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.
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)
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?
Regulator codes for a repressor • Pg 218 • If lactose is not present – repressor is located on the operator (preventing RNA polymerase to transcribe.
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
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
Cancer • Read page 225
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
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
Linked genes • Close together and on the same chromosome, called linkage groups
Gene Map • Rough estimation Of distances b/w genes.
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?
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?
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
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
Web • http://learn.genetics.utah.edu/content/disorders/whataregd/
12.2 • Pedigree • Map of generations phenotypic inheritance • Male square, female circle
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
Look at Disorders http://learn.genetics.utah.edu/content/disorders/whataregd/
Read Gene Therapy • This will be our next chapter…..