Unit 2 study questions

Question 1

Name the four general types of organisms based on their energy and carbon source

Answer 1

Photoautotroph- capture energy from light rays and transform it into chemical energy, uses inorganic carbon dioxide as carbon source, not dependent on living things
Chemoautotroph- gain energy from chemical compounds and use inorganic carbon dioxide
Chemoheterotrophs- derive energy from organic chemical compounds, dependent on life forms and require organic carbon
Photoautotrophs- dependent on life forms, organic carbon, capture energy from light rays, photosynthesize

Question 2

What is an essential nutrient

Answer 2

any substance, whether in elemental or molecular form, that be provided to an organism

Question 3

What are the six elements that are most abundant in cells?

Answer 3

carbon, oxygen, nitrogen, hydrogen, phosphorus and sulfur

Question 4

Provide the sources of the six main elements found in a cell

Answer 4

found in inorganic environmental reservoirs
carbon- CO2 in air, CO3(2-) in rocks and sediments
oxygen- O2 in air, certain oxides, water
Nitrogen- N2 in air, nitrate, nitrite, ammonium in soil and water
Hydrogen- water, H2 gas, mineral deposits
Phosphorus- mineral deposits, phosphate and phosphoric acid
Sulfur- mineral deposits, volcanic sediments, sulfate and hydrogen sulfide gas

Question 5

Explain the difference between osmosis and diffusion

Answer 5

Osmosis- diffusion of water through a selectively permeable membrane
Diffusion- atoms or molecules move in a gradient from an area of higher density or concentration to an area of lower density or concentration

Question 6

Define the term osmotic pressure and how it relates to a living cell

Answer 6

the minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane
isotonic- equal concentrations , diffusion of water is at same rate
hypotonic- solute concentration of external environment is lower than that of the cells internal environment, water flow into cell causing it to burst
hypertonic- solute concentration of external environment is greater than that of the cells internal environment, eater flows out of cell causing cell to shrink

Question 7

how does a cell take up large particulate matter in bulk?

Answer 7

Use of phagocytosis (endocytosis)

cell encloses the substance in its membrane, forming a vacuole and engulfing it

Question 8

define the optimal temp for the growth of mesophiles, thermophiles, psychrotrophs and psychrophiles

Answer 8

Mesophiles- intermediate temp, optimum is 20 to 40 celsius, inhabit plants, animals
Thermophiles- optimum temp is above 45 celsius, volcanic activity, directly exposed to sun
Psychrotrophs- grow slowly in cold by optimum temp is 15 to 30 celsius
Psychrophiles- optimum temp below 15 celsius and can grow at 0 celsius, cant grow above 20 celsius

Question 9

Discuss how pH, osmotic pressure, and temp affect cell growth

Answer 9

pH- depends on whether the microbe can survive and grow in acids or alkalis
osmotic pressure- high or low solute concentrations
temp- optimum growth temp

Question 10

What is the consequence of using oxygen and how do cells cope with this?

Answer 10

oxygen buildup can turn into toxins such as superoxide ion, hydrogen peroxide, and hydroxyl radicals
cells contain enzymes that neutralize the chemicals
superoxide ion is converted to hydrogen peroxide and normal oxygen by the enzyme superoxide dismutase. hydrogen peroxide is then converted to water and oxygen by the enzyme catalase

Question 11

Describe the various oxygen requirements of organisms

Answer 11

Aerobe- can use gaseous oxygen in its metabolism and possesses the enzymes needed to precess toxic oxygen products
Olbigate Aerobe- cannot grow without oxygen
Facultative Anaerobe- aerobe that doesnt require oxygen for its metabolism and is capable of growth in the absence of it
Anaerobe- lacks enzymes, cant tolerate any free oxygen
Aerotolerant Anaerobe- does not utilize oxygen but can survive and grow to a limited extent in its presence

Question 12

Describe the various symbiotic relationship between organisms

Answer 12

Mutualism- obligatory but mutually beneficial relationship
Commensalism- commensal receives benefits while coinhabitant is neither harmed nor benefits
Parasitism- host organism provides parasite with nutrients and habitat but host is harmed

Question 13

discuss what is happening during each of the four growth phases of a close culture of microbes

Answer 13

lag phase- appears not to be growing but cells are metabolically active, period of adjustment
Exponential growth phase- cells reach maximum rate of cell division, increase in curve
Stationary growth phase- population enters survival mode and multiplication and death rate are equal, depletion in oxygen and nutrients, pollutants
Death phase- death rate increases over multiplication rate

Question 14

list the ways one can quantify the number of bacteria in a culture

Answer 14

provide nutrients, a favorable environment, temp, oxygen or no oxygen

Question 15

Explain what is meant by the phrase “enzymes are catalyst”

Answer 15

enzyme increase the rate of chemical reactions that would normally take a very long time, they do not become part of the products or be consumed

Question 16

Explain the two mechanisms of inhibition of enzymes

Answer 16

competitive- bacteria can supply mimic molecule that binds to active site instead of substrate, enzyme shuts down bc cannot complete
noncompetitive- enzyme contains two sites substrate and active site and the site for a regulatory molecule. If the regulatory molecule binds in its site the reaction is blocked because regulatory molecule in regulatory site changes conformation of active site so the substrate cannot enter

Question 17

How does an enzyme contribute to a chemical reaction?

Answer 17

it speeds up the reaction with out becoming a product or being consumed

Question 18

Explain what happens when an enzyme is not at its optimal pH or temperature

Answer 18

only operate under the normal pH or temp of an organism’s habitat
can become chemically unstable (labile)
high temp- cause denaturation
high or low pH can also cause denaturation which causes the enzyme to change its shape and substrate cannot bind

Question 19

What sets of metabolic reactions occur in respiration?

Answer 19

glycolysis, krebs cycle, electron transport chain

Question 20

what are the differences between aerobic and anaerobic respiration?

Answer 20

aerobic- series of reactions that converts glucose to carbon dioxide and allows the cell to recover significant amounts of energy. relies on free oxygen as the final acceptor for electrons and hydrogens
Anerobic- can use same three pathways except uses NO3, SO42 and CO32 and other oxidezed compounds as final acceptor

Question 21

How many ATP are produced by aerobic respiration in a prokaryote, eukaryote, and why is there a difference

Answer 21

Pro- 38
Euk-36
@ ATP are used in ETS to get into mitochondria for EUK
In PRO, ETS is in the cell membrane

Question 22

What is the difference between respiration and fermentation?

Answer 22

Respiration involves microbes that use oxygen

Fermentation involves aerotolerant and facultative anaerobes, organic compounds are the final acceptors

Question 23

name three chemical products formed by fermentation

Answer 23

lactic acid, acetic acid, and ethyl alcohol

Question 24

Does fermentation require oxygen? Why?

Answer 24

????

Question 25

What are two types of light-dependent reactions that can occur?

Answer 25

Photophosphorylation and calvin cycle

Question 26

what is the function of light harvesting pigments in photosynthesis?

Answer 26

converts energy of photons into chemical energy which is released in the form of electrons electrons are transported to photosystem 1

Question 27

How is ATP produced from light in the light-dependent reactions?

Answer 27

light activates Photosystem 2, electrons are released from chlorophyll electrons are then transported to photosystem1 NADP receives electrons from photosystem 1 and hydrogen ions NADP turns into NADPH and ADP turns into ATP

Question 28

How does the calvin cycle produce glucose?

Answer 28

ATP adds a phosphate to a 5 carbon which then splits into two 3 carbon molecules gaining another phosphate ion each an Hydrogen ion is added to each 3 carbon chain while a phosphate is also released they combine to form fructose which then turns into glucose

Question 29

explain direction of DNA

Answer 29

contains phosphate, deoxyribose sugar and nitrogenous base purines and pyrimidines 5 prime to 3 prime

Question 30

Define a gene

Answer 30

the fundamental unit of heredity responsible for a given train in an organism

Question 31

outline the steps in DNA replication

Answer 31

uncoiling of the parent DNA unzipping of the hydrogen bonds Primer starts the replication by DNA polymerase III adds nucleotides

Question 32

What is the central dogma?

Answer 32

master code of DNA is first used to synthesize an RNA molecule and the information contained in the RNA is used to produce proteins

Question 33

Transcription

Answer 33

the formation of RNA using DNA as a template RNA polymerase recognizes a sequence of DNA called promoter region and binds with initiation codon causes polymerase to start transcription. Creates mRNA that compliments DNA template ending code causes polymerase to separate and mRNA is released mRNA made in 5 to 3 but reads 3 to 5

Question 34

Translation

Answer 34

mRNA heads towards ribosome in cytoplasm. Ribosomal subunits come together on mRNA and scans in the 5 to 3 direction. has to find the start codon, tRNA enter with amino acids two sites on ribosome, A site and P site and there is an exit site tRNA carrying anticodon to mRNA, creates an assembly line and amino acids attach to each other and create a peptide chain until stop codon

Question 35

why can prokaryotes perform simultaneous transcription and translation?

Answer 35

prokaryotes mRNA does not contain introns, does not need splicing

Question 36

describe how the lac operon works to control gene expression

Answer 36

operon is normally in off mode but if lactose is present it triggers the operon to turn on the repressor binds with operator(brake pedal) to create off mode but when lactose is present it binds with the repressor creating a new shape and allowing the promoter (gas pedal) to go and transcribe the gene when lactose depletes original shape of repressor returns and binds with operator to stop transcription

Question 37

What is an operon

Answer 37

a genetic operational unit that regulates metabolism by controlling mRNA production

Question 38

why is a frameshift mutation worse than a silent mutation?

Answer 38

Frameshift- when one or more bases is added or erased every amino acid after the mutation is different than what was coded Silent- alters a base but does not change the amino acid redundancy allows for there not to be problem

Question 39

what is a nonsense mutation

Answer 39

changes a normal codon into a stop codon that does not code for an amino acid this just stops the production of the protein

Question 40

describe how genes are transferred by transduction

Answer 40

bacteriophage infects cell A. During replication one of the bacteriophages picks up part of Cell A's DNA. Cell A lyses. the bacteriophage with cell A DNA infects another Cell B and releases cell A's DNA. Cell A DNA combines with cell B DNA. Bacteriophage becomes defective and cannot duplicate

Question 41

What is the role of conjugation in the transfer of drug resistance?

Answer 41

a cell can have a resistance plasmid or factor that could be copied and then transferred to another cell when attached by a pilus and then secreted through the membrane

Question 42

What is a genetically modified organism?

Answer 42

recombinant organisms produced through the introduction of foreign genes transgenic

Question 43

What is used to cut and past DNA?

Answer 43

Restriction endonucleases | they recognize palindromes and clip at these areas

Question 44

Name 3 products from genetic engineering

Answer 44

GMO food???

Question 45

What is a restriction enzyme?

Answer 45

restriction endonucleaes | cuts DNA at certain areas

Question 46

What are the steps in PCR?

Answer 46

Denaturation, priming and extension heat to separate strands add primers that bind to DNA add dna polymerase and nucleotides

Question 47

What is required in a tube for PCR to work?

Answer 47

primers, DNA polymerase, nucleotides, enzymes, magnesium

Question 48

How is a piece of DNA sequenced?

Answer 48

A=T | G=C

Question 49

What is the human genome project?

Answer 49

???

Question 50

define the term sterile

Answer 50

process that destroys or removes all viable microorganisms, including viruses and endospores

Question 51

Explain why cold is not a reliable method of disinfection

Answer 51

cold treatment slows down the growth of cultures | just retards the activities

Question 52

describe the four modes of action of antimicrobial agents, and give a specific example of how each works

Answer 52

Cell wall- blocking synthesis, digesting it, or breaking down its surface Cell membrane- loses selectively permeability DNA and RNA synthesis- prevent transcription and translation by binding, mutagenic agents Protein synthesis- denature proteins, can stop metabolism

Question 53

describe the factors that must be considered when trying to sterilize something

Answer 53

``` nature of microorganism being treated the nature of the material being treated degree of contamination time of exposure strength and chemical action of germicide ```

Question 54

describe how autoclave sterilizes

Answer 54

the normal atmospheric pressure will allow water to boil but the steam will stay at the same temp and not change. which is too low to kill microbes. the pressure must increase in order to raise the temp of the steam as well as the water which kills the microbes

Question 55

providing examples, describe the action of two chemicals that are used for disinfection.

Answer 55

Chlorine- gaseous and liquid o.6 to 1.0 parts of chlorine to 1 million parts of water is safe, high amounts believe to cause cancer Alcohols- concentrations of 50% or higher dissolve membrane lipids, once inside cytoplasm can denature protein but only in alcohol water solutions of 50 to 95%

Question 56

how does trying to remove an endospore compare to an enveloped virus?

Answer 56

Endospores are the hardest microbes to kill but if endospores can be killed by an agent than all other microbes can be killed as well

Question 57

What is microbial death?

Answer 57

the microbe stops growing or replicating

Question 58

How would you be able to sterilize a solution that is destroyed by heat?

Answer 58

cold sterilization Ionizing radiation- energy from radiation bombards cell and releases ions that destroy DNA (breakages), damage is also done to organelles Non-ionizing radiation- atoms are excited and are raised to a higher energy state but do not form ions, thus creating abnormal bonds in the DNA

Question 59

What types of treatments would be appropriate for sterilization of an organ transplant?

Answer 59

chlorhexidine, hydrogen peroxide

Question 60

What types of treatment would be appropriate for intricate instruments?

Answer 60

hydrogen peroxide, alcohols, iodine

Question 61

describe nitrogen fixation

Answer 61

a process occurring in ceratin bacteria in which atmospheric N2 gas is convertedby nitrogen fixing bacteria to a form NH4 usable by plants root nodules become special nitrogen fixating organs

Question 62

describe ammonification

Answer 62

nitrogen containing organic matter is decomposed by bacteria that divide the substances and amino acids which gives off NH4

Question 63

describe Nitrification

Answer 63

ammonia is converted to nitrite and nitrate by nitrifying bacteria Nitrate is the most oxidizing form of nitrogen occurs in two phases and requires two different types lithotrophic bacteria first gram negative bacteria oxidizes NH3 to nitrite and second bacteria perform final oxidation of NO2 to NO3 nitrate

Question 64

describe denitrification

Answer 64

nitrate is converted to nitrite then to NO then to N2O then into N2 which is a gas in the atmosphere can be done by many different bacteria

Question 65

what are the major sources of carbon, nitrogen, phosphorus and sulfur?

Answer 65

carbon-in the mineral state of organic resevoir in the bodies of organisms nitrogen- found in atmosphere phosphorus- inorganic, phosphate rock Sulfur- in solid form and originates from natural sedimentary deposits in rocks, oceans, lakes, and swamps

Question 66

Describe the trophic pyramid and the roles of producers and consumers

Answer 66

shows the producers, consumers and decomposers and traces the flow and quantity of available energy from level to another Producers- provide the energy source, create organic compounds from inorganic compounds consumers- feed on other living organisms and obtain energy from bonds present in the organic substrates they contain primary, secondary, tertiary, quaternary

Question 67

What is an ecosystem?

Answer 67

a collection of organisms together with its surrounding physical and chemical factors

Question 68

Define microbial ecology

Answer 68

the study of microbes in their natural habitats

Question 69

Example of bioremediation

Answer 69

decomposers breaking down human made compounds that are not naturally found on earth break down radioactive waster or styrofoam more than one microbe is needed genetically altering microbes to self destruct when they complete decomposing

Question 70

what is biotechnology

Answer 70

the practical applications of microorganisms in manufacturing products or carrying out a particular decomposition process belong to the large and diverse area

Question 71

what is sludge?

Answer 71

bioremediators aerobically decomposes remaining particles creating a suspension of material that is sludge

Question 72

how do microbes contribute to the breakdown of sewage?

Answer 72

2nd stages where bioremediators decompose remaining particles into sludge

Question 73

what is added to beer to provide bitterness?

Answer 73

hops

Question 74

what are the ingredients used for making beer?

Answer 74

barley, sugar and starch supplements, hops and yeast

Question 75

what organism is most commonly used in alcoholic fermentation?

Answer 75

yeast

Question 76

one rennin is added to milk, what are the two products?

Answer 76

curds and whey

Question 77

what substances can be added or removed to preserve food?

Answer 77

nitrogen salts, sugar, organic acids, salt, sulfur compounds and oxides

Question 78

what is the difference between a primary and a secondary metabolite?

Answer 78

primary- produced during the major metabolic pathways and are essential to microbe function secondary- by-products of metabolism that may not be critical to microbes function