Lecture 11 - Algae and Water Plants

Be able to draw the different diagrams for this lecture!

Chlorophyta

• green algae

• mostly freshwater, some marine

• cells contain same type of plastids and photosynthetic pigments as land plants

• photosynthetic pigments: chlorophyll a & b, carotenoids

Rhodophyta

• red algae

• most are multicellular marine macroalgae

• photosynthetic pigments: chlorophyll a & b, carotenoids, phycobilins (phycoerythrin)

• usually complex life cycles (3 generations)

• can live in deep ocean because of its color

Heterokontophyta

• “golden algae” gets pigment from:

  • chlorophyll a and c

  • carotenoids

  • xanthophyll

• AKA stramenopiles

• tertiary plasmids

• examples: diatoms and coccolithophores

Phaeophyta

• brown algae

• mostly marine, rarely freshwater

• multi-cellular

• pigments: chlorophyll a & c, carotenoids (canthophyll, fucoxanthin)

Accessory pigment

• chlorophyll b, c, d

• carotenoids

  • carotene: orange color

  • canthophyll: yellow color
    fucoxanthin: brown color

• phycobilins

  • phycoerythrin: red color

  • phycocyanin: blue color

Primary pigment

• chlorophyll a

• bacteriophyll (cyanobacteria)

Carotene

orange color

Chlorophyll a and b

a: main pigment, blue-green color

b: accessory. absorbs light and passes it to chlorophyll a, yellow-green color

Xanthophyll

yellow color

Phycoerythrin

red color

Phycocyanin

blue color

Thallus

entire body of seaweed structure

Blades

leaf-life structure; high surface area for photosynthesis

• helps capture as much light as possible

Floats

gas-filled (CO) bulbs that help keep blades closer to the surface (aka to the light source)

Stipe

stem-like structure; provides support

• NOT an actual stem

Holdfast

attaches the thallus to the seabed

Gametic life cycle

Zygotic life cycle

Alternation of 3 generations

Takes place in red algae

1. Gametophyte (haploid)

   • males release sperm from spermatangia; female eggs are in the carpogonium

2. Carposporophyte (diploid)

   • fertilizations and development directly on female gametophyte

   • produces 2N carpospores

     • these carpospores will be released, find a place to settle, and grow into a tetrasporophyte

3. Tetrasporophyte (diploid)

   • carpospores grow into 2N adult

   • meiosis produces tetraspores from the tetrasporangia

   • develop into male or female gametophytes

Alternation of 2 generations

type of sporic lifecycle, with a sporophyte and gametophyte (will go back and forth between the two)

• Laminaria life cycle - alternation of 2 generations

Gametophyte

Haploid

• males release sperm from spermatangia: female eggs are in the carpogonium

Sporophyte

Diploid

• produces haploid spores via meiosis

• spore-producing phase in the life cycle of plants and certain algae

Carposporophyte

Diploid

• fertilization and development directly on female gametophyte

• produces 2N carpospores

Tetrasporophyte

Diploid

• carpospores grow into 2N adult

• meiosis produces tetraspores from the tetrasporangia

• develop into male or female gametophytes

Seagrass

• only “true” marine plant

  • have roots, leaves, flowers, seeds

• live fully submerged in marine or brackish water

• form large meadows

Importance of seaweed from environmental and economic perspectives

• food

• coast protection

• pharmaceuticals

• fabrics

• energy source

• fertilizers

• tourism

Importance of seagrass habitats

they act as nurseries for sea life. can reproduce rapidly via asexual and sexual production. they are capable of making and taking carbon from the atmosphere. argued to be more efficient than the amazon rainforest.