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