Sinclair Community College | BIO 2205 Exam 2

Describe the Major differences between prokaryotic and eukaryotic DNA packaging and internal structures.

❃ How their DNA is packaged: bacteria and Archaea have nuclear material free inside the cytoplasm with no nucleus. They do not wind their DNA around proteins.

❃ Prokaryotic cells have no nucleus, no organelles, and a very small amount of DNA

❃ Eukaryotic Cells have nuclei and cell organelles, and the amount of DNA is large.

Define Biofilms

Colonies of bacteria that adhere together and adhere to environmental surfaces.

What structures do all bacteria posses?

❃ Cytoplasmic Cell Membrane - a thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of material into and out of the cell pool.

❃ Bacterial Chromosome or Nucleotide - Composed of condensed DNA molecules, DNA directs all genetics and heredity of the cell and codes for all proteins.

❃ Ribosome Particles - composed of Protein and RNA that are the site of protein synthesis.

❃ Cytoplasm - water-based solution filling the entire cell

Describe the three major shapes of bacteria as well as other less common shapes.

❃ Bacteria come in three common shapes: Coccus (sphere), Rod (bacillus), and curved (vibrio)

❃ Other unusual bacteria forms include star-shapes, club-shapes, cube-shapes, and filamentous branches.

What structures do some bacteria posses but not all?

❃ S-Layer

❃ Fimbriae

❃ Outer membrane

❃ Cell Wall

❃ Actin Cytoskeleton

❃ Pilus

❃ Glycocalyx /Slime Layer/Capsule

❃ Bacterial microcompartments

❃ Flagellum

❃ Endospore

❃ Intracellular membranes

❃ Nanowires / Nanotubes

Describe the structure and function of the different types of bacterial appendages

Appendages can be divided into two groups: those that provide motility and those that provide attachment points or channels.

❃ Provide Motility

- Flagella - made up of three distinct part:; the filament (helical structure composed of proteins inserted into a curved tubular hoo , the hook, and the basal body (a stack of rings firmly anchored through the cell wall to the cytoplasmic and outer membranes)

- Axial Filaments - corkscrew - shaped bacteria called spirochetes show an unusual wriggle mode of locomotion caused by two or more long spiral threads, which, function to help the spirochete move through rotation of the endoflagella which causes the axial filament to rotate around the body cell and give the spirochete a twisting motion.

❃ Provide attachment points/channels

- Fimbriae - small, bristle - like fibers sprouting off the surface of many bacterial cells, th

- Pili - a long, rigid, tubular structure made of a special protein their function connects two different cells in conjunction, which involves the partial transfer of DNA from one cell to another.

- Nanowires / Nanotubules - very thin, long, tubular extensions of the cytoplasmic membrane that bacteria use as channels. they are used to either transfer amino acids among one another or to harvest energy by shutting electrons from one electron - rich surface in the environment.

Explain how a flagellum works in the presence of an attractant.

Cells may posses just one or few flagella, in the presence of an attractant the flagellum assists cells, particularly bacteria, to move towards the source of the attractant through a process known as chemotaxis.

Differentiate between the two main types of bacterial envelope structure

❃ Gram-Positive Cells - thick, and one membrane

❃ Gram-Negative Cells - thin, and two membranes

Discuss why gram-positive cell walls are stronger than gram-negative cell walls.

Gram-Positive Cell walls are made of much thicker peptidoglycan, making them structurally stronger.

What substance in the envelope structure of some bacteria can cause severe symptoms in humans?

Lipopolysaccharide - located in the outermost layer of hte outer membrane in gram negative bacteria. Lipid a (endotoxin) stimulates fever and shock

Identify Five things that might be contained in bacterial cytoplasm

❃ Bacterial DNA

❃ Prokaryotic Ribosomes

❃ Inclusion or Granules

❃ Bacterial Endosphores

Detail the causes and mechanisms of endospore formation and germination

❃ Germination - The breaking of dormancy, it happens in the presence of water and a specific chemical or enviornment stimulus (germination agent) that has become present once again in the environment.

❃ Formation - usually occurs when nutrients have started to become scarce. Carbon depletion and nitrogen depletion are common triggers.

Name four divisions of prokaryotes ending in -cutes and describe their characteristics

❃ Gracilicutes - gram-negative cell walls, thin-skinned

❃ Firmicutes - gram-positive cell walls, thick and strong

❃ Tenericutes - lack cell walls

❃ Mendosicutes - archaea with unusual cell walls.

Define species and describe the limitations of the species designation

❃ A bacterial species is a collection of bacterial cells that share an overall pattern of similar traits.

❃ The boundaries that separate two closely related species in a genus are in some cases arbitrary, recent sophisticated ' big data' analysis of bacterial genomes confirms the differences between what we have been calling different species, individual members of a give species can show variants as well, therefore more categories within a species exists but they are not well defined.

List some differences between archaea and bacteria.

Archea, like eukarya have more complex RNA polymerases than bacteria, unline bacteria archaea cell walls do not contain peptidoglycan. Archaea also have different membrane lipid bonding from bacteria and eukarya.

Define the term endosymbiosis and the last common ancestor (LCA)

❃ endosymbiosis is a relationship in which a microorganism resides within a host cell and benefits the host cell

❃ many scientists believe that both bacterial and eukaryotic cells emerged from an earlier, now-extinct cell type called the LCA

List the types of eukaryotic microorganisms and denote which are unicellular and which are multicellular.

❃ Fungi - may be unicelluar or multicellular

❃ protozoa - unicellular

❃ Helminths - multicellular

❃ algae - may be unicelluar or multicellular

❃ Humans - multicelluar

Which Eukaryotic Microorganisms have a cell wall?

Fungi and most Algae

Differentiate among the flagellar structure of bacteria, archaea, and eukaryotes.

❃ Prokaryotes - basal body, hook, moves in propeller fashion

❃ Eukaryotes - connected with cell wall, whip like movement, 10x thicker, structurally more complex and covered by an extension of the cel lmembrane.

❃ archaea - may lack flagella all together, the flagella are hair-like appendages used for moving around and are attached directly into the outer membrane of the cell.

list the ways in which eukaryotic and bacterial cytoplasmic membranes may be alike and different

❃ Typlica bilayer of phospholipids with embedded protein molecules.

❃ Eukaryotic cell membranes contain sterols of various kinds

❃ Sterol rigidity makes eukaryotic membranes more stable

❃ Cytoplasmic membranes are similar to bacteria and Archaea, serving as selectively permeable barriers.

describe the structure of the nucleus

The nucleus is composed of the cell's DNA, pierced with holes called pores, allows large molecules to pass between the nucleus and cytoplasm and it has a nucleolus

diagram how the nucleus, ER, and golgi apparatus, together with vesicles act together.

1. the genetic information originates from the nucleus

2. the proteins are synthesized and ribosomes are depositied into the rER

3. the proteins are transported to the golgi apparatus to be chemically modified and packed into vesicles

What is the function of the mitochondria?

Energy generator that extracts chemical energy in nutrient molecules and stores it as ATP.

explain the importance of ribosomes and differentiate between eukaryotic and bacterial types.

they are important for protein synthesis, there is a membrane - bound nucleus in eukaryotes and not in bacteria.

discuss the function of chloroplasts and explain which cells contain them and why

❃ found in algae and plant cells, that can convert the energy of sunlight into chemical energy through photosynthesis

❃ primary producers of organic nutrients upon which other organisms ultimately depend.

describe the main protein fibers that make up the cytoskeleton

❃ actin filaments are found throughout the cell but are most highly concentrated inside the cell membrane. responsible for cell movement.

❃ microtubules are long hollow tubes that maintain the shape of eukaryotic cells when they don't have cell walls and transport substances from one part of a cell to another

❃ intermediate filaments - ropelike structures their main roles is in the structural reinforcement of the cell and organelles.

define heterotroph

Organisms that obtain food by consuming other living things

define saprobe

An organism that derives its nourishment from nonliving or decaying organic matter.

define parasite

An organism which lives on and feeds on another organism and causes it harm

explain the relationship between fungal hyphae and the production of mycelium

hyphae is a long branching filamentous structure of gunfus. these hyphae are collectively for mycelium.

describe the two ways in which fungal spores are formed; compare and contrast conidia and sporangium.

❃ sexual spores are formed by fusing two parental nuclei, followed my meiosis

❃ asexual spores are products of the miotic division of a single parent cell

❃ conidia are free spores that are not enclosed by a spore-bearing sac. they develop either by pinching off the tip of a special fertile hypha or by segmenting a preexisting vegatative hypha.

❃ sporangium is an enclosed capsule that contain spores produces in fungi and many more species.

❃ sporangiospores are produced inside specialized cells called sporangia and remain enclosed in the cells until maturity, conidia may be produced inside a cell but at maturity they will be exposed to the external environment.

List two beneficial and negative roles that fungi play in our world.

❃ beneficial - fungi are used in the production of enzymes, organic acids, vitamins, and antibiotics.

❃ negative - fungi can destroy crops, cause diseases in humans, and ruin clothing and food with mildew and rot.

What are the categories of protozoa based on their motility

❃ flagellates - use long, whip - like structures called flagella to move.

❃ ciliates - use short, hair - like strucutres called cilia that beat in unison to move the organisms

❃ amoeboids - use a crawling motion

❃ sporozoa - are nonmotile, they can move by themselves but they can form spore - like cells.

❃ plasmodium - use an unusual form of substrate - dependent motility to migrate across host cell membranes and invade host cells.

Give an example of a human disease caused by each of the four types of protozoa

❃ Amoeboid Protozoa - amoebiasis & brain infection

❃ Ciliated Protozoa - Balantidiosis

❃ Flagellated Protozoa - giardiasis, trichomoniasis, trypaniosomiasis, leishmaniasis

❃ non motile protozoa - malaria, toxoplasmosis, cryptosporidiosis, cyclosporiasis

List two major types of helminths and know the scientific and common names

❃ Flatworms / trematodes - phylum platyhelminthes

❃ roundworms / nematodes - phylum aschelminthes

Describe the Helminth Life Cycle

The complete life cycle of helminths incldues the fertilized egg, larval, and adult stages. In the majority of the helminths, adults reproduce sexually inside a host's body in nematodes the sexes are separate and usually differ in appearance, in trematodes the sexes can be either separate or hermaphroditic (male and female sex organs are in the same worm)

Summarize the arguments on both sides of debate regarding the classification of viruses as living organisms.

❃ one viewpoint is because most viruses cannot multiply independently from the host cell they are not living.

❃ another proposes that even though viruses do not exhibit most of the life process of cells, they can direct them in cells and thus are certainly more than inert and lifeless molecules.

Idenfity better terms for viruses than alive or dead

active or inactive

describe the size of viruses relative to other microorganisms

many viruses are much smaller than the average bacterium

describe the function and structures of viral capsids.

capsids exhibit symmetry due to the regular arrangement of subunits called capsomeres, its functions are to protect the virus's nucleic acid from attack by the hosts defensive cells and attach to a specific receptor sit on a cell membrane.

Distinguish between enveloped and naked viruses

❃ Enveloped: composed of a nucleocapsid surrounded by an envelope; envelope usually has spikes

❃ Naked: simplest virus, consisting of a geometric capsid assembled around a nucleic acid strand or strands

Explain the importance of viral surface proteins, or spikes.

they project from the nucleocapsid or the envelope, allowing viruses to dock with host cells. they are important for viruses to enter their host cells, replicate their genome, and produce progeny particles.

List the possible nucleic acid components viruses may possess and describe its genome relative to living organism's genomes

the genome of a virus may consist of DNA or RNA, which may be single stranded or double stranded, linear, or circular.

explain why some find it difficult to assign species names to viruses

Viruses are too changeable

demonstate how family and genus and common names in viruses are written

❃ Virus orders are written within -virales

❃ families are writting with -viridae

❃ genera end with -virus

Diagram the 6-step life cycle of animal viruses.

1. Adsorption - virus attaches to host cell via spikes to cell receptors.

2. Penetration - Virus is engulfed into a vesicle and its envelope is....

3. Uncoated, thereby freeing the viral RNA into the cell cytoplasm.

4. Synthesis: Replication and Protein Production. Under the control of viral genes, the cell synthesizes the basic components of new viruses: RNA molecules, capsomers, spikes.

5. Assembly. Viral spike proteins are inserted into the cell membrane for the viral envelope; nucleocapsid is formed from RNA and capsomers.

6. Release. Enveloped viruses bud off of the membrane, carrying away an envelope with the spikes. This complete virus or VIRION is ready to infect another cell. (Exocytosis)

Explain the differnt types of cytophathic effects induced by viruses

❃ virus induced damage ot the cell that alters its microscopic apperance

❃ poliovirus - cells are killed completely. they shrink, detach from the surface and lyse.

❃ adenovirus - cells round up and partially detach from the surface they tend to clump together

❃ respiratory syncytical virus - adjacent cells fuse forming a large cell with many nuclei

❃ cytomegalovirus - viruses can cause the formation of inclusion bodies in either the cytoplasm or nucleus fo the host cells.

discuss both persistent and transforming infection and its effect on host cells

❃ persistant - can last from a few week to the remainder of the host' life

❃ transforming - enter a host cell and permanently alter its genetic material, leading to cancer

Provide a thorough description of lysogenic and lytic bacteriophage infections.

❃ lysogenic - the host chromosome carries bacteriphage DNA

❃ lytic - the host cell becomes so packed with viruses that its lyses-split open thereby releasing the mature virions

list the three principle purposes and methods for cultivating viruses

❃ to isolate and identify viruses in clinical specimens

❃ to prepare viruses for vaccines

❃ to do detailed research on virla strucutre multiplication cycles, genetics, and effects oh host cells.

❃ using live animal innoculation

❃ using bird embryos

❃ using cell culture techniques

explain the relative importance of viruses in human infection and disease

❃ viruses are responsible for several billion infections each year, it is conceivable that many chronic diseases of unknown cause will eventually be connected to viral agents

Discuss the primary reason that antiviral drugs are more difficult to design than antibacterial drugs.

❃ the nature of viruses make it difficult to design effective therapies aganist them. Viral infection are difficult to treat because the drugs that attack viral replication also cause side effects in the host

name at least three non-cellular infectious agents besides viruses

❃ satelite viruses

❃ prions

❃ viroids

define what a prion is and the effect on the infected host

prions are implicated in chronic persistent diseases in humans and animals, a type of protein that can trigger normal proteins in the brain to fold abnormally.