Genetics › Genetic Engineering
How are restriction enzymes named?
from the organism they were taken from
from the organism they’ll be added to
from the scientist that discovered them
from the name of the experiment
randomized naming
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.
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?
green : yellow
2 : 2
green : yellow
1 : 3
green : yellow
3 : 1
green : yellow
4 : 0
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.
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.
III and IV
I and IV
II only
III only
II and IV
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.
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?
Yes, because it is possible that both the parent venus flytrap plants carry the recessive alleles for blunt teeth and purple leaves.
Yes, because although both parents express dominant traits, the phenotype of the offspring is determined completely by chance alone and not by the parents' genetics.
No, since both parents express dominant traits, it is not possible for the offspring to express recessive traits even if the offspring have only recessive alleles.
No, because both parents express dominant traits, it means that they can only be carrying dominant alleles, and that only these dominant alleles can be passed to the offspring.
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).
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?
BE, Be, bE, be
BE, be
BbEe, EeBb
BB, bb, EE, ee
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.
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?
yes, because it is possible that the two rams both carry a recessive allele for horn trait
no, because both rams have dominant alleles for curly horns
no, because both rams have genotypes for curly horns
yes, because although the two parent rams have curly horns, they both carry all recessive alleles that will produce offspring all with 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.
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?
light brown
blonde
black
patches or strands of pure black hair and of pure blonde hair
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.
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?
yellow, thick : yellow, thin : orange, thick : orange, thin
1 : 1 : 1 : 1
yellow, thick : yellow, thin
2 : 2
yellow, thick : orange, thick
2 : 2
yellow, thick : yellow, thin : orange, thick : orange, thin
4 : 0 : 0 : 0
In order to find the answer, it is necessary to do a dihybrid cross as shown:
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?
incomplete dominance
codominance
mixed dominance
this is not an example of any kind of dominance, since neither golden fleece trait nor white fleece trait is fully expressed by itself in the offspring
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.
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?
Short fingernails is dominant to long fingernails.
fingernail length is a codominance trait.
Fingernail length is an incomplete dominance trait.
Fingernail length is not determined by genetics.
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.