CELLS Definition of Cell A cell is the

CELLS

Definition of Cell A cell is the smallest unit that is capable of performing life functions.

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

o es l p m a x E s l l e C f Bacteria Nerve Cell Plant Stem Red Blood 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/C 004535/prokaryotic_cells. html

Eukaryotic Contain organelles surrounded by membranes Most living organisms Plant http: //library. thinkquest. org/C 004535/eukaryotic_cells. html Animal

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

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

Mitochondria Provides/releases energy that powers cellular activities *cellular respiration the more energy the cell needs, the more mitochondria it has

Ribosomes Each cell contains thousands Synthesize proteins may be freefloating or attached to ER

Cytoskeleton found throughout cytoplasm 3 functions: mechanical support anchor organelles help move substances

Endoplasmic reticulum Folded membranes attached to nucleus may be smooth: lacking ribosomes may be rough: has attached ribosomes

Golgi Apparatus takes in sacs of raw material from ER sends out sacs containing finished cell products “packing and shipping” station

Lysosomes sacs filled with digestive enzymes digest worn out cell parts digest food absorbed by cell If explodes, cell breaks down!

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 Membranebound 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