CELLS

Definition of Cell A cell is the smallest unit that is capable of performing life functions. Smallest living unit ; most are microscopic

Cell Theory Smallest living unit of structure and function of all organisms is the cell All living things are made of cells All cells arise from preexisting cells

Characteristics of All Cells A surrounding membrane  plasma or cell membrane Protoplasm/Cytoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA

Examples of Cells Plant Stem Bacteria Red Blood Cell Nerve Cell

Prokaryotic First cell type on earth, smallest Do not have structures surrounded by membranes Few internal structures One-celled organisms, Bacteria http://library.thinkquest.org/C004535/prokaryotic_cells.html

Eukaryotic Contain organelles surrounded by membranes Most living organisms Animal Plant http://library.thinkquest.org/C004535/eukaryotic_cells.html

Eukaryotes are bigger and more complicated Have nucleus Have organelles Have chromosomes can be multicellular include animal and plant cells

Organelles are membrane-bound cell parts Mini “organs” that have unique structures and functions Located in cytoplasm Cytoplasm  liquid – the jell-o of the cell

Cell Structures Cell membrane Outer membrane that controls movement into and out of cell

Nucleus Control center of the cell – stores chromosomes (DNA) Contains nucleolus – produces ribosomes

Nucleolus inside nucleus Contains RNA to build proteins

the more energy the cell needs, the more mitochondria it has Provides/releases energy that powers cellular activities *cellular respiration the more energy the cell needs, the more mitochondria it has Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates

Each cell contains thousands Synthesize proteins Ribosomes Each cell contains thousands Synthesize proteins may be free- floating or attached to ER Each cell contains thousands Make proteins Found on ribosomes & floating throughout the cell Made of RNA

Cytoskeleton found throughout cytoplasm 3 functions: mechanical support anchor organelles help move substances Within cytoplasm – acts as both a muscle and a skeleton ; for movement and stability

Endoplasmic reticulum Folded membranes attached to nucleus may be smooth: lacking ribosomes may be rough: has attached ribosomes Smooth  “storage organelle” ;

Ribosomes embedded on Rough endoplasmic reticulum

takes in sacs of raw material from ER Golgi Apparatus takes in sacs of raw material from ER sends out sacs containing finished cell products “packing and shipping” station Protein 'packaging and shipping station’ Move materials within the cell Move materials out of the cell

sacs filled with digestive enzymes Lysosomes sacs filled with digestive enzymes digest worn out cell parts digest food absorbed by cell If explodes, cell breaks down! Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Cell breaks down if lysosome explodes

Cytoplasm “jell” or fluid in which organelles are found Site where chemical reactions occur within a cell

Structures found ONLY in PLANT cells Cell wall Tough, flexible, fairly rigid outer layer (chain link fence) protects cell from rupturing

(central) Vacuole Membrane- bound storage sac Holds water, food, waste items Helps plants maintain shape

Chloroplasts filled with chlorophyll turn light energy into food energy (photosynthesis

How are plant and animal cells different?

How are plant and animal cells different? How are plant and animal cells similar? Differences  Plants have…cell wall, chloroplasts, vacuole Similarities  Both eukaryotic, surrounded by cell membrane

How do animal cells move? Some can crawl with pseudopods Some can swim with a flagellum Some can swim very fast with cilia

Pseudopods means “fake feet” extensions of cell membrane example: ameoba

Flagellum/flagella large whiplike tail pushes or pulls cell through water can be single, or a pair

Cilia fine, hairlike extensions attached to cell membrane beat in unison