UNIT 3 Flashcards
Most viruses are composed of what?
of a nucleic acid and a few proteins
Viroids are made up of what ? They are the … infective agents?
they are made up only of a nucleic acid (genetic material). /simplest
Viruses are …. and because of that they do not metabolize energy?
acellular (noncellular)
What can viruses not produce?(4)
ATP or conduct fermentation, cell respiration, or photosynthesis
Where can viruses reproduce?
only in systems that do perform these functions: living cells
Viruses are considered…?
Not alive
What does obligate intracellular parasites mean?
They are obligated to reproduce inside a cell.
Viruses are obligate intracellular parasites that ….and …. only within living cells of a specific hosts?
that develop and reproduce
How does viruses reproduce? What happens to the host cell?
Viruses reproduce using the host’s synthetic machinery and usually destroy the host cell in the process.
what is synthetic machinery?
Its everything in the cell (ribosome, DNA, like a factory which they intrude).
What happens when the host cell release the progeny of replicated viruses?
It infect new hosts. (cell)
Outside the cell, the individual viral particles are called?
virions
What is the virion genetic material?
its either DNA or RNA
What generally surrounds virion?
a capsid (or protein coat).
The characteristic shape of virion are determined by what?
by the protein coat
Are viruses affected by antibiotics? Why?
No ,because they lack the cell wall structure and ribosomal biochemistry of bacteria.
Viruses are described according to four different criteria. What are they?
1-Whether the genome is DNA or RNA
2-Whether the nucleic acid is single-stranded or double-stranded
3-Whether the shape of the virion is a simple or complex crystal
4-Whether or not the virion is surrounded by a membrane
Viruses that infect bacteria are called?
Bacteriophage (or phage)
How does bacteriophage recognize their host?
By means of specific binding between proteins in the capsid and receptor proteins on the host’s cell.
The virion are equipped with ….. that inject the phage nucleic acid into the host cell?
With tail assemblies
The virus may do what when entered in a host?
may reproduce immediately and kill the host, or postpone reproduction by integrating its nucleic acid into the host’s genome.
What are the two types of reproductive cycles?
(1) the lytic cycle and (2) the lysogenic cycle
What happens in the lytic cycle?
The infected bacterium lyses (breaks down), releasing the progeny phage
What are called the phage that only have lytic cycles ?
virulent viruses
What happens in the lysogenic cycle?
the host cell does not lyse (break down), but harbors the viral nucleic acid for many generations.
What are called the phage/virus that only have lysogenic cycles ?
temperate viruses
What are the three mains domains for all living organisms ?
Bacteria, Archaea, and Eukarya
Is it true that the two prokaryotic domains of Archaea and Bacteria differ from each other more radically than the Archaea from the Eukarya?
true
What are the most successful organisms on Earth in terms of number of individuals ?
Prokaryotes
Where can prokaryotes be found? What type of habitat on earth?
They are found in every type of habitat on Earth.
What are the three common body shapes of prokaryotes?
- Sphere or coccus (plural cocci)
- Rod or bacillus (plural bacilli)
- Helical or spirillus (plural spirilli)
What do Prokaryotes lack?
Nuclei, and membrane- enclosed organelles
How does the prokaryotes chromosome look like?
one circular chromosome
Is it true that many prokaryotes are motile(mobile)?
true
How do prokaryotes move(most of them)?
Most move with a flagellum (pl. flagella). Prokaryotic flagella rotate.
Do Prokaryotic cell walls differ from those of eukaryotes (plants, fungi, and algal protists)?
Yes
How do Prokaryotic cell walls differ from those of eukaryotes (plants, fungi, and algal protists)?
– Bacterial cell walls generally contain peptidoglycan (a polymer of amino sugars).
– Archaea, however, do not have peptidoglycan.
How can you find the differences in peptidoglycan content? What is the name of the substance reacted upon? What are the results?
From different reactions to the Gram stain/
• Gram (+) have lots of peptidoglycan and appear purple.
•Gram (–) have very little peptidoglycan and appear red.
How do prokaryotes reproduce asexually ?
by binary fission
How do prokaryotes reproduce sexually ?
by exchanging genetic information, called conjugation.
What type of cell have only all 3 metabolic pathways and what are they?
prokaryotes/obligate aerobes, obligate anaerobes, facultative anaerobes
What are the 4 categories of nutrition for prokaryotes? (They are the only one to have it)
photoautotrophs, photoheterotrophs, chemoautotrophs, and chemoheterotrophs.
Some prokaryotes play key roles in global….cycles and what are there names ?
nitrogen and sulfur/Nitrogen fixers & denitrifiers do so in the nitrogen cycle.
What generated the oxygen gas that permitted the evolution of aerobic respiration and the appearance of present-day eukaryotes ?
Photosynthesis by cyanobacteria
Is it true that only a big majority of known prokaryotes are human pathogens (i.e., disease- causing organisms)?
False , small/minority
Many prokaryotes are ……—they metabolize organic compounds in dead organisms and other organic materials.
decomposers
There are far more known (archaea/bacteria ) than(bacteria/archaea)
Bacteria,archaea
Taxonomy of bacteria has been based on characteristics, what are they?(6)
shape, color, motility, nutrition, antibiotic sensitivity, and gram-stain reaction
How many clades of bacteria have been proposed under a currently accepted classification scheme?
Over 12
What is chlamydia bacteria?
They are extremely small, and live only as parasites within cells of other organisms.
What is cyanobacteria?(what can they do?)
unlike other bacteria, they can
photosynthesize (similar to plants). Many species can also fix nitrogen. Ex., Anabaena
What is firmicute bacteria? (Produce)
They are very diverse. Some produce endospores (resting structures resistant to harsh conditions). Ex., Bacillus, Staphylococcus
What is actinomycetes bacteria? ( produce)
They produce important
antibiotics. Grow as branching filaments. Ex., Mycobacterium tuberculosis
What is mycoplasma bacteria?
the tiniest of all living organisms, lack conventional cell walls, and have very small genomes.
What is proteobacteria?
It’s the largest group of bacteria (ex., E.coli). Includes some nitrogen-fixers, such as Rhizobium
Archaea are famous for …. such as ..4..?
Archaea are famous for living in extreme environments:
high salinity, high temperatures, high or low pH, and low oxygen.
Archaea are divided into two main clades what?
Euryarcheota and Crenarcheota
Most know crenarcheota are both?
thermophilic and acidophilic
Some euryarcheota are ….(produce methane gas, CH4)
are methanogens
Some euryarcheota live in… (2)?
- Some live in the guts of herbivorous animals.
* Some in high-temperature environments on the ocean floor.
Some Euryarcheota are extreme ….? These salt lovers lend a pinkish color to salty environments; some grow in extremely alkaline environments.
halophiles
How did the modern eukaryotic cell arise from?
An Ancestral prokaryote
What would be the probable steps for the formation of modern eukaryotic cell? (4)
▪loss of the cell wall,
▪inward folding of the plasma membrane,
▪an infolded plasma membrane attached to the chromosome may have led to the formation of a nuclear envelope,
▪a primitive cytoskeleton evolved.
We define protists as all eukaryotes that are not….3 ?
plants, fungi, nor animals
Protist are monophyletic (one ancestor) or polyphyletic(many ancestors) ?
polyphyletic (i.e., many ancestors).
Most protist are …. and others live within other organism?
Aquatic
The great majority of protist are 2…. but many are multicellular, and a few are enormous ?
are unicellular and microscopic
_ is an outdated term applied to photosynthetic protists.
Algae
_ is an outdated term applied to protists once classified as animals.
Protozoa
_ is an outdated term applied to fungi-like protists.
Slime moulds
What are phylum pyrrophyta?
They are unicellular and photosynthetic.
- Reddish brown pigments.
- Major contributors to world photosynthesis. •Contribute to growth of coral reef.
- Cause “red tides”.
What are apicomplexa??
They are unicellular and heterotrophic.
• All are parasitic.
• The genus Plasmodium causes the disease malaria.
What are ciliophora (ciliates)??
They are unicellular and heterotrophic.
• Have numerous cilia.
• Have two types of nuclei.
What are bacillariophyta (diatom)??
They are unicellular and photosynthetic.
- Yellow or brown carotenoid pigments.
- Contribute to world photosynthesis.
- Have “glassy” cell walls made of silica.
What are Phaeophyta (Brown algae)??
They are mostly multicellular and photosynthetic.
• Brown carotenoid pigments.
• They include the largest of all protists (i.e., Giant Pacific kelp).
• Show tissue differentiation.
What are rhodophyta (red algae) ??
They are multicellular and photosynthetic.
• Red pigments.
• Their storage product is floridean starch.
• Their gametes are not flagellated.
What are chlorophyta (Green algae)??
They are mostly multicellular and photosynthetic.
• Green chlorophylls a & b, like plants.
• Their storage product is starch, like plants.
• Are sister to the plants (Plant kingdom).
What are choanoflagellida??
They are unicellular and heterotrophic.
•They have a flagellum.
•Body type similar to a characteristic type of sponge cell called the choanocyte (“collared” cell).
•Are sister to the Animal kingdom.
What is fungi?
They are heterotrophic eukaryotes with absorptive nutrition.
Fungi degrade….in the biosphere, and are …. of almost all vascular plants ?
dead organic matter//nutritional partners
Some fungi can be .. of plants and animals?
can be serious pathogens or parasites
What are the 3 groups of fungi and their meanings?
decomposers: absorb nutrients from dead organic matter,
parasites: absorb nutrients from living hosts,
or
mutualists: both partners benefit.
Some fungi ( yeast ) are ….? (Cellular)
Unicellular
Most fungi are ….? (Cellular)
Multicellular
Multicellular fungi are composed of ? (3)
Hyphae
Mycelium
Hyphae cell walls
What is a hyphae?
each of the branching filaments that make up the mycelium of a fungus. (tubular filaments)
What is a mycelium?
An underground mass of hyphae (the main body of the fungus)
An hyphae cell wall contains?
Chitin
What are the steps of asexual reproduction in fungi?
- Cell division by unicellular fungi: fission (also called budding).
- Production of spores.
- Breakage of the mycelium.
When and how do fungi sexually reproduce?
• Fungi reproduce sexually when hyphae of different mating types meet and fuse (see example of Zygomycota)
What are the 4 fungi phyla kingdom ?
▪Chytridiomycota ▪Zygomycota ▪Ascomycota; and ▪Basidiomycota.
These phyla (4 kingdoms fungi) differ in their ...?(2)
in their reproductive structures, and mechanisms of spore formation.
The Chytridomycota have …and ressemble..?
flagellated spores and gametes//probably resemble the ancestral fungi
The Zygomycota reproduce sexually by ….
fusion of hyphae. This makes zygosporangia that contain zygospores.
The Ascomycota have a sexual reproductive structure called ?
an ascus that contains ascospores
The Basidiomycota have a sexual reproductive structure called ?
a basidium that contains basidiospores.
What is Mycorrhizae ? (Association)
mutualistic associations of fungi with plant roots, enhance the ability of the roots to absorb water and nutrients. The fungus gets sugars and proteins from the plant.
What is Lichens ? (Association)
mutualistic associations of a fungus with a cyanobacterium (or a green alga), are found in some very inhospitable environments (very cold, very dry, etc)
Plants arose from ..? (Ancestor)
A common green algal (chlorophyta) ancestor
What are the traits the plants share with green algae? (3)
Chlorophyll a and b
Starch as a storage product
Cellulose in cell walls