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160 Cards in this Set
- Front
- Back
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• An important part of the biosphere
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– Crucial components of terrestrial ecosystems
– Enable the production of food and antibiotics – Some cause disease in plants and animals |
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• Secrete hydrolytic enzymes called _________ which degrade complex organic matter into simpler forms that can be absorbed.
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exoenzymes
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• Fungi include
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– Decomposers (saprobes)
– Parasites – Mutualistic symbionts |
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• Some are unicellular-
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yeast
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an interwoven mat of filaments that surrounds and can infiltrate the food source
• efficient absorption of nutrients - high surface/volume ratio • Nonmotile, but can grow quickly toward a food source! |
– Mycelium
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: individual tiny filaments of the mycelium
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Hyphae
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no crosswalls, a continuous mass of cytoplasm and nuclei
– coenocytic |
• Aseptate
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• Fungi reproduce by making
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spores
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• The hyphae from two separate organisms release different pheromones(______)
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sex hormones
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• The two different hyphae fuse, a process called
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plasmogamy
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• The filaments fuse, but the nuclei do not join immediately.
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– a heterokaryon
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• The two haploid nuclei then fuse, resulting in a diploid nucleus
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– Called karyogamy
– May occur only after considerable time has passed |
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• The diploid state is short lived and leads to
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meiosis.
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• Fungi evolved from a
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flagellated protist ancestor
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the species earliest to diverge from protists, the ______ do have flagella
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chytrids
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• Animals, Fungi and their protist relatives and ancestors are in the clade
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opisthokonts.
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• Diverged earliest in the history of fungi
• Unique characteristic- flagellated spores called zoospores. |
Chytrids
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• 1000 known species, including molds one can find on food
• Ex. Rhizopus stolonifer a black bread mold • Alternating life cycle representative of this group |
Zygomycetes
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-hyphae that spread out over food
-phase has a sporangia, a bulbous structure that produces haploid spores -when environment is harsh, zygosporangium form in which karyogamy and meiosis occurs |
•Coenocytic
•Asexual Sexual |
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• Formerly a branch of zygomycetes
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Glomeromycetes
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a specialized type of mycorrhizae
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• Arbuscular mycorrizae–
Penetrate plant cells and form shrub like structures called arbuscules |
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• Defining feature: an ascus, a sac that produces 8 sexual spores
– Known as sac fungi – This sexual phase sac is part of a fruiting body (projects out from mycelium). |
Ascomycetes
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conidia (spores) form on the tips of specialized hyphae
– Different from the bulbs of zygomycetes |
• Asexual phase
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Cup fungi, morels, yeasts, some molds
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• Ascomycetes include
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• Commonly used in research
• In the wild, grows on bread as mold, grows on forest floors after a fire. • Has a 24 hour circadian rhythm • Responds to red light |
Neurospora
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• Includes mushrooms, some molds, mycorrhizae, plant pathogens (rusts and smuts)
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Basidiomycetes
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transient diploid state which has a club shape (club fungi)
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• Basidium
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structure supports a large number of these cells (Ex. the mushroom cap)
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– Basidiocarp
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species are efficient decomposers of wood.
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Saprophobic
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- breakdown organic material- including cellulose and lignin from plant walls
– Make essential nutrients available in a usable form. |
Decomposers
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relationships with plants, algae, cyanobacteria and animals
some tropical ants search for leaves, take them to their nest which has a bed of fungi and wait for decay, which produces their food • Cattle rely on fungi in their digestive tracts to aid in plant digestion |
• Symbionts
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- millions of photosynthetic cyanobacteria or
green algae held within a fungal mass |
Lichens
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• Photosynthetic organism provides
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organic nutrients and fixed nitrogen
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lichen general forms
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A. fruticose
B. foliose C. crustose |
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caused by an ascomycete, carried by bark beetles, has destroyed billions of chestnut trees in the eastern US.
– Serious agricultural pests |
• Dutch Elm Disease
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secrete aflatoxins in stored grain and peanut harvests
• A carcinogen • Peanut allergies |
– Aspergillus
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infects rye, toxin ends up in flour and causes ergotism
• Hallucinations, nervous spasms, gangrene |
– Ergot
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• Called mycosis
• Skin infections: Ex. Athlete’s foot- an ascomycete • Systemic infections: usually very serious, spread throughout body – Begin with inhalation of spores • Ex. Coccidiomycosis |
Fungal Animal pathogens
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cause infections only in immunocompromised organisms
– Ex. Candida albicans- normal flora of vaginal tract- can cause yeast infection, also causes thrush in babies |
• Opportunists
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bakers and brewers yeast, also common model in research
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• Saccharomyces cerevisae
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• Tissues develop from
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embryonic layers
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• Unlike fungi, animals digest their food
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after it is ingested
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– For support- animal cells have
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structural proteins.
– Ex. collagen |
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• Animals are the only multicellular organisms that have…
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Muscle cells
Nerve cells |
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• The fertilized zygote undergoes A series of mitotic divisions without cell growth
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cleavage–
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– A hollow ball usually formed
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blastula
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– The embryo rearranges so that one end folds inward
– layers of embryonic tissues are made |
gastrulation occurs
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• A dorsal (top) and a ventral (bottom) side
• A left and right side • An anterior end (head) and a posterior end |
bilateral
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– Many have sensory equipment located in the anterior end and a central nervous system (brain)
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• Evolutionary trend called cephalization.
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• Sessile (attached) animals and drifting animals (jelly fish)
• Animals can interact with environment equally on all sides |
Radial symmetry:
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Enables more complex movement
• Central nervous system allows coordination – Burrowing, flying, swimming |
Bilateral symmetry
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: collections of specialized cells isolated from other cells by membranous layers
– Not in sponges- basal animals |
true tissues
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• In all other animals, layers develop during
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gastrulation
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• Animals with two tissue layers:
– Ex. Jellies and corals |
diploblasts
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• Animals with 3 tissue layers:
– All bilaterally symmetrical animals |
triploblasts
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Body Cavities
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coelom• Its fluid cushions suspended organs
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– A true coelom derives from
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mesoderm
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triploblastic animals that have a body cavity (pseudocoelom) only partially lined with mesoderm
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• Pseudocoelomates
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lack a body cavity
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• Acoelomates
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Protostome vs Deuterostome development
• 2 modes of development based on: |
– Cleavage- the plane of cell division
– Coelom formation – Fate of the blastopore |
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The plane of cell division is diagonal to the vertical axis
– Most have determinant cleavage- the position in the 8 cell embryo determines its fate irreversibly. |
• Protostome (Spiral cleavage):
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The plane of cell division is parallel or perpendicular to the vertical axis
– Most have indeterminant cleavage- any of the 8 cells could become a complete embryo – Makes identical twins possible! |
• Deuterostome (Radial cleavage)
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•Coelom formation
In gastrulation, the growing pouch is called |
archenteron
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solid masses of mesoderm split at the base of the archenteron to form the coelom.
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• Protostome
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the mesoderm buds from the top of the archenteron to form the coelom.
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• Deuterostome
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: the indentation during gastrulation that leads to the formation of the archenteron
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Blastopore
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the blastopore becomes the mouth.
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• Protosomes
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Bilateral symmetry, Deuterostome development defines a
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clade
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__ recognized animal phyla
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35
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• Most of the water that enters a plant, leaves via
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transpiration
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• Mostly carbohydrates (CH2O’s)
– The most abundant elements: C, H, O • Some Protein – Therefore: nitrogen and sulfur |
• The dry weight of plants:
– 96% organic material |
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– Determined by hydroponic culture
• Plants are grown in mineral solutions instead of soil |
Essential Elements
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Often the mineral that has the greatest effect on growth
– Proteins, nucleic acids, and chlorophyll • The atmosphere is almost 80% |
Nitrogen
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• No eukaryote can use
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N2
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Atmospheric N2 must be converted to:
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– Ammonium (NH4+), or
– Nitrate (NO3-) - the compound most readily absorbed |
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: the decomposition of organic matter by bacteria and fungi
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• The immediate source
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other species of bacteria convert the nitrate back to N2 gas.
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The problem
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• All life on Earth depends on a continuous
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nitrogenous cycle
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• The crucial step:
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nitrogen fixation
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nitrogen fixation
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– Taking the N2 out of the atmosphere and making ammonia (NH3), which is converted rapidly to ammonium (NH4+)
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Chemical reaction
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N2 + 8e-+ 8H+ + 16 ATP -> 2NH3+ H2 + 16 ADP + 16Pi• Very expensive in terms of energy!
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The enzyme
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nitrogenase
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the most common form of malnutrition
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protien deficiency
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: improving the quality and quantity of proteins in plants
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A Major goal of agricultural research:
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Ways to get more protein....
– Requires consumption of fossil fuels |
Fertilizer with fixed nitrogen
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Plants have _______ _____ that detect changes in their environment
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cellular receptors– Ex. Responses to hormones, injury, changes in climate
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How is the reception of a stimulus transferred into action?
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– Second Messengers: small intracellular molecules that amplify and transfer the signal from the receptor to other molecules
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: any growth in a plant that results in a curvature toward or away from a stimulus
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• Tropism
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the growth of
a shoot toward light |
• Phototropism:
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• Classic experiments first performed by Darwin and one of his sons
• Only the tip of grass seedling can sense light. |
Phototropism Experiments
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An Example of a Plant Hormone-Term used to describe a group of hormones that have multiple effects on plants
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Auxin
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• The most prominent response
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elongation of cells within young developing shoots
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– The most potent natural auxin
– The first plant hormone discovered – The chemical we will refer to as auxin |
Indolacetic acid
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• The major site of Auxin synthesis
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Apical meristem of a shoot
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_____concentrations inhibit growth
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Higher
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•The Acid Growth Hypothesis
Auxin stimulates proton pumps in the plasma membrane |
– Pumping H+’s out increases the membrane potential
– Lowers cell wall pH |
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1. Activates enzymes call expansins
– Break the cross links between cellulose 2. Allows more water to flow in- increases turgor 3. Enables the cell to elongate |
• Acidification of the cell wall…
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• The production of Auxin in apical buds probably leads to the inhibition of axillary bud growth
• Removal of the apical bud (and auxin) enables lateral branch growth |
Apical Dominance
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_______ auxins are used as herbicides
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synthetic
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– Induce rapid, uncontrolled growth
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• Leads to defoliation
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• A 50/50 mix of 2 synthetic
auxins • Used in the Vietnam war – To eliminate the enemy’s cover • Also contained a by-product: – dioxin – a carcinogen |
Agent Orange
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engineering has profoundly changed biotechnology
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genetic
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Sponges
• No true tissues, the only animals not in the |
Eumetazoan clade.
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– Water flows through pores into the________, the central cavity
– Water exits through a larger opening, the______ Suspension feeders |
spongoceol osculum
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each can function as male or female, function first as one sex and then switch
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Hermaphrodites
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line the interior of the spongocoel,
– have a collar surrounding a flagella – flagella creates current, collar captures food |
• Choanocytes
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– take up food from choanocytes and move it to other cells
– Make tough fibers |
Ameobocytes
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jellies (jelly fish), corals, hydras• Sac with gastrovascular cavity
– One opening- mouth and anus |
Cnidarians–
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• Tentacles are lined with
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cnidocytes
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– Ex. Nemotocyst
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sting
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-both polyp and medusa stages, some found in fresh water
-jellies, polyp stage reduced, swimming medusa |
hydrozoa
scyphozoa |
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-boxed shapes medusa, eyes, often toxic
-sea anemones, exist as polyp only |
Cubozoa
Anthozoa |
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Phylum-Platyhel Minthes
acelomates |
Flatworms
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Ex. Planarians• move using cilia
• Light sensitive eyespots • Basic centralized nervous system |
Turbellarians
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parasitic
complex life cycles, alternating sexual and asexual stages, many have multiple hosts Ex. Blood flukes: |
trematodes
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chronic disease- pain, anemia, dysentery,
cancer, death |
Schistomiasis:
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• no gastrovascular cavity, absorb food from host intestine
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tapeworm
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- anterior end with suckers and hooks
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scolex
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loaded with thousands of eggs, break off and exit in feces
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proglottids
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• Smaller than many protists, much more complex
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rotifers
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a digestive tube with mouth and anus- not seen in flatworms or cnidarians
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alimentary canal
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filled with fluid, acts like skeleton
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• Pseudocoelum-
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have a true coelom
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lophophorates
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– Circular crown of ciliated tentacles that surround the mouth
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lophophore
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look like plants, colonial
tube dwelling worms |
ectoprocts
phoronids |
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- hinged shell, resemble clams, common in ancient seas- 400 mil years ago
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Brachiopoda
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Proboscis or ribbon worms
Closed circulatory system |
Nemerteans
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• Most protected by calcium carbonate shell
• Oysters, clams, snails, slugs, octopuses, squid All are coelomates, with an open circulatory system |
Molluscs
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a belt of backward curved teeth that slides
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radula
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clings tenaciously to rocks in the intertidal zone, has an oval, segmented shell but the body is not segmented
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chitons
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includes most molluscs– Most have a single, spiraled shell
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gastropods
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• As a gastropod develops, its visceral mass rotates 180o
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torsion
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clams, oysters, scallops, mussels
shell divided in 2 halves |
bivalves
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octopuses, squids, nautilus
active predators have a complex brain only molluscs with a closed circulatory system |
cephalopods
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Segmented coelomates, closed circulatory system
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annelids
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most marine
each segment has paddle like structures for movement Earthworms and relatives• Eat through soil, leaving it aerated, their waste improves soil texture |
polychaetes
ogliochaetes |
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• Sparse bristles of chitin
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- chaete
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• Round worms: Non segmented body, pseudocoelomates
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Nematodes
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• Covered by a tough coat
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cuticle
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widely used in developmental research
– Study of aging and neuromuscular diseases such as Parkinson’s disease. |
C. Elegans
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– Ex. Pinworms, hookworms
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Parasitic nematodes:
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causes trichinosis
• Acquired by eating undercooked pork infected by juveniles encysted in muscle tissue |
– Trichonella spiralis
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• Most successful animal phyla
• Crustaceans, spiders, insects |
Arthropods
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• General characteristics:
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– segmented coelomates
– jointed appendages – Exoskeleton made of protein and chitin |
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• 4 major lineages:
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– Cheliceriforms, myriapods, hexapods, crustaceans
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all have claw like feeding appendages called chelicerae,
• no antennae, |
Cheliceriforms
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living fossils, little change for millions of years
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horseshoe crabs
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– Anterior
– Posterior |
cephalothorax
abdomen |
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– most cheliceriform species are
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arachnids
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• fang like spider characteristic
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chelicerae
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- an internal chamber with stacked tissue that most spiders have.
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• Book lungs
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• All terrestrial, three pairs of modified appendages for mouth parts
– Includes jaw like mandibles |
myriapods
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one pair of legs per segment
– Poisonous claws on front segment |
centipedes
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Ex. grasshoppers
• Nymphs (young) look like adults |
Incomplete metamorphosis
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Ex. Butterfly
• Larval stages specialized for eating and growing |
Complete metamorphosis
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• Mostly aquatic: lobsters, crayfish, krill
• Branched, specialized appendages |
Crustaceans
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– Unlike insects, they have appendages on the thorax and the abdomen (
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insects-thorax only)
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•woodlice, pill bugs- terrestrial
• lobsters, crayfish, crabs, shrimp • planktonic krill |
Isopods:
Decapods: Copepods: |
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Dueterostomes• Thin skin covers endoskeleton
• Water vascular system-unique Ex. stars, urchins, sea |
Echinoderms
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deuterostomes
– Tunicates – Lancelets – Vertebrates |
Chordates
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