World of The Cell

Chapter 4

How big is a cell?• The smallest “cell” is a ________• Mycoplasmas (very small bacteria are barely bigger)• Bacteria are just bigger than a single organelle of a animal cell• Plant and animal cells are bigger, you can see them with a

______ __________but not the naked eye!

Why can’t cells be huge?• All entrances and exits are

controlled by the ______ _______________– which is responsible for

_______, _______ ________ etc for the cell

• Upper limit_______ _______ _________– If the cell is too big it needs

too much stuff done and the membrane can’t keep up… Just like baby-sitting

But not too small…• Lower limit: Holding the

vitals– A cell can’t get too small

because it must be able to hold _____, and other _________ otherwise it can’t function

• First seen by _______ ________… looked through the FIRST compound microscope (which he invented)– described the cells in cork…

plant cells

How do we even know• What the eye cannot see itself we make tools to see…

• Light Microscope: Uses a series of lights and mirrors to magnify and object, it can magnify an object _____ times without losing __________

ways to see really small stuff…• Electron Microscope:

Use highly charged __________ to create images of very small things (much smaller than a cell) Can magnify up to ________ times– _________: runs

electrons along the surface of a object… doesn’t destroy it

– __________: sends electrons crashing through it… destroys the specimen

** either one the specimen must be long dead

SEM of a bug that was found on a daddy long legs

All cells by way of the Animal cell

• The animal cell is the flagship cell… all other cells can be described easily in relationship to it

• So… we will start with the animal cell

Animal Cell Statistics

• Animal cells is ____________ (True Nucleus) • Because of it’s large size (for a cell) it divides

its daily responsibility among its parts (_______________) – Like animals divide jobs among organs/ organ

systems

Broken into 3 categories1. Plasma Membrane2. Nucleus3. Cytoplasm

Plasma membrane• Protective

covering of the cell

• Made of a _____________ _________

• Also contains ____________/ intercalated proteins that serve various functions

Inside the membrane

• The lipids do not make up the whole membrane.

• There are important proteins with various jobs intercalated or ___________ within the lipids

Fig. 4.4, p. 53

one layerof lipidsone layerof lipids

membraneprotein

extracellularenvironment

cytoplasm

Membrane Specialization: Junctions

• Tight junctions: so tight that they bind the cells together like __________ sheets– ie. Small intestine to keep food from leaking out

• Desmosomes: __________ junctions that keep cells from falling apart– ie. Skin cells

• Gap Junctions: allow _____________ between cells– Especially in nerve cells and developing tissue

Fig. 4.23, p. 67adhering junction

free surface ofepithelial tissue

different kinds oftight junctions

gap junction

basement membrane(extracellular matrix)

Nucleus• Holder and protector of

genetic information• ________________:

outer covering• ___________: Ribosome

assembly• ___________: The

DNA/protein association within the nucleus

• Chromosomes: densely packed chromatin during ________ _______ ________ _ ___

Cytoplasm• The rest of the cell that

includes the…– __________: the working

components of the cell… kind of like your organs

– Inclusions: the ______ ____ ________that come in and out of the cytoplasm

– ________ they exist in: the gel- like coating _______ the __________ and nucleus

Ribosomes

• Dark staining organelles made of protein and ______

• _________________ ________________

• Sometimes attach to the ER, making it _______ ER

Endoplasmic reticulum

• The cells ‘circulatory system’ that accounts for ______ of the cells membranes

• Rough ER: membrane factory/ ________ producer

• Smooth ER: ________ synthesis/breakdown

Golgi Apparatus

• Also known as the golgi body

• Near the nucleus• The protein traffic

director, takes proteins _____ the ___________and _____ them to where they belong (in secretory vesicles)

BIG PICTURE BREAK• The _________makes

_________that are ___________ to the Golgi (in transport vesicles), where they are _________ and sent out of the cell (_________ vesicles) or float within the cell to kill off invaders (_______________)

Lysosomes• Bundles of digestive enzymes packaged by the Golgi

• digest _____ _______, invaders or _______ (phagocytosis)

• Can kill the cell itself if it lacks essential things such as oxygen, or vitamin A

http://highered.mcgraw-hill.com/olc/dl/120067/bio01.swf

Peroxisomes• __________dangerously

reactive free radicals in the body

• First they convert them to H2O2 and then to H20

• Abundant in ______ and _________ cells

• Replicate through ___________, not produced by the Golgi

Mitochondria• POWERHOUSE• _______ _________ bound

organelle… probably originally a free living prokaryote… it ____ _____ ______ ____ _______

• The membrane of mitochondria is the site of the electron transport chain ____ ______ _____ _____

• Busy cells have many mitochondria

Cytoskeleton• Protein structure that extends though

the cytoplasm acting as the cells skeletal/ muscular system– Intermediate filaments: strong and

stable. Form ____________ (anchor junctions)

– _____________: motility and shape change (actin and myosin)

– Microtubules: overall shape and organelle arrangement (_______ _________ _____ _____________)

• Naturally clear but can be stained with fluorescent markers.– Their presence/ absence/ structure has

proved useful in identifying _____ and ________ of cells

The eukaryotic cytoskeleton. Actin filaments are shown in red, microtubules in green, and the nuclei are in blue.

Centrioles

• Made of __________ these form the spindle fibers responsible for chromosome partitioning during cell division

• Also aid in the formation of _______ and _______

Cilia and Flagella• Cilia and flagella are formed

when ____________ push out against the cell membrane forming a projection

• _______ move things along the surface of the cell– I.e. cilia move particles along

and out of the lungs

• _______ propel the cell itself– Human sperm move via

flagella

Contractile Vacuole

– Some cells use contractile vacuoles for ______ and ___________

– Paramecium (one celled animal) uses contractile vacuoles for both

– _____ ____ _______… protecting it from exploding it… when it pushes out the water it propels it forward

What’s different in a Plant Cell?• There are 3 additional structural features that

Plant cells need1. _______ ______2. ___________3. ______ _______

Central Vacuole

• Storage facility created from the merging of smaller vesicles that can promote growth

• Stores – ______ (helps w/ growth/ movement)– Vital chemicals (food)– _______ ______– ________ to protect a plant from being eaten!

• It can also act as a ______ _________getting rid of foreign invaders

Chloroplasts• Plants are ________

____________: meaning they make their own food

• Do so from sunlight in a complex process called _____________

• Chloroplasts are the ________ ____ ________ for photosynthesis

More on Chloroplasts• Between inner and outer

membrane is the intermembrane space…

• ______ _________ (membrane) and all contain ________

• ______________ is where photosynthesis takes place… ________ in structures called granum

Cell Wall: protective covering• Plant cells need to be extra

strong… helps them deal with ______ _____ ________ and other stresses

• Helps circulate water and nutrients

• Made of ________ , pectin and ________… all strong structural carbohydrates

• Render plant cells motionless• _______ __________shared

by neighboring cells to increase adhesion

Prokaryotes: how they’re different• No true nucleus– Contain there DNA in circular

bundles called ________ or in bundles in a ‘nucleoid region’

• Have _________ to help make proteins

• Have a membrane and a ________ ____ _____… help maintain shape.

• _________… even more covering that help the prokaryote ‘stick’

Prokaryotic anatomy

Prokaryotes: what they do

• Many prokaryotes live off of other cells (__________)

• Need help adhering… capsule and pili– Pili are ______ _________that

anchor the prokaryote into its host

• Need to find something to mooch off of in the first place… _________

BioFilmsOften live together and work together to colonize areas. These associations are called _________.

One common type of biofilm is that that exists on your teeth and solidifies as plaque