Gene Regulation

Gene Regulation The ability of an organism to control which genes are expressed in response their environment: 1.Conserve energy and raw materials 2.Occurs as needed based upon changes in the cells internal and external environment. Protein synthesis and external factors

Gene Regulation ProkaryotesEukaryotes Simpler process Uses operons Xtra pieces of DNA Contains genes Much more complex system Uses regulatory proteins called transcription factors regulatory DNA such as a promoter (TATAAAA) Eukaryotic regulation

Eukaryotes- Gene Regulation Very Complex and individualized different cell types, each with their own needs, based upon their function. 2.Multiple chromosomes with 20,000-25,000 genes in a human that code for proteins.

Eukaryotic Gene Regulation There are many different factors involved in gene regulation. For example: 1. Accessibility to a gene Controlling the coiling of chromatin around the histones make gene inactive- note expressed. Uncoiling the chromatin make gene active. 2. Enhancer- contains DNA regulatory genes- work with Transcription factors. (proteins) 3. Transcription Factors- various types of proteins that can facilitate the following; opening th

Eukaryotic Gene Regulation 3. Transcription Factors -various types of proteins that can facilitate the following: a. opening the tightly coiled chromatin b. bend the DNA molecule to position the enhancer closer to the promotor. c. attract RNA polymerase d. block access to the promotor/gene 4. Promotor – Start region of the DNA 5. TATA box – 30 base pairs long-.helps position the RNA polymerase to the promotor.

mRNA Processing The DNA molecule and a gene contains extra nucleotides that do not code for a protein. These extra nucleotides are sometimes called “Junk DNA”. They can be remnants from our evolutionary past or contain genetic information that was brought in by viruses. DNA is universal

If a Chocolate cookie recipe represented a gene: INGREDIENTS: 1 cup butter, softened1 ½ cup white sugar inch nails½ cup chopped walnuts 2 eggs2/3 cup cocoa 2 teaspoons vanilla extract 2 cups all-purpose flour 4 yards of taffeta 3/4 teaspoon baking soda 1/4 teaspoon salt 2 cups semisweet chocolate chips 6 cubic feet of fine sand Would these cookies be edible? Function as intended?

MRNA Processing A gene contains both introns and exons. An intron is region of DNA or RNA that does not code for a protein. (remnants from our evolutionary past or DNA from viruses). An exon is the protein coding part of a gene.

mRNA Processing occurs after transcription in the nucleus. 1. Cuts out the introns 2. Splices the exons together. Next… additions: 1. A cap- G nucleotide is added to the spliced mRNA. 2. A tail- 50 – 250 A’s are added. The cap and tail: Facilitate the export of mRNA from the nucleus Protect mRNA from enzymes in the cytoplasm Help mRNA bind to the ribosome Composed of Enzymes and RNA

Prokaryotes An “Operon” controls the transcription of genes In response to changes in the environment. Gene Regulation occurs at the beginning of Transcription

Operon Operon- an entire gene regulating system in a prokaryote. It includes; promoter, operator and all corresponding genes.

Parts of an Operon 1.Operator- segment of DNA acts like an on/off switch 2. Promoter- location on DNA where RNA polymerase binds 3. Regulatory gene- makes a protein 4. Genes -codes for proteins- like enzymes

Lac Operon E. coli (bacteria) Lac Operon --controls the digestion of lactose -- an energy source

Lac Operon Contains: Operator- on /off switch (DNA) Promoter- Where RNA polymerase binds Regulatory gene- codes for a protein called a repressor 3 enzyme genes- which control the digestion of lactose

Lac Operon The regulatory gene makes a repressor protein. The Repressor binds to the promoter blocks RNA polymerase Prevents transcription of the digestion enzymes

Lac Operon Inducer- prevents the repressor from binding to the promoter RNA polymerase binds Transcription occurs. Inducer- found in food that contains lactose

1. When lactose is present, the inducer binds to the repressor and inactivates it. 2. RNA polymersase binds to promoter 3. Transcription of digestive enzymes occurs.

Lac Operon- animation Bozeman Biology Operon