Download Life Structure and Classification Chpt 8

Life Structure and Classification
What are living things like?
•
Any living thing is an organism
•
Organisms
•
: are organized
•
: grow and develop
•
: respond
•
: maintain homeostasis
•
:use energy
•
: reproduce
Organized
All living organisms are composed of cells
 Cells are smallest unit of life that carries
on the function of life
 Cells take in materials and use them in
complex ways
 Have orderly structure and instruction for
transfer of heriditary material

Living Things grow and
Develope
Single cell organisms increase cell size
 Multi-celled organisms grow by increasing
number of cells
 Changes that take place during lifetime is
known as development
 Figure 2 shows examples of development
 Life span is the length of time an
organism is expected to live

Living things Respond
Living things interact with their
surroundings
 Anything that causes change in an
organism is a stimulus and the reaction
to that is a response
 Organisms must respond to stimuli to
carry on daily activity and to survive

Maintain Homeostasis
Inside cells they must respond to stimuli
within (water or food levels within)
 Cells internally make adjustments
 This regulation of an organism’s internal
life maintaining conditions that is in
response to it’s environment is called
homeostasis

Living things use energy




All energy for cells originates from the sun
Plants use sun directly to produce energy
(photosynthesis) where H2O + CO2
produces C6H12O6 (carbohydrates) and O2
Animals and some other organisms take in
carbohydrates and oxygen to produce its
energy
Some bacteria deep in dark ocean floors use
stored energy in chemical compounds to
make food
Living things must reproduce

In order for an organism to continue to
its own kind it must be able to reproduce
itself
What do living things need to
survive
Place to live
 Needs water

◦ Water transport minerals within and between
cells
◦ Water is released by organisms and
homeostasis is maintained

Needs food source
◦ Animals need to take in food, where plants
produce their own food
◦ Organisms die and are decomposed by
 other organisms that are reused again
How are living things classified
section 2

Carolus Linnaeus
◦ Developed a system of organizing organisms by
similar structure in system called Binomial
Nomenclature.
◦ Used Scientific Names rather than common
names
◦ Modern classification use structure, hereditary
information and early stages of development
Binomial Nomenclature
Two word naming system (latin names)
 First word is the genus name (contain
similar species)
 Second word is the species name

◦ Can describe a feature, place or honor an
individual
◦ Ambystoma tigrinum (salamander named
because of tiger stripes)

Organisms of same species can reproduce
amongst themselves
Scientific Names
Why they are important
Help avoid confusion with common
names
 Organisms with similar evolutionary
histories are group together
 Gives descriptive information about
species (tiger salamander)
 It is organized efficiently

Classification Order

Organisms are classified in following
order:
◦
◦
◦
◦
◦
◦
◦
Kingdom
Phylum (Division in plants)
Class
Order
Family
Genus
species
Modern Classification

Today scientist use phylogeny to classify
organisms
◦ Uses fossils, evolutionary history and changes
over time to classify
Smallest group is a species
 Broadest group is Kingdom
 Figure 6 in book classifies a brottle nosed
dolphin

Tools for Identifying Organisms
Field guides and dichotomous keys aide to
identify organisms
 Dichotomous key (use 2 characteristics
that you choose between that leads to
identification of organisms)

◦ The key will lead to genus-species final name
of organism
Cell Structure
section 3

Viewing cell structure
◦ First developed by using two magnifying glasses
together to see larger view of cells
◦ Leeuwenhoek (Dutch) saw inside cells (1600’s)
called them beasties
Development of Cell Theory
Hooke in 1665 sliced a piece of cork and saw
empty space he called cells
 1830 Scheiden used a microscope to study plant
parts and called them cells
 Schwann observed animal cells
 Both men combined their ideas and were
convinced all living things are made of cells
 Mid 1800’s Virchow proposed that cells divide
and every cell comes from a cell that already
existed

Cell Theory
table 2 (page 221)
All Cells are made up of one or more
cells
 Cells are the basic unit of organization in
organism
 All Cells come from pre-existing cells

Cell organization
Scientists divide cells that have a membrane
bound structure and those that don’t
 Cells without a membrane are called
prokaryote cells
 Cells with a membrane around the cell are
called eukaryote cells
 Each cell performs specific functions but all
cells must take in nutrients, store, produce and
breakdown substances, take in and use energy
 Structure of cells perform certain functions

Cell Wall
Tough rigid outer coverings that protect
cells and give them shape
 Found in all plants, algae, fungi and most
bacteria
 Plants cell wall contain mostly cellulose
(carbohydrate) and allows water and
nutrients in and out

◦ Pectin (found in plant cell walls) is glue-like
structure that has thick structure (jams and
jellies)
◦ Lignin (makes cell walls rigid) found mostly in
plant cells that aide in supporting plants
Cell Membrane
All cells contain a cell membrane
 It is the outermost covering of cells
unless they have a cell wall
 Regulates interactions between cells and
environment
 Allows nutrients to move in and wastes
to leave cell

Cytoplasm
Gell-like substance inside cell membrane
is called cytoplasm
 Life processes take place here
 Prokaryote cells cytoplasm contains the
hereditary material
 All organelles are located here
 Cytoskeleton found in cytoplasm is
made of proteins that help cell change
shape, enable some cells to move

Manufacture of Proteins in Cells
Every cell activity involves proteins
 Proteins are part of cell membrane and
are part of all chemical reactions in cell
 Ribosomes produce protein in cells

◦ Found in cytoplasm
◦ Get their instruction from hereditary material
that tells them how, when and in what order
to make specific proteins
Membrane-bound Organelles
Organelles are structure in cytoplasm
that carry out life functions in cells
 Found in cytoplasm of eukaryotic cells
Nucleus is largest organelle
 Ribosomes are not membrane bound but
are considered an organelle

Organelles that produce Energy

Chloroplasts: (organelle found in plants)
◦ Contain chylorophyll (green pigments) that
captures sunlight to make sugars called glucose
◦ Captured light energy is stored in glucose as
chemical energy where plants utilizes glucose to
carry out life functions in cells
Organelles that produce Energy
Organelle that releases energy is
Mitochondria
Food (glucose and carbohydrates) is broken
down into CO2 and H2O and releases
energy
Sometimes called the powerhouse
organelle because it provides the energy
for cells
All plants and animal cells have these
Organelles that process,
transport and store materials
Endoplasmic reticulum (ER) takes up
considerable amount of space that
process and move materials around cell
like a conveyor belt
 Rough ER contains ribosomes where
protein is made and moved in cell
 Smooth ER process lipids and oils that
store energy

Organelles that process,
transport and store materials
After proteins is made they are
transferred to Golgi bodies where they
are packaged and moved to areas of cells
in vesicles
 Materials are also moved to outer
membrane for release outside of cell
 Vacuoles also are organelles that store
water, waste products, food and other cell
materials

Organelles that Recycle
Lysosomes are structures that break
down food molecules, cell waste, wornout cell parts and viruses
 Chemicals released from lysosomes break
down food and dead cells
 These chemicals are contained in
lysosomes and when a cell dies, the
chemicals are released and break down
the dead cell

Many Celled Organisms






Many celled organisms rely of other cells to
perform all life functions
Tissue is a group of similar cells that work
together to do one job
Tissues are organized into organs.
Organs are a group of tissues that work together
to perform a function (heart..nerve, blood and
cardic muscle tissue)
Group of organs working together perform a
certain function is an organ system
Organ systems work together to make up many
celled organisms (heart, arteries, veins, and
capillaries)
Viruses
section 4
Viruses causes many diseases
 Viruses are non-living strands of
hereditary material surrounded by a
protein coat

◦ Do not have nucleus, other organelles or a
cell membrane
Viruses rely on host cells to live inside
(living cells)
 Have two kinds of viruses: Active and
Latent

Active Viruses
Occurs when virus enters host cell and
immediately begins to make new viruses
 Destroys the host cells when it makes
new viruses
 Virus uses host cell to duplicate its
hereditary material and later releases
duplicated virus and kills host cell when
they are released


Figure 17 page 232
Latent Viruses
Some viruses enter host cell and remain
inactive for a period of time
 Does not immediately cause the host cell
to duplicate new virus
 At a later time it may begin to duplicate
and release new viruses that kill the host
cell
 AIDS, cold sores are examples

How do viruses affect
organisms
Viruses attach specific cells that match
host cells
 Many times viruses only attach to certain
host cells (potato leafroll)
 Some viruses can affect numerous
organisms (rabies)
 Viruses are moved by wind and inhaled
where they attach


Figure 18 page 233
Treating/Preventing Viral
Diseases
Treatment difficult because antibiotics do
not kill viruses
 Prevention is best method of avoiding
viral infections (eliminate mosquito to
fight yellow fever)

Natural Immunity
Human bodies fight viral infections by
making interferons
 Interferons are proteins that make a
protective covering for cells that are
infected (produced by healthy cells to
protect affected cells)

Vaccines
Vaccines are weakened viruses that can’t
enter host cells and duplicate, but cells
begin to make interferons that protect all
cells from infection
 Measles, mumps, small pox, chicken pox,
polio, and rabies
 Found vaccine by taking weakened cow
pox cells and entering them into healthy
people to prevent small pox (1786) Jenner

Virus Research
AIDS is a disease that is caused by
human immuno-deficiency virus (HIV)
 AIDS (acquired immune deficiency
syndrome)
 The HIV virus weakens the immune
system and body can’t fight infections like
pneumonia, TB
 People usually die from weakened system
rather than disease
