Ch 16: Molecular Basis of Inheritance Ch 17: From Gene to Protein Ch 18: Control of Gene Expression Ch 18: Gene Mutation

1928 Involved 2 strains of bacteria that caused pneumonia Key concept: Transformation

(1944) They were able to identify DNA as Griffiths transforming principle. Took extract (from heated smooth bacteria) and treated it with DNAase (digests DNA) - then mixed with rough bacteria and injected into rats -> the rats lived. In other side of experiment, treated extract with protease (digests proteins) -then mixed with rough bacteria and injected into rats -> rat died. This showed that DNA, not protein, has ability to transform cells.

Scientists were able to discover that DNA was responsible for containing the genetic information responsible for an organisms biochemical make up.

1950 Rules of base pairing Number of A ’ s = number of T ’ s Number of C ’ s = number of G ’ s If in a DNA molecule there were 23% A, What is the % of G? 1950 Rules of base pairing Number of A ’ s = number of T ’ s Number of C ’ s = number of G ’ s If in a DNA molecule there were 23% A, What is the % of G?

Worked with Maurice Wilkins. Process called x-ray diffraction is what ultimately proved the Double helix of DNA. Died in 1958 of ovarian cancer, most likely caused by the radiation she worked with.

Built the first model of DNA. Work based on previous data, including Franklin ’ s. Also provided the explanation for how DNA replicates.

Components: – Sides – Rungs – Purines and pyrimidines Nucleotides Semi-conservative Replication

Enzymes: – DNA Helicase- “ unzips ” DNA/unwinds strand. Replication fork formed here. – Leading strand. – RNA Primase- RNA primer to get replication going. – DNA Polymerase- “ attaches ” DNA nucleotides to template. – Lagging Strand – Okazaki Fragments- chunks of lagging strand – DNA Ligase- links Okazaki fragments together

One Gene / One Enzyme Hypothesis: – Genes control the production of enzymes. – Disorders such as PKU and albinism examples. – One gene / one protein (as not all enzymes are proteins) -> one gene / one polypeptide. DNA found in nucleus, protein synthesis occurs in cytoplasm. RNA must be transcribed from DNA and travel from the nucleus to cytoplasm.

Sugar is Ribose Uracil replaces Thymine Single stranded Three Types: – mRNA- carries message for what protein should be made from the nucleus to cytoplasm. – tRNA- transfers amino acids to ribosomes to build the polypeptide. – rRNA- along with proteins, makes up ribosomes.

Occurs in the nucleus; mRNA is made. Labeled mRNA has been photographed leaving nucleus. mRNA carries the code for what proteins are needed. Codons – Sequence of 3 bases coding for aa ’ s. – 64 possible combinations of bases; some aa ’ s have multiple codons. – 61 code for aa ’ s; 3 are stop codons.

Promotor site, coding region, termination site. RNA Polymerase is multi-functional. Introns and Exons: – Introns are intra-gene segments that are NOT expressed in the final protein. Removed by rybozymes. Occurs in nucleus. – Exons ARE expressed in final protein. Leave nucleus as a mature mRNA molecule.

Occurs in cytoplasm when mRNA joins with a ribosome and tRNA molecules. mRNA is translated/converted into a polypeptide sequence. Remember, this is a proteins primary structure!

Initiation – Ribosomal subunits join together at the start codon AUG; tRNA connects to mRNA to begin process. Elongation – Polypeptide lengthens; a ribosome can accommodate 2 tRNA ’ s. Termination – Occurs when ribosome reaches stop codon; no amino acid is coded for. Ribosome dissociates.

Eukaryotic Cells mechanisms grouped by where they occur. Transcriptional Control – Nucleus- rate at which transcription occurs. – Due to organization of chromatin and transcription factors that get things going. Post-Transcriptional Control – Nucleus- rate of processing of introns/exons and rate that it leaves the nucleus.

Translational Control – Cytoplasm – Life expectancy of mRNA, ability to bind to ribosomes Post-Translational Control – Cytoplasm – Further modification of the polypeptide produced.

Operon – A series of genes that code for specific products and the regulatory elements that control those genes. Composed of several parts.

Promoter – Sequence of DNA where RNA polymerase attaches. Operator – Sequence of DNA where a repressor protein can attach. – It is coded for by a regulator gene – When a repressor protein is attached here, transcription does not occur.

Structural Gene – One or several genes that code for enzymes. – When transcribed, metabolic pathways are active Regulator Gene – Located outside the operon. Codes for a repressor protein that binds to an operator, in turn regulating the activity of a structural gene.

An alteration in the normal sequence of DNA. A substance that causes an alteration in the normal sequence of DNA. The organism that causes an alteration in the normal sequence of DNA.

Type of mutation where only one base in the DNA sequence is changed. Ex: The dog ate the cat The dog ate the car KEY: mild to severe mutation. Could result in a different Amino acid being put into the protein (sickle cell anemia)

Type of mutation where a base is added or deleted in the DNA sequence and every codon from that point on is changed. Ex: The dog ate the cat Thd oga tet hec at KEY: the protein will be non-functional, probably resulting in death of the organism.