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…..
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