FNR 201 Exam 2(Ch 4.3-6.2)

cells

cells

basic units of living organisms
(Prokaryotic & Eukaryotic)

Prokaryotic cells

Lack nucleus & membrane-bound organelles
Always unicellular
E.g. bacteria & archaea

Eukaryotic cells

Well-defined nucleus
Membrane-bound organelles
May be uni- or multicellular

Cell Division

Process in which cells "reproduce"

Binary Fission

Prokaryotic cells
Splitting of one cell into two exact clones

Mitosis

Nuclear division in eukaryotic cells
Precedes total cell division

Cytokinesis

Cell division in eukaryotic cells

Marine Viruses

Not capable of reproduction without a host cell
Very small: 10-400 nanometers
Abundant & diverse
All are pathogens
DNA or RNA surrounded by protein
No metabolism
Relies on host for energy

Viron

virus particle outside of host
composed of:
nucleocapsid core(dna or rna)
capsid(protein coat to protect)

Virus Shapes
1.)Isocahedral
2.)Enveloped
3.)Helical
4.)Binal

1.)capsid with 20 triangular faces
2.)Spherical shape and spiked
3.)Capsid spirals around nucleic acid core
4.)Icosahedral "heads" and helical "tails"

Retroviruses

store genetic information in the form of nucleic acid (RNA)

Lysogenic

reproduce by inserting their DNA into the DNA of the host cell.

Bacteriophages

viruses that infect bacteria

Lysis

Rupture of host cell and release of virions

Lytic Cycle

rapid
Infection -> Replication -> Lysis

Lysogenic Cycle:

slower
•Virus remains dormant before replication

Planktonic viruses

Mostly icosahedral or binal
Most have lytic cycles

Sediment viruses

Mostly helical
Most have lysogenic cycles

Ecological role of viruses

Control populations of bacteria and plankton
Alteration of biogeochemical cycles & planktonic food webs

Marine Bacteria
Domain:Eubacteria

All are prokaryotes
Replicate via binary fission
Both pathogens & symbionts
Larger than Viruses

Bacterial Shapes
1.)Bacillus
2.)Coccus
3.)Spirillum

1.)Rod shaped
2.)Spherical shape
3.)Corkscrew shape
-uncommon in marine

How Do Bacteria Gain Nutrients?

Autotrophs
-Produce organic molecules from inorganic matter
-Mostly photosynthesis
Heterotrophs
-Absorb organic matter across cell wall via osmotrophy
-i.e.- Decomposers

Cyanobacteria

blue-green bacteria
photosynthetic(aerobic)
Can occur as:
Single cells (free floating
Long filaments
Dense mats (stromatolites)

Stromatolites

Dense coral-like 'mounds'
Stabilize sediment and clarify water
Cyanobacteria form thin 'living skin' over the mound

Photosynthetic pigments:

Chlorophyll a and chlorophyll b

Accessory pigments:

Carotenoids and phycobilins

Chromic adaptation:

Changes in accessory pigments in response to changes in the quality of light
Photoprotective pigments

Anaerobic bacteria

Green and purple; sulfur and non-sulfur
Do not produce oxygen as by-product

Obligate anaerobes

Cannot tolerate oxygen

Faculative anaerobes:

Respiration with low oxygen or in dark
Anaerobic when light present

Chemosynthetic Bacteria

Autotrophs
Energy derived from chemical reactions
environments without light
Less efficient than photosynthesis
Live in many places

Heterotrophic Bacteria

All heterotrophic bacteria are decomposers
Secrete mucus to attach to floating particles
Osmotrophy, Exoenzymes

Osmotrophy

Absorption of organic matter across the cell wall & membrane

Exoenzymes

digestive enzymes used to break down organic molecules too large to absorb

Nitrogen Fixation

Process that converts nitrogen dissolved in seawater to ammonium ions (NH4+)
Nitrogen required by cells to form amino acids & nucleotides
Only occurs in some cyanobacteria & few archaea

heterocysts

Thick-walled cell in which nitrogen fixation takes place in many filamentous bacteria

Chemosynthetic bacteria(symbiotic)

Bacteria living within deep-sea vent species
Bacteria provide hosts with organic food molecules
Host provides carbon dioxide & sulfides

Bioluminescent bacteria

Photophores : Organs with cultures of luminescent bacteria
Host uses light bioluminescence for capturing prey, confusing predators, & communication

Marine Archaea
Domain:Archaea

All are prokaryotes
Similar in size to bacteria
Cell walls lack special sugar-amino acid compounds
Cell membranes contain different lipids
Many occur in extreme environments

Halobacteria

photosynthetic and thrive in high salinity

Hyperthermophiles

tolerate high temerature
Up to 120°C (248°F)

Haptophytes(Marine Protist)

Most are photosynthetic
Most are coccolithophores
Surface coating of disc- shaped scales (coccoliths) of calcium carbonate
Significant members of phytoplankton
Haptonema : Unique structure between flagella used to capture food

Stramenophiles(Marine Protist)

Closely related to haptophytes
Photosynthetic & non
two flagella:
One is simple & senses light
One is complex & used for swimming
Heterokont: Different flagella
Dinoflagellates are also heterokont

Diatoms(Photosynthetic Stramenophile)

Structure:
Frustule: Glassy cell wall composed of silicon etc.
Valve: ½ of the frustule; 1 fits over the other like a petri dish
2 basic shapes:
Centric (radial symmetry)
Pennate (biradial symmetry)

Alveolata

Alveoli : Membranous sacs beneath cell membrane
Pellicle: Complex combination of cell membrane & alveoli
Examples:
Dinoflagellates
Ciliates

Dinoflagellates

0.002 - 2 mm in size
Mostly golbular & with 2 flagella (Heterokont)
Dinosporin : Unique, decay-resistant chemical associated with the cellulose plates
mostly marine and planktonic

Dinoflagellate Structure

Heterokont flagella
Cingulum : Horizontal groove around middle of cell, short flagella
Sulcus: Longitudinal groove, long flagellum
Unarmored dinoflagellates: None or few cellulose plates in pellicle
Armored dinoflagellates: Multiple layers of plates

Dinoflagellate Nutrition

Photosynthetic: chlorophylls a & c
Mixotrophic : supplement photosynthesis with -->
Osmotrophy : Absorbing dissolved nutrients
Phagotrophy : Engulfing particles by phagocytosis

Dinoflagellate Ecological Roles

Major component of phytoplankton:
--Provide food to many organisms
Migrate vertically in water column:
--ecological advantage
Zoozanthellae: symbiotic dinoflagellates

Ciliates

Alveolates with Pellicle
Protozoans with cilia for locomotion & feeding
Membranelles: ribbon-shaped or tufted groups of cilia that increase effectiveness of locomotion/feeding
Cystosome: permanent site for phagocytosis of food

Ciliates Ecological Roles

Some harbor autotrophic symbionts or plastids
Most heterotrophic & primary consumers
Suspension feeders with membranelles
Feed on diatoms & other phytoplankton

Marine Fungi

Less than 1% of all fungi are marine
Eukaryote cell walls of chitin
Salt is toxic to fungi
Important nutrient recylers

Mycelium

Body of fungi
-Whether unicellular yeasts or filamentous hyphae

Glycogen

Polysaccharide that acts as food storage

Obligately marine fungi

require salt or brackish water

Facultatively marine fungi

Form spores in salt water, but fungi primarily terrestrial or freshwater
Salt is toxic to fungi

Marine Lichen

symbiosis btwn fungi and algae
Algae photosynthesize
Fungi provides substrate for algae
occur on intertidal rocky shore

Phylum Chlorophyta

Green Algae
-Chlorophyll a and b
-Certain cartenoids
Structure: Unicellular or small multicellular filaments, tubes or sheets
Some species have a coenocytic thallus

Coenocytic Thallus

Cell grows but doesn't divide, nucleus divides
One giant cell or a few large cells

Phylum Rhodophyta:

Red Algae
Chlorophyll a and d
Highest diversity
Primarily marine
Form algal turfs, important ecological roles
Structure: multicellular & less than 1m long, Blade-like branching filaments, Some are heavily calcified

Ecology of Red Algae

Some red algae are annual
Epiphytes: Organisms that grow on other plants
Epizoics: Organisms that grow on animals
Coralline algae: cell walls contain CaCO3

Phylum Phaephyta

Brown Algae
-Carotenoid pigment fucoxanthin
Masks green coloration of chlorophyll a & c
-benthic, temperate
-gas bladder
-trumpet cells

Inner vs. Outer continental shelf based on__________ of algae?

compensation depth
(sunlight sufficent for metabolism but not growth)

Algal Structure:
1.)Thallus
2.)Holdfast
3.)Stipe

1.)Algae body, usually composed of photosynthetic cells
2.)Structure attaching thallus to a surface
3.)Stemlike region between holdfast & thallus

Photosynthetic Pigments
1.)chlorophyll b
2.)chlorophyll c
3.)chlorophyll d

all have chlorophyll a
1.)Chlorophyta (greens)
2.)Phaeophyta (browns)
3.)Rhodophyta (reds)

Accessory Pigments

-Carotenes, xanthophylls, phycobilins, etc.
-Absorb various colors
Color of thallus due to wavelengths of light NOT ABSORBED by the alga's pigments

Cell Wall Composition of Algae

Primarily cellulose
May contain CaCO3
Many algae secrete slimy mucilage for protection
-Holds moisture & may prevent desiccation
-Can be shed to remove organisms

Fragmentation

Asexual (algal) Reproduction
Thallus breaks into pieces & each piece grows a new alga
Huge accumulations of algae formed by fragmentation

Spore Formation

Asexual (algal) reproduction
Spores release from specialized location on thallus
Spores are haploid (unpaired chromosomes)

Sexual (algal) Reproduction

Haploid gametes fuse to form a diploid zygote
Paired chromosomes, one set from each gamete

Alternation of Generations

Possess two or more multicellular stages
Asexual sporophyte
Sexual gametophyte
Minimize the effect of negative mutations

Algal Response of Herbivory

- Avoidance: Grow in crevices or grow in low turfs
- Tolerance: Rapid growth & release many spores
- Deterrence: Produce calcium carbonate or toxins

Halophytes

marine flowering plants
Vascular:
Phloem : Carries food from leaves
Xylem : Carries water from roots
Seed-bearing

Aerenchyme

Important gas filled tissue in marine plants for...
Buoyancy : Maximize exposure to sunlight
Connect to air: Allow gas transport & exchange
Tannins: Reduce herbivory & infection

Seagrasses

Hydrophytes : Live beneath the water
Vegetative Growth:
Grow by extension and branching
Flower are small and inconspicuous in most species
Pollen and seeds carried by water currents or feces

Seagrass Structure
1.)Stems
2.)Roots
3.)Leaves

1.)Cylindrical internodes separated by nodes
Rhizomes : Horizontal stems with long internodes
2.)Absorb nutrients & interact with bacteria, bear root hairs
3.)Sheath : No chlorophyll & protects
Blade : Chlorophyll & photosynthesis

Salt Marsh Plants

Plants bordering shallow bays and estuaries at the mouth of rivers.
Less adapted to marine life than seagrasses
Must be exposed to air during ebb tide

Salt Marsh Plants: Structure

Smooth cordgrass grow in tufts of vertical stems connected by rhizomes
Culm : Vertical stem
Tiller : Additional stems
One culm produces many tillers
Pollenated by wind
Seed dispersal by water
Also have aerenchyme!

Salt Marsh Plants: Adaptation

-Leaves with thick cuticle to prevent water loss
-Well-developed vascular tissues for water transport
-Specialized glands that secrete salt
-Succulent parts - high water content

Red Mangrove Roots

Stilt roots: Aerial roots of red mangroves
Prop roots: High on trunk
Drop roots: Underside of branches
Lenticles: Scar-like openings on root surface
Connect aerenchyme to atmosphere

Black Mangrove Roots

Roots originate below ground
Cable roots: spread away from trunk
Anchor roots: penetrate below cable roots
Pneumatophores: Aerial roots that grow upward from cable
Lenticles on pneumatophores ventilate root system