Transcript Classifying Nature

Biology Today (BIOL 109)
Talk Two:
Classifying Nature
Chapter Two
Biological classification
• Used to group and categorize organisms into groups such
as genus or species. These groups are known as taxa.
• Think about classification that is used in everyday life
– What would happen if grocery stores did not use a classification
system?
– What about libraries, movie stores, department stores, etc.?
• About 1.8 million species have been given scientific names
– nearly 2/3 of these are insects
• Total number of living species is estimated to be between 13
and 14 million
– with most being insects and microscopic life forms in tropical
regions
Biological
classification
• So with all these things
on the planet how can you
learn and understand
them?
• Start with the simplest,
(Cells), and work upwards!
• Start with similar
characteristics and work
out how things are
different.
• Remember the different
levels of organization!
– If it wasn’t a big
enough job in the first
place!
From the wikimedia free licensed
media file repository
Living Things are Alike
• Common Characteristics like:
• Cells:
Fundamental unit of life is the cell – all living things
are made up of cells.
• Tissues:
– Similarly specialized cells that perform a common
function.
• Organs:
– Similarly specialized tissues that perform a common
function.
Levels of
Biological Organization I
Cellular
Nerve Cell
Organelle
Mitochondrion
Molecular
Chloroplast
Nucleus
CH2OH
O
H H
Water
Glucose
DNA
Atomic
Hydrogen
ƒ1-2
Subatomic
Chapter 1
Carbon
Proton
Nitrogen
Neutron
Oxygen
Electron
5
Levels of
Biological Organization II
Organismal
Pronghorn
Antelope
Organ System
Nervous
System
Organ
Tissue
ƒ1-2
Brain
Nervous
Tissue
Chapter 1
6
Levels of
Biological Organization III
Biosphere
Ecosystem
Community
Earth’s
surface
Air
Bushes
Water Hawk
Snake
Pronghorns
Soil
Grass
Hawk
Snake
Pronghorns
Population
Herd of Pronghorns
ƒ1-2
Chapter 1
7
Biological classification
• Modern biological classification has its root in the
work of Carl Linnaeus, who grouped species
according to shared physical characteristics.
• Linnaeus attempted to describe the entire known
natural world and gave every species a two-part
name.
– Linnaeus is often known as “The Father of
Taxonomy”
•
Carl Linnaeus
These groupings were later revised to improve
consistency with the Darwinian principle
of common descent.
• He established that all species of life have
descended over time from common ancestors, and
proposed the scientific theory that this branching
pattern of evolution resulted from a process that
he called natural selection.
Charles Darwin
From the wikimedia free licensed
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Life’s History
Animals diversified in
the ocean about 600
million years ago.
Plants colonized land
about 440 million
years ago and were
followed shortly by
animals.
Humans of any sort
are a very recent
evolutionary
development (~ 7
million years ago).
in the ocean
There are two major types of
cells
1. Prokaryotic
2. Eukaryotic
• The eukaryotic cell
is more complex and
contains organelles
Nucleus
(contains
DNA)
Eukaryotic cell
Prokaryotic cell
DNA
(no nucleus)
Organelles
• The DNA of a
eukaryotic cell is
contained in the
nucleus
Biological
Evolution
Figure 6.2
• First true cells were
prokaryotic.
– Eukaryotic cells evolved
later, followed by the
other kingdoms.
Biological evolution is a
change in life forms that
has taken place in the
past and will take place in
the future.
Adaptation is a
characteristic that
makes an organism able
to survive and reproduce
in an environment.
Box 6.2 (1)
Box 6.2 (2)
Box 6.2 (3)
Components of a Cell
Components of a Eukaryotic
Cell
• Nucleus--contained within a cell by nuclear
envelope. The nucleus contains DNA.
• Ribosomes--these structures make protein.
• Endoplasmic Reticulum--this is a membrane
network composed RER--rough has ribosomes
makes proteins, and SER--smooth makes lipids.
• Golgi Apparatus--modifies proteins involved in
secretion.
• Endomembrane system--Composed of nuclear
envelope, ER, Golgi, Lysosomes and Vesicles, these
organelles all work together to make protein
sorting and protein secretion possible.
The Mitochondria
• Contain their own DNA and
protein-synthesizing machinery
– Ribosomes, transfer RNAs,
nucleotides.
– Thought to have evolved from
endosymbiotic bacteria.
– Divide by fusion
– The DNA is in the form of
circular chromosomes, like
bacteria
– DNA replication is
independent from DNA
replication in the nucleus
The Mitochondria
Site of Cellular Respiration
• This process requires oxygen.
• Composed of three stages:
– Glycolysis--glucose splitting,
occurs in the cell. Glucose is
converted to Pyruvate.
– Krebs cycle--Electrons are
removed--carriers are
charged and CO2 is produced.
This occurs in the
mitochondrion.
– Electron transport--electrons
are transferred to oxygen.
This produces H2O and ATP.
Occurs in the mito.
The Chloroplast
• Contain their own DNA and
protein-synthesizing machinery
– Ribosomes, transfer RNAs,
nucleotides.
– Thought to have evolved from
endosymbiotic bacteria.
– Divide by fusion
– The DNA is in the form of
circular chromosomes, like
bacteria
– DNA replication is
independent from DNA
replication in the nucleus
The Chloroplast
• Membranes contain chlophyll and
it’s associated proteins
– Site of photosynthesis
• Have inner & outer membranes
• 3rd membrane system
– Thylakoids
• Stack of Thylakoids = Granum
• Surrounded by Stroma
– Works like mitochondria
• During photosynthesis, ATP
from stroma provide the energy
for the production of sugar
molecules
3 Domains and 6 Kingdoms
A Closer Look at the Taxa
•As one goes from the
Kingdom to the Species
(DOWNWARD)…An
increase in the similarity
between organisms
occur.
•There are fewer
numbers of different
kinds of organisms
From the wikimedia free licensed media file
repository
Categories Within Kingdoms
•
•
•
Kingdoms are divided into groups called phyla
Phyla are subdivided into classes
Classes are subdivided into orders
•
Orders are subdivided into families
•
Families are divided into genera
•
•
Genera contain closely related species
Species is unique
Human Classification
• Kingdom : Animalia (animal in Latin)
• Phylum : Chordata (spinal cord)
• Class : Mammalia (mammary glands)
• Order : Primates (two mammary glands)
• Family : Hominidae (bipedalism)
• Genus : Homo
• Species : sapiens
Classifying Organisms
• Phylogenetics – based on common
evolutionary descent
– Phylogeny – a representation of organisms
based on and describing evolutionary
relationships. It is the cornerstone of a
branch of biology called systematic taxonomy.
– Systematics – the study of the evolution of
biological diversity
Classifying Organisms cont.
• Phylogeny - based on various evidence, including form
and structure (observable traits). Must be based on
homologous, not analogous structures
– a. Homologous structures - similarity in structure due to
common descent, not reliant on function. E.g. vertebrate
forearms: human hand, bat wing, whale fin, cat leg.
– b. Analogous structures - similarity in structure based on
adaptation for the same function, not common descent.
E.g. wings have developed independently in insects,
reptiles, birds, and bats.
Homologous Structures
All have the same
bones, but are used
in different ways and
for various functions
–
remember,
homologous structures
have common ancestry!
Homologous Structures
Analogous Structures
Wings of bat, bird, and insect have the same function, but are not from
the same descent
Comparison Between Homology
and Analogy
• Phylogenetics is usually based on a combination of
these lines of evidence:
– Fossil record
– Morphology
– Embryological patterns of development
– Chromosomes and DNA
– How do you think these lines of evidence help to
determine evolutionary relationships?
Fossils
From the wikimedia free licensed media file
repository
Embryology
The
formation
and early
development
of living
organisms
Chromosomes and DNA
Analyze to
find links
between
organisms
Archaea
One of two groups of prokaryotic organisms, organisms with no
nuclear membrane. (Bacteria are the other group.)
Archaea are
believed to be the
earliest form of
life on Earth.
Although both
ARCHAEA
archaea and
bacteria are
simple life-forms,
archaea are very
different from
bacteria.
Archaea do not require sunlight for photosynthesis, as plants
do, and they do not need oxygen. Archaea absorb CO2, N2, or
H2S and give off methane gas as a waste product.
Archaea are best known for living in extremely hostile environments
(very hot, very acid, or very salty), but they can also be found in less
extreme conditions.
Bacteria – the Most Abundant Organisms
Bacteria (Staphylococcus
aureus; yellow spheres)
adhering to nasal cilia.
E. Coli bacteria
Mycoplasma
hyopneumoniae
Borrelia burgdorferi, the bacterium
that causes Lyme disease.
There are more bacteria in your mouth than there have been people
living since the dawn of humans.
• Don Bryant and David M. Ward,
(2007) Science. 317(5837):523-6
More Bacteria!
•
Candidatus Chloracidobacterium
thermophilum:
• Aerobic phototrophic Acidobacterium
• New genus and species. It also
belongs to the Acidobacteria phylum, a
poorly characterized phylum that was
not previously known to include
bacteria capable of photosynthesis.
• Give the hot springs in Yellowstone
their remarkable yellow, orange, red,
brown and green colors.
From the wikimedia free licensed media file
repository
The Domain Eukarya is divided into 4
Kingdoms:
Protista
Fungi
Plantae
Animalia
PROTISTS
• Protists
are eukaryotes
because they all have a nucleus.
• Most have mitochondria.
• Many have chloroplasts with
which they carry on
photosynthesis.
• Many are unicellular and all
groups (with one exception)
contain some unicellular
members.
A better name for
Protists would be "Eukaryotes
that are neither Animals,
Fungi, nor Plants".
From the wikimedia free licensed media
file repository
FUNGI
Fungi sometimes look like plants, but they’re not!
Fungi can’t photosynthesize, because they don’t have chloroplasts;
they get their nutrients from the organic material they live in.
 Are Decomposers --feed on dead organic material.
 Some fungi feed on living organisms, such as plants, animals
and even other fungi. This causes diseases and infections in
these organisms (like athlete’s foot and ringworm in humans).
 Some fungi live as symbiotic partners with algae. The
result: lichen
Other differences from plants:
• fungi don’t have roots, they have a mycelium.
• fungi’s cell walls are made of chitin, not cellulose.
PLANTS
No vascular system
Vascular system
Mosses,
Liverworts,
Hornworts
Seed Plants
(reproduce by
seeds)
Seedless Plants
(reproduce by
spores)
Ferns, Horsetails,
Club Mosses
Gymnosperms
(“naked seeds”)
Conifers
Cycads
Gingkoes
Angiosperms
(flowers, seeds
enclosed in
fruit)
Flowering Plants
The Plant Cell wall
• Cell walls are held
together by the middle
Lamella.
• Made up of:
•
•
•
•
•
•
•
•
Cellulose
Xyloglucan
Pectin
Proteins
Ca ions
Lignin
other ions
Water
The Plant Cell wall
• The cell wall is the organelle
that ultimately controls the
shape of plant cells and
consequently of organs and
whole organisms.
• It is sometimes naturally
strengthened and made
considerably more resistant
to such abuses as pathogen
infection by the release of
specific oligosaccharides and
enzymes and by overlaying or
impregnation with cutin,
suberin, waxes or silica
ANIMALS
Invertebrates (no
backbone)
Vertebrates
(backbone)
Animal Classification
As you can see, we mammals (4000 species) are far
outnumbered by the other vertebrates, or chordates (38,300).
And vertebrates (42,300) are definitely outnumbered by
invertebrates (989,700 species). The biggest categories of
invertebrates: INSECTS!
Summary
• Classification is based on similarities and
evolutionary history
• Prokaryotic cells
– Have no organelles
– No nucleus – one single chromosome
• Eukaryotic cells
– Many organelles
– Large complex genome containing many
chromosomes
Summary – and thoughts for
the next few weeks
• Biological evolution continues at act today in
all species
• Natural selection continues to act today by
both differential mortality and differential
reproduction
• One frequent result of evolution within
species is geographic variation
The end
Any Questions?