Plant Cell Structures and Organisms

• Study notes for chapters 17, 18, 19, 20, 22, 23, 24

Bacteria and Archaea (Chapter 17)

• Prokaryotes are single-celled organisms lacking a nucleus or membrane-bound organelles
  • Includes bacteria and archaea

Internal Structures

• Nucleoid is the region where DNA resides
• Ribosomes use mRNA to synthesize proteins
• Plasmids are circles of DNA apart from the chromosome

External Structures

• Cell membrane is the outer boundary that regulates entry and exit
• Cell walls are outside the membrane and protect from osmotic pressure, giving the cell its shape
  • Multi-layered cell wall (peptidoglycan) are gram-positive cells identified via Gram Stain
• Glycocalyx: polysaccharides that surround the cell wall and help the cell attach to surfaces
• Flagella is used for movement
• Pili helps with attachment

Cell Shapes

• Cocci: spherical shape
• Bacilli: rod shape
• Spirillum: spiral shape

Metabolic Diversity

• Photoautotrophs use sunlight as an energy source and CO2 as a carbon source
• Chemoautotrophs use inorganic chemicals for energy and CO2 as a carbon source
• Photoheterotrophs use sunlight for energy and organic compounds as a carbon source
• Chemoheterotrophs use organic compounds for both energy and carbon source Obligate aerobes need oxygen
• Obligate anaerobes are killed by oxygen, may live in the digestive tract
• Facultative anaerobes can live in aerobic or anaerobic environments
• Nitrogen fixation converts atmospheric nitrogen (N2) to ammonia which is needed for plant growth
• Symbiosis is the relationships between different species
  • Mutualism: both species benefit
  • Commensalism: one species benefits and the other is unharmed
  • Parasitism: one species benefits (parasite) and the other is harmed (host)
• Pathogens are bacteria/viruses/microorganisms that cause disease

Protists (Chapter 18)

• Eukaryotic organisms have a nucleus
• Endosymbiont explains the evolution of eukaryotes

Endosymbiosis

• Primary endosymbiosis: chloroplasts in red algae, green algae, and plant cells have 2 membranes, indication of a single event
• Secondary endosymbiosis: chloroplasts in brown algae & euglena have 3 membranes, indicating they developed from 2 successive events

Protist Groups

• Algae resemble plant cells, are aquatic, and are photosynthetic protists
• Slime/water molds resemble fungal cells, are heterotrophic protists with filamentous feeding structures, uni/multicellular
• Protozoa resemble animal cells, are one-celled, heterotrophic, and motile, with ciliates being complex protozoa with hairlike cilia

Fungi (Chapter 20)

• Heterotrophic eukaryotes

Structure

• External Digestion excretes digestive enzymes and absorb minerals & nutrients (mold)
• Hyphae: threadlike filaments that branch toward a food source
• Mycelium: a collection of hyphae
• Fruiting body: hyphae above the surface (mushroom)
• Spores: reproductive cells (sexual or asexual)

Ecological and Practical Uses

• Lichen: fungi with green algae or cyanobacteria living among hyphae. Fungi absorb minerals & water while algal cells produce sugar by photosynthesis (break down rock, harbor nitrogen-fixing bacteria, food source)
• Mycorrhizae: exchange material with roots
• Parasites: harm plants & animals (ringworm, athlete's foot, yeast infections, etc)

Plants (Chapter 19)

• Plants are multicellular, autotrophic, eukaryotes, using photosynthesis for energy

Advantages and Disadvantages to Life on Land

• Advantages include unlimited sunlight, lots of CO2, and few pathogens or herbivores
• Disadvantages include maintaining moisture inside cells to prevent drying out, supporting the body in a non-buoyant medium, reproducing & dispersing offspring without water, anchoring bodies in soil, and obtaining resources from soil & air

Adaptations

• Cuticle: waxy layer on leaf to prevent drying out
• Stomata: allows gas exchange
• Vascular tissues: bundles of tubes that transport water, minerals, and sugar throughout plant
• Root systems are below ground to absorb water & minerals while anchoring plant in soil
• Alternation of Generations involves a gametophyte (haploid) phase and a sporophyte (diploid) phase
  • Gametophyte (haploid)
    • Spores divide by mitosis to yields multicellular haploid gametophyte
      • Gametes are produced via mitosis
  • Sporophyte (diploid)
    • Fertilized egg from diploid zygote develops via mitotic cell division into multicellular sporophyte
      • Spores are formed via meiosis
        • Pollen is male gametophyte and is spread by bugs Seed carries dormant plant embryos with food and protection against drying out
  • Flowers produce pollen and egg cells
    • Fruits develop after fertilization to protect & disperse plant offspring

Plant Phylogeny

• Nonvascular Plants (Bryophytes)
  • Lack vascular tissue, roots, leaves, seeds, or flowers
  • Small and compact because lack physical support
  • Materials move from cell to cell via diffusion & osmosis
  • Live in moist shady habitats where they will not dry out
  • Small sporophyte
  • Requires water for sexual reproduction
    • Example: Mosses
    • Dominant form: gametophyte
• Seedless vascular plants
  • Lack seeds, true roots, stems, or leaves
  • Vascular tissues allow them to grow taller
  • Conspicuous sporophyte
  • Haploid spores grow underside of leaves
  • Require water for reproduction
    • Example: Ferns
    • Dominant form: sporophyte
• Gymnosperms (“naked seed" plants)
  • Have pollen & seeds
  • Sporophytes are large & conspicuous
    • Cones: location where spores form by meiosis
    • Ovules are female cone scales which produce megaspore
    • Reproduction does not require water; gymnosperm seeds have a tough outer coating dispersed by wind or animals
      • Example: Conifers
      • Dominant form: sporophyte
• Angiosperms
  • Sporophytes are large and conspicuous
  • Flowers are reproductive structures
    • Pollen sacs are male gametophytes
    • Ovule → megaspores → female gametophytes
  • Seeds contain embryo & endosperm (ovules develops into seed & ovary develops into fruit)
  • Pollen reproduces and is transported by wind & animals
    • Example: flowering plants
    • Dominant Form: Sporophyte

Plant Form and Function (Chapter 22)

• Eudicots versus Monocots
  • Monocots
    • Have one cotyledon
    • Veins usually parallel
    • Vascular tissue scattered
    • Fibrous roots (main root withers)
    • Pollen grain has one opening
    • Floral organs usually in multiples of three
  • Eudicots
    • Have two cotyledons
    • Veins usually netlike
    • Vascular tissue usually arranged in a ring
    • Taproot (main root) usually present
    • Pollen grain has three openings - Floral organs usually in multiples of four or five
• Cotyledons are embryos &quotseed leaves&quot that form embryonic shoots & roots

Vegetative Plant Parts

• Roots
  • Fibrous root system (monocot): slender & shallow
  • Taproot system (eudicots): thick & deep & has less branches
  • Root hairs are extensions of epidermis that absorb water & minerals at roots tip
• Shoots
  • Stems have nodes where leaves attach
  • Internodes are spaces between nodes
  • Terminal bud contains undeveloped tissue at shoot tip
  • Axillary bud is an undeveloped shoot that can form into new branch/flower
• Leaves
  • Blades are flat
  • Petiole supports blades (stalklike)
  • Simple leaves are undivided blades
  • Compound Leaves are divided into leaflets attached to one petiole
  • Veins are vascular bundles inside leaf (monocots have parallel veins, dicots have netted veins)
  • Mesophyll is found within ground tissue inside leaf, cells with chloroplasts produces sugar by photosynthesis
• Herbaceous vs. Woody plant
  • Herbaceous plant has a green soft stem
  • Woody plant has tough bark covered wood
• Plant cell features

Plant Cell Features

• Chloroplast: photosynthesis
• Central vacuole: stores water & variety of chemicals
• Cell wall: rigid and contains cellulose (primary and secondary)
• Plasmodesmata are cytoplasmic channels through cell wall that connects adjacent cells

Three Plant Tissues

• Ground tissue system makes up most plant body and supports photosynthesis, respiration, storage
  • Parenchyma has most abundant and metabolic functions
  • Collenchyma provides flexible support
  • Sclerenchyma provides rigid support
    • Pith is the center of stem
    • Cortex is the ground tissue that fills space between epidermis & vascular bundles
• Dermal tissue system covers plant
  • Epidermis is coated w/ waxy cuticle
    • Cuticle conserves water & protects plant
    • Stomata are pores in cuticle, allow gas exchange in leaves
    • Guard cells surround and control stomata opening & closing
• Vascular tissue system transports materials embedded in ground tissue
  • Xylem transports water (one-way)
    • Tracheids are long narrow cells
    • Vessel elements are wide barrel cells
  • Phloem transports sugars & dissolved organic compounds
    • Sieve-tube elements are conducting cells (separated by sieve plates)
    • Companion cell transfers material in & out of sieve tube
    • Vascular cylinder (root)
    • Vascular bundles (stems)

Plant Growth

• Determinate vs. Indeterminate growth
  • Indeterminate growth never stops growing
  • Determinate growth stops growing when reaching mature size
• Meristems regions with growth occurs and active cell division
  • Apical meristem (primary growth) produces tissue to lengthen shoots & roots
    • Roots have root cap
    • Shoots also use this

Apical Dominance

• Apical dominance: the inhibition of axillary bud by terminal bud
• Lateral meristems (secondary growth) thickens roots & stem (woody plants)
  • Vascular cambium produces secondary xylem toward inside stem & secondary phloem toward outside
  • Cork cambium produces parenchyma cells toward inside & dense waxy cells (cork/outer protective layer of bark) toward outside
  • Wood
    • Heartwood is secondary xylem that is unable to conduct water
    • Sapwood transports water & dissolved minerals
    • Tree rings occur between alternating moist & dry seasons
  • Bark produces by secondary growth and is collection of all tissue outside vascular cambium

Plant Nutrition and Transport (Chapter 23)

• Essential elements
  • Macronutrients are required in large amounts
    • Carbon, oxygen, & hydrogen are most abundant macronutrients
  • Micronutrients are required in smaller amounts
• Soil is how plants absorb nutrients
• Vascular Tissue is the transportation system that connect plant parts
  • Xylem: water, minerals & hormones are pulled up to leaves
  • Phloem: sugar is pushed to non-photosynthetic cells
• Water uptake occurs in roots
  • Root hairs are present
  • Endodermis is the innermost layer of cells in root cortex
  • Casparian strip is a waxy barrier ensuring incoming material pass through cell
• Water transport occurs in plants
  • Xylem sap
  • Cohesion-Tension Theory says cohesion the tendency for water molecules to form hydrogen bonds with one another
    • Transpiration pull: when water evaporates, adjacent molecules move closer to stomata
    • Evaporation
      • Cohesion/adhesion
  • Stomata (stoma) are pores in leaves that close when plants conserve water
    • Guard cells determine whether stoma is open or close
  • Cuticle is waxy layer on leave which prevents water loss
• Nitrogen fixing bacteria helps plants obtain useful forms of nitrogen (symbiotic relationship)
  • Nodules are locations where some nitrogen fixing bacteria live in growths on roots
• Sugar movement occurs in plants as pholem sap
  • Companion cells are present
  • Pressure flor theory
    • Phloem sap moves from high pressure at source to low pressure at sinks
    • Water movement causes pressure changes in phloem tissue
    • Sugar source is photosynthesis
    • Sugar sink requires sugar, no photosynthesis

Reproduction and Development of Flowering Plants (Chapter 24)

• Asexual vs Sexual reproduction
  • Sexual reproduction yields genetically unique offspring with traits from 2 parents
  • Asexual reproduction yields genetically identical offspring with mitotic division
• Alternation of Generations
• Flowers
• Sporophyte produces plants
• Gametophyte produced through haploid spores through meiosis
• Label
  • Sepals are whorl 1 (calyx) which encloses & protect inner floral parts
  • Petals are whorl 2 (corolla) which attracts pollinators
  • Stamen is whorl 3 male reproductive parts
    • Anther is a pollen producing bud attached to filament
    • Filament is stalklike and holds anther
  • Carpal is whorl 4 female reproductive parts
    • Stigma is top of style and receives pollen
    • Style stalks
    • Ovary encloses ovules
    • Ovule
• Angiosperm life cycle
  • Male Gametophyte Production
    • Microspore (4)
    • Pollen grain
      • Tube cell
      • Generative cell -Tough outer coating
• Stamen → anther → 1 cell meioses → 4 haploid spore → mitosis → pollen grain
  • Female Gamete Production
    • Megaspore
    • Embryo sac
      • 5 haploid cells
      • Haploid egg cell
      • Large central cell with 2 polar nuclei
• Carpel → ovary → ovules → 1 cell meiosis → 1 haploid spore → mitosis → embryo sac
• Pollination occurs when pollen grain lands on receptive stigma
  • Pollen tube grows toward oule when spleen grain germinates, 2 sperm nuclei travel through pollen tube to ovule
• Double fertilization occurs by sperm nuclei fertilize egg & 2 polar nuclei diplot zygote & triploid endosperm - 2 sperm cells - Haploid zygote - Triploid (3n) endosperm
  • Pollen lands on stigma
    • Tube call creates tube to overly
    • Cell divides 2 sperms
    • 1 fertilize egg (haploid zygote), 1 fertilize central cell (troploid endosperm)
• Seed
  • 3 parts
    • Seed coat is tough outer layer that protects embryo from damage, dehydration, and predators
    • Endosperm
    • Embryo
  • Seed dormancy is when growing stops & slows metabolism
  • Germination (monocot and dicot) is the resumption of growth after period of dormancy once reach favorable conditions
• Fruit develops from ovary enclosing the developing seed, protect & disperse seeds

Test your knowledge of cell structures and functions, including those in plants. The quiz covers topics from cell walls and turgor pressure to parenchyma and sclerenchyma cells. It also explores organism classification, focusing on domains and the characteristics of protozoa.