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UNIT 3.1 - GENETICS. Cell DIFFERENTIATION AND SPECIALIZTION. Student Expectation 5C - describe the roles of DNA, ribonucleic acid (RNA), and environmental factors in cell Differentiation. Student Expectation 6D - recognize that gene expression is a regulated process .
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UNIT 3.1 - GENETICS Cell DIFFERENTIATION AND SPECIALIZTION Student Expectation 5C-describe the roles of DNA, ribonucleic acid (RNA), and environmental factors in cell Differentiation. • Student Expectation 6D- recognizethat gene expressionis a regulated process.
Part A. Specialized Cells • Cells with a specific structure and function Ex: Blood Cell, leaf cells
Cell Differentation • the process of converting stem cells into specialized cells in multicellular organisms Stem Cells • a cell that can differentiate (develop) into a specialized cell
1. How do cells decide what cells they will become? • “Transcription Factors” are proteins produced by the cell that tell the cell what genes to turn on • They direct the modification of the cell’s structure • Allow the cell to begin carrying out specialized functions
EXAMPLE: Female vs male embryo • Before four weeks of age, all fetuses are exactly the same. • Around 4 weeks a special protein called Sex determining Region Y (SRY) which starts producing hormones and proteins that will make a male become male.
2. What is the Role of DNA in cell differentation? • Segments of the DNA code for the proteins that make specialized cells • – Segments not needed are coiled tightly around histones
3. What is the role of RNA in cell differentation? • Role of RNA • – RNA assemble proteins through TRANSLATION based on the “code” from DNA
Watch the video below about Stem cells and be prepared to answer quetsions • http://Stem Cell Video
Topic B. Gene Expression • Now that the stem cells has differentiated and become a specialized cell, it must be told which genes to produce! • Gene • Sections of DNA that code to make specific proteins • Gene Expression • A gene is expressed when it is used to make proteins
6. How are genes activated or suppressed? • RNA Polymerase must be able to bind to the DNA in order for genes to be expressed. • Regulatory genes allow or suppress the expression of another gene
7. E.Coli • Eats whatever we eat • Lipids • Proteins • Carbohydrates • Creates enzymes to digest food depending on what we eat.
8. Positive Gene Regulation • When we drink milk, E.coli must produce lactase in order to digest lactose. • It does that with something called the lacoperonwhich codes for lactase Lac operon The gene that codes for lactase and can only be activated when lactose is present
9. The lacoperon a section of DNA above the gene to be expressed that allows RNA polymerase to bind to the DNA Regulatory gene =
10.What happens to the lacoperon when NO milk is present? • No lactose =repressor protein is active = lactase is not made
11. What happens to the lacoperon when milk is present? • Milk present = repressor protein falls off = gene is expressed = lactase is made. • The E.coli can now digest the milk you just drank!
12. How do eukaryotes regulate genes? • Eukaryotes like humans do not need to rely on operons like bacteria, instead they use transcription factors which operate as activators and repressors Transcription Factors • Proteins that bind to DNA sequences, controlling the transcription of genetic information to RNA.
13. How can the environment influence gene expression(action)? A. Poor nutrition can affect the height that a person grows regardless of genetic disposition
B. Drugs and Chemicals can inhibit protein production Ex: Thalidomide was a drug distributed in the 1950s to help women with morning sickness. One side effect was that it interfered with the limb development, causing some babies to be born without arms
C. Low temperatures can cause Himalayan rabbits to produce black pigment in their skin
E. Neighboring cells can send signaling proteins to alter gene
14. What influences cell differentation more? DNA or the environment? • It depends on the case. • Both Genetic (DNA) and environmental factors influence development but not always equally
15. Gene Expression LARP • A. What are the three different types of cells • B. What does each of the chromosomes code for? • 1. 2. 3. • C. How did the cell know which chromosome should be activated?
