Exam 2 Study Guide

what is metabolism

sum of chemical reactions that break down complex molecules, and those that build complex molecules

what are the types of metabolism

catabolism and anabolism

what is catabolism

chemical reactions that break down complex molecules

what is anabolism

chemical reactions that build complex molecules

according to what sources may organisms be classified

carbon and energy

what do autotrophs do

convert inorganic carbon dioxide into organic carbon

what do heterotrophs do

use fixed organic carbon compounds

phototrophs obtain their energy from what

light

chemotrophs get their energy from what

chemical compounds

what are some important electron carriers

FAD/FADH2, NAD+/NADH, NADP+/NADPH

what is considered the energy currency of the cell

adenosine triphosphate (ATP)

what does ATP do

stores chemical energy in its 2 high energy phosphate bonds for later use to drive processes requiring energy

what are enzymes

biological catalysts

what is the function of enzymes

increase the rate of chemical reactions inside the cell by lowering the activation energy required for the reaction to proceed

what do substrates bind to

enzyme’s active site

what happens in the process of induced fit

alters the structures of both the active site and the substrate, favoring transition-state formation

are cofactors organic or inorganic ions

inorganic

what are cofactors

inorganic ions that stabilize enzyme conformation and function

are coenzymes organic or inorganic molecules

organic

what are coenzymes

organic molecules required for proper enzyme function and are often derived from vitamins

what is an enzyme lacking a cofactor or coenzyme called

apoenzyme

what is an enzyme with a bound cofactor or coenzyme called

holoenzyme

what do competitive inhibitors do

regulate enzymes by binding to an enzyme’s active site preventing substrate binding

what do noncompetitive (allosteric) inhibitors do

bind to allosteric sites, inducing a conformational change in the enzyme that prevents it from functioning

when does feedback inhibition occur

product of metabolic pathway noncompetitively binds to an enzyme early on in the pathway, ultimately preventing the synthesis of the product

what is the first step in the breakdown of glucose

glycolysis

what does glycolysis result in

formation of ATP

how is ATP formation from glycolysis produced

substrate level phosphorylation, NADH, 2 pyruvate molecules

glycolysis does NOT use oxygen and is not oxygen dependent

true

many intermediates are used to synthesize important cellular molecules such as

amino acids, chlorophylls, fatty acids, and nucleotides

what is most of the ATP generated during cellular respiration of glucose made by

oxidative phosphorylation

what is the electron transport system (ETS) composed of

series of membrane associated protein complexes and associated mobile accessory electron carriers

where is the electron transport system (ETS) found in prokaryotes

embedded in the cytoplasmic membrane

where is the electron transport system (ETS) found in eukaryotes

inner mitochondrial membrane

each ETS complex has a different redox potential

true

how do electrons move from electron carriers

more negative redox potential to more positive redox potential

to carry out aerobic respiration what does a cell require as the final electron acceptor

oxygen

what do organisms performing anaerobic respiration use

alternative electron transport system carriers for the ultimate transfer of electrons to the final non oxygen electron acceptors

microbes show great variation in the composition of their electron transport systems

true

what can the variation in ETS in microbes be used for

diagnostic purposes to help identify certain pathogens

as electrons are passed from NADH and FADH2 through ETS the electrons do what

lose energy

where is the lost energy from electrons stored through as electrons pass from NADH and FADH2 through ETS

pumping of H+ across the membrane, which generates a proton motive force

the energy of the proton motive force can be harnessed by

allowing hydrogen ions to diffuse back through the membrane by chemiosmosis using ATP synthase

what happens are hydrogen ions diffuse through down their electrochemical gradient

components of ATP synthase spin, making ATP from ADP and Pi by oxidative phosphorylation

what forms more ATP during oxidative phosphorylation

aerobic respiration

how much ATP does aerobic respiration form during oxidative phosphorylation

max of 34

how much ATP does anaerobic respiration form during oxidative phosphorylation

1-32

what does fermentation use as a final electron acceptor

organic molecule

why does fermentation uses an organic molecule as a final electron acceptor

to regenerate NAD+ from NADH so that glycolysis can continue

fermentation does not involve an…

electron transport system

no ATP is made by the ____ process directly

fermentation

how much ATP does fermentation make

very little, only 2 molecules per glucose molecule during glycolysis

what are microbial fermentation processes used for

production of foods, pharmaceuticals, identification of microbes

what does pyruvate do during lactic acid fermentation

accepts electrons from NADH and is reduced to lactic acid

lactic acid production by the normal microbiota prevents…

growth of pathogens in certain body regions and is important for the health of the GI tract

what happens during ethanol fermentation

pyruvate is first decarboxylated (releases CO2) to acetaldehyde, accepts electrons from NADH, reducing acetaldehyde to ethanol

what is ethanol fermentation used for

alcoholic beverages, rise of bread products, biofuel production

how do most bacterial cells reproduce

divide by binary fission

what is generation time

bacterial growth is defined as the doubling time of the population

what are the 4 phases of pattern of growth that cells in closed systems follow

lag, log (exponential), stationary, death

what are other patterns of cell divisions

budding (asymmetric division), and formation of hyphae and terminal spores

what are biolfilms

communities of microorganisms enmeshed in a matrix of extracellular polymeric substance

how do cells in biofilms coordinate their activity

communicating through quorum sensing

where are biofilms commonly found

surfaces in nature and in human body, where they may be beneficial or cause severe infections

pathogens associated with biofilms are often more…

resistant to antibiotics and disinfectants

what are obligate aerobes

depend on aerobic respiration and use oxygen as terminal electron acceptor, cannot grow without oxygen

what are obligate anaerobes

cannot grow in the presence of oxygen, depend on fermentation and anaerobic respiration using a final electron acceptor other than oxygen

what are facultative anaerobes

show better growth in the presence of oxygen but will also grow without it

what are aerotolerant anaerobes

don’t perform aerobic respiration, but can grow in the presence of oxygen

what enzyme do most aerotolerant anaerobes test negative for

catalase

what are micoaerophiles

need oxygen to grow, use lower concentration than 21% oxygen

what are the main enzymes involved in the detoxification of the reactive oxygen species

peroxidase, superoxide dismutase, catalase

which enzyme is usually present in cells that can tolerate oxygen

superoxide dismutase

Peroxidase, superoxide dismutase, and catalase are usually detectable in cells that perform

aerobic respiration and produce more ROS

bacteria are generally considered

neutrophiles

what are neutrophiles

grow best at neutral pH close to 7

what are acidophiles

grow optimally at a pH near 3

what are alkaliphiles

organisms that grow optimally between a pH of 8 and 10.5

how do extreme acidophiles and alkaliphiles grow

slowly or not at all near neutral pH (7)

microorganisms grow best at their...

optimum growth pH

growth occurs slowly or not at all between

min growth pH and above max growth pH

what are psychrophiles

grow best in the temperature range of 0–15 °C

what are psychrotrophs

thrive between 4°C and 25 °C

what are mesophiles

grow best at moderate temperatures in the range of 20 °C to about 45 °C

Pathogens are usually

mesophiles

what are thermophiles and hyperthemophiles 

adapted to life at temperatures above 50 °C

Adaptations to cold and hot temperatures require

changes in the composition of membrane lipids and proteins.

what are halophiles

require high salt concentration in the medium

what is halotolerant

organisms that grow and multiply in the presence of high salt but do not require it for growth

Halotolerant pathogens are an important source of

foodborne illnesses because they contaminate foods preserved in salt

more bacteria require what to grow

high moisture

what is DNA

hereditary information found within cells

Chromosomal Theory of Inheritance 

• scientifically demonstrated until the 1915 publication of the work of Thomas Hunt Morgan and his colleagues.

what are nucleic acids composed of

nucleotides

what do nucleotides contain

a pentose sugar, a phosphate group, and a nitrogenous base

Deoxyribonucleotides within DNA contain

deoxyribose as the pentose sugar

DNA contains

pyrimidines cytosine and thymine, and the purines adenine and guanine

Nucleotides are linked together by

phosphodiester bonds between the 5ʹ phosphate group of one nucleotide and the 3ʹ hydroxyl group of another

A nucleic acid strand has

free phosphate group at the 5ʹ end and a free hydroxyl group at the 3ʹ end

the amount of adenine is approximately equal to the amount of

thymine in DNA