Bio 122 Section 2

Microbes

Bacteria or Archaea, virtually all unnamed and undescribed

Bacteria

Prokayotic; cell walls made of petidoglycan; plasma membranes similar to eukaryotes; distinct ribosomes/RNA polymerase; some pathogenic

Archaea

Prokaryotic/unicellar; cell walls made of polysaccharides; unique plasma membranes; RNA polymerase/ribosomes similar to eukaroyotes; No known pathogens

Infectious disease

spread by being passed from infected individual to uninfected individual

Koch’s Postulate

Microbe must be present in diseased individuals and absent from healthy individuals; Organism must be isolated and grown in a pure culture away from the host organism; Injection of organism from the pure culture into a healthy experimental animal should result in disease; organism should be isolated from the diseased experimental animal, again grown in pure culture, demonstrated by its size, shape, and color to be same as original organism

Germ theory of disease

infectious diseases are caused by bacteria and viruses

Antibiotics

molecules that kill bacteria

Extremophiles

Bacteria or archaea that live in high-salt, high-temperature, low-temperature, or high-pressure habitats

Astrobiologists

use extremophiles as model organisms in search for extraterrestrial life

Cyanobacteria

linear of photosynthetic bacteria; first organisms to perform oxygenic photosynthesis

Fission

splitting of a cell into two daughter cells

Plasmids

extracellular loops of DNA

Conjugation

act of joining

Conjugation tube

forms between cells that are transferring and receiving a plasmid; morphological trait unique to bacteria and archaea

Phototrophs

use light energy; ATP produced by cellular respiration

Organotrophs

oxidize reduced organic molecules; ATP is produced by cellular respiration/fermentation

Lithotrophs

Oxidize inorganic molecules; ATP produced by cellular respiration with the inorganic compound serving as electron donor

Autotrophs

manufacturing own carbon-containing compounds; consumed by heterotrophs

heterotrophs

consumes other plants/animals

Fermentation

strategy for making ATP without using electron transport chains

Methanotrophs

Use methane as primary electron donor and carbon source

Crenarchaeota

only life-forms present in certain extreme environments(high-pressure, very hot, very cold, very acidic)

Eurarchaeota

live in every conceivable habitat(including high-salt, high-pH, low-pH environments)

Eukarya

Third domain on the tree of life, range from single-celled organisms the size of bacteria to sequoia trees/blue whales.

Protists

diverse group of organisms that includes all eukaryotes except green plants, fungi, and animals

Malaria

worlds more chronic public health problem, caused by Plasmodium

harmful algal bloom

toxin-producing protists reach high densities in a particular area; causes red tides

food chain/food webs

describes relationships among organisms

Plankton

small organisms that live near the surface of oceans or lakes and drift along/swim only short distances

Phytoplankton

photosynthetic species of plankton; basis of food webs in freshwater/marine environments

Primary Producers

species that produce chemical energy by photosynthesis

Global Carbon Cycle

movement of carbon atoms from carbon dioxide molecules in the atmosphere to organisms in the soil or the ocean and then back to the atmosphere

Carbon Sink

long-lived carbon reservoir

paraphyletic

lineages grouped under the name protist

colony

loose aggregation of cells

peudopodia

large protists that surround and ingest other protists through engulfment by long, fingerlike projections.

filter feeders; suspension feeders

Species that feed by beating their cilia to create water currents to often attach themselves to a substrate and collect food by sweeping particles into their mouths.

absorptive feeding

nutrients taken up directly from the environment

Decomposers

feed on dead organic matter/detritus

Parasites

live inside other organisms and absorb nutrition directly from env inside their host; damages host.

Secondary endosymbiosis

photosynthetic protists obtain chloroplasts by eating other photosynthetic protists; chloroplasts in these protists are surrounded by four membranes instead of two

Cell Crawling

sliding movement accomplished by streaming of pseudopodia

Sexual reproduction evolved in protists

produces offspring genetically different from parents

green plants

green algae and land plants

sister group

closest living relative

Cuticle

waxy, watertight sealant; gives plants ability to survive in dry environemnts

stomata

has pore that opens/closes; allows gas exchange

Seed

structure that encloses/protects developing embryo; often attached to a structure that aids in dispersal by wind, water, or animals.

flower

reproductive organ responsible for success of angiosperms in terms of geographical distribution, num of individuals, and num of species.

Adaptive radiation

single lineage produces large number of descendant species that are adapted to a wide variety of habitats

root system/shoot system

two basic systmes for acquiring and transporting nutrients; connected by vascular tissue

plasmodesmata

connect cytoplasm of adjacent cells

Dermal tissue/epidermis

single layer of cells that covers plant body/secretes cuticle; first line of defense against pathogens

Ground Tissue

makes bulk of plant body/primary location of photosynthesis/carbohydrate storage

Vascular tissue

specialized tissue for water and nutrient transport

Xylem

conducts water/dissolved ions from root system to shoot system

Phloem

conducts sugar, amino acids, chemical agents, other substances throughout plant body

tracheids/vessel elements

Xylem contains these

pits

sides and ends of tracheids

perforations

vessel elements have these

sieve-tube members

long, thin cells that have perforated ends called sieve plates

Companion cells

contain all organelles (lots of ribosomes, mitochondria, and chloroplasts) normally found in a plant cell

indeterminate growth

occurs in meristematic tissues/ result of two processes: production of new cells by mitosis/cytokinesis, cell enlargment

Apical Meristems

tips of roots and shoots; involved in primary growth (length)

Lateral Meristems

increase width of the stem or trunk during secondary growth

root cap

group of protective cells that covers the growing region of the root

zone of cellular division

contains apical meristems (cells actively dividing)

zone of cellular elongation

made up of cells recently derived from the apical meristem (actively increasing in length)

zone of cellular maturation

older cells complete differentiation into dermal, vascular, ground tissues

root hairs

epidermal cells produce these outgrowths, greatly increasing surface area of dermal tissue

mucigel

root cap cells synthesize/secrete this slimy substance, helping lubricate root tip.

shoot apical meristem

shoots grow here

leaf primordia

both sides of a shoot apical meristem, newly developing leaves emerge as this

Evapo-transpiration

water loss via evaporation occurs when stomata are open and air surrounding leaves is drier than air inside leaves

water potential gradient

water moves down this gradient(moving up the plant) to replace water lost to transpiration

turgor pressure

water trapped inside vacuole of plant cells must maintain this to keep cells inflated

capillarity

movement of water up a narrow tube

surface tension

a pull that exists on water molecules at an air-water interfacead

adhesion

the attraction of unlike molecules

cohesion

mutual attraction among like molecules

translocation

movement of sugars through a plant from sources to sinkss

source

tissue where sugar enters the phloem

sink

tissue where sugar exits the phloem

Limiting nutrients

nitrogen, phosphorus, and potassium

zone of maturation

nutrient uptake occurs just above root tip in this region

epiphytes

plants adapted to grow in absence of soil; get nutrients needed from rainwater, dust, particles collected in tissues/crevices of bark

carnivorous plants

trip and kill insects/other animals, absorb prey nutrients

phototropism

directed movement by an organism toward light; plants positively towards blue light

photoperiodism

response by an organism based on relative lengths of day and night; plants do length of night

gravitropism

ability of plants to move in response to gravity

statolith hypothesis

amyloplasts primary gravity sensors in plants

amyloplasts

dense, starch-storing organelles

hormone

organic compound produced in small amounts in one part of a plant/transported to target cells in another part, causing a physiological response

Coleoptiles

embryotic shoots; phototropic

Cytokinins

group of plant hormones that promote cell division

Gibberellic acid

promote cell elongation and to increase rates of cell division in roots and shoots

Abscisic Acid

closes guard cells (stomata), causes plant dormancy in fall, when in roots serves as an early warning for drought stress

ethylene

hormone strongly associated with three aspects of senescence in plants: fruit fading, flower fading, abscission of fruits/flowers(dropping)

angiosperms

flowering plants, produces true flowers

meiosis

sexual reproduction based on this, nuclear division that halves the chromosome number