to one ancestor• what kind of mutation is that?

DNA and Mutations – Lets looks at different mutations

THE DOG BIT THE CAT

DNA and Mutations - Substitution

THE DOG BIT THE CAT

• Substitution - Replace just one letter:

THE DOG BIT THE CAR

DNA and Mutations - Deletion

THE DOG BIT THE CAT

• Deletion: Delete just one letter (T):

THE DOG BIT HEC AT

DNA and Mutations-Insertions

THE DOG BIT THE CAT

• Insertion - Add just one letter (E):

THE DOE GBI TTH ECA T

Cells have “proof reading” proteins that constantly check the DNA and fix errors, so most are corrected

Protein Synthesis- you try it!

DNA transcription and translation- you try it!