Exam 1 Flashcards
We wished to determine the abundance of bacteria in a sample of milk. To do this ten-fold serial dilutions of a one milliliter milk sample were prepared. One milliliter of the fourth dilution was plated in a pour plate. After incubation, the plate had 32 colonies. How many bacteria were in the original milk sample?
320,000 cells per ml
Which of the following statements is/are correct?
A. Flagella allow bacteria to glide on surfaces
B. Flagella allow bacteria to swim
C. The directed movement of bacterial cells in response to a gradient of a chemical, is called chemotaxis
Flagella allow bacteria to swim and The directed movement of bacterial cells in response to a gradient of a chemical, is called chemotaxis
Bacteriostatic compounds
are biological or chemical agents that stop bacteria from reproducting
An isolated colony on a streak plate typically contains millions of cells that are the progeny of a single cell
this is a true statement
Toxic hydrogen peroxide produced in some bacteria can be broken down into water and oxygen by which enzyme
catalase
Which of the following is NOT likely to be a reason for why exponential growth stops in bacterial cultures grown in a lab? A. accumulation of waste products B. exhaustion of nutrients C. harmful changes in pH D. Bacteria becoming dormant
bacteria becoming dormant
which of the following are required for microbial cell growth?
A. Reduced cofactors
B. anabolic intermediates
C. Energy conserved in chemical bonds.
all,
A. Reduced cofactors
B. anabolic intermediates
C. Energy conserved in chemical bonds.
The growth of almost all bacteria in the environment
is typically limited by the availability of one or more nutrients
Antoni can Leeuwenhoek developed and used
a microscope with a single lens to view bacteria
the cell membrane of bacteria
is semi permeable and is usually a lipid bilayer
prokaryotes and eukaryotes
have many things in common because they share a common ancestor
Penicillin interferes with bacterial cell growth by
inhibiting the formation of shor polypeptide crosslinks between strands of polysaccharide in peptioglycan that re made of repeated units of Nacetylglucosamine (NAG) linked to N-acetylmuramic acid
Bacterial cells reproduce by binary fission, which results in exponential growth of the population. If the size of a bacterial population at time zero (t0) is 20 cells and the generation time is 30 minutes, how many cells will be in the population after 3 hours of growth?
1280 cells
There are similarities and differences between gram negative and positive bacteria. Which of the following is not true?
A. The cell wall of Gram-negative cells is composed of only one or two layers of peptidoglycan whereas the cell walls of Gram-positive bacteria have many peptidoglycan layers.
B. Only gram positive bacteria have lipopolysaccharide that extends out the cell surface
C. The cell membranes of both Gram-negative and Gram-positive bacteria are lipid bilayers.
D. There is a second membrane (called the outer membrane) just outside the cell wall of Gram-
negative bacteria, but this is absent from Gram-positive bacteria.
Only Gram positive bacterial calls have lipopolysaccharide that extends out the cell surface.
Which of the following statements about phospholipids is true?
a. They are comprised of molecules that are entirely hydrophilic.
b. They are comprised of molecules that are entirely hydrophobic.
c. They are the principle components of bacterial cell membranes.
d. have “heads” and “tails” that both have phosphate groups.
They are the principle components of bacterial cell membranes
