Genetics: Key Concepts, DNA, and Genetic Disorders
Genetics: Key Concepts and Applications
The physical location of a gene on a chromosome is the locus.
Different versions of a given gene are called alleles.
A combination of alleles is known as a genotype.
The physical trait caused by a combination of alleles is known as a phenotype.
What is the sequence of nucleotides in the complementary strand of DNA that will match the following strand of DNA? ATGATAGCC? TACTATCGG
The presence of a widow’s peak is controlled by a dominant allele (P), while the absence of a widow’s peak is controlled by a recessive allele (p).
What would be the genotype of a person who has a widow’s peak? A or B could be correct
What would be the genotype of a person who does not have a widow’s peak? pp
Achondroplasia (Dwarfism) is an autosomal dominant genetic disorder. If a child inherits both dominant alleles, it will not survive more than a month or two. Below is the Punnett square for two dwarf parents.
What is the probability that these parents will have a child with achondroplasia who will survive to adulthood? 50% (2/4)
What is the probability that these parents will have a child who will not survive more than a few months? 25% (1/4)
What is the probability that these parents will have a normal child? 25% (1/4)
What is the genotype of someone who is a carrier for a genetic disorder? Heterozygous
What is the advantage of being a carrier of sickle cell anemia? You have protection from malaria without the sickle cell phenotype
Which of the following is an autosomal recessive genetic disorder? Cystic fibrosis
Which of the following genetic disorders causes a lack of clotting factor in the blood which can lead to severe bleeding from even minor injuries? Hemophilia
In a species of flower, the color of the petals is determined by a trait that demonstrates incomplete dominance. If a red flower and a blue flower are crossed, what color will the flowers of the offspring be? Purple
In a species of flower, the color of the petals is determined by a trait that demonstrates codominance. If a red flower and a blue flower are crossed, what color will the flowers of the offspring be? Red and Blue
Which of the following is NOT one of the nitrogenous bases found in RNA? Thymine
Which of the following is NOT a type of RNA? cRNA (Chromosomal RNA)
Which of the following would demonstrate a replacement mutation to the following strand of DNA? AATGTC AATGTA – Replacement mutation
What happens during translation when the mRNA codon UAG is reached? The string of amino acids stops being translated
A trait which is controlled by multiple genes is called a polygenic trait.
A trait which is controlled by multiple genes and environmental factors is called a multifactorial trait.
When mRNA is being prepared to be sent out of the nucleus, introns are cut out, while exons are kept.
Cells that have not differentiated and can be triggered to develop into any type of cell are known as stem cells
Which of the following can be used to treat people with genetic disorders? Gene therapy
List the three components that make up a nucleotide. Sugar, Phosphate, Nitrogenous Base
Explain how the structure of DNA was discovered by Watson and Crick (and Rosalind Franklin). Watson and Crick made models of DNA. They were having trouble figuring out the structure until they were given a photograph taken by Rosalind Franklin that showed that DNA was a double helix. The photo was given to them without Rosalind’s permission – both men received the Nobel Prize, and Franklin received no recognition.
Explain why a frameshift mutation causes drastic changes to the amino acid sequence. A frameshift mutation is caused by an insertion or deletion in the DNA sequence. This offsets the entire sequence by one base pair, thus altering every codon from the insertion or deletion until the sequence ends. This can also add premature stop codons, or skip over existing stop codons, thus making the amino acid chain much shorter or longer than normal. In all cases a frameshift mutation completely changes the sequence. It would be similar to adding or deleting a letter in a sentence. Each word would change.
Describe how one DNA technology that we discussed in class works. What is one use or potential use for that technology. Ex: Transgenic organisms are created by inserting genes from one species into the genome of another species. This is done first by cutting out the target gene(s) with restriction enzymes, and then making many copies of the gene(s) using PCR. The genes are then inserted into the genome of the target organism using a method like a bacterial plasmid, or a gene gun. This technology can be used to create food plants and animals which are larger and are resistant to disease and pesticides.
Explain why stem cell research OR GMO foods are controversial. Include at least one reason why it could be good to use this technology, and one reason why it could be bad to use this technology.
Stem cell research is controversial because the best type of stem cells to use come from human fetuses. Stem cell technology can be good because stem cells can be used to research and treat a wide variety of conditions from cancer to genetic disorders, to organ replacement. Stem cell research could be bad because of the moral question of whether or not the fetus that the cells are taken from is considered living yet. If the fetus is considered living, then harvesting fetal stem cells is akin to murder.
GMO foods are controversial for several reasons. While GMO foods could provide the answer for global hunger by producing larger food crops, many people are concerned over health and moral issues. GMO foods can create larger, disease and pest resistant crops which could feed the world. Some are concerned however that GMO foods are linked to cancer. GMO foods can also be patented which creates situations where large corporations are suing small farms.