BIO 1101 - Prokaryotes, Protists, Fungi

Compared to eukaryotic cells, how is the prokaryotic cell wall unique in its structure and function?

Prokaryotic cell wall contains peptidoglycan.

In what ways is the internal organization of a prokaryotic cell different than that of a eukaryotic cell?

The arrangement of DNA is different - prokaryotes lack a membrane-bound nucleus. The genome of prokaryotes consists of circular chromosomes with few proteins. They also have plasmids - DNA molecules that replicate independently

Some prokaryotes have specialized membranes that can perform metabolic processes.

How are prokaryotes able to exist in populations of immense size?

They are able to reproduce quickly and efficiently through binary fission

What are the four major modes of nutrition? Be able to outline the energy sources, carbon sources and types of organisms that utilize these methods.

Photoautotroph - They obtain energy directly from light. Energy source (light), carbon source (CO2+, HCO3-), type of organisms (photosynthetic prokaryotes like cyanobacteria, plants, protists like algae)

Chemoautotroph - They obtain energy directly from chemicals. Energy source (inorganic chemicals), carbon source (CO2+, HCO3-), type of organisms (unique to certain prokaryotes)

Photoheterotroph - They use light for energy. Energy source (light), carbon source (organic compounds), type of organisms (certain salt-loving and aquatic prokaryotes)

Chemoheterotroph - They use chemicals for energy. Energy and light source (organic compounds), type of organisms (many prokaryotes, protists, fungi, animals, some plants)

How do prokaryotes vary with respect to their requirements for oxygen?

Obligate aerobes - Requires oxygen to grow (cellular respiration)

Obligate anaerobes - Cannot use oxygen (use fermentation/anaerobic respiration instead)

Facultative anaerobes - Does not oxygen to grow

Which organisms are capable of nitrogen fixation and why is this process vital to the survival of other organisms?

Prokaryotes are capable of nitrogen fixation

This process is vital because it has a large impact on

other organisms. E.g., increasing nitrogen available to plants (by supplying nitrogen compounds produced from ammonia - plants cannot use atmospheric nitrogen)

Why is nitrogen essential to life?

Nitrogen is essential for the production of amino acids and nucleic acids in all organisms. Prokaryotes can metabolize nitrogen in a few ways

Describe three examples of metabolic cooperation between prokaryotes.

1) Anabaena cannot carry out photosynthesis and nitrogen fixation at the same time, because photosynthesis produces O2, which inactivates

the enzymes involved in nitrogen fixation. Anabaena forms filamentous chains - some include a specialized cell (heterocyst) with a thickened cell wall that restricts O2 entry. Intercellular connections allow heterocysts to transport fixed nitrogen to neighboring cells and to receive carbohydrates

2) Biofilms - Channels in the biofilm allows nutrients to reach cells in the interior and wastes to be expelled

3) Sulphate-consuming bacteria coexist with methane-consuming archaea on the ocean floor. Bacteria consume and produce sulfur compounds. Methane produced through metabolism may be used as an energy source by those in the upper layers.

What are some unique features of organisms placed in the Domain Archaea?

Some prokaryotes can live in extreme conditions ("extremophiles"). This includes halophiles (extremely saline environments) and thermophiles (extremely hot environments),

What are the various roles that bacteria play in the biosphere?

Chemical recycling - Chemoheterotrophic prokaryotes function as decomposers

Prokaryotes also convert some molecules to forms

that can be taken up by other organisms. E.g., autotrophic prokaryotes use CO2 to make organic

compounds, which are then passed through food chains

Ecological interactions

In what ways do bacteria impact humans?

Bacteria impact humans both beneficially and harmfully (mutualistic bacteria vs pathogenic bacteria)

What process may have given rise to the nucleus and endomembrane system?

Endosymbiosis

Nucleus evolved from the endosymbiont of an archaea. Genome of eukaryotic cells may be the produce of genetic annealing

Eukaryotes became what they engulfed. Golgi and ER might have originated from infoldings of the membrane

How can the endosymbiosis model explain the origin of mitochondria and plastids in eukaryotes?

What is meant by the term serial endosymbiosis and what evidence supports this?

It is the idea that mitochondria evolved before plastid

Prokaryotic ancestors of mitochondria or plastids gained access to the cell as prey/parasites,

A larger cell engulfed a smaller cell and packaged it using vesicles

Outline the evidence supporting the endosymbiotic origin of mitochondria and plastids

Mitochondria and plastids each have individualized functions, similar to how prokaryotes could have had.

They each contain their own DNA, cytoplasm, and membrane, ribosomes, and tRNAs

Which organisms are included in the protists?

Includes amoebae, paramecium, algae, dinoflagellates, diatoms, euglena, slime molds.

Why was the concept of Kingdom Protista abandoned?

Many biologists thought that the oldest lineage of eukaryotes consisted of organisms without conventional mitochondria and with fewer membrane-bounded organelles than other protist groups. However, they do have mitochondria (reduced ones)

What types of cellular structure, modes of nutrition, and modes of reproduction occur in protists?

The organelles that protists use are mostly the nucleus, endoplasmic reticulum, Golgi apparatus, and lysosomes.

Some protists are photoautotrophs - which use energy from light to acquire carbon from carbon dioxide and contain chloroplasts.

Some are heterotrophs - absorbing organic

molecules or ingesting larger food particles.

Some are mixotrophs, combined with photosynthesis and heterotrophic nutrition.

They reproduce asexually and sexually

Asexual reproduction - Involves mitosis; offspring are clones of the parents

Sexual reproduction - Involves meiosis; fertilization increases genetic variation

What are the distinguishing characteristics of Euglena? Which nutritional modes exist in Euglenids?

Commonly found in pond water

They have contractile vacuole, nucleus, chloroplast, and plasma membrane

They have a pocket at one end of the cell from which

one or two flagella emerge (one short, one long).

They have an eyespot and light detector (aids and enhance photosynthesis)

They have a pellicle, which are protein bands beneath

the plasma membrane that provides strength and flexibility (they lack a cell wall.)

They are mixotrophs. When photosynthesis is unavailable, they become heterotrophic, absorbing organic nutrients from their environment

They also engulf prey through phagocytosis

What are the distinguishing features of Paramecium? What structure is involved in both locomotion and feeding in Paramecium?

They have contractile vacuoles that collect excess water from periodically expel it through the plasma membrane

They have a macronucleus and micronucleus

They have vacuoles (food vacuoles/waster vacuoles)

Cilia are involved in locomotion and feeding, as it runs along an oral groove, which helps move food into the cell

The brown algae are multicellular protists. How are these protists unique? What sort of habitats do they occupy?

Some brown algal seaweeds have specialized tissues

and organs that resemble those in plants, such as a holdfast (resembles root), which anchors the alga, and a stipe (resembles stem), which supports the leaflike blades

(Analogous structures)

They occupy marine habitats. especially along temperate coasts, where the water is cool

What are the distinguishing features of red and green algae?

Phycoerythrin. mask the chlorophyll (more red pigment in deeper waters) and allow them to absorb blue and green light

Red algae are the most abundant algae in the warm coastal waters of tropical oceans

Most red algae are multicellular. They have no flagellated stages in their life cycle and depend on water currents to bring gametes together for fertilization

Green algae are divided into several groups -charophytes and chlorophytes (main)

Most chlorophytes are unicellular and live in freshwater, but there are also some marine and terrestrial species

They carry out photosynthesis despite subfreezing temperatures and are protected by snow

Most have complex life cycles, with both sexual and asexual reproductive stages. Nearly all species reproduce sexually, by means of biflagellated

gametes

What are some distinguishing characteristics of slime molds and Amoeba?

Slime molds form a plasmodium, a single mass of cytoplasm that is undivided by plasma membranes and contains many nuclei (product of mitosis, without cytokinesis). They are absorptive heterotrophs

Amoeba contains a small mass of jellylike cytoplasm, which is differentiated into a thin outer plasma membrane

How are each of the above example protists related phylogenetically to the Kingdoms Animalia, Plantae and Fungi?

What are two key ecological roles that protists play in the biosphere? Provide examples of each.

Symbiotic protists and photosynthetic protists play an important role

Photosynthetic dinoflagellates provide food for corals and help build the reef. Corals support reef diversity by providing food to some species and habitat to many others

How do fungi obtain their nutrients?

They obtain their nutrients by absorption; they excrete hydrolytic enzymes into their surroundings, breaking down complex molecules

How is this nutritional mode directly related to ecological roles fungi play in the biosphere?

Decomposers/saprotrophs are essential to carbon cycling. they break down and absorb nutrients.

Mutualistic fungi absorb nutrients from a host organism, and they reciprocate with actions that benefit the host

What is meant by the term yeast?

A single celled fungus

What is the basic body structure of a multicellular fungus?

They form a network of tiny filaments called hyphae - tubular cell walls surrounding the plasma membrane and cytoplasm of the cells

Hyphae are divided into cells by cross-walls, or septa (some fungi)

Septa have pores large enough to allow ribosomes,

mitochondria, and even nuclei to flow from cell to cell

How does the fungal cell wall compare in chemical composition with the bacterial cell wall and the plant cell wall?

Fungi cell wall is composed of chitin - a nitrogen-containing polysaccharide

Do the structures we commonly call mushrooms represent the majority of the fungal body? Explain.

No, the mushroom structure of a fungus usually represents a small fraction of the organism's total mass

What kind of organism is currently considered the common ancestor of fungi and animals?

It was an aquatic, single-celled, flagellated protist

What evidence supports the previous hypothesis?

Paleontology and molecular systematics indicate that fungi are closely related to animals. Collectively, they are in the same clade called opisthokonts

Explain how fungi form mutualistic relationships with the following organisms, describing how each of the partners involved benefits from this ecological interaction.

a) Plants b) Animals c) Photosynthetic microorganisms

a) Fungal endophytes exist within plant tissue. They have been shown to benefit certain grasses and other nonwoody plants by making toxins, defending the host against herbivores and pathogens. They also increase the plant's tolerance to heat, drought, or heavy metals.

b) Leaf-cutter ants cannot digest on their own, so they carry to their nests and feed to the fungi. As the fungi

grow, their hyphae develop specialized swollen tips that are rich in proteins and carbohydrates, which the ants feed on. They break down leaves into substances the insects can digest, and also detoxify compounds that could harm the ants.

c) In most lichens, each partner provides something the other could not obtain on its own. The algae provide carbon compounds; the cyanobacteria

also fix nitrogen and provide organic nitrogen

compounds. The fungi provide a suitable

environment for growth.

What are three ways in which humans benefit from fungi?

Food source, cheese ripening yeast, fuel production, antibiotic production, etc.

What are examples of pathogenic fungi? Provide one example where the host is a plant and one example with an animal host. In each case, briefly describe the effect that the fungus has on its host

Ophiostoma ulmi - The cause of Dutch elm disease. Transmitted by the elm bark beetle, infection leads to a blockage of water and nutrient transport, and death of the tree.

Grosmannia clavigera, along with the mountain pine beetle, has been responsible for the loss of over 17.5 million hectares in BC. Found on specialized head

structures of the beetle, and is transferred between

trees by the burrowing insect. Once the beetle bores

into the tree, the fungus is transferred to the nutrient-rich portion of the tree where it grows, where may compromise the tree's defenses against the

beetle and cut off nutrient and water transport, leading to tree mortality.

1. autotroph 2. heterotroph 3. phototroph 4. chemotroph

Description: a prokaryote that obtains both energy and carbon as it decomposes dead organisms:

A) 1 only B) 4 only C) 1 and 3 D) 2 and 4 E) 1, 3, and 4

Description: an organism that obtains both carbon and energy by ingesting prey:

A) 1 only B) 4 only C) 1 and 3 D) 2 and 4 E) 1, 3, and 4

D)

D)

Which of the following obtain energy by oxidizing inorganic substances-energy that is used, in part, to fix CO2?

A) photoautotrophs B) photoheterotrophs C) chemoautotrophs D) chemoheterotrophs that perform decomposition E) parasitic chemoheterotrophs

C)

You have found a new prokaryote. What line of evidence would support your hypothesis that the organism is a cyanobacterium?

It is able to form colonies and produce oxygen.

Which of the following traits do archaeans and bacteria share? 1. composition of the cell wall 2. presence of plasma membrane 3. lack of a nuclear envelope 4. identical rRNA sequences 5. presence of histones associated with DNA:

A) 3 only B) 1 and 3 C) 1 and 5 D) 2 and 3 E) 2 and 5

D)

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan, but still possesses a cell wall. What is likely to be true of this species? 1. It is a bacterium. 2. It is an archaean. 3. The optimal pH of its enzymes will lie above pH 7. 4. The optimal pH of its enzymes will lie below pH 7. 5. It could inhabit certain hydrothermal springs. 6. It could inhabit alkaline hot springs.

A) 1, 3, and 6 B) 2, 4, and 6 C) 2, 4, and 5 D) 1, 3, and 5 E) 1, 4, and 5

C)

Which of the following was derived from an ancestral cyanobacterium?

A) chloroplast B) mitochondrion C) hydrogenosome D) mitosome E) Two of the responses above are correct

A)

The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?

A) cyanobacteria → green algae → land plants B) cyanobacteria → green algae → fungi → land plants C) red algae → brown algae → green algae → land plants D) cyanobacteria → red algae → green algae → land plants

A)

Unikonta is a supergroup that includes all of the following except ________.

A) fungi B) protists C) animals D) plants

D)