MIDTERM 2 EXAM KEY NOTES Flashcards

Question

whats aerobic respiraiton and its steps

Answer 1

the process cells use to break down glucose using oxygen adn therefore producing energy. 1. glycolysis in cytoplasm breaks into 2 pyruvate + 2atp + nadh 2. TCA cycle (krebs, in mitochondria) breaks into pyruvate, 3Co2 (waste) + nadh and fadh2 and some atp. 3. the etc in mitochondria generates lots of atp and uses nadh and fadh2 as drop off electrons. the final electron acceptor is o2 and forms h20. without it , etc stops and no atp!

Answer 2

NO3- (NITRATE) SO42- (SULFATE) not as affective as o2 as anaerobic respiraiton doesnt produce much energy. still more than fermentation tho

Answer 3

Obligate aerobes: oxygen required for survive Facultative anaerobes: can use oxygen when available and can survive by anaerobic respiration and/or fermentation is its necessary Obligate anaerobes: cannot survive when oxygen is present. Oxygen is extremely poisonous for organisms who do not have protective measures.

Answer 4

anaerobically no oxygen. Lactobacillus bulgaricus and streptococcus thermophilus are put into milk. (Both gram positive lactose fermenting bacteria) Lactose fermented to lactic acid leads to acidifying the product, thickening the solution as well as L. bulgaricus and S. thermophilus performs other metabolic activities. All of this contributes to the taste + texture of yogurt. Acidification of yogurt (+ high incubation temp) suppresses growth of other bacteria such as E. Coli.

Answer 5

Yeast (saccharomyces cerevisiae), a unicellular eukaryote (fungi) is used for many food processes, including production of alcohol from various sources of starch. Types of starch contribute to the type of alcohol beverage produced. Alcohol production begins to inhibit yeast growth after a while, and distillation is necessary with a higher alcohol percentage. Some sources of starch, are grape, rice, barley, agave, and sugarcane, which turn to glucose, pyruvate, then go through ethanol fermentation and distillation for some alcohols.

Answer 6

Some cyanobacteria are also capable of nitrogen fixation Nitrogen fixation converts atmospheric N2 to ammonia (NH3) Nitrogen is ESSENTIAL for making DNA, proteins, etc. Most organisms can not use N2 as their nitrogen source and depend on ammonia produced by nitrogen fixers. The only problem with this is that: Nitrogen fixation cannot happen when there are other O2 around. Plus, cyanobacteria produces O2 through oxygenic photosynthesis during carbon fixation. So… in this case, how do we resolve it? One word: HETEROCYSTS!

Answer 7

ilamentous bacteria show true multicellularity. Cells in multicellular bodies specialize their function and depend on one another for survival. Some cells in cyanobacteria filament terminally differentiate to HETEROCYSTS, which are cells specialised for nitrogen fixation. Heterocysts CAN'T survive on their own and they also cannot photosynthesize and depend on neighbouring vegetative cells to provide glucose.. Etc. Heterocysts form a barrier to block O2 from entering, allowing nitrogen fixation inside the cell! Now, heterocysts can provide fixed nitrogen to the neighbouring cells!

Answer 8

Detect 16s rRNA genes in environmental samples to accelerate identification of new species. (this is basically just a technique used in microbiology and ecology to classify bacteria and archaea present in a given environment) this is just a specific genetic market found in all bacteria and archaea.

Answer 9

Proteobacteria Gram negative Very diverse, there's a variety of free living and symbiotic(means they live with their host) microbes Photoautotrophs, chemoheterotrophs, etc Escherichia Coli (E. coli), Vibrio cholerae, etc Ancestors of eukaryotic mitochondria through endosymbiosis. (recall, endosymbiosis is when one cell engulfs another instead of digesting it, the engulfed cell becomes a functional part of the host) So in this case, a eukaryote primary cell engulfed a proteobacterium, then evolved into the mitochondria.

Answer 10

Cyanobacteria Gram negative Only bacterial photoautotroph which does oxygenic photosynthesis Ancestors of eukaryotic chloroplasts through endosymbiosis. Fun fact: chloroplasts(organelle in plants and algae that do photosynthesis) came from cyanobacteria via endosymbiosis.

Answer 11

gram negative: proteobacteria, chlamydia, spirochete, and cyanobacteria. gram positive: Staphylococcus sp. Streptococcus sp. Bacillus sp. Bacillus anthracis

Answer 12

true. they must live inside a host to survive.

Answer 13

Symbiosis: two different species living together in a close relationship (like gram negative and positive bacteria) Symbiont means they live with their host (usually smaller species) Types of symbiotic relationship: there are 3 types: Mutualism: both host and symbiont gain benefit Commensalism: one of the species gain benefit, the other is not harmed Parasitism: One of species harm the other for their benefit causing disease in many cases

Answer 14

false. It is estimated that there are at least an equal number of symbiote microbes living on our body as compared to the number of human cells. (some estimate up to 10 times more microbial cells) Many of these are beneficial, while others cause disease.

Answer 15

Disease: disturbance in the normal functioning of an organism. Infectious disease: any disease caused by a microorganism. From my understanding, diseases can be caused from genetics, lifestyle, or environmental factors, (like cancer, diabetes, heart disease…) while infectious diseases are caused by microorganisms such as the flu, lyme disease, malaria… Bacteria, eukaryotic protists, fungi, and viruses are all known to have species who cause diseases in humans Members of archaea have NOT been conclusively associated with any specific disease.

Answer 16

A Pathogen is a microorganism that causes a specific disease. Pathogenesis is the process in which a pathogen causes the disease. Requirements of pathogenesis: Entry into host Attack and invade host cells/tissues Evade host defenses (block/avoid) Obtain nutrients from the host and reproduce Exit from the original point of infection and spread

Answer 17

Biofilm helps pathogenesis Secretion of capsule/slime layer forms structures to support bacterial communities to co-exists which helps with attachment and avoidant of host defense.

Answer 18

Bubonic plague (black death) Caused by yersinia pestis, gram negative, non-motile coccobacillus. Transmission through fleas Ravaged human population worldwide in the 1340s, and killed about ⅓ of the European population. A couple thousand cases are still reported today every year.

Answer 19

Obligate and Opportunistic Pathogens Obligate pathogens are bacteria which will cause the disease in the pathogen (at least by a high chance) Opportunistic pathogens which is when bacteria co-exist with their host normal microbiome. Only begins to cause a disease when the host triggers it, such as a weakened immune system. Not all bacterial pathogens cause diseases. Many can co-exist with their host without causing any harm.

Answer 20

M. haemolytica is a gram negative bacillus that normally lives in the upper respiratory tract of healthy farm animals such as cows. M. haemolytica is an opportunistic pathogen which causes BPP when animals are stressed. It is kept under control in healthy animals as the host's immune system keeps the bacterial population low in the upper respiratory tract. Sometimes, m. haemolytica can travel down the respiratory tract but is quickly cleared/purged. Stress ultimately compromises the animals immune system! Increased bacterial population in the nasopharynx. More M. haemolytica travelling down the lung, colonizing the region.

Answer 21

Acute pneumonia accompanied by fever, nasal discharge, lack of movement, and loss of appetite. BPP rarely occurs when animals are kept healthy and distressed. It happens when animals are put into stress such as long distance transportation. This is why they call it shipping fever.

Answer 22

Escherichia coli is also a gram negative bacillus, normal resident of animal intestines, many are non-pathogenic. E. coli O157:H7 E. coli serotype with O-antigen 157 and H antigen 7 One of the most frequently isolated E. coli serotype in food poisining. This is a normal resident in bovine intestine! It is transmitted to humans through contaminated food. It causes severe to acute hemorrhagic diarrhea and abdominal cramps.

Answer 23

Exotoxin: toxins are produced by bacteria which are used to attach the host. For E. coli O157:H7, it produces shiga toxins. Endotoxins: outermost layer of gram negative outer membrane which has many sugars attached to it. This gets released when the cell is killed and elicits a strong immune respone of host. This is also called lipopolysaccharide (lps) Sugars at the further end of LPS is called O-antigen. (E.coli O-157:H7 has a O-antigen type 157)

Answer 24

Bacillus anthracis is a gram POSITIVE streptobacillus. Causative agent of anthrax Spore forming, along with many other members of genus bacillus The only obligate pathogen in the genus (the bacteria which will cause the disease in the host) Anthrax is infection through skin contact, lung infection caused through inhaltion, and may become fatal is untreated. B.antraxis spores have been used for bioterrorism. For example, late 2001 in usa, physical mailing of B. antraxis spores killed 5 victims, more hospitalized.

Answer 25

Unikonta: including fungi and animals SAR: stramenopiles, Alevolates, Rhizarians Archaeplastida: plants Excavata Phylogenetic relationship of some eukaryotes still remain unsolved.

Answer 26

A protist is a polyphyletic group of eukaryotic organisms which are not plants, fungi, or animals. It used to be apart of the kingdom of eukaryotes, but is not classified under it anymore. They are observed in all four supergroups of eukaryotes (unikota, sar, archaeplastida, excavata) Many protists are chemoheterotrophs while others a photoautotrophs.

Answer 27

Stromatolites are the earliest fossils of life, observed from about 3.5 billion years ago. Ancient greek, stroma lithos, layered rocks. The first cellular life of earth was prokaryotes. Some prokaryotes build thin, mineralized layers on top of another, which resulted in stromatolites Stromatolites were built mainly by cyanobacteria, which perform oxidative photosynthesis.

Answer 28

Oxygen Revolution Earth in the beginning had minimum oxygen (O2) and therefore the first cellular life on earth were anaerobes. Earths oxygen is produced by biological activity through oxygenic photosynthesis. As cyanobacteria populated earth, it started to produce oxygen. (earliest oxygen production at 3.5 billion years ago) Eventually, oxygen started to saturate water and the atmosphere. Huge rises in atmospheric O2 begun around 2.7 billion years ago after water was completely saturated with O2 Oxygen is extremely reactive and poisonous. This caused a huge impact on existing protists and many obligate anaerobes did not survive, and some anaerobes found anaerobic niches where they still survived til this day. Many organisms did in fact adapt then evolve and created aerobic respiration.

Answer 29

(prokaryotes) go back to your notes and study the image

Answer 30

Evidence for the bacterial origin of mitochondria The mitochondria is very similar to gram negative bacteria. The two things they have in common are: Two membranes, inner and outer Circular genomes (bacterial chromosome vs the mitochondrial DNA) Molecular machines inside the cytosol such as ribosomes for protein translation Homologous proteins in the inner membrane.

Answer 31

primary: (chloroplast and mitochondria) engulfed: cyanobacteria what it became: chloroplasts examples organisms: plants, red and green algae secondary: engulfed: red or green algae what it became: complex plastids examples organisms: diatoms, dinoflagellates, euglena

Answer 32

Primary endosymbiosis is supported by evidence similar to those supporting mitochondrial endosymbiosis Cyanobacteria and the chloroplast shares multiple morphological and genetic similarities including: Photosynthetic pathways Systems for transcription and protein translation. The cyanobacterial origin of chloroplasts is widely accepted, although there are debates on how it is done.

Answer 33

Red algae and green algae has been engulfed by another eukaryote in multiple independent occasions resulting in spread of oxygenic photosynthesis to other eukaryotic clades.

Answer 34

1️⃣ Red Algae (Rhodophyta) → Gave Rise To: Some members of the following groups acquired photosynthesis by engulfing red algae: ✅ Stramenopiles → Includes: Diatoms (major oceanic primary producers) Brown algae (kelp forests) ✅ Alveolates → Includes: Dinoflagellates (some photosynthetic, some cause red tides) Apicomplexans (e.g., Plasmodium, which causes malaria, originally had plastids) ✅ Cryptophytes → Contain a nucleomorph (remnant of red algae nucleus). ✅ Haptophytes → Marine phytoplankton involved in ocean carbon cycling. 2️⃣ Green Algae (Chlorophyta) → Gave Rise To: Some members of the following groups acquired photosynthesis by engulfing green algae: ✅ Excavata → Includes: Euglenids (e.g., Euglena) → Photosynthetic protists that can switch to heterotrophy. ✅ Rhizarians → Includes: Cercozoans (some acquired chloroplasts from green algae).

Answer 35

1️⃣ Observing Algae-Protist Symbiosis Today: Paramecium bursaria ✅ What is it? Paramecium bursaria is a non-photosynthetic protist (ciliate, Alveolate, SAR supergroup). It does not have its own chloroplasts but hosts symbiotic green algae inside its cytoplasm. ✅ How it Supports Secondary Endosymbiosis: The Paramecium does not digest the algae but keeps them alive inside its cytoplasm, where they perform photosynthesis. This relationship suggests how secondary endosymbiosis could have happened in the past, where a heterotrophic protist engulfed algae and retained their plastids (chloroplasts), leading to new photosynthetic lineages. If this symbiosis became permanent, it could eventually lead to a new type of photosynthetic eukaryote. 2️⃣ Traces of Endosymbiosis in Cryptophytes (e.g., Cryptomonas ovata) ✅ What is it? Cryptophytes are a group of algae that gained photosynthesis by engulfing red algae through secondary endosymbiosis. They provide clear genetic and structural evidence of this process. ✅ How it Supports Secondary Endosymbiosis: SO HERE ARE THE FOUR THINGS THAT FINALLY BACK IT UP: Presence of a Nucleomorph → Cryptophyte plastids still contain a "nucleus remnant" from the red algae they engulfed. This nucleomorph contains DNA, proving that cryptophytes once had a fully functional red algal endosymbiont. Four Separate Genomes in Cryptophytes → Nuclear DNA (from the host protist). Nucleomorph DNA (from the engulfed red algae). Plastid DNA (from the cyanobacteria that was originally inside the red algae). Mitochondrial DNA (from the α-proteobacteria that became the mitochondria). ✅ Additional Evidence from Other Organisms: Nuclear DNA * DNA of the host protist which engulfed the Red algae * Mitochondrial DNA * Remains of alpha-proteobacteria genome which got engulfed during Mitochondrion endosymbiosis * Plastid DNA * Remains of cyanobacterial genome which got engulfed during primary endosymbiosis * Nucleomorph DNA * Remains of red algae nuclear DNA which got engulfed during secondary endosymbiosis

Answer 36

✅ Nuclear DNA (the dna of the host protist which engulfed the red algae) ✅ Nucleomorph (remains of nuclear dna of the red algae) ✅ Plastid DNA (remains of cyanobacteria DNA which got engulfed during primary endosymbiosis originally held by red algae) ✅ Mitochondrial DNA (the remains of alpha-proteobacteria which got engulfed during mitochondrial endosymbiosis)

Answer 37

Endosymbiosis In Tree of life Mitochondrion endosymbiosis: archean engulfed an alphaproteobacteria Primary endosymbiosis: ancestral Archaeplastida engulfed a cyanobacteria Secondary endosymbiosis: red algae engulfment gave rise to photosynthetic haptophyes, cryptophyes, stramenopiles, alveolates Green algae engulfment gave rise to photosynthetic rhizarians and excavates.

Answer 38

HUMAN Nuclear DNA (human origin) Mitochondrial DNA (proteobacterial origin) GREEN ALGAE AND PLANTS Nuclear DNA (human origin) Mitochondrial DNA (proteobacteria origin) Plastid DNA (cyanobacteria origin) CRYPTOPHYTES Nuclear dna (human origin) Mitochondrial dna (proteobacteria origin) Plastid dna (cyanobacteria origin) Nucleomorph DNA (green algae origin)

Answer 39

Algae: photosynthetic protists who gained oxygenic photosynthesis through primary or secondary endosymbiosis. Primary production on earth through photosynthesis comes from 30% algae, 20% prokaryotes such as cyanobacteria and 50% by land plants. Algal Blooms: Rapid growth of algae due to an increase in nutrients (runoffs from fertilized agricultural lands, untreated factory waste water, etc,,, all can be sources of increased nutrients) Caused by both algae and cyanobacteria Usually, one species dominates a bloom at a time, but a dominant species may change over time! Algal blooms damage environments and its inhabitants' water. Water hypoxia is a severe environmentla issue caused mainly by human activities, leading to low oxygen levels and threatening marine life. (though bacterial decomposition of dead algae) Harmfal algal blooms increase due to climate change.

Answer 40

Dinoflagellates and the Red Tide Alveolate in the SAR group Unicellular algae About half are chemoheterotrophs while others are photoautotrophs/mixotrophs. Photoautotrophic dinoflagellates contain carotenoids as one of their photosynthetic pigments Carotenoids are the orange pigment and carrot etc. Algal bloom of dinoflagellates causes red tide. Red tide is caused by other algae too such as heterosigma akashiwo.

Answer 41

Haptophytes Unresolved group in the eukaryotic tree Mostly marine, unicellular photoautotrophs and mixotrophs Two flagella for motility plus a haptonema for surface attachment and/or predation Surface of haptophytes are covered with small scales made of polysaccharides. Some haptophyes like emilliana hyxleyi have hard, calcified scales. ✅ Final Answer (Simple & Clear) Haptophytes are a group of marine algae. Emiliana huxleyi is a type of haptophyte with calcified scales. It creates huge ocean blooms visible from space. Dead E. huxleyi sink to the ocean floor, forming massive structures like the Cliffs of Dover over time

Answer 42

Straw like hair (latin, stramenopiles), as many members have flagellum with fine, hair-like projections. Diatoms, a unicellular photoautotrophic stramenopile, one of the most abundant photosynthetic organisms in oceans and lakes. Diatoms have glass like cell wall made of silicon dioxide for mechanical protection vs predation.

Answer 43

Diatoms of various shapes are distributed in aquation systems like oceans, rivers and lakes. (distribution is correlated reasonably well with location, season, etc). Diatoms are well preserved due to their silica shell Forensic limnology isolates diatoms fro mcrime scenes to better understand case. For example, using diatoms on victim body to match it to crim location Not as useful as legal evidences due to amount of variation in samplating tho.

Answer 44

Brown algae (seaweeds) Multicellular photoautotrophic stramenopile and the largest most complex algae. Have organ like structures which are analogous to plants Blades : increase surface area (leaf–like) Stipe: support the blades (stem-like) Holdfast: anchor the alga (root-like) Can get up to 60cm tall (some have gas filled goats to help the blades get closer to the water surface Plant like reproduction cycle

Answer 45

Alternating diploid and haploid stages Diploid: cell with a pair of chromosomes (2n) n = 23 pairs for humans, 46 chromosomes total Haploid: cell with a single set of chromosome(n) Human example: 1 diploid adult (n =46) produces haploid, unicellular gametes (sperm/egg n =23) thru meiosis Haploid perm (n=23) fuses with haploid egg (n=23) producing a diploid, unicellular zygote (n=46) Diploid zygote divides by mitosis to grow into diploid adult (n=46)

Answer 46

plants and some algae produce multicellular bodies in both diploid and haploid stages

Answer 47

Alternates between: Sporophyte: spore producing, diploid multicellular form. Gametophyte: gamete producing, haploid multicellular form

Answer 48

Simplified understanding: unlike animals, plants alternate between two multicellular stages: Sporophyte (diploid, 2n) Produces haploid spores through meiosis Spores grow into gametophytes (haploid stage) gametophyes(haploid, n) Produces haploid gametes (sperm and egg thru mitosis) Gametes fuse to form a diploid zygote, grows into a sporophyte) Key takeaways: Animals: only the diploid stage is multicellular Plants and some algae: both diploid and haploid stages can be multicellular Sporophyte (diploid, 2n) makes spores, --> and gametophyte (haploid, n) makes gametes which then match with a haploid unicellular gamete from another body, create diploid unicellular zygote through fertilization, and then mitosis creates sporophyte. Diploid sporophyte produces haploid spores by meiosis Haploid spores divide by mitosis to become the haploid gametophyte Haploid gametophyte produce haploid gametes by mitosis Two haploid gametes fuses, producing a diploid, unicellular zygote Diploid zygote grows by mitosis to become the diploid sporophyte.

Answer 49

🔹 Simple Step-by-Step Explanation 1️⃣ Sporophyte (2n) → Produces Zoospores (n) The large sporophyte (2n) is the main seaweed you see. It undergoes meiosis to create haploid zoospores (n). Zoospores swim using their flagella, spreading out in the water. 2️⃣ Zoospores (n) → Grow into Male & Female Gametophytes (n) Half of the zoospores develop into female gametophytes (n). The other half develop into male gametophytes (n). 3️⃣ Gametophytes (n) → Produce Gametes (Egg & Sperm) (n) Female gametophytes produce eggs (n). Male gametophytes produce sperm (n) These gametes do not grow on their own; they must fuse. 4️⃣ Gametes Fuse → Zygote (2n) → New Sporophyte (2n) Sperm fertilizes egg → forms a diploid zygote (2n). The zygote grows into a new sporophyte (2n), completing the cycle. in summary: Sporophytes (2n) produce zoospores (n) by meiosis. Zoospores develop into separate male & female gametophytes (n). Male gametophytes make sperm (n), female gametophytes make eggs (n). Fertilization → Zygote (2n) → Grows into a new sporophyte.

Answer 50

Direct ancestors of primary endosymbiosis The “source organisms” of secondary endosymbiosis 1️⃣ Primary Endosymbiosis → Produced Archaeplastida (red algae, green algae, land plants). 2️⃣ Archaeplastida became the source for Secondary Endosymbiosis → Red & green algae were engulfed by other eukaryotes. 3️⃣ This spread photosynthesis to new groups like diatoms, dinoflagellates, Euglena, and cryptophytes. ✅ Archaeplastida = The “original source” of photosynthesis in eukaryotes. ✅ Secondary endosymbiosis explains why so many non-plant eukaryotes can photosynthesize! 🚀

Answer 51

Green algae: Green algae is a paraphyletic group which is missing the embryophytes (plants) Two main groups of green algae: Chlorophytes: the sister group to the clade streptophyta (charophytes + plants) Charophytes: the closest relative to land plant .

Answer 52

Charophytes, green algae Closest relative to plants (determined by molecular phylogeny of nuclear, mitochondrial, and plastid DNA, as well as morhplogical features Charophtes and plants: Both synthesize cell wall using ring like protein structure, embedded in plasma membrane Both have flagellated sperm Both have similar nuclear, mitochondrial, and chloroplast DNA Both have ✅ Sporopollenin is a tough, chemically stable polymer that protects spores and pollen grains from harsh environments.

Answer 53

False! we are obligate aerobes becaue our cells require oxygen for survival and ATP production through aerobic respiration. While our muscles can temporarily use anaerobic fermentation, we cannot live permanently without oxygen like true facultative anaerobes.

Answer 54

Nitrogen fixation is carried out by the enzyme nitrogenase, which converts atmospheric nitrogen (N₂) into ammonia (NH₃), a usable form for living organisms. However, nitrogenase is extremely sensitive to oxygen (O₂) and becomes inactivated in its presence. heterocysts allow for nitrogen fixation by having a thick wall blocking out oxygen (O2) photoynthesis from entering, then sharing their nutrients developed to other cells to sustain colony!

MIDTERM 2 EXAM KEY NOTES Flashcards

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