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 CellAnimal

Cell

Different kinds of animal cells

white blood cell

red blood cell

cheek cellssperm nerve cell

muscle cell

Amoeba

Paramecium

Examples of Animal CellsMuscle cells Red blood cells

Cheek cells

Cell or Plasma Membrane

(2,5)

Cellmembrane

Proteins

Proteinchannel 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

CHROMATINin non-dividing cells

DNA is condensed & wrapped around proteins forming

as CHROMOSOMES in dividing cells

Nucleolus(13,14)

• Inside nucleus

• Makes 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

RibosomesCan be attached

to Rough ER

OR

Be free (unattached

) in the cytoplasm

Golgi Bodies (8,12)

• Stacks of flattened sacs (PANCAKES)

• Modify, sort, & package molecules for storage OR transport out of cell

• Vesicles 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 enzymes

• Break 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 LungsRespiratory 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 hairGuard Cells

Examples of Plant cells

Xylem cellsPollen

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

cellsAnimal cells Plant cellsIrregular

shapeNo cell wallRegular shapeCell wall

presentNo chloroplast

Have chloroplastVacuole small or

absentLarge central

vacuoleGlycogen as food

storageStarch as food

storage

• http://www.youtube.com/watch?v=Yu21ShnKhHk&feature=related

Cell Types• Cells can only be observed under microscope

• Three Basic types of cells include:

Animal Cell Plant CellBacterial

Cell

Number of CellsAlthough 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 cell Animal cell bacteria

Cell SizeQuestion:

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 SizeQuestion:

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!