Protein Synthesis

1. Protein Synthesis Reading the DNA molecule to make proteins.

2. Genes and Proteins • Nucleotides contain information which is put to work through the production of proteins. • Proteins are 3D shapes composed of a long chain of amino acids (A.A.) • Each human cell contains about 80,000 genes.

3. How DNA controls cell functions • DNA instructs cell to make amino acids. • Amino Acids link together to form proteins.  20 different amino acids. • Proteins control the cells chemistry and what a cell will do. • Proteins allow us to display our traits.

4. What are the “players” in making Proteins? • DNA stores the code to make and build proteins • RNA brings amino acids for protein synthesis. • Amino acid by amino acid, the proteins are assembled. DNA  Ribosomes Amino Acid  Protein

5. RNA is like DNA, but is different in 3 key ways: • RNA is single stranded • The sugar in RNA is RIBOSE • The four Nitrogen bases are: • Cytosine • Guanine • Adenine • Uracil(replaces Thymine)

6. Three Different kinds of RNA • Messenger RNA (mRNA) • Ribosomal RNA (rRNA) • Transfer RNA (tRNA)

7. Messenger RNA (mRNA) • Carries genetic information from DNA (in nucleus) to ribosomes (in cytoplasm) • “Bar Code”

8. Ribosomal RNA (rRNA) • Clamp on to mRNA and reads its information to assemble amino acids in the correct order. • Connects the amino acids together (Makes the protein) • Makes up the Ribosome (with Proteins) • “Register/Scanner”

9. Transfer RNA (tRNA) • Transports Amino Acids to the ribosome to be assembled into a protein. • “Conveyer Belt”

10. Transcription: Transfer of information from DNA to Ribosomes • Similar to DNA replication (4 step process) • DNA Molecule unzips, and unpaired bases are exposed • RNA NUCLEOTIDES base pair with complementary DNA nucleotides on the Master Strand.

11. DNA master strand sequence: AGC TAA CCG mRNA base-pair strand sequence: UCG AUU GGC

12. When base pairing is completed RNA nucleotides combine (develop backbone) to form mRNA. • DNA reconnects and mRNA leaves the nucleus to enter the cytoplasm.

13. The Genetic Code • mRNA is the genetic messenger, which carries the message on how to build the proteins. • Proteins are built from chains of smaller molecules called Amino Acids. • A code is needed to convert mRNA into proteins. • There are 20 different amino acids with only 4 types of bases: A, U, G, C

14. How the bases form a code for Proteins: • Codon is a 3 nucleotide sequence that codes for an amino acid. • The order of nitrogen bases in the mRNA will determine the type and order of amino acids in a protein. • There are many possible combos, and mRNA codons. • AUG = start protein production • UAA = stop protein production

15. DNA and m-RNA • A 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

16. Translation: from mRNA to Protein • Translation = converting info in a sequence of nitrogen bases in mRNA into a sequence of amino acids that make up a protein. • Occurs in the ribosomes (in cell’s cytoplasm)

17. Translation: from mRNA to Protein • The mRNA sequence (protein blueprint) passes through the rRNA which acts as a register/scanner • tRNA attaches to amino acids in cytoplasm and brings them to the rRNA • One end of tRNA molecule is attached to one of 20 different A.A., the opposite end has a 3 base sequence called an anticodon

18. Anticodon of tRNA matches and bonds to correct codon on mRNA molecule • tRNA molecules detach and leaves the amino acid behind for the rRNA to connect to the AA sequence being formed. • Process is repeated until the “STOP” codon is reached… the Amino Acid chain breaks off, and a complete protein is made.

19. Errors in Stored Information • Cells may make proteins that have amino acids in the wrong order • Errors are the result of change in base sequences in a DNA molecule • These errors are called MUTATIONS

20. Mutations in Reproductive Cells • Mutations affect the reproductive cells of an organism by changing the sequence of nucleotides in a gene in the egg or sperm • If these cells take part in fertilization, the changed gene would be part of the genetic makeup of the offspring • This mutation may produce negative results ( death of embryo) or positive results in very few cases ( faster or stronger individuals)

21. Mutations in Body Cells • If radiation hit a body cell such as your skin tissue, this would not be passed on to your offspring. However, severe effects may result for the individual such as cancer. • Aging is the result of a buildup of cells that do not work properly • Some mutations effect cell division which results in cells either dividing rapidly or not dividing at all.

22. 3 types of Mutations: • Point Mutation – A change in a single base pair Ex. CAT to CAR = incorrect Amino Acid (replaced) • Frameshift – A single base is either addedor deleted. Results in an entirely new amino acid sequence. (addition or deletion) • Chromosomal – Affect the distribution of genes to gametes during meiosis. They cause non-disjunction: the failure of chromosomes to separate

23. All 3 mutations will cause defective proteins to be produced • Cells or organism with mutation will not work correctly • Cells or organism with mutation may die

24. Causes of Mutations • Many occur naturally • Materials causing mutations are called mutagens. • May be influenced by the environment: 1. Chemicals 2. Ultraviolet light 3. Radiation ( large amt. of energy = bursts DNA) 4. High temperatures

25. Assignment • Mini Lab pg 306 • Do a lab write up, answer the analysis ?’s 1-3 and write a conclusion statement. • Problem Solving lab – pg 305 • Answer the Thinking Critically Questions 1-4