Classifying Nature
(Chapter 6)
Living Things are Alike
• Common Characteristics like:
• Cells
• Tissues
• Organs
Our Study of Life
• How do our bodies work?
– Physiology
• What is our place in Nature?
– Ecology
• Our Bodies, like Life, are Organized!
Levels of
Biological Organization I
Cellular
Nerve Cell
Organelle
Mitochondrion
Molecular
Chloroplast
Nucleus
CH2OH
O
H H
Water
Glucose
DNA
Atomic
Hydrogen
Subatomic
ƒ1-2
Carbon
Proton
Chapter 1
Nitrogen
Neutron
Oxygen
Electron
4
Levels of
Biological Organization II
Pronghorn
Antelope
Organismal
Organ System
Nervous
System
Organ
Tissue
ƒ1-2
Brain
Nervous
Tissue
Chapter 1
5
Levels of
Biological Organization III
Biosphere
Earth’s
surface
Air
Ecosystem
Community
Bushes
Water Hawk
Snake
Pronghorns
Soil
Grass
Hawk
Snake
Pronghorns
Population
Herd of Pronghorns
ƒ1-2
Chapter 1
6
How do we fit in?
• Where do we fit in the classification of all
organisms?
• What is a classification?
• Why be classified?
• We are in the Kingdom Animalia and are
Mammals!
HowFigure
do we6,1
fit in?
Animalia – development by
means of an embryonic stage
No cell walls. Do not
undergo photosynthesis
Plantae – contain a cell wall
carry out photosynthesis
Non-motile life stages.
Fungi - contain cell wall
Do NOT photosynthesize
Protista – No cell walls
reproduce by spores – motile
Monera – the bacteria:
single-cell organisms
There are two major types
of cells
1. Prokaryotic
2. Eukaryotic
• The eukaryotic cell
is more complex and
contains organelles
• The DNA of a
eukaryotic cell is
contained in the
nucleus
Nucleus
(contains
DNA)
Eukaryotic cell
Prokaryotic cell
DNA
(no nucleus)
Organelles
•
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)
Components of a Cell
Components of a 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.
Mitochondria are not part
of the endomembrane system
• Contains its own genetic material
• Has 37 genes
• Directly passed on by your mother
• Does not change
Components of a Cell
• Mitochondria make most of our ATP!
• Mitochondria have a double membrane-this is required for ATP production.
• Mitochondria have highly folded inner
membrane called cristae--this is where
ATP is made.
• Mitochondria perform cellular respiration-literally cell breathing. Oxygen is used
and CO2 is made. ATP is the end result.
• Fermentation occurs when there is no
oxygen.
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.
Box 6.2 (3)
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
The Plant Golgi Network
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 plant cell wall is a layer of
structural material external to the
protoplast, built from
polysaccharides and proteins.
• The wall contains components for
signaling and communication by
symplastic continuity through
plasmodesmata and maintains
molecular connections with the
plasma membrane and
cytoskeleton
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
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?