L11: Algae

Algae

• photosynthetic protists that gained oxygenic photosynthesis by primary or secondary endosymbiosis

How much photosynthesis is done by algae?

• 30%

Algal bloom

• rapid growth of algae due to increase in nutrients

  • run-off from fertilized agricultural lands

  • untreated factory waste water

• both algae and cyanobacteria

• damages environment and organisms that live there

  • water hypoxia by decomposing dead algae

  • damage gills

  • production of algal toxins

• increase due to climate change

Dinoflagellates

• alveolate in SAR

• unicellular algae

• chemotrophs, photoautotrophs, and mixotrophs

Red tide

• dinoflagellates contain carotenoid pigment (photosynthetic)

• algal bloom causes the red tide

Haptophytes

• unresolved group

• mostly marine, unicellular photoautotrophs and mixotrophs

• 2 flagella for mobility and a haptonema for surface attachment and/or predation (swimming)

• surface of haptophytes covered with small scales made of polysaccharides.

Emiliana hyxleyi

• Haptophyte

• hard calcified scales

Cliffs of Dover

• Emiliana hyxleyi bloom seen from outer space

• dead bodies of them (calcium) accumulate on ocean floor over time

Chrysochromulina

• Haptophyte

• 2 flagellas and a haptonema used for attachment

Stramenopiles

• S in SAR

• “straw hair”, many have flagellas and hair-like projections

• diatoms, unicellular photoautotrophs. One of the most photosynthetic organisms in oceans and lakes.

  • grass like cell wall

  • different shapes live in different areas

• can use diatoms found on victims body to link body to location (see if it has been moved after death). Not admissible in court.

Brown algae

• multicellular photoautotrophic

• organ-like structure analogous to plants

  • blades like leaves

  • stipe like stem

  • holdfast like roots

• up to 60 m tall

• growth cycle similar to plants

Human sexual reproduction

1. diploid multicellular adult (2n) goes through meiosis

2. Haploid unicellular gamete (n) (sperm or egg) meets with another gamete and fertilizes

3. Diploid unicellular zygote (2n) forms and go through mitosis

4. Repeat

Altercation of generation

• plants and some algae produce multicellular bodies in both diploid and haploid stages

  1. diploid multicellular body (2n)- SPOROPHYTE goes through meiosis

  2. Haploid unicellular spore (n) goes through mitosis

  3. Haploid multicellular body (n) GAMETOPHYTE goes through mitosis

  4. Haploid unicellular gamete (n) and another gamete fertilize

  5. Diploid unicellular zygote (2n) goes through mitosis

  6. Repeat

Sporophyte

• spore producing diploid multicellular form

Gametophyte

• gamete producing haploid multicellular form

Zoospores

• Example Brown Algae because it moves with flagella

• About half of zoospores develop into female haploid multicellular gametophytes and other half into male gametophytes

Archaeplastida

• direct ancestor of primary endosymbiosis

• englufed in secondaru emdosymbiosis

Green algae

• paraphyletic group missing plants

• 2 main groups

  • chlorophytes: sister group to streptophyta (charophytes + plants)

  • charophytes: closest relative to land plants

Similarities between chloroplasts and green algae

• both cell wall composed of ring-like protein

• both have flagellated sperm

• similar nuclear, mitochondria, and chloroplast DNA

• both have sporopollenin

Sporopollenin

• tough layer surrounding charophytes zygotes to prevent drying out

• enabled ancestral charophytes to live on land