Transcript No Slide Title

Figure 20.UN01
Which of these trees is not like the others…..
(a)
A
B
D
B
D
C
C
C
B
D
A
A
(b)
(c)
Figure 24.18
Euryarchaeotes
Crenarchaeotes
UNIVERSAL
ANCESTOR
Nanoarchaeotes
Proteobacteria
Bacteria
Spirochetes
Cyanobacteria
Gram-positive
bacteria
Domain Bacteria
Chlamydias
Prokaryotes
Archaea
Domain Archaea
Korarchaeotes
Domain
Eukarya
Eukaryotes
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
Protists-ARE ONE
type of Eukaryote!
DIVERSITY
Many are important
ocean
photosynthesizers!
p500
Parasitic protists
• Trichomonas
• Giardia- beavers
• Malaria p501
Figure 20.20
Euglenozoans
Forams
Diatoms
Red algae
Green algae
Land plants
Domain Eukarya
Ciliates
Amoebas
Fungi
Animals
Methanogens
COMMON
ANCESTOR
OF ALL LIFE
Thermophiles
Domain
Archaea
Nanoarchaeotes
Proteobacteria
Chlamydias
Spirochetes
Gram-positive
bacteria
Cyanobacteria
(Chloroplasts)*
Domain Bacteria
(Mitochondria)*
Eukaryotes have a Nucleus
ORIGIN OF THE NUCLEAR ENVELOPE
1. Ancestor of the
eukaryotes.
Chromosomes
Where did it come from?
Plasma membrane
2. Infoldings of
plasma membrane
surround the
chromosomes.
3. Eukaryotic cell.
Nucleus
Endoplasmic
reticulum
Eukaryotes also have mitochondria and
chloroplasts-Endosymbiosis!
Lynn Margulis
Figure 25.3
Cytoplasm
DNA
Ancestral
prokaryote
Plasma
membrane
Endoplasmic
reticulum
Engulfing
of aerobic
bacterium
Engulfing
of photosynthetic
bacterium
Nucleus
Nuclear
envelope
Mitochondrion
Mitochondrion
Ancestral
heterotrophic
eukaryote
Plastid
Ancestral
photosynthetic
eukaryote
Figure 25.3
Cytoplasm
DNA
Ancestral
prokaryote
Plasma
membrane
Endoplasmic
reticulum
Engulfing
of aerobic
bacterium
Engulfing
of photosynthetic
bacterium
Nucleus
Nuclear
envelope
Mitochondrion
Mitochondrion
Ancestral
heterotrophic
eukaryote
Plastid
Ancestral
photosynthetic
eukaryote
Figure 20.21
populations
Methanogens
Thermophiles
Cyanobacteria
Proteobacteria
Domain Bacteria
HOW?
Domain
Archaea
So sometimes whole organisms
were engulfed-but genes
were also
being
swapped Ancestral cell
Plantae
Domain Eukarya
How do we show endosymbiosis
on a phylogenetic tree?
Figure 29-16
Engulfing of a
protist that already
engulfed a
photosynthetic
prokaryote
SECONDARY ENDOSYMBIOSIS
Predatory
protist
Photosynthetic
protist
Nucleus
Chloroplast
Nucleus
1. Photosynthetic
protist is engulfed.
Some ate a green
algae and some ate
a red algae.
2. Nucleus from
photosynthetic
protist is lost.
Organelle with
four membranes
1 2
3 4
Figure 25.4
Cyanobacterium
Membranes
are represented
as dark lines in
the cell.
Primary
endosymbiosis
Secondary
endosymbiosis
Red alga
Dinoflagellates
Plastid
1 23
Stramenopiles
Secondary
endosymbiosis
Nucleus
Heterotrophic
One of these
eukaryote
membranes
was lost in
red and
green algal
descendants.
Secondary
endosymbiosis
Plastid
Euglenids
Green
alga
Chlorarachniophytes
Figure 25.5
Many protists are multicellular!
This is a
colonial
protist
with
rigid cell
wallswhat 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?
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
•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!
Multicellularity evolved many times
Ex Algae (“protists”), Plants, Fungi and Animals
Figure 25.6
Flagellum
Cytoplasm
Chlamydomonas
Outer cell wall
Inner cell wall
Gonium
Few totally new
genes…..
Pandorina
Outer cell wall
Cytoplasm
Volvox
Extracellular matrix (ECM)
Figure 25.7
What do we know?
Multicellularity in animals…
Individual
choanoflagellate
Choanoflagellates
OTHER
EUKARYOTES
Sponges
Animals
Collar cell
(choanocyte)
Other
animals
Figure 32-11a
Choanoflagellates are sessile protists; some are colonial.
Colony
Choanoflagellate cell
Food
particles
Water current
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 “coopting” 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
Choanoflagellate
Hydra
Fruit
fly
Mouse
“CCD” domain
Text goes over taxonomy of protists…which we
will skip.
And then text goes over functional importance..
Protists-ARE ONE
type of Eukaryote!
DIVERSITY
Many are important
ocean
photosynthesizers!
p500
Parasitic protists
• Trichomonas
• Giardia- beavers
• Malaria p501
Development is obviously only important in
multicellular organisms
How do we get such diversity of morphology?
Small changes in development can yield big
differences in shape or morphology.
See P 449-CH23
Two kinds of developmental changes
1. Homeotic mutations affect placement and
number of body parts
(typically Hox mutations)
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
What is going on here?
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…
Figure 23.16
Chimpanzee infant
Chimpanzee adult
Chimpanzee fetus
Chimpanzee adult
Human fetus
Human adult
Heterochrony…paedomorphosis..Some species
of salamander retain juvenile characteristics
(external gills) into sexual maturity
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
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)