Main Idea #4 Gene Expression is regulated by the cell, and mutations can affect this expression

Controlling Gene Expression Transcription Factors proteins that ensure that a gene is used at the right time and that proteins are made in the right amounts Structure of DNA the structure of DNA provides some inhibition

Mutations Mutation - a permanent change in a cell’s DNA; changes in the genetic material of a cell

Types of Mutations Point mutations chemical changes in just one base pair of a gene Can be enough to cause a genetic disorder

Point Mutation

Point Mutations Point mutations within a gene can be divided into two general categories: Base-pair substitutions Base-pair insertions or deletions

Point Mutations 1. Substitutions point mutation in which one base pair is exchanged for another Missense mutations - most substitutions are missense.The DNA code is altered so that it codes for the wrong amino acid Nonsense mutations - a substitution type that changes the codon for an amino acid to a stop codon. Cause translation to terminate early. Most always leads to proteins that cannot function normally

Missense Mutation

Nonsense Mutations

2. Insertions and Deletions Insertions and deletions involves the gain or loss of a nucleotide in the DNA sequence Insertion - additions of nucleotides to the DNA sequence Deletion - loss of a nucleotide

2. Insertions and Deletions These mutations have a disastrous effect on the resulting protein more often than substitutions do Insertion or deletion of nucleotides may alter the multiples of three from the point of insertion or deletion, producing a frameshift mutation because they change the “frame” of the amino acid sequence

Insertion

Deletion

Chromosome Mutations Large portions of DNA also can be involved in a mutation. A piece of an individual chromosome containing one or more genes can be deleted or moved to a different location on the chromosome, or even to a different chromosome. Such rearrangements of the chromosome often have drastic effects on the expression of these genes.

Chromosome Mutations Deletion (1)- results in the loss of a piece of chromosome due to the breakage of that chromosome; genetic information will be lost Duplication (2)- results in the copying of a segment of the chromosome Inversion (3)- a segment of a chromosome breaks off and reattaches itself to the chromosome in a reversed order

Chromosome Mutations Insertion (1) - a segment of a chromosome breaks off and reattaches itself to another homologous chromosome Translocation (2) - segments of chromosomes break off and exchange places on different chromosomes

Causes of Mutation 3. Mutagens Spontaneous mutations can occur during DNA replication, recombination, or repair Mutagens are substances (physical or chemical agents) that can cause mutations

Biotechnology 13

The Big Idea Genetic technology improves human health and quality of life

Main Idea #2 Researchers use genetic engineering to manipulate DNA

DNA Technology An organism’s genome is the total DNA in the nucleus of each cell DNA tools can be used to manipulate DNA and to isolate genes from the rest of the genome

DNA Technology Some bacteria contain powerful defenses again viruses. These cells contain proteins called Restriction enzymes. Restriction enzymes recognize and bind to specific DNA sequences and cleave the DNA within the sequence Scientists use restriction enzymes as powerful tools for isolating specific genes or regions of the genome.

DNA Technology EcoRI specifically cuts DNA containing the sequence GAATTC. The ends of the DNA fragments, called sticky ends, contain single-stranded DNA that is complementary.

DNA Technology The type of biotechnology in which an electric current is used to separate DNA fragments according to the size of the fragments is a process called gel electrophoresis When an electric current is applied, the DNA fragments move toward the positive end of the gel. The smaller fragments move farther faster than the larger ones.

DNA Technology The unique pattern created based on the size of the DNA fragment can be compared to known DNA fragments for identification

DNA Fingerprinting Protein-coding regions of DNA are almost identical among individuals. The long stretches of noncoding regions of DNA are unique to each individual. When regions of DNA are cut by restriction enzymes, the set of DNA fragments produced is unique to every individual. DNA fingerprinting involves separating these DNA fragments to observe the distinct banding patterns that are unique to every individual