Chapter 7 Exam 2 Flashcards
What is a mutation?
Mutations are heritable changes in the sequence of the bases in DNA. Mutations can occur in any cell. Mutations in somatic cells in the body can cause detectable changes to phenotypes and are an important cause of many types of cancer. Only mutations in germ cells that form sperm and eggs can be passed on to future generations
How does a mutation differ from damaged DNA?
Mutations can (but not always) result from Damaged DNA
What is a point mutation?
a mutation affecting only one or very few nucleotides in a gene sequence
What is a frameshift mutation?
caused by pesticides with large flat ring structures insert themselves between base pairs in the DNA helix
What are heritable changes and mutations in germ cells?
can be passed on to future generations
Cancer and mutations in somatic cells:
mutations in somatic cells in the body can cause detectable changes to phenotypes and are an important cause of many types of cancer (uncontrolled cell division)
What are silent mutations?
a change to the DNA sequence that can have no effect if they are located outside of the coding regions of genes or don’t change the protein sequence. Because of the exons in genes make up about 1-1.5% of human DNA, most mutations actually do not change the phenotype
What is the connection between DNA polymerase and mutation?
DNA polymerase and other replication proteins can repair most of the errors that they have made- they can proofread- and remove the incorrect nucleotide if it is the last one of the 3’ end
What is a mutagen?
otherwise known as chemical agents in the environment that can damage DNA. If the damage is not repaired then the altered DNA structure can lead to mutation when it is replicated
What are some types of radiation that cause damage
ultraviolet light, decay of radioactive elements (particularly radon), cosmic radiation, medical x-rays and nuclear medicine, consumer products
What are free radicals?
radiation causes direct damage to the bases in DNA or the formation of highly reactive chemical structures called free radicals that can damage DNA
What are oxygen radicals?
Oxygen radicals are very reactive and quickly form new covalent bonds with adjacent DNA, RNA, or protein molecules
What are chemical mutagens?
chemical mutagens include compounds in tobacco products, industrial chemicals, food and water, vehicle exhaust
How do geneticists identify that a new mutation has occurred?
A pedigree analysis should show that a new mutation may have occurred. DNA based genetic testing can confirm diagnosis. Phenotypes for many genetic disorders can overlap the effects of teratogens; teratogenic effects must be considered
What are X-linked recessive mutations?
a mode of inheritance in which a mutation in gene on the X chromosome causes the phenotype to be expressed either in males or in females who are homozygous for the mutation
Paternal vs. Maternal mutation:
more mutations arise in the father than in the mother and paternal age was a significant factor. Increasing paternal age increased the number of mutations
What are the human mutation rates?
about 1 error in 100 million base pairs or about 6-70 new mutations in each child. Estimated 60 new mutations per generation
What is the connection between fragile-x syndrome and trinucleotide repeats?
some genes have nucleotide repeats that can easily increase (or decrease) in number each generation
What is fragile-X syndrome?
the most common form of severe inherited mental disability in humans. 1/2000 males
What is apoptosis?
cell death in response to DNA damage
What is the epigenome?
the epigenome and the pattern of gene expression can change during a lifespan, depending on environmental conditions
What is the role of histone modifications and DNA methylation in epigenetics?
DNA is wound around clusters of histones proteins to form nucleotides and nucleosomes are in turn coiled to form chromosomes, if a chemical modification to the histones takes place at the gene promoter, then transcription can either be shut off or turned on at a higher rate. DNA methylation of promoter bases usually turns off genes
What is genetic imprinting?
genetic imprinting involves selective use of only one of the paternal or the paternal copies of a gene and the silencing of the second copy. Imprinting is reset during gamete formation
What is Beckwith-Wiedemann Syndrome?
A growth disorder involving enlarged organs, high birth weight, and a predisposition to cancer. It’s caused by abnormal patterns of imprinting to genes located on chromosome 11. Involves failed silencing of maternal copies of the genes in the affected region of chromosome 11
What is Diethylstilbestrol (DES) and what are its multigenerational epigenetic effects?
a type of synthetic estrogen. Was used during the 1950’s-70’s by pregnant women and those trying to get pregnant, was thought to reduced miscarriages and to aid the child’s growth. Adverse effect from exposure to DES extend through at least three generations: mother, child, grandchild
What is recombinant DNA?
DNA that has been formed artificially by combining constituents from different organisms
How is recombinant DNA used in biotechnology?
the use of recombinant DNA technology to produce proteins or other biological molecules like: ethanol/biodiesal/other fuels, herbicide and insect resistant crops, faster growing animals, animal models for human diseases, proteins to treat human diseases, proteins or DNA for vaccines, proteins for industry, enzymes to make food, wash clothes, etc.
What does the word ‘transgenic’ mean?
of, relating to, or denoting an organism that contains genetic material into which DNA from an unrelated organism has been artificially introduced
What is a GMO?
A genetically modified organism is any organism whose genetic material has been altered using genetic engineering techniques
What is a clone?
Clones consist of genetically identical individuals, and that means they must reproduce asexually
What are some examples of plant and animal clones that may be encountered in daily life?
bacterial or mold colonies, potatoes, strawberries/raspberries, apples, oranges, grapes, aspen groves, micro-organisms
What is the difference between a ‘variety’ and a ‘clone’?
True-breeding plants or pure-breeding animals are not clones. They still reproduce sexually. They are instead homozygous for alleles for the traits that we associate with the variety or breed. Peas, carrots, lettuce, tomatoes, purebred dogs, cats and cattle are examples of this
How Recombinant DNA works:
- Restriction enzymes cut specific base sequences everywhere they occur in human chromosomes
- The same restriction enzymes cut the same base sequences in plasmid DNA
- The plasmid DNA and the human DNA fragments are mixed in a solution with enzymes that link them together
- The result is recombinant DNA molecules with both human and plasmid DNA
- Recombinant DNA inserted into host cells is copied each time the host cells divide
What are the attributes of plasmid cloning vectors?
In Recombinant DNA Technology, the plasmid functions as vector to carry the recombinant DNA into bacterial cells where it replicates and the genes it carries may be replicated an expressed
What are the restriction enzyme palindrome site structure?
restriction enzymes cut both DNA strands at specific recognition sites. Most useful sites are symmetrical ‘palindromes’ like GATC, GAATTC, GGCCGCC, etc.
What are the reasons for using cDNA inserts?
its advantages are that is allows smaller more specific inserts with just the features needed
What are some potential hots to produce human proteins or other proteins?
bacteria, yeast, plants, animals
The PCR polymerase chain amplification is used to make inserts:
many recombinant DNA inserts are now made using the Polymerase Chain Reaction (PCR)
What are some examples of transgenic plants?
rice, soybeans, sugar beets
What are some examples of transgenic animals?
silk-producing goats, healthier pigs, cows with more milk
What are some examples of Round-up ready crops:
sugar beets, alfalfa, corn, soybeans, cotton
What are some of the advantages of transgenic crops?
o Increased profitability
o Reduction of tillage, which is less damaging to soils
o Reduced overall pesticide and insecticide usage
o Potential to increase nutritional value of crop
o Potential to produce value-added materials such as proteins for industry
o Potential to produce products for human health needs
What are some of the concerns with transgenic crops?
o Potential health risks include allergies to added proteins
o Environmental risks include transfer of transgenes to related wild plants
o Reduction of genetic diversity
o Increased susceptibility of clones to pathogens
o Incompatibility with organic farming practices
What are some examples of animal models for human diseases and what were they used to study?
o Obese mouse: used to study weight gain and weight loss products
o Rhino mouse: used to study immune deficiency conditions
o Curly tail mouse: used to study neural tube defects
o Onco mouse: used to study cancer
