Lecture 3- Cell chemistry and nutrition

Question 1

what are macronutrients?

Answer 1

elements required in large amounts to build macromolecules (they are the building blocks of cell material)

Question 2

what are the macromolecules and how much of the dry weight of the cell do they consume?

Answer 2

C, H, O, N, P, S
make up 90% of cells dry weight

Question 3

what is a protein made of?what percent of dry weight do proteins consume?

Answer 3

amino acids
55%

Question 4

what macronutrients do proteins have?

Answer 4

C, H, O, N and S

Question 5

what are lipids made of? what macromolecules do they contain?

Answer 5

C, H, O and P
fatty acids and glycerol

Question 6

what are carbohydrates made of? what macromolecules do they contain?

Answer 6

C, H, O and N
sugars

Question 7

what are nucleic acids made of? what macromolecules do they contain?

Answer 7

nucleotides
C, H, O, N, P

Question 8

what are 4 inorganic macronutrients?

Answer 8

K, Mg, Ca, Fe

Question 9

what do inorganic macronutrients do?

Answer 9

serve as metabolic co- factors

Question 10

what is the function of potassium?

Answer 10

enzymes involved in protein synthesis require K+

Question 11

what is the function of iron?

Answer 11

electron carriers require Fe2+

Question 12

what is the function of Mg?

Answer 12

helps stabilize membranes and nucleic acids

Question 13

what is the function of Ca2+?

Answer 13

helps stabilize cell walls and plays a role in heat stability of endospores

Question 14

what are micronutrients?

Answer 14

elements required in very small amounts and usually serve as cofactors for enzymes

Question 15

what percentage of the cell is carbon? what percentage of the cell is oxygen? what percentage of the cell is nitrogen?

Answer 15

C: 50%
O: 17%
N: 13%

Question 16

what are growth factors?

Answer 16

small organic molecules required for growth

Question 17

there are 3 classes of growth factors, what are they?

Answer 17

amino acids: (20 amino acids are needed for protein synthesis)
purines and pyrimidines
vitamins

Question 18

function of purines and pyrimidines?

Answer 18

needed to make nucleotides (adenine, guanine, thymine, cytosine, uricil) for DNA and RNA
they are thus the building blocks for DNA and RNA

Question 19

what is the function of vitamins?

Answer 19

small molecules used to make organic cofactors
non protein component that is required by some enzymes

Question 20

what are the 3 requirements of growth factors?

Answer 20

1. many have no growth factor requirements (E.coli)
2. some bacteria require many growth factors
3. addition of growth factors to medium may promote growth (have to do in lab)

Question 21

what are some growth factors?

Answer 21

PABA
Folic acid
biotin
B12
B1
B6
nicotinic acid
vitamin K
lipoic acid

Question 22

what can be said about H and O in respect to cell nutrition? where is it found?

Answer 22

found in H2O and organic media components

Question 23

what can be said about P in respect to cell nutrition? how is it provided? why? where is it limiting?

Answer 23

provided as phosphate salt (PO43-) because its usually acquired as PO43- in the environment
in freshwater systems phosphate salt is often limiting (because it turns the lakes green)

Question 24

what does limiting mean? what happens when it runs out?

Answer 24

if you run out of a nutrient or you don’t have much of it compared to other nutrients
when it runs out, growth stops despite other nutrients present

Question 25

what are the 3 possible sources of nitrogen?

Answer 25

inorganic N
organic N
atmospheric N2

Question 26

what can be said about inorganic N in respect to cell nutrition? how is it provided? what is it used to make? does it need to be reduced?

Answer 26

provided as salts
must be reduced to NH3 (used to make amino acids)

Question 27

what can be said about organic N in respect to cell nutrition? how is it provided? does it need to be reduced?

Answer 27

provided as N rich organic molecules
does not need to be reduced

Question 28

what can be said about atmospheric N2? is it reduced? what is it used to make? what can it be done by?

Answer 28

N2 is reduced to 2NH3 (nitrogen fixation)
NH3 is used to make amino acids
energetically expensive
can only be done by some bacteria and archaea (NOT EUKARYOTES)

Question 29

what are two possible sources of sulfur?

Answer 29

inorganic S
organic S

Question 30

what can be said about inorganic S in respect to cell nutrition? what is it provided as? does it need to be reduced?

Answer 30

provided as salts (MgSO4)
must be reduced to the level of S2 (used to make amino acids)

Question 31

what can be said about organic S in respect to cell nutrition?

Answer 31

premade amino acids
less energy to assimilate

Question 32

what are the two groups an organism can be placed in based on how they obtain carbon?

Answer 32

heterotrophs
autotrophs

Question 33

what do heterotrophs do? what do they use? are they reduced?

Answer 33

use organic carbon
one or more C is reduced (ex. C atom with one or more H’s)
ex. carbohydrates, organic acids, amino acids

Question 34

what do autotrophs do? what do they use? do they require energy?

Answer 34

use inorganic carbon (CO2) as their sole source of carbon
requires energy to assimilate
photosynthesis