Biology Exam 2

prokaryotic cells

not having a nucleus or internal membrane system

only care about these organisms when they make us sick (bacteria- many harmless, some pathogenic, and some symbiotic (to us))

eukaryotic cells

have a nucleus and internal membrane system

plant, animals, fungi

PARTS OF THE PROKARYOTIC CELL

PARTS OF THE PROKARYOTIC CELL

cell wall

made up of peptidoglycan (carbohydrate, chains linked together by short amino acid segments (5)

gram positive cell wall

retains dye when stained; thick layer of peptidoglycan attached to plasma membrane by teichoic acids

gram negative cell wall

does not retain dye

thin layer of peptidoglycan w/ a 2nd outer membrane (contains toxins that the immune system releases into bloodstream ex- e. coli)

most antibodies can penetrate one CW type or the other

glycocalyx (capsule)

external to CW; not all bacteria can make a glycocalyx

capsule: rigidly organized, like a 2nd cell wall, makes an organism more pathogenic; helps hide organism from immune system

slime layer: loosely organized, helps initiate infection, allows bacteria to stick to tissues, so it can infect them

bacterial flagella

external to CW

made up of protein flagellin

hollow tube embedded in CW and PM

a rotor turns - the flagella whirls in a circle for motility

fimbriae

similar to flagella

same structure, but shorter for sticking to surfaces to help initiate an infection

sex pilus

a hollow tube

a bacterium must have a special gene in order to build a sex pilus

any bacterium can receive the pilus

the builder makes a copy of its DNA and sends it via the pilus to the receiver

the receiver may metabolize (“eat”) the DNA or it can integrate the genes into its own DNA and start to use it

the receiver is now a new organism with a new set of DNA

it is not limited to same species sharing

*horizontal gene transfer- it’s how the genes for antibiotic resistance can be shared rapidly in a bacterial community

bacterial DNA

circular; one circular chromosome includes all the genes for normal function and survival

plasmids- smaller circular DNA fragments

F plasmid- where the sex pilus is

R plasmid- carry genes for antibiotic resistance

ribosomes

“read” mRNA and build proteins

two subunits- large 505 and small 305

assembled = 705en

endospore

not all bacterial species can make an endospore

a dehydrated cell, wrapped in protein

made when environmental conditions deteriorate

can persist indefinitely- will come back to life when favorable conditions return

they can’t be destroyed by normal food preservation (ex: clostridium botulinum, B anthracis

PARTS OF THE EUKARYOTIC CELL

PARTS OF THE EUKARYOTIC CELL

endomembrane system

all the membrane originates in the ER

includes nuclear envelope, ER, golgi apparatus, vacuoles, ribosomes, etc

nuclear envelope

surrounds the nucleus, a double membrane (outer membrane is continuous with the ER)

nuclear pore: where things enter and leave nucleus; surrounded by proteins that regulate what enters/leaves (guard proteins)

genome DNA: nucleolus- a region of genomic DNA, contains genes for RNA enzymes

nuclear lamina: a scaffold of intermediate filaments that supports the shape of the nucleus

endoplasmic reticulum

a network of tubules surrounding the nucleus and continuous w/ the outer membrane of nucleus

rough ER: has a granulated appearance due to ribosomes; processes proteins that have a special destination either inside/outside the cell; builds new membrane by integrating membrane proteins into new membrane

smooth ER: does not have a granulated appearance due to lack of ribosomes; synthesizes lipids (fats, steroids, phospholipids (contributes to new membrane building)); detoxifies non-polar drugs by making the molecule polar thru the addition of a hydroxyl, so it can be filtered out by kidneys

golgi apparatus

series of sacs called cisternae which backs up to the rough ER

cont. processing proteins w/ special destinations

rough ER transfers PSDs to cisface cisterna via a vesicle