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11.1 Gene Regulation

11.1 Gene Regulation. Only a fraction of the genes in a cell are expressed at any given time. Expressed genes are genes that were transcribed to the RNA. Certain DNA sequences act as binding sites for RNA polymerase, and start and stop signs for transcription.

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11.1 Gene Regulation

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  1. 11.1 Gene Regulation • Only a fraction of the genes in a cell are expressed at any given time. • Expressed genes are genes that were transcribed to the RNA. • Certain DNA sequences act as binding sites for RNA polymerase, and start and stop signs for transcription.

  2. Every cell can express different genes. • Pancreas secretes many digestive enzymes, amylase, that help break down starches. Expression of this genes allows it to function. Our marrow cells would not need to have this protein produced. • Morphogenesis (cell differentiation, cell specialization)

  3. Expression in Prokaryotes • Operon – series of genes • Pg 218 • E. Coli • The lac genes are turned off by repressors and turned on be the presence of lactose. • What happens if there is no lactose?

  4. Regulator codes for a repressor • Pg 218 • If lactose is not present – repressor is located on the operator (preventing RNA polymerase to transcribe.

  5. In Eukaryotes • TATA box – a warning to the RNA Polymerase. • Introns (bad) and Exons (good) • Around 28-30 base pairs long • Helps the Genome project

  6. Regulation and Development • Homeotic Gene • Control the organs and tissues, and determine the basic body plan of animals. • Homeobox – a certain sequence for “hox genes” • Pg 224

  7. Cancer • Read page 225

  8. 12.1 Inheritance and Human Genetics • Sex Chromosomes – X or Y • Male XY, Female XX • Autosomes 1-22 • Germ Cell vs. Somatic Cell • SRY – on the Y chromosome (sex-determining region

  9. Sex linked genes and traits • If on the X chromosome – most females are carriers and males express the trait • X Chromosome inactivation in females. Form barr bodies in females

  10. Linked genes • Close together and on the same chromosome, called linkage groups

  11. Gene Map • Rough estimation Of distances b/w genes.

  12. In your Notes • Write TACAATGCTCAAACT • 1. mRNA Strand to match • And Decode • Replace 3rd A with a C • Now Transcribe and translate again. • What happened? • What type of mutation?

  13. Write same DNA sequence again • Now insert a T after the 2nd T in the DNA strand • What does that do to the amino acids produced? • What type of mutation is this?

  14. Mutations • Gene mutations – single gene • Point mutation is a mistake on just one nucleotide • Nucleotides can be deleted or inserted (pg 307) • Frameshift mutation This is an example of sickle cell: Substitution

  15. Chromosomal Mutations • Changes in the number or structure of chromosomes. (locations of genes, number of copies of genes) • Deletion • Duplication • Inversion • Translocation • Nondisjunction (too few or too many chromosomes

  16. Web • http://learn.genetics.utah.edu/content/disorders/whataregd/

  17. 12.2 • Pedigree • Map of generations phenotypic inheritance • Male square, female circle

  18. Complex characteristics – not just genetic but also environmental. • Height, personality, skin color, health in general Multiple alleles – blood type, fur color Polygenic – skin color, eye color Codominance – both expressed – AB blood, roan cow Incomplete dominance – share X – linked – most recessive, on X

  19. Look at Disorders http://learn.genetics.utah.edu/content/disorders/whataregd/

  20. Read Gene Therapy • This will be our next chapter…..

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