Micro Exam 3

what major nutrient does all life require?

Carbon

what characterizes heterotrophs?

they obtain their CARBON from organic compounds

what characterizes autotrophs?

they obtain their CARBON from CO2

how is ENERGY obtained in eukaryotes?

from organic compounds or light

what characterizes chemoorganotrophs?

they obtain ENERGY from organic compounds

what characterizes phototrophs?

they obtain ENERGY from light

what results from energy generating reactions?

ATP

what occurs in chemoorganotrophy in prokaryotes?

oxidation of organic compounds to make ATP

what occurs in phototrophy in prokaryotes?

light energy used to make ATP

what occurs in chemolithotrophy in prokaryotes?

oxidation of inorganic compounds to make ATP

what characterizes an organic compound?

has BOTH carbon and hydrogen

what occurs in exergonic reactions?

energy is produced, the reaction proceeds spontaneously

what occurs in endergonic reactions?

they require energy input to proceed

how long does it take for H2 + O2 to convert to H2O?

many years

what is energy of activation?

the energy required to break bonds

what is a catalyst?

an agent that lowers energy of activation, bringing molecules to a reactive state

what characterizes enzymes?

biological catalysts, lower energy of activation, increase rate of reaction 10^8 - 10^20 times; do NOT affect energetics or equilibrium of a reaction, ONLY affect rate/speed at which a reaction proceeds; specific, recycled

what is oxidation?

giving electrons away

what is reduction?

adding electrons (reducing the charge)

what is an electron donor?

the energy source

what mediates reduction and oxidation?

electron carriers (NAD+ NADH)

what is the different between NAD+ and NADH?

NAD+ is oxidized and NADH is reduced

how does NAD+ change to NADH?

the NAD+ enzyme carries electrons from the substrate (electron donor) and transfers them into the NAD+, making NADH and oxidized substrate

how is energy conserved?

in the form of phosphate bonds

what is fermentation?

a redox reaction occurring with NO exogenous terminal electron acceptor

what is respiration?

a redox reaction REQUIRING an exogenous electron acceptor

what is the exogenous electron acceptor in aerobic respiration?

molecular oxygen

what is the electron acceptor in anaerobic respiration?

it can vary (nitrate, nitrite, etc)

what reactants go IN for glycolysis?

C6H12O6, 2ATP, NAD+

what products come OUT of glycolysis?

2 pyruvate, 2NADH, 4ATP

what is the overall result of glycolysis?

2ATP

is oxygen required for glycolysis?

no, the reaction occurs in the ABSENCE of oxygen

what is produced from fermentation?

lactic acid, ethanol + CO2, H2 + CO2, NAD+

what is the main purpose of fermentation?

to produce NAD+ for glycolysis

when is fermentation done?

only out of necessity, NOT ideal

what all occurs in the glycolysis/fermentation cycle?

glucose is oxidized (stripped of electrons), those electrons go to carriers and turn NAD+ into NADH and the glucose turns into 2 pyruvate molecules, which are then fermented to create NAD+ to restart the cycle

why does fermentation yield a low amount of ATP?

there is only PARTIAL oxidation of organic C compounds and the difference is small in reduction potentials

what can happen to the two pyruvate after glycolysis instead of fermentation?

they can create 2NADH + 2CO2 and start Kreb's cycle

what are the products of Kreb's cycle?

2FADH, 2NAD(P)H, 4NADH, 4CO2, and 2GTP

what occurs in the electron transport?

the electron carriers from glycolysis (2NADH) and Kreb's cycle (2NADH, 2FADH, 2NAD(P)H, 4NADH) go to and move down the chain, gradually giving their electrons to the terminal electron receptor (TEA)

what is the function of the TEA?

the terminal electron acceptor (oxygen in aerobic resp) accepts electrons and hydrogen to make water

what occurs after the TEA accepts the electrons/hydrogen?

hydrogen atoms leave the cell and move over to the ATP synthase to create 34ATP

what is the equation for respiration?

C6H12O6 + O2 -> 6CO2 +H2O + 34ATP

what is ATP synthase?

a reversible enzyme, can be used to create PMF (important for fermenters)

what important force is the production of ATP linked to?

proton motive force

what does anoxygenic mean?

oxygen is not produced

what occurs in replication?

a copy is made of DNA

what occurs in transcription?

RNA is made from a DNA strand

what occurs in translation?

proteins are made for an RNA strand

what characterizes DNA strands?

held together by hydrogen bonds, antiparallel (can only add to 3' end with the hydroxyl group)

what is a genome?

all the DNA in one cell

what characterizes a chromosome?

a large molecule (1-10 million base pairs), most bacteria have one circular chromosome that encodes all "housekeeping genes"

what are housekeeping genes?

genes that are necessary under all conditions

what characterizes plasmid?

smaller circular dsDNA molecules in many bacteria; encode accessory functions

how many base pairs are in a gene?

1,000

what is the function of a gene?

to encode a single protein

what characterizes semiconservative DNA replication?

one new strand of DNA is added to the old strand

in what direction do DNA strands grow?

5' to 3'

what do DNA polymerases do?

they add new nucleotides to free the 3' -OH groups

what does De novo DNA synthesis require?

a primer made of RNA to start the process

what does helicase do?

it unwinds DNA by breaking hydrogen bonds

where does replication start?

the origin of replication; occurs in both directions at the same time

what performs "normal" DNA synthesis?

DNA polymerase III

what occurs in leading strand synthesis?

the new strand is made continuously, starts at 5' with the RNA primer and goes towards the 3' end by using DNA polymerase III

what occurs in lagging strand synthesis?

a new strand is made in fragments

what synthesizes the RNA primer and why?

primase synthesizes RNA primers because DNA synthesis cannot begin a new chain

what does DNA polymerase I do?

it replaces RNA with DNA

what does ligase do?

it joins the two fragments of DNA that result from DNA polymerase I

what characterizes a gene?

it is a functional unit of genetic information that is transcribed into RNA; can encode proteins, mRNA, rRNA, tRNA, or even regulatory RNA

what is the function of messenger RNA (mRNA)?

it codes for protein sequences and is therefore translated

what is the function of ribosomal RNA (rRNA)?

it is not translated; it is part of the ribosome (23S, 16S, 5S)

what is the function of transfer RNA (tRNA)?

it is not translated; "translates" mRNA sequences into amino acid sequences at the ribosome

what do ribozymes do?

catalyze enzymatic reactions

does RNA polymerase need a primer to start synthesizing the RNA?

no

what characterizes a holoenzyme?