Bacterial Nutrition and Energetics (Lecture 7)

Question 1

What is metabolism?

Answer 1

all the biochemical reactions taking place in an organism

Question 2

catabolism

Answer 2

energy releasing process

Question 3

anabolism

Answer 3

energy using processes

Question 4

What catalyzes reactions?

Answer 4

enzymes

Question 5

Most enzymes are proteins but are all proteins enzymes?

Answer 5

no not all proteins are enzymes

Question 6

Are enzymes reusable?

Answer 6

yes

Question 7

Are enzymes specific?

Answer 7

yes highly specific

Question 8

What do enzymes have where the “magic” happens?

Answer 8

active sites

Question 9

Enzyme-substrate complexes

Answer 9

enzymes bind to the substrate at the active site on the enzyme and increase the probability of a chemical reaction

Question 10

Cofactors

Answer 10

many enzymes contain small non-protein molecules that participate in catalysis but are NOT substrates

Question 11

prosthetic groups

Answer 11

cofactors that are inorganic molecules (typically metal ions)

Question 12

coenzymes

Answer 12

cofactors that are an organic molecule which included NAD+, NADP+, FAD, coenzyme A

Question 13

apoenzyme

Answer 13

if an enzyme requires a cofactor to catalyze a reaction and that cofactor is not bound to the enzyme

Question 14

holoenzyme

Answer 14

an enzyme bound to its cofactor that is active

Question 15

Feedback inhibition

Answer 15

hinders a metabolic pathway by having a product of the pathway inhibit an earlier reaction

Question 16

Noncompetitive inhibition

Answer 16

change the shape of an active site by binding to a different site on the enzyme

Question 17

Competitive inhibition

Answer 17

blocking the active site so the substrate cannot bind

Question 18

Can feedback inhibition be competitive or noncompetitive?

Answer 18

yes

Question 19

Essential nutrients

Answer 19

those that must be supplied from the environment

Question 20

Macronutrients

Answer 20

major elements in cell macromolecules (C, O, H, N, P, S) and ions necessary for protein function (-Mg2+, Ca2+, Fe2+, K+)

Question 21

Micronutrients

Answer 21

trace elements necessary for enzyme function (Co, Cu, Mn, Zn)

Question 22

What is bacterial growth dependent on?

Answer 22

the acquisition of these nutrients and a variety of physical factors

Question 23

What allows for faster bacterial growth?

Answer 23

an environment rich in these nutrients

Question 24

What results in slow growth and starvation?

Answer 24

environment poor in these nutrients

Question 25

What can starvation lead to?

Answer 25

cell death or a metabolically dormant state

Question 26

What element is most present in wet weight of cells?

Answer 26

oxygen

Question 27

What element is most present in dry weight of cells?

Answer 27

carbon

Question 28

Growth factors

Answer 28

when bacteria/organisms are unable to synthesize all organic compounds

Question 29

Examples of growth factors:

Answer 29

vitamins, amino acids, purines, pyrimidines

Question 30

What is the most commonly required growth factors and what do they function as?

Answer 30

vitamins; coenzymes

Question 31

Types of culture medium

Answer 31

1. liquid
2. solid

Question 32

Liquid media

Answer 32

-referred to as broth

-allows for easily scalable growth, and easy-to-manipulate growth conditions

-allows for continuous culture

Question 33

Solid media

Answer 33

• referred to as plates

-similar to liquid media but with addition of agar to make solid

-allows for differentiation by morphology and separation of microbes

Question 34

Pure culture

Answer 34

culture containing only a single kind of microbe

Question 35

Colony morphology

Answer 35

the physical appearance of bacteria grown on solid media

Question 36

True or false:
Colonies with millions of bacteria are assumed to be all different

Answer 36

false all identical

Question 37

Semi-solid media

Answer 37

-slightly less solid medium that allows for motile bacteria to move

-Ex. MIO

Question 38

What three things can Semi-solid media detect?

Answer 38

1. motility
2. enzyme tryptophanase (pink rings after Kovacs reagent)
3. enzyme ornithine decarboxylase (produces deep purple color)

Question 39

Complex media

Answer 39

a chemical unidentified medium or complex medium such as nutrient broth or agar

Question 40

Defined/Synthetic Medium

Answer 40

the chemical composition of the medium is known

Question 41

Bacterial colony

Answer 41

a visible cluster of bacteria growing on the surface of or within a solid media presumably cultured from a single cell

Question 42

Culture media can be modified to _____________ or ___________ between microbial species

Answer 42

select for; differentiate

Question 43

Selective medium

Answer 43

contains ingredients to inhibit the growth of species and allow growth of others

Question 44

MSA (manitol agar salt)

Answer 44

a selective medium used for the isolation of staphylococci

Question 45

Differential medium

Answer 45

contains specific chemicals to indicate species that possess or lacks a biological process

Question 46

MAC (MacConkey Agar)

Answer 46

-selective and differential media
-designed to isolate Enterobacteriaceae and differentiate based on their ability to ferment lactose

Question 47

When will a MAC plate turn red?

Answer 47

if a colony pH is below 6.8

Question 48

What do MAC plates contain?

Answer 48

bile salts and crystal violet to inhibit growth of Gram + organisms

Question 49

What may low pH cause?

Answer 49

precipitation of bile salts surrounding the colony causing a haze to form around the colony

Question 50

Streak plate isolation

Answer 50

spreads out individual cells to form discrete colonies of species