Protein Synthesis DNA to Proteins

Biochemical DNA –made of 3 component parts Chromosome –DNA + protein (sugar, phosphate, bases) Information is stored by the sequences of the bases Chromosome –DNA + protein Gene –certain area of chromosome where the bases are sequenced to store information for ONE protein Protein – made up of number of amino acids

Inheritance Genotype – combination of two alleles Phenotype – expression of a particular trait Influenced by Genotype Environment

Biochemical and Inheritance How does one get from a particular genotype (coded for in the genes) to the expression of it in the phenotype Connect both biochemical to inheritance knowing that expression of a traits phenotype is influenced by proteins sometimes a phenotype = a protein PKU, albino, ALD

Protein Proteins – What do they do? ‘workhorses’ of the cell Once a protein is synthesized it can combine with other proteins to perform a particular function Three classes of proteins Structural – support in the cell like the muscle cell building block, myosin Regulating proteins - including enzymes and hormones, like the enzyme that breaks down starch molecules, salivary amylase Transporter proteins – like the oxygen transporter, hemoglobin

Protein They are so important in the cell much of the cellular machinery is concerned with translating the genetic information of DNA into specific proteins.

How does information in one section of DNA coding for a particular trait become a protein (sequence of amino acids)?

Involves RNA RNA differs from DNA Sugar is ribose (DNA deoxyribose) One more oxygen in RNA sugar RNA has the base uracil (DNA has thymine) Single stranded (DNA double stranded) RNA is smaller and more of it RNA can go between nucleus (eukaryotic) and cytoplasm (DNA in nucleus only of eukaryotic)

Involves RNA Three kinds of RNA mRNA tRNA rRNA

Two Processes 1) Transcription – synthesis (formation) of an RNA molecule (mRNA) using the genetic information in DNA Copying DNA to RNA 2) Translation – the actually manufacturing of a protein (putting together amino acids from the information in the mRNA molecule Using RNA to assemble the polypeptide

Generally: How and Where The genetic information in a particular region of DNA (gene) is TRANSCIBED (copied) to produce a specific molecule of RNA (mRNA) This occurs in the nucleus (eukaryotic organisms)

Generally: How and Where The mRNA proceeds from the nucleus into the cytoplasm to a ribosome Here the information is TRANSLATED into a corresponding specific sequence of amino acid’s to form a newly produced protein molecule (involves tRNA & rRNA)

Step 1) Transcription Production of mRNA mRNA molecules (nucleotides) are put together from the sense strand of DNA The RNA bases are complementary to the nucleotide sequence of the DNA strand One substitution thymine is uracil

Step 2) Translation mRNA becomes associated with a ribosome (rRNA) this is where translation occurs. The ribosome slowly moves along the length of the mRNA molecule As it moves along the ribosome ‘reads’ the information in the mRNA molecule ‘word by word’ Each word consists of 3 adjacent nucleotides (codon) in the mRNA

Continue Translation Each sequence of 3 nucleotides (codon) triggers the addition of a specific amino acid Amino acids are bonded by a particular type of bond – Peptide Many protein bonds = polypeptide chain or a protein

Continue Translation tRNA Actually does the translating The Dictionary Recognizes the codons by having at their ‘business end’ an anticodon The other end has an amino acid attached to it that is specified for that particular anticodon Therefore 3 base codon in mRNA specifies a particular amino acid

Continue Translation There are 20 amino acids (the building blocks of proteins) Each one is signaled by at least one codon, most by several codons NOTE: most synonyms are identical in their first 2 nucleotides and differ only in their third positions Important to note for when we discuss miscopying! NOW PRACTICE!!!