Exam 3 Flashcards
Prokaryotic spherical shape
Coccus
Prokaryotic rod shape
bacillus
Prokaryotic spiral shape
spirillus
Prokaryotes in clusters
staphylo-
Prokaryotes in chains
strepto-
Prokaryotes in pairs
diplo-
How do cell walls of Bacteria differ from those of Archaea?
- Archaeal wall contain various polysaccharides and proteins
- Bacterial walls contain peptidoglycan
How do Gram-negative cells differ from Gram-positive cells?
Gram-positive typically has a thick peptidoglycan layer and is less virulent. Gram-negative typically has a thinner peptidoglycan layer, an outer membrane that is often toxic, and is typically more virulent.
How and why do Gram-positive and Gram-negative cells stain differently?
Peptidoglycan traps crystal violet, which masks the safranin dye in Gram-positive cells. In Gram-negative cells, crystal violet is easily washed away, revealing the red safranin dye.
How do capsules and endospores help protect bacteria cells in harsh environments? How do they differ in structure?
Capsules are a sticky polysaccharide or protein layer that provide protection and adhesion for the cell. Endospores form in response to stress. The cell packages a copy of its chromosomes, lyses, and allows the endospore to remain dormant.
- behavioral response of a cell or an organism to an external stimulus
taxis
Positive-toward stimulus, Negative-away from stimulus
How can prokaryotes evolve so quickly when the number of mutations per cell division is actually lower than what is seen in eukaryotes?
Their rapid reproduction and mutation allow populations of prokaryotes to evolve quikly
Cells pick up stray pieces of DNA from the environment and new fragments are often inserted into plasmids
Transformation
Viruses called bacteriophages transfer DNA from one cell to another.
Transduction
Prokaryotic cells can directly transfer DNA via a pillus that pulls the cells together and shares the F factor
Conjugation (read up on this process)
Why are transformation, transduction and conjugation all considered mechanisms of horizontal gene transfer?
They all result in genetic recombination as a result of moving genes from one species to another
Bacteria that are all Gram-negative, but are otherwise very diverse
Proteobacteria
Bacteria that require an animal host
Chlamydia
Bacteria that are spirilli and have internal filaments
Spirochetes
Bacteria that photosynthesis and may be ancestor to chloroplasts
Cyanobacteria
What traits are shared by Archaea that distinguish them from Bacteria?
Histones present in some Archaea
Methionine initiates protein synthesis
>1 RNA polymerase
Resistant to streptomycin and chloramphenicol
What traits have led biologists to place the Archaea as sister to the Domain Eukarya?
I don’t know histones?
Aside from being pathogens, what other roles do prokaryotes play on the planet?
- Decomposition
- Complete nutrient cycles by converting inorganic molecules into usable forms
- Symbiosis
How does the Serial Endosymbiosis Theory (SET) build upon the Endosymbiont Theory that was presented earlier this semester?
This theory suggests that some organisms experienced more than one episode of endosymbiosis to become the organisms they are today
What evidence is there to support SET?
Evidence of a vestigial nucleus called a nucleomorph
What three groups discussed in class belong to the Excavata supergroup?
Diplomonads, Parabasalids, and Euglenozoans
What three main groups discussed in class belong to the SAR clade?
Stramenopiles, Alveolites, and Rhizarians
What main group did we discuss in class that belongs to the Archaeplastida supergroup?
Green Algae
What two main groups discussed in class belong to the Unikonta supergroup?
Amoebozoans and Opisthokonts
What traits unite Diplomonads and Parabasalids?
Reduced mitochondria and anaerobic (typically)
What trait unites Stramenopiles?
Presence of two types of flagella, hairy and smooth
What trait unites the Alveolites?
Presence of small sacs just inside the plasma membrane (alveoli)
What trait unites the Amoebozoans?
Presence of pseudopodia that are lobed or tubular
What trait unites the Opisthokonts?
Flattened mitochondrial cristae and a shared amino acid sequence in elongation factor 1-alpha protein
What features of fungi have led early biologist to place them in the same taxon as plants?
multicellular eukaryotes cell walls produce spores can reproduce asexually grow from the ground
What features show that fungi are most definitely not very closely related to plants?
glycogen as a storage polysaccharide
chitin as a structural polymer
chemoheterotroph
zygotic meiosis
What is a gametic life cycle?
The gamete is the only cell that is haploid
What kind of organisms use a gametic life cycle?
Animals, some protists and algae
What is a zygotic life cycle?
The zygote is the only cell that is diploid
What kind of organisms use a zygotic life cycle?
Fungi, some algae
What kind of organisms use a sporic life cycle?
Plants and many algae
What are hyphae and how do they help fungi efficiently absorb nutrients?
Hyphae are filaments that compose most fungi. They extend into the ground or wherever they’re growing and can absorb or exchange nutrients
What is plasmogamy?
Fusion of cytoplasm in fungi
What is karyogamy?
Fusion of nucleus in fungi
What is meant by heterokaryotic?
Condition where a multinucleate cell contains genetically different nuclei
What are some characteristics of Chytrids?
- flagellated zoospores
- protest-like
What are some characteristics of Zygomycetes?
- multinucleate structure
- survives harsh conditions
What are some characteristics of Glomeromycetes?
- form arbuscular mycorrhizae
- obligate symbionts
What are some characteristics of Ascomcetes?
- produce spores inside a sac-like structure called an ascus
- asexually reproduce by budding or with conidiospores
What are some characteristics of Basidiomycetes?
- produce spores on the outside of a club-like basidium
- asexually reproduce by budding or with conidiospores
Give an example of mutualism that involves fungi.
Lichens = fungus + cyanobacteria or green algae
Give an example of parasitism involving fungi.
Plant rusts or Athletes foot
What kind of plants are in the Archaeplastida supergroup?
Rhodophytes, Chlorophytes, Charophytes, and Embryophytes
What separates Rhodophytes from the other Archaeplastida?
Floridian starch, phycoerythins and phycobilins in Rhodophytes. Pressence of chlorophyll a and b, and starch is stored in plastids in the others
What are the stages of alternation of generations?
- ) Sporophyte-produces spores by meiosis
2. ) Gametophyte-produces gametes by mitosis
How did land plants overcome the challenge of maintaining water balance?
- Waxy cuticle secreted by the epidermis minimizes water loss to the air.
- air pores and stomata for gas exchange (and water loss)
- rhizoids absorb H2O (and minerals) from soil.
How did land plants overcome the challenge of obtaining resources?
- apical meristems produce directed growth
- roots capture H2O and minerals from soil
- leaves effectively intercept light
- vascular tissue(xylem and phloem)
What provides land plants with structural support?
Lignin
-Areas of active cell division at the growing tips of roots and stems that allow plants to direct growth in response to a stimulus
Apical meristems
-allowed plants with rhizoids and small roots to obtain soil resources on land.
Mycorrhizae
How did land plants overcome the challenge of reproduction and dispersal?
- Sterile jacket of cells surrounds the gametes and spores
- Sporopollenin, a complex biopolymer, prevents desiccation of spores and gametes.
- The evolution of pollen means that free standing water is no longer needed for sexual reproduction.
- Seeds = protection and nutrition for embryo; dormancy prevents untimely germination
-produce and nourish the cells that are directly involved in reproduction.
Sporangia and Gametangia
What were, most likely, the first land plants?
Liverworts
-conducts water and minerals from the soil to the rest of the plant.
Xylem tissue
-conducts organic products throughout the plant.
Phloem tissue
What did plant roots most likely originate from?
Roots are most likely modified stems
What are some characteristics of microphyll leaves?
- small
- single, unbranched vein
- no leaf gaps
- limited to one phylum
What are some characteristics of megaphyll leaves?
- large
- highly branched veins
- leaf gaps
- found in nearly all extant plant phyla
How are homospores produced?
sporangium–>single type of spore–>typically bisexual gametophyte–>egg or sperm
How are heterospores produce?
megasporangium–>megaspore–>female gametophyte–>egg
microsporangium–>microspore–>male gametophyte–>sperm
What are some characteristics of taproots?
- present in all seed plants (except monocots)
- taproot=primary root
- deepest roots
- generally tallest plants
- can be specialized for storage
What are some characteristics of fibrous roots?
- found in monocots
- primary root dies without forming a taproot
- adventitious roots emerge from the stem
- generally shallow, but well anchored
What are some characteristics of root hairs?
- extension of epidermal cells
- site where most absorption occurs
What is the function of lateral roots?
-increase anchorage and absorption
Leaf arrangement with 1 leaf per node
alternate
Leaf arrangement with 2 leaves per node
opposite
Leaf arrangement with 3 or more leaves per node
whorled
What are the three main types of tissue?
Dermal, Vascular, and Ground
What are characteristics and functions of parenchyma cells?
- alive at maturity
- thin 1°wall only
- storage, absorption, secretion (active metabolism)
What are characteristics and functions of collenchyma cells?
- alive at maturity
- irregular, non-ligified 1° wall
- flexible support
What are characteristics and functions of sclerenchyma cells?
- dead at maturity
- lignified 2°wall
- support defense
What are characteristics and functions of the tracheary elements?
- conduct water and minerals
- ± elongated
- thickened 2°walls with pits
- dead at maturity
What are characteristics and functions of tracheids?
- narrow, less specialized
- overlapping, tapered ends
What are characteristics and functions of vessel elements?
- wide, limited to angiosperms
- ± stacked on end
What are characteristics and functions of sieve elements?
-conduct sugar and other compounds
- ± elongated
-Living at maturity but the protoplast is limited
(no nucleus, ribosomes, or cytoskeleton)
-Companion cells support the sieve-tube elements.
What are characteristics of primary growth?
- takes place in apical meristems
- increases stem/root length
- located in the shoot tips, root tips, and axillary buds
- occurs in all plants
What are characteristics of secondary growth?
- takes place in lateral meristems
- Increases stem/root diameter
- Vascular cambium produces secondary vascular tissue
- Cork cambium replaces the epidermis with a thicker periderm
- occurs in seed plants but lost in many clades
What are three functions of the root cap?
- Secretes mucilage (hyperhydrated polysaccharide)
- Exudes proteins into the rhizosphere
- Detect gravity (stratoliths)
What does the protoderm produce?
epidermis
What does the procambium produce?
primary vascular tissue
What does the ground meristem produce?
ground tissue
How does an angiosperm seed differ from a gymnosperm seed?
Angiosperm seeds are enclosed within an ovary (fruit) while gymnosperm seeds are unenclosed on the surface of scales or leaves
