(v.) cell structure

gen bio 01:119:115

cell

smallest unit that carries out all activities associated with life

→ can be generalized “can do everything” or specialized

all share common feature and evolutionary history

morphology

the study of the form or external structure of things

prokaryotes

tiny (typical size 1-10 um)

nucleoid: DNA unbound

no membrane- bound organelles

plasma/cell wall membrane

ribosomes in cytoplasm

cell wall

eukaryote

has true nucleus

typically larger (10-100um)

DNA inside of nucleus

membrane-bound organelles

ribosomes in cytoplasm or attached to rough er

some have a cell wall

common features of all cells

bound by plasma membrane

distinct internal environment

store, replicate and transmit genetic information

reproduce through division

metabolism (converting energy into a useable state)

interact with/respond to environment

maintains homeostasis

generally limited in cel size (surface area limits)

surface area to volume ratio

total surface area = [sum of the surface areas (heightxwidth) of all box sides x number of boxes]

total volume = [height x length x width x number of boxes]

surface to volume (S-to-V) ratio [surface area +volume]

plasma membrane

what all material must pass to enter cell

surface area limits rate at which materials pass

advantageous to maximize surface area to volume ratio

components of eukaryotic cells

nucleus, cytoplasm, DNA, nucleolus

nucleus

central control structure due to containing genetic material

→ compartment that contains most DNA (chromosomes, chromatin)
surrounded by nuclear envelope (double membrane)

nuclear pores

nuclear laminate

nucleolus

double membrane

separates nucleoplasm from cytoplasm

nuclear pores

protein complexes that regulate transport in and out between nucleus and cytoplasm

nuclear lamina

helps with replicating DNA and synthesis, present to give nucleus its structure

nucleolus

makes ribosomes, located within nucleus

mitochondria

organelle acquired through endosymbiosis

organelle found in eukaryotic lineages

aerobic respiration

double membranes, have own dna, have own ribosomes

heart has most mitochondria

chloroplast

organelle acquired through endosymbiosis

organelle found in photosynthetic lineages like plants and algae

where photosynthesis occurs

evidence for endosymbiosis

existence of double membranes, ingested by engulfed anaerobic bacteria

similar size, morphology, enzymes, and ribosomes to bacteria

→ dna sequences very similar to living dna

divide via binary fission

binary fission

asexual reproduction that involves splitting

ribosomes

structures responsible for protein synthesis or polypeptide chains

relocated in the nucleolus

present in all cells

not membrane bound → not an organelle because it does not have a phospholipid bilayer surrounding it

can be in cytoplasm or associated in rough er

made up of proteins and RNA

free ribosomes

all cells, mitochondria and chloroplasts, responsible for making smaller proteins for survival

bound ribosomes

attached to the endoplasmic reticulum, make proteins that exist the cell and used somewhere else

endomembrane system

internal membrane system

membrane: lipid bilayer, enclosed

lumen

the inside of a phospholipid bilayer

membrane bound organelles

divides cells into compartments

membrane communication and transport

connected through vesicles: transfer of membrane segments

phospholipid bilayer: continuous so there is no folding

→ vesicles formed, transport of phospholipid bilayer pinching off

vesicles

regulates protein folding, movement and metabolic functions

components of endomembrane system (membrane bound)

nuclear envelope, vacuole, endoplasmic reticulum, golgi apparatus, plasma membrane, lysosomes

endoplasmic reticulum

internal membrane complex that is directly linked to the nucleus

single continuous lumen

connected to outer membrane of nuclear membrane

folds proteins and moves/transfer to golgi apparatus

rough endoplasmic reticulum

ribosomes attached, proteins synthesized, transported into lumen, tertiary structure proteins

smooth er

lipid synthesis, often very little except in specific cells, responsible for detoxification

ex: liver

golgi apparatus

many membrane compartments, no continuous lumen/with er (not attached as it acts as a post office)

modifies and transports proteins

vesicle fuses with golgi, moves through cisternae, and could be passed through vesicle

polypeptide chain formed, enter lumen of endoplasmic reticulum, folded in vesicles and becomes 3d → ships

cisternae

stacks of membranous sacs

vacuoles

large vesicles derived from endomembrane system

maintenance compartments

function caries by cell, often storage

ex: food vacuole, contractile vacuole (water), central vacuole (structure)

lysosomes

compartment containing hydrolytic/digestive enzymes

made in rough endoplasmic reticulum → processed in the golgi apparatus

inactive until food is present → activated by fusing with food vacuole

hydrolytic enzymes digest food particles