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Which of these trees is not like the others…. B. A. D. Figure 20.UN01. B. C. D. C. C. B. A. A. D. (a). (c). (b). Figure 24.18. Domain Eukarya. Eukaryotes. Korarchaeotes. Euryarchaeotes. Archaea. Domain Archaea. Crenarchaeotes. UNIVERSAL ANCESTOR. Nanoarchaeotes.

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slide2

Figure 24.18

Domain

Eukarya

Eukaryotes

Korarchaeotes

Euryarchaeotes

Archaea

Domain Archaea

Crenarchaeotes

UNIVERSAL

ANCESTOR

Nanoarchaeotes

Prokaryotes

Proteobacteria

Chlamydias

Bacteria

Spirochetes

Domain Bacteria

Cyanobacteria

Gram-positive

bacteria

slide3

Who are the Eukaryotes?

How do they get their energy?

Which lineages are good monophyletic groups?

When did they evolve? GO back to your timeline….

Fossils 1.8bya (but lipids made by Euk. around 2.7 bya)

Multicellularity?

600mya

slide4

Protists-ARE ONE type of Eukaryote!

DIVERSITY

Many are important ocean photosynthesizers! p500

  • Parasitic protists
  • Trichomonas
  • Giardia- beavers
  • Malaria p501
figure 20 20

Figure 20.20

Euglenozoans

Forams

Diatoms

Ciliates

Red algae

Domain Eukarya

Green algae

Land plants

Amoebas

Fungi

Animals

Nanoarchaeotes

Domain

Archaea

Methanogens

Thermophiles

COMMON

ANCESTOR

OF ALL LIFE

Proteobacteria

(Mitochondria)*

Chlamydias

Spirochetes

Domain Bacteria

Gram-positive

bacteria

Cyanobacteria

(Chloroplasts)*

slide6

Eukaryotes have a Nucleus

Where did it come from?

ORIGIN OF THE NUCLEAR ENVELOPE

1. Ancestor of the

eukaryotes.

Chromosomes

Plasma membrane

2. Infoldings of

plasma membrane

surround the

chromosomes.

3. Eukaryotic cell.

Nucleus

Endoplasmic

reticulum

slide7

Eukaryotes also have mitochondria and chloroplasts-Endosymbiosis!

Lynn Margulis

figure 25 3

Cytoplasm

DNA

Ancestral

prokaryote

Engulfing

of aerobic

bacterium

Plasma

membrane

Figure 25.3

Engulfing

of photo-

synthetic

bacterium

Nucleus

Endoplasmic

reticulum

Nuclear

envelope

Mitochondrion

Mito-

chondrion

Ancestral

heterotrophic

eukaryote

Plastid

Ancestral

photosynthetic

eukaryote

figure 25 31

Cytoplasm

DNA

Ancestral

prokaryote

Engulfing

of aerobic

bacterium

Plasma

membrane

Figure 25.3

Engulfing

of photo-

synthetic

bacterium

Nucleus

Endoplasmic

reticulum

Nuclear

envelope

Mitochondrion

Mito-

chondrion

Ancestral

heterotrophic

eukaryote

Plastid

Ancestral

photosynthetic

eukaryote

figure 20 21

Figure 20.21

How do we show endosymbiosis on a phylogenetic tree?

So sometimes whole organisms

were engulfed-but genes

were also

being

swapped

HOW?

Fungi

Domain Eukarya

Plantae

Chloroplasts

Methanogens

Domain

Archaea

Mitochondria

Ancestral cell

populations

Thermophiles

Cyanobacteria

Proteobacteria

Domain Bacteria

slide11

Figure 29-16

SECONDARY ENDOSYMBIOSIS

Engulfing of a protist that already engulfed a photosynthetic prokaryote

Some ate a green algae and some ate a red algae.

Predatory protist

Photosynthetic protist

Nucleus

Chloroplast

Nucleus

1. Photosynthetic protist is engulfed.

2. Nucleus from photosynthetic protist is lost.

Organelle with four membranes

4

3

2

1

figure 25 4

Figure 25.4

Secondary

endo-

symbiosis

Dinoflagellates

Membranes

are represented

as dark lines in

the cell.

Red alga

Cyano-

bacterium

Plastid

2

1

3

Primary

endo-

symbiosis

Stramenopiles

Secondary

endo-

symbiosis

Plastid

Nucleus

Heterotrophic

eukaryote

One of these

membranes

was lost in

red and

green algal

descendants.

Euglenids

Secondary

endo-

symbiosis

Green

alga

Chlorarachniophytes

figure 25 5

Figure 25.5

Many protists are multicellular!

This is a colonial protist with rigid cell walls-what do we mean by colonial?

When did multicellularity evolve?

What traits would need to evolve in order to be a multicellular organism? What would you have to be able to do?

slide14

More on multicellularity…

  • integration!
  • Stick together
  • Communicate
  • Ways of moving materials around
  • Germ vs Soma-controls on mitosis and meiosis
  • Differentiated cells are arranged in tissues
slide15

Genes regulated so that even though all cells contain all the animals genes, particular genes are active only in particular cells at certain times during a lifetime

  • These things require changes in controls over developmental processes and changes in gene expression rather than new cellular structures or genes not present in unicellular organisms!
slide16

Multicellularity evolved many times

Ex Algae (“protists”), Plants, Fungi and Animals

figure 25 6

Figure 25.6

Flagellum

Cytoplasm

Chlamydomonas

Outer cell wall

Inner cell wall

Few totally new genes…..

Gonium

Pandorina

Outer cell wall

Cytoplasm

Volvox

Extracellular matrix (ECM)

figure 25 7

Figure 25.7

What do we know? Multicellularity in animals…

Individual

choanoflagellate

Choano-

flagellates

OTHER

EUKARY-

OTES

Sponges

Animals

Collar cell

(choanocyte)

Other

animals

slide19

Figure 32-11a

Choanoflagellates are sessile protists; some are colonial.

Colony

Choanoflagellate cell

Food

particles

Water current

slide20

Genome of a single celled choanoflagellate vs animals

Many protein domains in common (domain is a key part or functional region of a protein)

Choanoflagellate had the same domains that in animals are important in cell adhesion and signaling.

So evolution of multicellularity involved the “co-opting” of existing genes that had been used for other purposes

As well as one small new piece the CCD domain in the cadherin protein

figure 25 8

Figure 25.8

Choano-

flagellate

Hydra

Fruit

fly

“CCD” domain

Mouse

slide22

Text goes over taxonomy of protists…which we will skip.

And then text goes over functional importance..

slide23

Protists-ARE ONE type of Eukaryote!

DIVERSITY

Many are important ocean photosynthesizers! p500

  • Parasitic protists
  • Trichomonas
  • Giardia- beavers
  • Malaria p501
slide24

Development is obviously only important in multicellular organisms

How do we get such diversity of morphology?

slide25

Small changes in development can yield big differences in shape or morphology.

See P 449-CH23

Two kinds of developmental changes

slide27

Numbers of legs

Expression of a particular Hox gene suppresses the formation of legs in fruit flies (and presumably all insects) but not brine shrimp

(Pinpointed the exact amino acid changes)

Hox gene 6

Hox gene 7

Hox gene 8

Ubx

About 400 mya

Drosophila

Artemia

slide29

2. Heterochronic (allometric) changes or mutations

  • These affect the timing or rate of development of different body parts (rate of mitosis)
  • parts pulled and stretched at different rates to make “new” morphologies…
slide30

Figure 23.16

Chimpanzee infant

Chimpanzee adult

Chimpanzee fetus

Chimpanzee adult

Human fetus

Human adult

slide32

Heterochrony…paedomorphosis..Some species of salamander retain juvenile characteristics (external gills) into sexual maturity

slide33

Sticklebacks-Ex from text…

Lakes with predators-make spines

No predators-no spines

What is genetic basis of this evolutionary change?

Change in nucleotide sequence OR change in how the gene is expressed or regulated

slide34

Thoughts on which is more risky?? Easier??

Change in way gene is regulated…

Pleiotropic effects of gene can be controlled (turn off spine production but other functions of gene on other parts of body retained)