1	DNA and Gene Expression
2	DNA Deoxyribonucleic Acid Double helix Carries genetic information Located in the nucleus The monomer is a nucleotide A phosphate A ribose sugar A nitrogenous base
3	What are the bases in DNA A – adenine T – thymine C – cytosine G – guanine Base pair rules
4	Where is DNA located in the Cell?
5	Where are the genes located? Genes are located on the chromosomes. Every species has a different number of chromosomes. There are two types of chromosomes: autosomes and sex chromosomes
6	"Genes are located on the..." Genes are located on the chromosomes which are found in the nucleus of a cell. When a cell is undergoing cell reproduction, the chromosomes are visible. Chromosomes appear when the chromatin condenses and become visible. Most of the time (90%) the genetic material in the form of chromatin. A genome is the complete genetic information contained in an individual. (gene + chromosome)
7	What is gene expression? Gene expression is the activation of a gene that results in a protein.
8	Gene expression takes place differently in prokaryotes and eukaryotes. What is a prokaryotes? Eukaryotes? Prokaryotes No membrane bound organelles (nucleus) More primitive organisms Only one circular chromosome Bacteria are the only organisms that are prokaryotes. Eukaryotes Membrane bound organelles ( specialize in function –nucleus, mitochondria, chloroplast) Chromosomes are in pairs and not circular All organisms that are not bacteria: protist, fungi, plants and animals
9	"In Prokaryotes there are three..." In Prokaryotes there are three (3) regulatory elements that control gene expression. Structural genes – genes that code for a specific polypeptide (protein). Promoter – DNA segment that recognizes RNA polymerase. Operator – element that serves as a binding site for an inhibitor protein that blocks transcription.
10	"In Eukaryotes," In Eukaryotes, following mitosis or meiosis, DNA recoils but certain regions remain relaxed for transcription. The areas of relaxed DNA are called euchromatin. Transcription is the Reading of the DNA and Changing the code to mRNA. Translation is changing The mRNA into a trait by Using tRNA to interpret the mRNA.
11	"DNA in eukaryotes has regions..." DNA in eukaryotes has regions of coding and noncoding DNA. The regions of DNA that code for proteins or traits are called EXONS, while the regions that do not code for proteins are called INTRONS.
12	"In prokayotes," In prokayotes, transcription and translation occur in the cytoplasm. In eukaryotes, transcription occurs inside the nucleus in a two step sequence of events. Pre-mRNA includes both introns and exons for the gene. mRNA is only the coding portion (exons). Translation occurs in the cytoplasm at the ribosomes. Reminder: The are three (3) types of RNA Messenager (mRNA) Transfer (tRNA) Ribsomal (rRNA)
13	Translation RNA Single stranded Does not contain thymine but has uracil instead. tRNA carries 3 base pair code for specific amino acid. Amino acids compose polypeptid chains. One or more polypeptide chains compose a protein proteins provide the “blueprints” for our characteristics and functions.
14	Enhancer Control Eukaryote genes on a DNA strand also have noncoding control sequences that facilitate transcription. These are called enhancers. Transcription factors are additional proteins that bind to RNA polymerase and enhancers to help with transcription.
15	Cell Differentiation Cell differentiation is the development of cells into cells with specialized functions. Examples: muscle cells, liver cell, red blood cells As organisms grow and develop, organs and tissues develop to produce a characteristic form. The process is call morphogenesis.
16	Homeotic Genes Homeotic genes are regulatory genes that determine where certain anatomical structures, such as appendages, will develop in an organism during morphogenesis. These seem to be the master genes of development
17	Homeobox In Drosophila (fruit flies) the specific DNA sequence within a homeotic gene that regulates patterns of development is the homeobox. The same or very similar homeobox sequences have been found in many other eukaryotic organisms
18	Cancer Leading cause of death in the United States A genetic disease caused by a mutation in the genes that control cell division
19	"Tumor – abnormal proliferation of..." Tumor – abnormal proliferation of cells that results from uncontrolled, abnormal cell division Benign – a tumor that remains within a mass Malignant tumor- uncontrolled dividing cells that invade and destroy healthy tissue elsewhere in the body Metastasis – spread of cancer cells beyond their original site
20	Kinds of Cancer Carcinomas – grow in skin and tissues that line the organs of the body Example: lung and breast Sarcomas – grow in bone and muscle tissue Lymphomas – solid tumors that grow in tissues that form blood cells Example: leukemia
21	"In normal cells," In normal cells, that frequency of cell division is governed by several factors: Adequate nutrition Attachment to other cells, membranes or fibers Division stops if cell become crowded (usually after 20 – 50) divisions Cancer cell continue dividing and ignore the normal messages to stop dividing.
22	What Causes Cancer? Mutations that alter the genes coding for growth factors. May occur spontaneously Result from exposure to an carcinogen ( any substance that increases the risk of caner.) Usually there is more than one mutation. There are two types of genes that control cell division Proto-oncogens Tumor suppressing genes (p53 gene)