Chapter 8: Life’s structure and Classification
Living Things
What are living things like?
• Organism: Any living thing
• Can vary in size (bacteria---gigantic oak tree----humans)
• Have different behaviors and food requirements
Similarities between all living things
• They are organized• All organisms are made up of cells (the smallest unit of an
organism that carries on the function of life)• They grow and develop
• Infant—adult• Organisms change as they grow (development)
• They respond• Living things must interact with their environment• Stimulus: Anything that causes some change in an
organism. • Response: the reaction to a stimulus-Results in
movement
Similarities between all living things (continued..)
• They maintain homeostasis• Ability of an organism to maintain proper internal conditions
despite changes in the environment.
• They use energy• All organisms require energy for everyday life functions (staying
organized, carrying on activities-finding/making food)
• They reproduce• Making their own kind
• Living things need to replace those individuals that die
What do living things need?
• A place to live• Suited to their unique needs (temperature,
sunlight, space etc..)• Water• Important functions: transporting materials within
a cell and between cells. • We are made up of 60-70% of water!• Food sources• Take in substances (protein, fats, sugars) from
other animals• Plants and some bacteria make their own food
Cell Structure -What are cells?
-What are the functions of each part of a cell?
- What is the difference between unicellular and multi-cellular
organisms?
A little history
• 1600’s : Leeuwenhoek made a simple microscopeled to types of microscopes we use today
• Discovered cells under microscope– Robert Hooke looked at a cork and saw many empty
little boxes—named them cells• 1800’s: Schleiden(plant cell) and Schwann (animal
cell): all living things are made up of cells• Virchow: main contributor to the cell theory
The Cell Theory• All organisms are made up
of one or more cell
• The cell is the basic unit of organization in organisms– Basic unit of structure and
function
• All cells come from cells– Divide to form new, identical
cells
Prokaryotic vs Eukaryotic Cell• Prokaryotic: only found in ONE-
celled organisms– Cells without membrane-bound
structures – Ex: Bacteria
• Eukaryotic: – More complex internal structure– Cells with membrane bound
structures– Ex: protists, fungi, plants and
animals
Prokaryote vs Eukaryote
Cellular organization- Main structures
Just Plant Just Plant CellCell
Both Plant and Both Plant and Animal CellAnimal Cell
Just Animal Just Animal CellCell
Cell wallCell wall Cell membraneCell membrane Centrioles Centrioles
ChloroplastsChloroplasts CytoplasmCytoplasm CytoskeletonCytoskeleton
NucleusNucleus
MitochondriaMitochondria
GolgiGolgi
VacuoleVacuole
Endoplasmic reticulumEndoplasmic reticulum
RibosomeRibosome
(Lysosome)(Lysosome)
Organelle: parts of the cell
Cell structure Description/function
• Cell Membrane– Protective layer surrounding every cell– Regulates interactions (what goes in and out) between the cell and its
environment• Nutrients move in, waste moves out
• Cytoplasm– Gelatin like substance which cells are filled with– Where the cells organelles are located– Most of cells life processes occur here
• Nucleus– contains a membrane, nucleolus, and hereditary material (DNA)– Control center(all cellular activities are directed here)
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Eukaryotic Cell
Membrane
Cell structure Description/function continued
• Mitochondria– Powerhouse of the cell-releases energy
that is needed by the cell
• Golgi bodies– Stacked flattened membranes– Package material for release to the
outside of the cell
• Vacuole– Membrane-bound spaces– Temporary storage of materials (stores
water, waste products, food etc.)
Cell structure Description/function continued
• Endoplasmic reticulum (ER) – Series of folded membranes– Transport materials inside cell
• Ribosomes – Make proteins
Proteins: part of cell membranes and needed for chemical reactions that take place in the cytoplasm
• Chloroplasts (plant only) – Contains chlorophyll
Use light to make sugar-food and energy for plants
Cell structure/function• Lysosome
• Break down & Recycle!• Contain digestive chemicals
that break down food molecules, cell wastes, worn out cell parts and viruses and bacteria that enter cell
• When cell dies, release chemicals to breakdown cell contents
Animal vs Plant Cell
Unicellular vs Multicellular organisms • Unicellular organism:
– one celled organism (perform all life functions on their own)
• Multicellular organisms:– many celled organisms (cells cannot function alone)
– Celltissueorganorgan systemsorganism
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Many-Celled Organism