Gene Mutations
Chromosome Mutations
Mutations
Every now and then cells make mistakes in copying their own DNA- inserting an incorrect base or sometimes even skipping a base as the new strand is put together. These mistakes are called mutations. Mutations are ______in the DNA sequence that affect genetic information. Gene mutations result from changes in a single nucleotide base. Chromosomal mutations involve changes in whole chromosomes.
Gene Mutations
2 Types of gene mutations:
- Point Mutations result in the ______of a base.
- Frameshift Mutations result in the ______or ______of a base, causing different amino acids to be made.
Chromosome Mutations
4 types of chromosome mutations:
- Deletion, ______, inversion, translocation.
Think-Pair-Share!
What is a mutation?
What are the 2 classes of mutations?
Name the 2 types of gene mutations.
Name the 4 types of chromosome mutations.
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Section 12-5 / Gene Regulation: Prokaryotic & Eukaryotic
Gene Enhancement
Regulation and Development
Gene Regulation
Only some of the genes in a cell are expressed at any given time. An expressed gene is a gene that is ______into RNA (turned on/used). How does the cell determine which genes will be expressed and which will remain off? Molecular biologists have found that certain DNA sequences serve as ______(binding sites for RNA polymerase). Others serve as start and stop signals for transcription. Cells are filled with DNA-binding proteins that attach to ______DNA sequences and help regulate gene expression (turn on/off).
As we see, there is a promoter to one side of the gene. But what are the “regulatory sites” next to the promoter? These are places where other proteins can attach to regulate transcription. The actions of these proteins help to determine whether a gene is turned on or off.
/ Prokaryotic Gene Regulation
Lac operon genes are found in certain ______and help them to use lactose as food. If lactose is present the lac operon will turn the gene ___ as RNA Polymerase binds to the promoter.
After the lactose food is used up, the gene is turned off by a Repressor Protein binding to the ______.
Repressor proteins stop gene transcription by ______the DNA strand so that RNA Polymerase cannot read it.
The lac operon turns on when lactose is present because the DNA strand will ______out, causing the repressor protein to fall off. RNA polymerase then attaches to the promoter and can easily read the straight DNA strand.
Eukaryotic Gene Regulation
Unlike prokaryotes, eukaryotic genes do not contain ______to regulate gene expression, instead, they have a short nucleotide sequence of –TATA- for a ______site.The TATA Box helps position where RNA polymerase needs to bind to begin transcription.Short DNA Promoter sequences are found just before the TATA box to help position it correctly.
Gene Enhancement
There are special ______that bind to enhancer sequences of a gene that help to regulate gene expression in several ways:
- Many proteins can bind to different enhancer sequences at the same time = more efficient.
- Some proteins enhance transcription by opening up tightly coiled ______.
- Help attract RNA polymerase to begin transcription.
/ Regulation & Development
Gene regulation in eukaryotes is more complex than in prokaryotes because: Cell specialization requires genetic specialization. All eukaryotic cells carry the entire genetic code, each type of cell performs a different function in a different part of the body.
Hox genes control the ______of cells and tissues of developing embryos. Animals share many common patterns of development because we all share the same ______(ATGC) but have different numbers and arrangements of chromosomes.
- Example: Fruit flies can grow legs on their head if the hox gene is tampered with during development.
Think-Pair-Share!
What does it mean for a gene to be “expressed”?
What are the 2 parts in front a DNA sequence that tells a gene where to start being read?
What’s an example of a bacteria gene to digest lactose?
What genes are responsible to body plan development in embryos?