Cells

Types of Cellsprokaryotes

no organellesbacteria cells

eukaryotesorganelles

animal cells

plant cells

also fungus & protist cells

Cell size comparison

• Most bacteria• 1-10 microns

• Eukaryotic cells• 10-100 microns

Bacterial cellAnimal cell

micron = micrometer = 1/1,000,000 meterdiameter of human hair = ~20 microns

Why study cells?

• Cells• Bodies are made of cells• Cells do all the work for life

Tissues Organs Bodies

The work for life• STERNGRR

• Synthesis: build molecules (carbs, lipids, proteins, nucleic acids)• Transport: move materials in/out & within the cell• Excretion: remove wastes• Respiration: gas exchange; make energy • Nutrition: take in & digest food• Grow & repair• Regulation: control internal conditions (homeostasis)• Reproduction: make more cells• Respond to external environment

ATP

The main jobs of cells• Cells have 3 main jobs:

• Make energy• Need energy for all activities• Need to clean up waste produced by energy production

• Make proteins• Proteins do all the work in the cell, so we need lots of them

• Make more cells• For growth• For repair (replace damaged or diseased cells)

ATP

Our organelles doAll of these jobs?!

AWESOME!!

Parts of the Cell Theory

• All living things are made of one or more cells

• Cells are the basic unit of structure & function in organisms

• Cells come only from the reproduction of pre-existing cells

Cell Scientists

• Robert Hooke• looked at cork

under a microscope

• 1st to use term “cell”

Cell Scientists

• Anton van Leeuwenhoek

• looked at pond water

• 1st to see living cells

• called them “animalcules”

Cell Scientists

• Schleiden, Schwann, & Virchow

• came up with the cell theory

Cell Scientists

• Schleiden• 1838• claimed plants

are made of “independent, separate beings” called cells

Cell Scientists

• Schwann• 1839• claimed animals

are also made of cells

Cell Scientists

• Virchow• 1855• stated that living

cells must come from other living cells

Cell Scientists

• Louis Pasteur• 1860’s• disproved

spontaneous generation

The Cell Theory

Prokaryotic vs Eukaryotic Cells

Prokaryotic Cells• Appeared 3.5 billion years ago• Primitive, simple• Small in size (less than 10 µm)• No membrane-bound organelles• DNA in cytosol (nucleoid region)• Single, circular chromosome• “Naked” DNA• Smaller ribosomes (70S)• BACTERIA

Eukaryotic Cells• Appeared 1.5 billion years ago• Complex• More than 10 µm in size• Contain membrane- bound organelles• Larger ribosomes (80S)• Paired, linear chromosomes• DNA wrapped around histones

(proteins)• NUCLEUS

• Let’s draw a prokaryotic cell and label it ….

Prokaryotic reproduction

• Asexual = binary fission• Produces two

identical daughter cells

DNA Copies

Cytokinesis

Clones!

Prokaryotic reproduction

• Sexual = conjugation• Uses conjugation

pili to exchange plasmids

Parts of aEukaryotic Cell

Plasma Membrane• Also called the

Cell Membrane• Separates

cell from its environment

Plasma Membrane• Semi-

permeable• Allows only

certain molecules to enter or exit

Plasma Membrane• Phospholipid

Bilayer• Embedded with

proteins

• Cholesterol is embedded in bilayer to help membrane fluidity

Nucleus• “Boss” or

“Brain” of the cell

• Controls cellular activities

• Contains DNA (chromosomes)

Nucleus• Nuclear

Membrane• Surrounds nucleus• Double membrane• Contains nuclear

pores (holes)

Nucleus• Nucleolus

• Produces ribosomes

• Ribosomes leave through nuclear pores

Cytoplasm• Cytosol

• Fluid portion• Organelles

• Membrane-bound compartments that carry out specific functions

Mitochondria• Breaks down glucose

to CREATE ENERGY (ATP)• Active cells (muscle) ->

hundreds of mitochondria• Inactive cells (fat) -> few

mitochondria

• Have own DNA & ribosomes

• Have a double membrane

Ribosomes• Create proteins• Composed of 2

interlocking subunits

• Some float free in cytosol

• Some attach to the ERsmall

subunit

large subunit

ribosome

Endoplasmic Reticulum (ER)

• Intracellular highway

• 2 Types• Rough ER• Smooth ER

Endoplasmic Reticulum (ER)

• Rough ER• Covered in

ribosomes• Transport and

develop proteins• may be used in

membranes, enzymes, and cell communication

Endoplasmic Reticulum (ER)

cytoplasm

cisternalspace

mRNA

ribosome

membrane ofendoplasmic reticulum

polypeptide

signalsequence

ribosome

Synthesizing proteins

Endoplasmic Reticulum (ER)

• Smooth ER• Lacks ribosomes• Produces lipids,

estrogen, & testosterone

• Helps detoxify drugs & poisons

• Increased use = increased smooth ER

• Possibly linked to increased tolerance

Endoplasmic Reticulum (ER)

• Transport (FedEx/UPS of the cell)

• Collects, packages, modifies, and distributes materials made in the cell

• Prevalent in cells that secrete substances

Golgi Apparatus

• Lysosomes• Contain digestive

enzymes• Digest organic

molecules, worn organelles, or dying cells

Vesicles

lysosomes

nucleus

Vesicle transport

vesiclebuddingfrom roughER

fusionof vesiclewith Golgiapparatus

migratingtransportvesicle

protein

ribosome

• Central vacuole• Large, fluid-filled

organelle• Stores water, ions,

enzymes & waste• Can be up to 90% of

cell’s volume• Why so big in plants?

Vacuoles – Plant cells

• Food vacuoles• Store and process

food• Contractile

vacuoles• Removes excess

water from cell• Prevents cell from

exploding

Vacuoles – Animal cells

Working together …

vesicle

ER

vesicle

Golgi complex

vesicle

vacuole

• Centrosome• Assembles

microtubules• May contain

centrioles• Used during cell

division

Centrosome

• Cilia• Hair-like• Short &

numerous• Flagella

• Tail-like• Long & less

numerous

Cilia/Flagella

Plant Cellversus

Animal Cell

• Cytoskeleton• Network of

microtubules & filaments

• Gives the cell shape

• Holds organelles in place

Animal Cells Only!

• Cell Wall• Rigid layer

surrounding plasma membrane

• Made of cellulose• Pores allow water,

ions, & other molecules to pass

• Bacteria (peptidoglycan), some protists & fungi (chitin) also have cell walls

Plant Cells Only!

• Chloroplast• Contain chlorophyll• Site of

photosynthesis• Energy (sunlight)

food• Contain own DNA

& ribosomes• Have a double

membrane

Plant Cells Only!

Any Questions??