Reference no: EM133248433

1. A Gram-negative cell wall contains an outer membrane called the lipopolysaccharide (LPS). This LPS is found in the outer leaflet of the outer membrane. The innermost portion of the LPS is called lipid A, which is an endotoxin. When are endotoxins released from a bacterial cell?

2. Bacterial DNA has a distinctive arrangement when cell replication and division begins. Describe its arrangement, and discuss why bacteria do not have a nucleus.

Active Transport:

3. Why must a cell use energy to bring nutrients into the cell?

a. Nutrients are usually found in a low concentration outside the cell and must be transported against their concentration gradient. Energy is required whenever something is moved against its concentration gradient.

b. Nutrient molecules are too big to be moved through the membrane and must be brought into the cell by endocytosis. Endocytosis always requires energy.

c. Nutrients are not found free in the environment; they must be taken from other cells. Taking nutrients from other cells requires energy.

d. Nutrient molecules are naturally high in energy (which is why they are useful for cells). The energy required to transport a molecule is always equal to its free energy.

4. Which of the following molecules would the cell be most likely to move through the membrane using the process of efflux?

a. amino acids

b. sugar molecules

c. minerals

d. antibiotics

Bacterial cell division:

5. Where does the process of DNA replication begin?

a. at a sequence of DNA called the "promoter"

b. anywhere along the DNA chromosome

c. at a sequence of DNA called the "origin of replication"

d. at the site that the previous round of replication ended

6. Once the process of DNA replication has begun, how soon can a bacterial cell begin a new round of DNA replication?

a. The cell can begin a new round of DNA replication once the two daughter cells have split from each other.

b. The cell must finish one round of cell division and then the daughter cells require a short "resting phase," during which time they make more cellular components. This can take up to an hour, at which point the cell may begin the process of DNA replication again.

c. The cell must finish one round of cell division and then the daughter cells require a short "resting phase," during which time they make more cellular components. This can take up to a day, at which point the cell may begin the process of DNA replication again.

d. A new set of replication forks can begin to form while the DNA strand is still being replicated by the first set of replication forks.

7. What properties would you look for in the cell envelope of Gram-negative bacteria that is not present in Gram-positive bacteria?

a. thick peptidoglycan layer, teichoic acid

b. thick peptidoglycan layer, periplasm

c. lipopolysaccharide, periplasm

d. lipopolysaccharide, teichoic acid