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If a blue zebra (genotype of Bb) mates with a pink zebra (genotype of bb), what will be the possible gametes of the blue zebra and what will be the possible gametes of the pink zebra?
Gametes contain half the genetic information as other cells in the body. If the genotype for the blue zebra is Bb, this means that half the genetic information for this phenotype of color would be a gamete containing B or a gamete containing b. Similarly, the possible gametes for the pink zebra with genotype bb would be b or b.
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If a green horse (genotype of Gg) mates with a yellow horse (genotype of gg), what will the phenotype and phenotypic ratio of the offspring be?
In order to find the phenotypic ratio, it is first necessary to find the genotypes of the offspring. This is done by doing a Punnett square, as shown in linked photo.
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Which of the following methods of genetic engineering is capable of inserting DNA into a specific location of the host cell’s chromosomal DNA?
Homologous recombination is a natural process in many organisms that cells use to repair DNA, increase genetic variation of offspring during meiosis, or to transfer DNA between individual in viruses or bacteria. In genetic engineering, a section of chromosomal DNA is replaced with a modified version of that segment. Since specific sequences of DNA are being replaced rather than just inserted between natural occurring sequences, this method allows DNA to be placed in specific location in the cell’s chromosomal DNA.
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Viruses can be modified to be used as vectors in genetic engineering. Which characteristic(s) of viral vectors limits their usefulness for gene therapy in humans?
I. The vector replicates rapidly in targeted cells, damaging the cell.
II. Viral vectors have low efficiency at introducing DNA to cells when compared with transformation.
III. Viruses often randomly insert genes into the host chromosome, potentially disrupting gene functions and causing cancer in the host.
IV. The host’s own immune response to the viral vector can cause complications for the patient.
Viral vectors are modified so that they can infect cells, but they cannot replicate. Viral vectors are also much more efficient at introducing DNA to cells than transformation. Even though the virus has been modified to be harmless, however, the host’s immune system can still attack it, leading to a potentially dangerous immune response. Many viruses randomly insert their DNA into host chromosomes, possibly inserting the DNA in the middle of a host gene and interrupting the gene’s function. If the affected host gene is important in cell replication, DNA repair, or programmed cell death, this could lead to cancer.
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Two rams both have curly horns, which is a dominant trait. The recessive trait is straight horns. Is it possible that the offspring of these two rams will have straight horns?
It is possible that the genotypes of both parent rams are Cc and Cc. This would mean that both parents carry the recessive allele for straight horns (c). By doing a Punnett square, we can see that there is a possibility of an offspring with straight horns.
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What is the role of calcium chloride in making bacterial cells competent for transformation?
Positively charged calcium ions are attracted to both the negatively charged plasmid DNA and the negatively charged plasma membrane, overcoming the usual repulsion between the two and allowing them to bind. Heat shock is used to open pores during the transformation process, so that the bound plasmid DNA can enter the cell. Bacteria defenses generally destroy viral DNA, not bacterial plasmid DNA. Calcium is used as a signal in many cell processes, but this is not the purpose of calcium chloride in transformation.
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A bacterial colony is transformed with a plasmid containing a foreign gene of interest and is then plated and incubated. The plasmid has been designed so that it will express both this gene and a gene that codes for a green fluorescent protein. The gene that expresses the fluorescent protein is known as what?
A reporter gene is a gene that is introduced to cells along with a gene of interest in order to determine which cells have been successfully transformed. Since both genes are on the same plasmid, if the bacterial colonies after incubation fluoresce green then they also have the gene of interest, which may not be detected as easily. Knockout and knock-in genes refer to genetic changes chromosomal DNA and are not introduced using plasmids. A promoter refers to a part of a gene that regulates its expression.
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If a sheep with golden fleece mates with a sheep with white fleece, the offspring has phenotype of platinum fleece (a mix of golden fleece and white fleece). This is an example of what type of dominance?
In the problem, platinum fleece is stated to be a mix of white fleece and golden fleece. This is an example of incomplete dominance. Codominance in such a case would yield patches or some form of separation between white fleece and golden fleece patches on the offspring, where the traits can fully be expressed in patches or parts of the organism. Mixed dominance is not a real genetic term.
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Scientists often introduce foreign genes from other organisms, including eukaryotes, into bacteria in order to mass-produce the gene product. What difference between bacteria and eukaryotes complicates this process?
Bacteria do not perform post-transcriptional modification of mRNA. None of the other answers are actual differences between bacteria and eukaryotes. Bacteria begin translating mRNA into amino acids before transcription has even completed, giving them no opportunity to modify the mRNA transcript before translation. Therefore, a cDNA copy must be made from the already modified mRNA produced by the eukaryotic organism and then introduced into the bacterial cell. That way the bacteria can transcribe and translate the cDNA without having to modify the mRNA transcript.
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Suppose that yellow wings (Y) is dominant to orange wings (y) and that thick antennas (T) are dominant to thin antennas (t). If a butterfly with yellow wings and thick antennas (YyTt) mates with a butterfly with orange wings and thin antennas (yytt), what will be the phenotypic ratio of the offspring?
In order to find the answer, it is necessary to do a dihybrid cross as shown:
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Which of the following is not generally introduced into a cell during genetic modification?
Vectors are used to deliver the target gene into the cell. The selectable marker gene, when expressed, shows that the genes were successfully introduced into the cell. A promoter is used to initiate transcription of both the target gene and the marker gene, and a terminator ends their transcription. While ligase is often used to make recombinant DNA to be inserted into a cell, it is not necessary to introduce ligase into the cell.
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A rabbit with brown fur and long ears has genotype BbEe. Brown fur (B) is dominant to white fur (b) and long ears (E) is dominant to short ears (e). What are the gametes that this rabbit will produce?
Gametes contain half the information as other cells. Gametes will receive one allele for each trait. From this particular rabbit with genotype BbEe, each gamete will contain one allele for fur color (either B or b) and one allele for ear length (E or e). Hence, the possible gametes for this rabbit with genotype BbEe are BE, Be, bE, and be.
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A flower with black petals and a flower with green petals produce offspring. The offspring has patches of black and patches of green on its petals. What kind of dominance is expressed?
The type of dominance expressed in this offspring with patches of green and patches of black on its petals is codominance. Codominance is when the traits (in this case, petal color) is expressed fully in patches (or other kinds of separations), but that both traits can be seen in the offspring, and that the trait is not an intermediate of the two combined traits. If intermediate trait did result (greenish black or blackish green all over the offspring), then this would be incomplete dominance. Intermediate dominance and mixed dominance are not real genetic terms.
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A pig has blue fur and a curly tail. Blue fur (B) is dominant to yellow fur (b). Curly tail (C) is dominant to straight tail (c). What are all the possible genotypes for this pig with blue fur and curly tail?
For each trait, there must be two alleles (one from mother and one from father). In this genotype, two traits are being asked for, so there should be a total of two genes with two alleles each in the genotype. Because the pig expresses the dominant traits of blue fur and curly tail, this indicates that the pig at least has to have one of each dominant allele in its genotype: B_C_. This leaves us with two blanks that we can fill in with either dominant or recessive alleles. Regardless, the dominant traits will still be expressed, because there is at least one dominant allele for blue fur and one dominant allele for curly tail. With this, we have four possibilities that will all yield the phenotype of blue fur and curly tail: BBCC, BbCC, BBCc, Bbcc.
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Suppose a venus flytrap plant has sharp teeth and red leaves. Sharp teeth (T) is dominant to blunt teeth (t). Red leaves (R) is dominant to purple leaves (r).
Is it possible that two venus flytrap plants both with sharp teeth and red leaves have an offspring with blunt teeth and purple leaves?
It is possible for the parents to have genotypes that contain recessive alleles that will yield an offspring with the recessive traits. This can be seen by doing a dihybrid cross of the two parents both with genotypes of TtRr (which would express sharp teeth and red leaves; additional note: both parents HAVE to have this genotype in order to have an offspring with the recessive traits of blunt teeth and purple leaves — please refer to the Punnett square to see why).
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Suppose a person with genotype of ff will have long fingernails. Suppose a person with genotypes of Ff or FF will have short fingernails. How would this trait of fingernail length be described?
It can be seen that short fingernails is dominant by the genotypes of Ff and FF, both of which contains at least one dominant allele of short fingernails (F). It can be seen that long fingernails is recessive to short fingernails by the genotype of a person with long fingernails carrying two recessive alleles of short fingernails (ff). If in this case, fingernail length was co-dominant, some fingers would probably have long nails and some fingers short nails if genotype Ff. If incomplete dominance, genotype of Ff would be a middle ground length between long and short. Mixed dominance is not a real genetics terms.
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Suppose the trait of hair color has incomplete dominance.
If a person with blonde hair and a person with black hair produces an offspring, what will be a likely hair color of the offspring?
Incomplete dominance is where two traits intermix together, usually to create some kind of in-between trait. With blonde hair and black hair, the offspring will likely have a hair color that will be between the two extremes — likely brownish hair. There will be patches or strands of pure blonde and pure black hair in the offspring if hair trait was co-dominant, but it states in the problem that hair color trait has incomplete dominance. It may also be possible that the child will have only blonde hair or only black hair, but this is less likely and also will not be demonstrating the concept of incomplete dominance, as the question is asking for. Any of the other answers are equally likely to occur since the two parents have very different hair colors.
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Suppose fur color expresses incomplete dominance. Pure fur colors are blue (BB) and pink (PP). A monster with a genotype of Bb will have the incomplete dominance of purple fur.
What will be the phenotypic ratio of the offspring of a purple parent monster and a pink parent monster?
It can be seen that the phenotypic ratio of the offspring will be purple : pink of 2 : 2. This can be seen by doing a Punnett square and keeping in mind that fur color in this problem has incomplete dominance.
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How are restriction enzymes named?
Restriction enzymes are named from the organism they were taken from. They function to cut DNA in bacteria, a crucial step in the process of sequencing DNA, as you need it to be broken down into smaller segments.
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A diagram that depicts a human's genetic information with chromosome pairs is called a __________.
A karyotype is a diagram that depicts all 23 pairs of chromosomes by showing their shapes relative to one another. The process of karyotyping involves examining chromosomes to identify any genetic problems that could result in a disorder or disease.
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