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.

• 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…..