Protein Synthesis DNA to Proteins Biochemical DNA made

Protein Synthesis DNA to Proteins

Biochemical • DNA –made of 3 component parts » (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 – m. RNA – t. RNA – r. RNA

Two Processes • 1) Transcription – synthesis (formation) of an RNA molecule (m. RNA) 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 m. RNA 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 (m. RNA) • This occurs in the nucleus (eukaryotic organisms)

Generally: How and Where • The m. RNA 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 t. RNA & r. RNA)

Step 1) Transcription • Production of m. RNA – m. RNA 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 • m. RNA becomes associated with a ribosome (r. RNA) this is where translation occurs. • The ribosome slowly moves along the length of the m. RNA molecule • As it moves along the ribosome ‘reads’ the information in the m. RNA molecule ‘word by word’ – Each word consists of 3 adjacent nucleotides (codon) in the m. RNA

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 • t. RNA – 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 m. RNA 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!!!