Lecture 11: Algae Flashcards

1
Q

Algae

A

Photosynthetic protists who
gained oxygenic
photosynthesis via primary
or secondary endosymbiosis

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2
Q

How much of Earth’s oxygen does algae produce?

A
  • 30% by algae
  • 20% by prokaryotes such as
    cyanobacteria
  • 50% by land plants
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3
Q

Algal Blooms

A

Rapid growth of ‘algae’ due to increase in nutrients from fertilized agriculture lands, untreated factory waste water, etc.

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4
Q

Which two organisms cause algal blooms

A

Caused by both algae and cyanobacteria

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5
Q

how do algal blooms affect the environment?

A
  • Water hypoxia through bacterial decomposition
    of dead algae
  • Mechanically damaging gills
  • Production of algal toxins

Concerns for environmental conservation and economic damage by affecting aquacultures and tourism.

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6
Q

what is increasing algal blooms

A

climate change

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7
Q

Alveolate in the SAR supergroup

A
  • Unicellular algae
  • About half are chemoheterotrophs, others are
    photoautotrophs/mixotrophs
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8
Q

Algal bloom of dinoflagellates causes

A

red tide

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9
Q

Photoautotrophic dinoflagellates contain ___ as one of their photosynthetic pigments

A

carotenoids

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10
Q

what group do Haptophytes belong to?

A

‘Unresolved’ group in the eukaryotic
phylogenetic tree. Compromises of mostly marine, unicellular photoautotrophs and mixotrophs

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11
Q

morphology of Haptophytes

A
  • Two flagella for motility plus a haptonema for surface attachment and/or predation
  • Surface of haptophytes are covered with small scales made of polysaccharides
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12
Q

some Haptophytes have ___ scales

A
  • Some haptophytes like Emiliana hyxleyi have hard, calcified scales
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13
Q

Stramenopiles, of SAR supergroup morphology

A
  • Straw-hair (Latin, Stramen-pilos), as
    many members have flagellum with fine, hairlike projections
  • Diatoms, a unicellular, photoautotrophic Stramenopile
  • One of the most abundant photosynthetic organisms in oceans and lakes
  • Diatoms have glass-like cell wall made of silicon dioxide for mechanical protection vs. predation
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14
Q

Diatoms of various shapes are distributed in

A

aquatic systems such as oceans, rivers and lakes

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15
Q

Diatoms are well preserved due to their

A

silica shell

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16
Q

Forensic limnology isolates diatoms from crime scenes to better understand the case. However why isn’t it useful as legal evidence?

A

Not as useful as legal evidences due to the amount of variation in samples

17
Q

Brown algae (seaweeds)

A

Multicellular photoautotrophic
Stramenopile, and the largest, most
complex algae

18
Q

Brown algae (seaweeds) morphology

A

Have organ-like structures which are analogous to plants:
* Blades: increase surface area (leaf-like)
* Stipe: support the blades (stem-like)
* Holdfast: anchor the alga (root-like)
* Can get up to 60 m tall
* Some have gas-filled floats to help the blades get closer to the water surface
* Plant-like reproduction cycle

19
Q

Diploid

A

Cell with a pair of chromosomes (2n)
* n=23 for human, 46 chromosome total

20
Q

Haploid

A

Cell with a single set of chromosome (n)

21
Q

Human example for sexual reproduction

A
  1. Diploid adult (n=46) produces haploid, unicellular gametes (sperm/egg, n=23) via meiosis
  2. Haploid sperm (n=23) fuses with haploid egg (n=23), producing a diploid, unicellular zygote (n=46)
  3. Diploid zygote divides by mitosis to grow into diploid adult (n=46)
22
Q

For reproductive cycle of animals,
multicellularity only occurs

A

during the diploid stage

23
Q

Alternation of generation

A

Plants and some algae produce multicellular bodies in both diploid and haploid stages

24
Q

Sporophyte

A

Spore-producing, diploid
multicellular form

25
Q

Gametophyte

A

Gamete-producing, haploid
multicellular form

26
Q

Alteration of Generation process

A
  1. Diploid sporophyte produces haploid spores by meiosis
  2. Haploid spores divide by mitosis to become the haploid gametophyte
  3. Haploid gametophyte produces haploid gametes by mitosis
  4. Two haploid gametes fuses, producing a diploid, unicellular zygote
  5. Diploid zygote grows by mitosis to become the diploid sporophyte
27
Q

Brown algae spores are called

A

zoospores since they can move with
flagella

28
Q

About half of zoospores develop into

A

haploid multicellular female
gametophyte, the other half develop
into male gametophyte

29
Q

Female and male gametophytes
produce

A

gametes (egg and sperm),
which meet and fertilize into the
diploid zygote

30
Q

Archaeplastida

A
  • Direct ancestors of primary endosymbiosis
  • The ‘source organisms’ of secondary
    endosymbiosis
31
Q

‘Green algae’ is a ___ group which is missing the Embryophytes (___)

A

paraphyletic
(plants)

32
Q

Two main groups of green algae:

A
  • Chlorophytes: the sister group to the clade Streptophyta (Charophytes + plants)
  • Charophytes: the closest relative to land plant
33
Q

Charophytes, Green algae

A
  • Closest relative to plants
  • Determined by molecular phylogeny of nuclear,
    mitochondrial and plastid DNA, as well as morphological features
34
Q

Charophytes and plants:

A
  • Both synthesize cell wall using ring-like protein structure, embedded in plasma membrane
  • Both have flagellated sperm
  • Both have similar nuclear, mitochondrial and chloroplast DNA
  • Both have sporopollenin
35
Q

Sporopollenin

A

tough layer which surrounds
charophytes zygotes to prevent it from drying out

36
Q

Sporopollenin eventually enabled ___

A

ancestral charophytes to live permanently on land, above
water surface

37
Q

Plants have sporopollenin walls which encase

A

plant spores

Note the difference: Charophyte sporopollenin encases their zygotes, plant sporopollenin encases their spores.