Genotype vs Phenotype

An organism’s genotype is its genetic makeup, while its phenotypes are the physical traits determined by its genes. Here, we see an example of how the genotype of a bacterial cell determines its phenotype. The cell on the left contains a plasmid DNA with a gene, shown in red, for resistance to the antibiotic ampicillin while the cell on the right does not. Because this gene allows bacteria to grow in the presence of ampicillin, the cell on the left can survive to multiply and form colonies on the antibiotic-treated plates shown here. However, the cell on the right dies when exposed to ampicillin, since it does not possess a gene for antibiotic resistance. If we call the gene “amp,” for ampicillin resistance, then the genotype of the cell containing it is ampR while that of the cell lacking the gene is ampS, for ampicillin sensitivity. The phenotype of the ampR cells is survival, while that of the ampS cells is death. However, the ampR cell can mate with the ampS cell by a process known as conjugation, and can transfer a copy of its antibiotic resistance gene to the ampS cell. As shown, the cell on the left donates a plasmid containing the amp gene to the cell on the right through a linkage formed between the membranes of the two bacteria. The genotype of both cells is now ampR, and the phenotype of each is survival, since both can now form colonies in the presence of ampicillin, as shown.

Question 1: Genotype is the ___________of an organism while phenotypes are the ______________ determined by its genes.
  1. genetic makeup, physical traits
  2. gene, plasmid
  3. cell, proteins
  4. DNA, proteins


Answer 1 Answer - (a) Genetic makeup, physical traits

Question 2: What is the way to write up the genotype of a cell which is ampicillin resistance?
  1. ampS
  2. ampR
  3. ampC
  4. ampN


Answer 2 Answer - (b) ampR

Question 3: Cells which do not contain a plasmid with the ampicillin resistance gene will ___________ if it is plated on agar that contains the antibiotic, Ampicillin, and the genotype of this cell is designated as ___________.
  1. survive, ampR
  2. survive, ampS
  3. die, ampR
  4. die, ampS


Answer 3 Answer - (d) die, ampS

Question 4: During conjugation, an ampR E. coli can ___________ with an ampS cell and transfer the ____________ gene.
  1. mate, ampR
  2. survive, ampS
  3. die, ampR
  4. die, ampS


Answer 4 Answer - (a) mate, ampR