Transcript File

Learning goals: Lecture 2, Biological Diversity
(Basic ideas; Prokaryotes, Protists)
Readings: Chapters 1 (review), 26, 27, and 28 (read all of
these, but the parts covered in lecture are by far the most
likely to be on a test ).
Biological Diversity
What we mean by the term;
diverse organisms solve
problems differently; why
solving problems differently is
important to you; review some
ideas from Chapter 1.
The tree of life (Ch. 26)
The tree of life.
Prokaryotes (Ch. 27)
Shapes; genome organization;
reproduction; metabolism;
representative groups;
importance
Protists (Ch. 28)
Characteristics;
endosymbiosis, colonial
organisms; sexual
reproduction, representative
groups
Biological Diversity
What we mean by the term
Diverse organisms solve problems differently
Why solving problems differently is important
Ideas from Chapter 1
Biodiversity is simply a term to describe
the incredible variety of forms of life.
One might think that only a few types of
beetles would be “enough” to make the
world work, but there are actually about a
quarter of a million species.
Cornell University
Biological Diversity
What we mean by the term
Diverse organisms solve problems differently
Why solving problems differently is important
Ideas from Chapter 1
But an extremely important biological
truth is that each species of life solves
the problems of survival and
reproduction differently.
www.lrc.rpi.edu
www.augsburg.edu/home/biology/
www.entomology.umn.edu
Biological Diversity
What we mean by the term
Diverse organisms solve problems differently
Why solving problems differently is important
Ideas from Chapter 1
retina
light
lens
mirror
Ostracod picture 1
Ostracod picture 2
retina
Biological Diversity
What we mean by the term
Diverse organisms solve problems differently
Why solving problems differently is important
Ideas from Chapter 1
An example of how differences are important: molecules of the
antibiotic penicillin prevent the formation of the cell wall* in
bacteria, which prevents their growth. Animal cells do not have a
cell wall, just a membrane. Thus, we can take penicillin to kill
bacteria living inside us, but without killing ourselves. This would
not be possible if bacteria and animals didn’t solve the
problem of how to contain the cell contents in different ways.
* This is a simplification
Some important concepts from Chapter 1 that you should review from
your high school biology course
1. Fig. 1.2 properties of life
2. Fig. 1.3 - levels of
biological
organization
3. A closer look at
cells - eukaryotic
and prokaryotic
(Fig. 1.8).
Prokaryotes often
also have a cell
wall around the
membrane.
Some
important
concepts
from Chapter
1 that you
should review
from your
high school
biology
course
4. Fig. 1.14 natural
groupings of life
Canis familiaris - genus capitalized, species
name not, italics. Family (e.g. Canidae) not
italicized
Some
important
concepts
from Chapter
1 that you
should review
from your
high school
biology
course
5. Fig. 1.23
- tree
like
graphs
show
relation
ships
Some important
concepts from Chapter
1 that you should
review from your high
school biology course
robin
Phylogenetic trees are
graphs that display genetic
relationships of species.
They are calculated from
molecular data, or from
data on visible features
dove
Unique feature
evolved in only this
branch (=clade):
feathers
dog
bat
Unique feature
evolved in only this
branch (clade): hair
Unique (or derived) features are
the clues for determining
relationships
time
The tree of life (Ch. 26)
The tree of life
(also some Figures
discussed with later
chapters)
The tree of life (Ch. 26)
Geological time and Fossils
The tree of life
Fig. 26.22. The Tree of Life is really a better
description of how life forms are related than
a set of names, although we must still use
names too. Don’t try to memorize all of
this! We will learn important aspects as we
discuss the various groups.
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Fig. 27.3 The
Gram stain
divides bacteria
into Grampositive and
Gram-negative
bacteria (which
often are the
more
pathogenic
ones).
Fig. 27.2 Shape helps in
classifying prokaryotes
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
All the strands
are part of the
one
chromosome,
making a loop.
Fig. 27.8. The single chromosome (DNA + proteins)
of a prokaryote contains all the directions for making
a living cell. The chromosome of a prokaryopte is
not organized into a nucleus, although it is generally
located in one part of the cell).
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Reproduction in prokaryotes occurs primarily by cell
division - each cell divides into two daughter cells.
However, bits of DNA can be exchanged between
cells under certain circumstances, resulting in a form
of sexual reproduction (making new combinations of
genes).
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Fig. 27.10 photosynthetic bacteria
Metabolism (the chemical reactions of life) is
extremely diverse in prokaryotes. Prokaryotes are
structurally simple, but far more diverse
metabolically than eukaryotes.
One way to divide types of prokaryotic metabolisms
is into autotrophic (can make the complex
chemicals of life starting only with carbon dioxide
and an energy source) and heterotrophic (requires
chemicals more complicated than CO2)
Another way to divide is into phototrophic (energy
derived from light) and chemotrophic (energy
derived from inorganic molecules like amonia)
All four combinations occur in prokaryotes.
Different forms of life
solve the problem of
obtaining energy in very
different ways.
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Fig. 26.22
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Fig. 27.13
Learn about:
Chlamydias
Spirochetes
Cyanobacteria
Read about and
know characteristics
Prokaryotes (Ch. 27)
characteristics
genome organization
reproduction
metabolism
representative groups
importance
Fig. 27.16 Lyme disease.
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Fig. 27.1
Protists in
pond water,
light
microscope
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
It is difficult to describe the exact
characteristics of protists because we don’t
know how to organize them into natural
groupings yet. Look at the enormous diversity
of protists at the left.
They do have some common features
eukaryotic
single-celled, or, if multicellular, only a few
differentiated cell types.
sexual reproduction
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
The protist cell ( and in fact all
eukaryotic cells) has some unusual
features that are best explained as
the results of endosymbionts.
(symbiosis means living with another
organisms, endosymbiosis means
living inside another organism)
evolving into a part of the host cell. If
two organisms benefit each other,
they are said to be engaging in
mutualism. (Fig. 26.13). The first
evidence of eukaryotes appears in
the fossil record about 2 billion years
ago.
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Multicellular eukaryotes first appear in the fossil record some 1.5
billion years ago. It is likely that a first step towards multicellular
organisms was the appearance of colonial organisms - groups of
cells functioning as a unit, like this flat algal species (Fig. 26.16). If
some cells develop different features, they are said to be
differentiated or show differentiation.
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Sexual reproduction to a biologist means
making new combinations of genes.
Protists (and all eukaryotes) have, at least
at some point in their life cycle, two sets of
the genes needed for life. A complete set of
necessary genes is called a genome.
Two genome states -
Meiosis and
syngamy have
opposite effects on
the number of
genomes
2N
Haploid - one genome - 1N
Diploid - two genomes - 2N
1N
Syngamy
meiosis
1N
2N
Both haploid and diploid cells
can undergo cell division asexual reproduction.
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Fig. 28.31 In the single-celled Chlamydomonas, the
gametes (sex cells, having the function of eggs and
sperm) are unlike sperm and eggs in that they look the
same. This is called isogamy. When cells join, it is
called syngamy. A diploid cell formed by syngamy is
called a zygote.
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Fig. 26.22
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Diatoms
Single-celled
protists that make
unique cell walls
of, essentially,
glass.
Fig.
28.16
These have an
extensive fossil
record.
Fig. 28.15 diatom
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Brown algae
Many brown algae
are quite complex
and large, and
many are
harvested to be
used in food (nori
in sushi, also in
making various
gels that are used
to thicken food).
Fig.
28.18
Fig. 28.20 edible
seaweed
Protists (Ch. 28)
characteristics
endosymbiosis
colonialism
sexual reproduction
representative groups
Fig. 28.7
Cellular slime “molds”
The life cycle includes a single-celled amobae,
and a multicellular “slug”. What is an
organism?
Some thoughts on how
bacteria and protists solve the
same problem in different
ways:
Problem: osmoregulation
(water regulation). When cells
are placed in a hypotonic
solution (one with less solute
than in a cell), water tends to
rush into the cell (osmosis). If
you put human blood cells in
distilled water, they swell up
and burst (lyse).
Both fresh-water bacteria and
protists live in a hypotonic
solution.
Protist solution to problem (for
some protists): Contractile
vacuole - pumps out water
Bacterial solution to
problem (in part): Rigid
cell wall prevents lysis.
Learning goals: Lecture 2, Biological Diversity
(Basic ideas; Prokaryotes, Protists)
Readings: Chapters 1 (review), 26, 27, and 28 (read all of
these, but the parts covered in lecture are by far the most
likely to be on a test ).
Biological Diversity
What we mean by the term;
diverse organisms solve
problems differently; why
solving problems differently is
important to you; review some
ideas from Chapter 1.
The tree of life (Ch. 26)
The tree of life.
Prokaryotes (Ch. 27)
Shapes; genome organization;
reproduction; metabolism;
representative groups;
importance
Protists (Ch. 28)
Characteristics;
endosymbiosis, colonial
organisms; sexual
reproduction, representative
groups