HOW GENES ARE CONTROLLED Chapter 11

Transcription (DNA to RNA) occurs in nucleus Translation (RNA to protein) is rapid; can make an average-sized polypeptide in less than a minute Overall = DNA RNA PROTEIN REVIEW

Every body cell has the same DNA as zygote How do cells become different from another if all contain identical genetic instructions? HOW GENES ARE REGULATED

Operon – – Promoter – – Operator - GENE EXPRESSION IN PROKARYOTES

Requires elaborate regulation of gene expression since so complex Process can be turned on or off, as well as sped up or slowed down, during multiple points of protein synthesis GENE REGULATION IN EUKARYOTES

Flow of genetic information from chromosome to an active protein Each control knob indicates a gene expression “knob” “PIPELINE” ANALOGY

In multicellular organisms, the process of gene regulation can cross cell boundaries Cell can produce and secrete chemicals (like hormones) that affect gene regulation in another cell CELL SIGNALING

Affects our anatomical structures HOMEOTIC (HOX) GENES

Oncogene – Proto-oncogene – – Change in growth factors can cause cancer Tumor-suppressor gene – GENETIC BASIS OF CANCER

Carcinoma Sarcoma Lymphoma TYPES OF CANCER

Risks: – Carcinogens 1 substance known to cause more cases and types of cancer than any other is tobacco – “Inherited” cancer Prevention – Diet (some food reduce risk) – Reduce exposure to carcinogens – Regular checks CANCER RISK & PREVENTION