Gene Expression

1. Gene Expression General Biology Name______________________

2. _______ _____of Molecular Biology • DNA determines a cell or organism’s ______ • physical (the structures of a cell or organism) • Physiological (how a cell or organism acts) • Possibly behavioral traits (how an organism acts) • You know that DNA contains a code, but how does DNA’s code actually do anything? ____ __________ _____

3. Gene Expression needs _____ • Gene Expression = How ______result from _______. • DNA is stored and protected in the ______ in eukaryotic cells. • Proteins are built at the _______which are outside the nucleus. • RNA acts as a go-between to get DNA’s message out of the nucleus to where it can be used to build proteins.

4. What is a gene? • A gene can be defined in several ways: • A unit of _________ which can pass on traits by cell reproduction • A section (segment) of DNA that holds the code for the production of an _______ molecule • A section (segment) of DNA that holds the code for a ______________ or ________ • A section (segment) of DNA that holds the code for a _________ (or part of a trait)

5. What’s RNA? How is it different from DNA? • RNA = _____________________ • Made of ___________ • Each nucleotide has a phosphate, sugar and Nitrogen base • ___________ Stranded • Three types: _______________ • Is able to leave the nucleus • Contains the Nitrogen Bases ______________ • Uracil instead of Thymine

6. There are 3 types of RNA ________ ________ ________

7. Protein Synthesis • Building Proteins (protein synthesis) takes place in two major steps: _____________(in the nucleus) then ___________(at the ribosomes)

8. Transcription • =Building ______using ______as a template. • Takes place in the __________. • Uses an Enzyme called _________________. • Click DNA  RNA  protein  trait

9. Steps of Transcription • DNA _________& the DNA base pairs separate at the location of the gene to be expressed. • The enzyme RNA polymerase builds an RNA strand that is ______________to one side of the DNA at the gene location. • When it’s finished the RNA can ________the nucleus and the DNA returns to normal.

10. Transcription Practice*Don’t forget – use U instead of T EXAMPLE 1. • DNA: T A C C C A A G G C CC A T T • mRNA: ___________________________ EXAMPLE 2. • DNA: T A C G G C A T A G C G A C T • mRNA: _____________________________

11. How does the RNA message get translated into a protein? • Every 3 nucleotides on a mRNA is called a _______. • Each codon codes for a particular _________.

12. mRNA codon Chart 3rd

13. Translation • =Building a _________(polypeptide) using RNA as a template. • The RNA message is “decoded” or “translated” by building a protein. • Takes place at the _____________. • Click DNA  RNA  protein  trait

14. Proteins • ___________ have many functions and make up many structures in cells and organisms. • __________are the monomer units of proteins. • The polymers are called ____________ (chains of amino acids connected by covalent bonds called peptide bonds) • Once the polypeptide is properly ________and is functional, it can be called a PROTEIN.

16. Proteins are made of amino acids Amino Acid Polypeptide An immature polypeptide folds to become a functional PROTEIN Proteins differ from each other by which amino acids they contain and what order they are in. folds polypeptide protein

17. Practice: Translation EXAMPLE 1. • mRNA: A U G GG U U C C G GG U A A • Polypeptide: ____________________________ EXAMPLE 2. • mRNA: A U G C C G U A U C G C U G A • Polypeptide: ____________________________

18. Steps of Translation 1 2 3 • The ribosome attaches to the mRNA. • As the mRNA moves through the ribosomes, the tRNAs bring in the amino acids one by one and they bond to each other to form a long polypeptide chain. • The tRNA’s are recycled. • When the polypeptide is finished it is released and the mRNA is recycled.

19. Summary of Protein Synthesis (Gene Expression)

20. Mutations • Despite proofreading, sometimes mistakes are made when the DNA is copied. • _________= a spontaneous change in the DNA code. • ____________change the genetic code in a single gene (one or a few nucleotides). This may cause the gene to make a different protein or a nonfunctional one. This could change the resulting trait. • Mutations are _______ always bad. Some may be helpful or neutral (no effect).

21. What causes mutations? • Sometimes mutations are just errors that occur during the DNA replication process • Sometimes cells can ________ the damage, but when they cannot, the DNA base sequence changes permanently. The cell may die or malfunction. • Some mutations arise from ___________ • Mutagens are chemical or physical agents in the environment • Some chemicals • Radiation (UV light, gamma rays, x-rays) • Some viruses (ex. HPV) • In sexually reproducing organisms, mutations only pass on to the next generation if they occur in the sex cells.

22. Gene Mutations: Types of Point Mutations

23. _______Mutations • ____________Mutations • Addition/Insertion: One or more nucleotides is __________/inserted into the gene • Deletion: One or more nucleotides is removed/____________ from the gene • ____________: One or more nucleotides is substituted or swapped with a different nucleotide.

24. Sickle Cell Anemia: An example of a Substitution Mutation

25. Types of _________Mutations Chromosomal mutations involve a change in the number or structure of chromosomes. Chromosomal mutations involve larger sections of the genome than point mutations do.

26. Chromosomal Mutations • ____________: Part of the chromosome is deleted • ____________: One or more gene(s) on the chromosome gets duplicated (repeated) • ____________: Parts of a chromosome are reversed • ____________: Part of one chromosome breaks off and attaches to another chromosome.

27. Do Genes Control everything? • No…a cell/organism’s DNA is only part of the story. • Gene expression can be heavily influenced by ____________factors. • Nature vs. nurture argument

28. Does every section of the genome (DNA) code for something? • Not necessarily… • Genesare known as “________” regions, since they code for polypeptides and determine traits. • Scientists used to think that most of DNA’s code was made up of “non-coding” regions. These regions apparently did not code for any polypeptides. • Recent studies suggest that much of the ‘noncoding’ regions are important in _____________the expression of the ‘coding’ regions. • Simpler organisms (ex. Sponges) have _______non-coding regions than more advanced organisms (ex. Humans)

29. Does every cell express every gene in the genome? • Not necessarily. • A cell will only express the genes that it needs for its own particular traits. • Each organism started life as just one cell. During the development process, an organism’s cells become more and more _______________and specialized for particular functions. This is called _______________ ___________________

30. Differentiation in C. elegans • A fertilized egg develops into an adult worm after many cell divisions. Daughter cells from each cell division follow a specific path toward a role as a particular kind of cell. This involves each cell type expressing (making proteins from) only the genes it needs.

31. _________Cells • Stem cells are _____________cells. • They can specialize to become any type of cell in the body. • Early embryos are made entirely of embryonic stem cells. • Adults also have some stem cells for example in bone marrow.

32. ______________Combine an egg cell with a donor nucleus to make a cloned embryo

33. _________ _________Use normal genes to add to or replace defective genes

34. ___________ _________ • GMO = Genetically Modified Organism click • Ex) GM Glowing Animals click • Ex) GM crops - ex) insect resistance • EX) GM bacteria producing insulin and growth hormone • There are some concerns about the unintended consequences that a shift to GM farming and ranching may have on agriculture. click • Many (not all) companies label foods so consumers can decide whether or not to use GM products