Basic Structure of a Cell

CELL THEORY All living things are made of cells Cells are the basic unit of structure and function Cells come from the reproduction of existing cells (cell division)

Two Main Types of Eukaryotic Cells Plant Cell Animal Cell

Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium

Examples of Animal Cells Muscle cellsRed blood cells Cheek cells

Cell or Plasma Membrane (2,5) Cell membrane Proteins Protein channel Lipid bilayer Composed of double layer of phospholipids and proteins Surrounds outside of ALL cells Controls what enters or leaves the cell – selectively permeable

Jelly-like substance Found in ALL cells Contains organelles Provides a place for chemical reactions to take place Cytoplasm

Controls the activities of the cell Contains DNA in chromosomes Genes control cell characteristics Nucleus (12,15)

Nuclear Envelope/Membrane Double membrane surrounding nucleus Contains nuclear pores for materials to enter & leave nucleus Nuclear pores

Inside the Nucleus (14,16) The genetic material (DNA) is found DNA is spread out And appears as CHROMATIN in non-dividing cells DNA is condensed & wrapped around proteins forming as CHROMOSOMES in dividing cells

Nucleolus (13,14) Inside nucleusInside nucleus Makes ribosomes that make proteinsMakes ribosomes that make proteins

Endoplasmic Reticulum - ER Two kinds of ER ---ROUGH & SMOOTH Connects to nuclear envelope & cell membrane Functions in Synthesis of cell products & Transport

Rough Endoplasmic Reticulum (Rough ER) (11,11) Has ribosomes on its surface –Makes membrane proteins –TRANSPORT proteins out of cell

Smooth Endoplasmic Reticulum (7,1) Smooth ER lacks ribosomes –Makes membrane lipids (steroids) –Regulates calcium (muscle cells) –Detoxic substances (Liver)

Ribosomes (10,10) Made of PROTEINS “Protein factories” for cell Join amino acids to make proteins Process called protein synthesis 

Ribosomes Can be attached to Rough ER OR Be free (unattached) in the cytoplasm

Golgi Bodies (8,12) Stacks of flattened sacs (PANCAKES)Stacks of flattened sacs (PANCAKES) Modify, sort, & package molecules for storage OR transport out of cell Vesicles pinch off the endsVesicles pinch off the ends vesicle CIS TRANS

Golgi Animation Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES

Lysosomes (3,7) Contain digestive enzymesContain digestive enzymes Break down food, bacteria, and worn out cell partsBreak down food, bacteria, and worn out cell parts

Cytoskeleton (5,6) Helps cell maintain cell shape Also help move organelles around Made of proteins –Ex. Microfilaments –Ex. Microtubules

Mitochondrion (plural = mitochondria) (4,3) “Powerhouse” of the cell Generate cellular energy (ATP) Site of CELLULAR RESPIRATION Has its own DNA What kind of cells would have MORE mitochondria?

What do mitochondria do? Burns glucose to release energy (ATP) Stores energy as ATP “Power plant” of the cell

Cilia & Flagella Function in moving cells and movement of particles across a membrane Cilia -short and many (spirit fingers) Flagella - longer and fewer (ex sperm tail)

Cell Movement with Cilia & Flagella

Cilia Moving Away Dust Particles from the Lungs Respiratory System

Centrioles (1) Found only in animal cells Made of bundle of microtubules Appear during cell division Help to pull chromosomes apart

Centrioles & the Mitotic Spindle

Vacuoles (8) Storage of wastes, water, and nutrients Small or absent in animal cells Plant cells have a large Central Vacuole No vacuoles in bacterial cells

Plant Cell

Different kinds of plant cells Onion Epidermal Cells Root Hair Cell root hair Guard Cells

Examples of Plant cells Xylem cells Pollen Guard Cells

Cell Wall (4) Supports and protects cell Found outside of the cell membrane Found in plants, fungi, & bacteria cellulose in plants peptidoglycan in bacteria chitin in Fungi

Chloroplasts (9) Plant cells ONLY Contain chlorophyll Photosynthesis – (energy from sunlight makes food (glucose) Contains its own DNA

Differences between plant cells and animal cells Animal cellsPlant cells Irregular shape No cell wall Regular shape Cell wall present No chloroplast Have chloroplast Vacuole small or absent Large central vacuole Glycogen as food storage Starch as food storage

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Cell Types Cells can only be observed under microscope Three Basic types of cells include: Animal CellPlant Cell Bacterial Cell

Number of Cells Although ALL living things are made of cells, organisms may be: Unicellular – composed of one cell Multicellular - composed of many cells that may organize into tissues, etc.

Prokaryotes Cells that lack a nucleus or membrane- bound organelles –Nucleoid region (center) contains the DNA –Single, circular chromosome Surrounded by cell membrane & cell wall Contain ribosomes E.x. bacteria

Eukaryotes Cells that HAVE a nucleus and membrane- bound organelles Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles E.x. protists, fungi, plants, and animals

CELL SIZE

Which Cell Type is Larger? _________ > _____________ > ___________ Plant cellAnimal cellbacteria

Cell Size Question: Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?

Factors Affecting Cell Size Surface area (plasma membrane surface) is determined by multiplying length times width (L x W) Volume of a cell is determined by multiplying length times width times height (L x W x H) Therefore, Volume increases FASTER than the surface area

Cell Size When the surface area is no longer great enough to get rid of all the wastes and to get in enough food and water, then the cell must divide Therefore, the cells of an organism are close in size

Cell Size Question: Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse? About the same size, but … The elephant has MANY MORE cells than a mouse!