Protein Synthesis

Protein Synthesis

Levels of Genetic Organization

Macromolecules of Evolution Nucleic acids are the instructions for making proteins, proteins make up traits, and traits that are best fit for the environment are passed on. • Nucleic Acids - DNA and RNA • universal code (blueprints) for making proteins • inherited genetic information

Macromolecules of Evolution Nucleic acids are the instructions for making proteins, proteins make up traits, and traits that are best fit for the environment are passed on. • Proteins - determine physical traits • structure - materials for building cells • function - a. carry substances throughout the body, in & out of cells • b. trigger muscle movements c. assist with all chemical reactions in the body d. protect the body against disease

Nucleic Acids Nucleotides are the building blocks of nucleic acids. 

Nucleic Acids • Nucleotides bond together to form nucleic acids • a phosphate group of one nucleotide attaches to the sugar of another nucleotide (covalent bond) • bases bond with complimentary bases (hydrogen bond)

DNA Replication • A half of the DNA ladder is a template to make a copy of the whole • Occurs before cell division – mitosis or meiosis

DNA Replication A G C T T C G A A G C T G T C G A C A G C T C G A C A G C T G T C G A C A G C T G T C G A C • DNA Synthesis • The DNA bases on each strand act as a template to synthesize a complementary strand • Recall that Adenine (A) pairs with thymine (T)and guanine (G) pairs with cytosine (C) • The process is semiconservative because each new double-stranded DNA contains one old strand (template) and one newly-synthesized complementary strand

DNA Replication • 3’ end has a free deoxyribose • 5’ end has a free phosphate • DNA polymerase: • can only build the new strand in the 5’ to 3’ direction • Thus scans the template strand in 3’ to 5’ direction

DNA Replication DNA polymerase • Initiation • Primase (a type of RNA polymerase)builds an RNAprimer(5-10 ribonucleotides long) • DNA polymerase attaches onto the 3’ end of the RNAprimer

DNA Replication • Elongation • DNA polymerase uses each strand as a template in the 3’ to 5’ direction to build a complementary strand in the 5’ to 3’ direction • results in a leading strand and a lagging strand

DNA Replication Determine the sequence of the developing DNA strand! Template DNA Strand Sequence: G T C T A C T T G Complementary DNA Strand Sequence: C A G A T G A A C DNA replication video…. ….and another video …and another for good measure. OK, fine. One more There are more on my website under Resources

RNA Overview RNA is the other type of nucleic acid. RNA stands for ribonucleic acid Its structure is a single strand of nucleotides RNA’s function is to decode genes within the DNA to make proteins Like DNA, it has 4 nitrogenous bases – guanine and cytosine adenine and uracil

RNA Overview 6. There are 3 types of RNA: messenger, transfer, and ribosomal

Differences Between DNA & RNA A. Sugars B. Number of strands C. Bases D. Location 1. DNA deoxyribosesugar double-stranded A-T G-C in the nucleus 2. RNA ribose sugar single-stranded A-U G-C in nucleus, cytoplasm & ribosome

Protein Synthesis Overview DNA RNA protein traits transcription translation

Protein Synthesis DNA RNA Protein Trait

Transcription In the first step of protein synthesis, ageneiscopied A half of the DNA helix is used as a template to create messenger RNA (mRNA) This occurs in the nucleus of the cell

Transcription Determine the sequence of the developing messenger RNA strand! Template DNA Strand Sequence: G T C T A C T T G Messenger RNA Sequence: C A G A U G A A C

Translation mRNA leaves the nucleus and travels to the ribosome

Translation 2. Transfer RNAs (tRNA) meets mRNA at the ribosome with the appropriate amino acids (building blocks of proteins) 3. Amino acids attach together (peptide bond) to form a polypeptide chain

Translation • a 3-base sequence of mRNA called a codon codes for a specific amino acid • a 3-base sequence of tRNAcalled an anti-codon bonds with a corresponding codon, delivering its amino acid

Translation Glu Met Asp peptide bond Use the codon chart to determine the amino acid sequence of the developing polypeptide chain!

Proteins Amino acidsbond together to make proteins. Proteins differ due to the number, kind, sequence and arrangement of amino acids. Amino acids are attached to one another by peptide bonds to form polypeptide chains. The 3D form of the protein determines its function.

Levels of Protein Structure • Polypeptide chains spontaneously arrange themselves • into 3-dimensional structures to form functional • There are four levels of arrangement from primary, • the straight chain of amino acids, to quaternary, • several polypeptide chains bonded together. 1º - a straight chain of amino acids 2º - chains bend and twist 3º - twisted chain folds even more; bonds form to hold the 3-dimensional shape 4º - Several polypeptide chains in the tertiary structure come together. This is a functional protein!

Human Genes & Proteins 46 Chromosomes (23 pairs) approximately 25,000 genes = approximately 25,000 proteins 1 protein = approx. 500 amino acids 1 amino acid = 3 nucleotides 25,000 proteins x 1500 nucleotides = 37,500,000 nucleotides If there are approx. 3,000,000,000 DNA base pairs on all 46 chromosomes, then…How much of our DNA codes for proteins? What do they call the rest of the DNA that does not code for proteins?

Protein Synthesis