Gene Regulation

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Gene Regulation

• How does a cell known what gene to express at a
  given time?
• 12-5

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By the end of this lesson, you should be able to

1. Describe a gene
2. Explain how prokaryotes control gene expression
   by looking at the lac gene
3. Explain how eukaryotes control gene expression
4. Relate gene expression to development

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Entrance Question

• Compare the function of RNA DNA

RNA Function DNA Function
Synthesizes (makes) proteins Holds all of the cells instructions for making proteins
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Now, think about this.

• Do all of your cells hold the same DNA?
• Do they all have the same instructions?
• Do they all know how to make every protein your
  body needs?
• Are they all making every possible protein that
  you need all of the time?
• How does each cell know what protein to make and
  when to make it?

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Prokaryotic Gene Regulation

• Escherichia coli - (E. coli), is a bacterium that
  is commonly found in the lower intestine of
  warm-blooded animals. Most E. coli strains are
  harmless, but some can cause serious food
  poisoning in humans, and are occasionally
  responsible for costly product recalls. The
  harmless strains are part of the normal flora of
  the gut, and can benefit their hosts by producing
  vitamin K2, or by preventing the establishment of
  pathogenic bacteria within the intestine.

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Lac geneImportant Vocabulary

• Operon a group of genes that operate together
• Promoter location on the DNA that is the
  binding site of the RNA polymerase

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Lac GeneImportant Vocabulary

• Repressor normally turns off the expression of
  the lac gene so RNA polymerase cant bind to the
  DNA in the O region
• Lactose a sugar that, if present binds to the
  repressor causing it to move from the gene so RNA
  polymerase can bind and the lac gene is expressed

O region Operator the region on the DNA that
controls gene expresssion by turning on or off
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Eukaryotic Gene Regulation

• MUCH MORE COMPLEX!!!!
• What were introns and exons?
• What else looks different?

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Differences

• Operons are not present
• Instead they have
• TATA box marks the beginning gene position for
  the RNA polymerase
• Enhancer sequences areas on the DNA before the
  gene that regulate gene expression when proteins
  bind to it

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Development and genes

• As you grow from a zygote to your size today,
  your cells
• Divide
• Differentiate become specialized and take on
  different functions
• What controls differentation?
• Your hox genes special genes that control what
  parts of the body individual cells and tissues
  will develop into
• What would happen if the hox genes were mutated?

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Dr. Herricks Case Study

• In 1904, a student from the West Indies came to
  the Chicago physician with a puzzling condition
• He feels well most of the time but reports odd
  reocurring events like.
• One day after a short swim he became tired and
  could hardly move
• He was short of breath and had pain in his joints
  and muscles
• This lasted a few weeks and required some bed
  rest
• He also had frequent fevers and infections
• Dr. Herrick examined him and noticed the whites
  in his eyes had a yellowish tint

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Dr. Herricks Case Study Contd

• His left abdominal area was tender to the touch
  and sore
• His family history shows he has two brothers and
  three sisters, none with this condition
• However, his uncle and grandpa had similar
  conditions
• His grandma died a young woman
• His parents do not have this condition
• BONUS WHAT IS THE CAUSE OF THIS??????
  IDEAS??????