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| What are mutations? | They're changes in the genetic material. Sometimes cells make mistakes in copying their own DNA, inserting an incorrect base or skipping one. |
| What's the difference between gene mutations and chromosomal mutations? | A gene mutation produces changes in a single gene; those that produce changes in whole chromosomes are chromosomal mutations. |
| What are point mutations? | They're gene mutations involving changes in one or a few nucleotides because they happen at a single point in the DNA sequence. Substitutions, insertions & deletions are included. |
| What are frameshift mutations? | They're mutations that shift the "reading" frame of the genetic message by inserting or deleting a nucleotide. By doing that, every amino acid that follows the point of the mutation changes; it can alter a preotein so much that it can't perform its normal functions. (see examples on 307) |
| What happens when a chromosomal mutation involves deletion. | All of part of a chromosoms is lost, while duplications produce extra copies of parts of a chromsome. |
| What happens in chromsomal mutations when inversions are involved? | Inversions reverse the direction of parts of chromosomes. |
| What happens in translocations of chromosomal mutations? | One part of a chromosome breaks off and attaches to another. |
| What are 3 possible repercussions of mutations? | 1) Many have little or no effect of the expression on genes of function of proteins coded; 2) Some cause dramatic changes in protein structure or gene activity; 3) Some are sources of genetic variability in a species, and some of those can be beneficial. |
| What is meant by polyploidy? | It's the condition in which an organism has extra sets of chromosomes. (see examples on 308) |
| What is an expressed gene? | Its a gene that is transcribed into RNA. |
| What are regulatory sites? | They're places where other proteins, binding directly to the DNA sequences at those sites and regulate transcription. This helps determine whether a gene is turned on or off. |
| What is meant by an "operon"? | It's a groups of genes that operate together. (E. coli example on pg. 309 & picture on 310) |
| What do scientists know about turning lac genes on and off? | Lac genes, found in prokaryotes, are turned off by repressors and turned on by the presence of lactose. |
| What is the operator? | It's a region to which a repressor can bind, preventing transcription of the genes. |
| How are most of the eukaryotic genes controlled? | Most are controlled individually, and they have regulatory sequences that are much more complex than those of the lac operon found in prokaryotic genes. (See pg. 311 about the expression of available genes in the cells of different tissues.) |
| What is the TATA box? | It is a short region of DNA before the start of transcription; it seems to help position RNA polymerase by marking a point just before the point at which transcription begins. Eukaryotic promoters are usually found just before this TATA box. |
| What is the main reason that gene regulation in eukaryotes is so complicated? | An enormous number of proteins can bind to different enhancer sequences (which are found before the point at which transcription begins. |
| What is differentiation? | It's the process in which cells become specialized in structure and function. |
| What is the function of hox genes? | They control the differentiation of cells and tissues in an embryo. If there is a mutation in these genes, there can be a complete change in the organs that develop in specific parts of the body. (see Drosophila example on pg. 312) |
| Explain what a promoter is. | Its an area of mRNA where the RNA polymerase binds and then starts the process of transcription. |
