BASIC STRUCTURE OF A CELL MS. GAYNOR HONORS GENETICS

BASIC STRUCTURE OF A CELLMS. GAYNOR

HONORS GENETICS

CELL THEORY

CELL TYPESCELL TYPES

Three Basic types of cells include:

Animal Cell(Eukaryote)

Plant Cell(Eukaryote)

Bacterial Cell

(Prokaryote)

**SMALLEST

NUMBER OF CELLSNUMBER OF CELLSAlthough ALL living things are made of cells, organisms may be:

Unicellular – composed of one cellMulticellular- composed of many cells

that may organize into tissues, etc.

I look BIG here, I’m

very small!

I look BIG here, I’m

very small!

MULTICELLULAR MULTICELLULAR ORGANISMSORGANISMS

Cells in multicellular organisms often specialize (take on different shapes & functions)

CELL SPECIALIZATIONCELL SPECIALIZATION

Cells in a multi-cellular organism become specialized by turning different genes on and off

This is known as DIFFERENTIATION

ALL CELLS…

Contain 4 basic cell structures:

Cell MembraneCytoplasmRibosomesDNA

**not an organelle

PROPROKARYOTES: KARYOTES: THE FIRST CELLSTHE FIRST CELLS

Simplest and smallest type of cellEx: bacteria

NO nucleus NO/FEW organelles1 Single, circular chromosome (piece of DNA)

PROKARYOTESPROKARYOTESNucleoid region (center) contains the DNA (NO nulceus)

Surrounded by cell membrane & cell wall (made of peptidoglycan)

Contain ribosomes in their cytoplasm to make proteins

Has cilia for reproduction and flagella for movement

EUKARYOTESAll eukaryotic cells HAVE:a Nucleusmembrane-bound

organelles

These cell types includes:protistsfungiplantsanimals

More complex type of cells

THINK: “You carry a lot…of

stuff”

TWO MAIN TYPES OF EUKARYOTIC CELLS

Plant Cell

Animal Cell

CELL ORGANELLESMS. GAYNOR

HONORS GENETICS

ORGANELLESORGANELLESVery smallPerform various functions for cellFound in the cytoplasmMay or may not be membrane-

bound

BASIC ANIMAL BASIC ANIMAL CELL ORGANELLESCELL ORGANELLES

Nucleolus

Nucleus

Nuclear envelope

Ribosome (attached)Ribosome (free)

Cell Membrane

Rough endoplasmic reticulum

Golgi apparatus

Mitochondrion

Smooth endoplasmicreticulum

Centrioles

BASIC PLANT CELL BASIC PLANT CELL ORGANELLESORGANELLES

CELL OR PLASMA MEMBRANECELL OR PLASMA MEMBRANESTRUCTURE Made of double layer (bilayer) of:

phospholipids and proteins Surrounds outside of ALL cellsFUNCTION (JOB) Controls what enters or leaves the cell

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

CELL WALLCELL WALLSTRUCTURE• Found in:• plants

• Made of cellulose• Fungi

• Made of chitin• Bacteria

• Made of peptidoglycan

• NO IN ANIMAL CELLS!!!FUNCTION (JOB)• Protect• Maintain shape

Cell wall

CYTOPLASMCYTOPLASMSTRUCTURE• Jelly-like substance• Mostly water

• aqueous solutionFUNCTION (JOB)• Provides a solution

for chemical reactions to take place in

• Holds organelles in place

cytoplasm

NUCLEUSNUCLEUSSTRUCTURE• Contains the DNA• Bounded by a

nuclear envelope (membrane) with pores

• Usually the largest organelle

FUNCTION (JOB)• Controls the normal

activities of the cell

20

NUCLEAR ENVELOPENUCLEAR ENVELOPEDouble membrane

surrounding nucleusAlso called nuclear membraneContains nuclear pores for

materials to enter & leave nucleus

Connected to the rough ER

Nuclear pores

NUCLEOLUS

STRUCTUREInside nucleusInside nucleusCell may have Cell may have 1 to 31 to 3

nucleolinucleoliDisappearsDisappears when cell when cell

dividesdividesFUNCTION (JOB)Makes ribosomes Makes ribosomes

(ribosomal subunits)(ribosomal subunits)

STRUCTURE Bean shapeDOUBLE membrane Has its own DNA “Powerhouse” of cell Makes cellular energy

(ATP) Site of CELLULAR

RESPIRATION (burning glucose)

MMITOCHONDRIONITOCHONDRION(PLURAL = MITOCHONDRIA)(PLURAL = MITOCHONDRIA)

INTERESTING FACT ---INTERESTING FACT ---Mitochondria

Come from cytoplasm in the EGG cell during fertilization

Therefore …You inherit your

mitochondria from your mother!

CHLCHLOORROOPLASTSPLASTSSTRUCTUREBean shapeDOUBLE membraneHas its own DNA

FUNCTION (JOB)Found only in autotrophsCarries out

photosynthesis

RIBRIBOSOMESOSOMESSTRUCTUREMade of PROTEINS and rRNAThink: “RIB”s are meat; meat is protein

FUNCTION (JOB)Make proteinsamino acids to make proteinsProcess called TRANSLATION

RIBOSOMES (CON’T)RIBOSOMES (CON’T)

Can be attached to Rough ER (proteins made

exit cell)

OR

Be free (unattached) in the

cytoplasm

(proteins made stay INSIDE cell)

ROUGH ENDOPLASMIC ROUGH ENDOPLASMIC RETICULUM (RER)RETICULUM (RER)

STRUCTUREHas ribosomes on

its surfaceFUNCTION (JOB) Helps to make

proteins for export out of cell

GOLGI APPARATUSGOLGI APPARATUSSTRUCTURE Hollow flattened sacs Looks like a stack of

pancakes with syrup dripping off

FUNCTION (JOB) Receives cell products (like

proteins) from Rough ER Modifies (changes) and

packages proteins for shipment OUT of the cell

Proteins are packages into vesicles (the “syrup drips”)

Transport

vesicle

CIS

TRANS

CENTRIOLESCENTRIOLES

STRUCTURE Found only in animal cells

inside CENTROSOMES Paired structures near

nucleus (“t” shape”) Made of microtubules

FUNCTION (JOB) Appear during cell division Help to pull chromosome

pairs apart to opposite ends of the cell

CENTRIOLES & THE MITOTIC CENTRIOLES & THE MITOTIC SPINDLESPINDLE

**Made of MICROTUBULES (Tubulin)

NOW…LET’S PRACTICE