bio exam two

robert hooke

1st to involve cells in 1665

schleiden and schwann

proposed cell theory

rate of cell’s diffusion is affected by

1) surface area available

2) temperature

3) concentration gradient

4) distance

as cell size increases, the time for diffusion

increases

as cell size increases, volume

increases more rapidly than surface area

rate of transport depends on

distance to membrane and area of membrane available

resolution

minimum distance two points can be apart and still be distinguished as two separate points

transmission electron microscopes

transmit electrons through material

spanning electrons microscope

beam electrons onto specimen surface

all cells share simple structural features

1) nucleus/nucleoid with genetic material

2) cytoplasm

3) ribosomes to synthesize proteins

4) plasma membrane

centrally located genetic material in prokaryotes

• non-membrane bound nucleoid

• single circular molecule of DNA

centrally located genetic material in eukaryotes

DNA organized into linear chromosomes segregated into nucleus

cytoplasm

semifluid matrix interior of cell

ribosomes

large, macromolecular machines composed of RNA and protein that synthesize cellular proteins

plasma membrane is

phospholipid bilayer

prokaryotic cells are

simples organisms

two domains of prokaryotes

archaea and bacteria

there are no organelles

common to all prokaryotes

magnetosome

• in bacteria that can move along magnetic field

• consist of spherical membranes with iron oxide crystals

prokaryotes can have infoldings of plasma membrane to

segregate metabolic reactions

bacterial microcompartments

• cellular compartments bound by semipermeable protein shell

• isolate specific metabolic process or store particular substance

cytoskeletons influence

shape of cell wall

cell wall determines

strength and shape of cell

bacterial cell walls are composed of

peptidogylcan

antibiotics target

cell wall to burst cell

components of prokaryotic cell

• cell wall

• capsule

• flagella

• pili/fimbriae

capsule

enables cell to attach to surfaces in environment

flagella

locomotion

pili/fimbriae

exchange genetic material during conjugation

archaeal membrane lipids have

saturated hydrocarbons that are covalently attached to glycerol at both ends

bacterial flagella

protein rings embedded in plasma membrane with extending cell wall

archaeal flagella

disk of membrane proteins with extending protein filaments (pilus)

hallmark of eukaryotic cells

compartmentalization; achieved through membrane-bound organelles and endomembrane system

both plant and animal cells have

• plasma membranes

• vesicles

• cytoskeleton

plant cells have

• central vacuole

• cell wall outside of plasma membrane

• internal chloroplasts

• specialized vacuoles

nucelus is

largest organelle in eukaryotic cell

nucleus has

genetic info for protein synthesis

nucleolus

region of ribosomal RNA synthesis

nuclear envelope is composed of

two phospholipid bilayer membranes; outer membrane is continuous with ER

nuclear pores are found on

surface of nuclear envelope

nuclear pores

• allow ions/small molecules to diffuse between nucleoplasm and cytoplasm

• control passage of proteins and RNA-protein complexes

in eukaryotes, DNA is

divided into multiple linear chromosomes

chromatin

chromosomes organized with protein

two subunits of ribosomes

ribosomal RNA and proteins; only join to form when actively synthesizing proteins

messenger RNA

carries coding info from DNA to direct protein synthesis

transfer RNA

carries amino acids

ribosomal RNA

carries out protein synthesis in ribosomes

endomembrane system

• only in eukaryotes

• series of membranes throughout cytoplasm that divides cells into compartments for different cellular functions

endoplasmic reticulum

• largest internal membrane

• phospholipid bilayer embedded with proteins

largest components of ER

• cisternal space/lumen: space inside

• cytosol: exterior

rough ER

• ribosomes attached to membrane

• depending on protein’s sequence, either sends it to lysosomes/vacuoles or embeds in plasma membrane

smooth ER

• synthesize carbs, lipids, steroids

• stores intracellular Ca2+

• modifies foreign substances to be less toxic

golgi apparatus

package and distribute molecules synthesized at one location and used at another

molecules from golgi apparatus arrive at

cis face by transport vesicles

molecules from golgi apparatus exit through

trans face by secretory vesicles

lysosomes

membrane-bound digestive vesicle that arise from golgi apparatus

lysosomes contain enzymes that

catalyze breakdown of macromolecules and eliminate engulfed cells by phagocytosis

lipid droplets

neutral lipid core surrounded by single layer of phospholipid

microbodies

variety of vesicles with enzymes in eukaryotic cells

peroxisomes

microbodies that oxidize fatty acids

large central vacuole

• store dissolved substances

• expands to increase tonicity of plant cell

• cell growth

tonoplast

membrane-bound vacuole with channels for water to maintain tonicity and osmotic balance

plant cells grow by

expanding vacuole

contractile vacuole

pump water to maintain water balance in cell

storage vacuole

for storage or segregating toxic materials from rest of cytoplasm

structural similarities of mitochondria and chloroplasts

• double membrane

• contain their own DNA and protein synthesis machinery

functional similarities of mitochondria and chloroplasts

energy metabolism

structure of mitochondria

• outer membrane

• intermembrane space

• inner membrane with cristae

• matrix

structure of chloroplasts

• outer membrane

• inner membrane

• granum (stacks of thylakoid disks)

• stroma (cytoplasm)

thylakoids

light-capturing photosynthetic pigments on surface

stroma

fluid matrix with enzymes to synthesize glucose during photosynthesis

plastids

organelles in photosynthetic eukaryotes that are site of photosynthesis (chloroplasts, leucoplasts, amyloplasts)

endosymbiosis

eukaryotic cells evolved from symbiosis between different species of prokaryotes

cytoskeleton

network of protein fibers that support shape of cell and anchor organelles to fixed location

three types of fibers

• microfilaments/actin filaments

• microtubules

• intermediate filaments

microfilaments

two loosely twined protein chains of actin

cellular movement of microfilaments

contraction, crawling, pinching

microtubules

• largest fiber; tubulin subunits

• organize cytoplasm and move materials within cell

intermediate filaments

fibrous protein molecules twined together in overlapping arrangement; most durable

centrioles

barrel-shaped pairs of organelles in animals and protists

centrosome

• region surrounding centrioles

• divides and organizes spindle fibers during mitosis/meiosis

centrosomes are not in

plants and fungi

at leading edge of cell

actin filaments polymerize—> extension forces edge of cell forward to move

cell walls in plants and protists

cellulose

cell walls in fungi

chitin

extracellular matrix

mix of glycoproteins around animal cell (sub. for cell wall)

integrins

• extend into cytoplasm and attach to microfilaments and intermediate filaments

• influence cell behavior; important for plasma membrane

adhesive junctions include

• adherens junctions

• desmosomes

• hemidesmosomes

adhesive junctions

attach cytoskeletons of neighboring cells or cells to ECM

separate/tight junctions

connect plasma membranes of adjacent cells in sheet so materials pass through, but not between

communicating junctions include

gap junctions and plasmodesmata

communicating junctions

chemical/electrical signal passes directly from one cell to adjacent one

surface markers

integral proteins or glycolipids in plasma membrane that identify cell

adheren junctions are formed by

cadherin molecules on cell surface

cadherin

single-pass transmembrane protein

desmosomes

cadherin-based junction unique to vertebrates

separate junctions are in

invertebrates and vertebrates

tight junctions

unique to vertebrates; contain claudins

gap junctions are in

invertebrates and vertebrates

gap junctions permit

small substances (simple sugars, amino acids) to pass between cells