cell structure and func EUKARYOTIC CELLS

eukaryotic cells

• posses membrane-bound nucleus

• more complex than prokaryotic cells

• COMPARTMENTALIZATION (their hallmark)

  • achieved thru membrane-bound organelles and endomembrane system

• has cytoskeleton for support and maintains cellular structure

animal and plant cells

• both largely have the same structure

• both have plasma membrane

  • contain most of the same organelles

plant cells

• have extra components not seen in other eukaryotic cells

• cell wall outside of plasma membrane

• chloroplasts and specialized vacuoles

nucleus

• stores genetic info

• most eukaryotic cells posses a single nucleus

• has nucleolus and nuclear envelope, nuclear pores, and chromatin

nucleolus

region where ribosomal RNA synthesis takes place

nuclear envelope

• 2 phospholipid bilayers

• has nuclear pores

nuclear pores

control movement in and out

chromatin

packages DNA into a compact form within the nucleus

ribosomes

• cell’s protein synthesis machinary

• found in ALL cell types in all 3 domains

• free in cytoplasm OR associated w/ internal membranes

ribosomal RNA

• catalyst for amino acids into assembling polypeptide chains

  • rRNA protein complex

messanger RNA and transfer RNA

for protein synthesis

endomembrane system

• series of membranes throughout the cytoplasm

• divides cell into compartments where diff. cellular functions occur

• one of the fundamental distinctions betw. eukaryotes and prokaryotes

rough endoplasmic reticulum

• attachment of ribosomes to the membrane gives rough appearance

  • synthesis of proteins to be secreted, sent to lysosomes/plasma membrane

smooth endoplasmic reticulum

• relatively few bound ribosomes

• synthesis, store Ca detoxification

golgi apparatus

• flattened stacks of interconnected membranes (golgi bodies)

• functions in packaging and distributing molecules synthesized @ one location and used at another within the cell or outside of it

• has cis and trans faces

• vesicles transport molecules to destination

lysosomes

• membrane bound digestive vesicles

• arise from golgi apparatus

• contains enzymes that catalyze breakdown of macromolecules

• fuse w/ target to initiate breakdown

  • recycle old organelles/digest cells and foreign matter that the cell has engulfed by phagocytosis

microbodies

• variety of enzyme-bearing, membrane enclosed vesicles

• peroxisomes

peroxisomes

• contain enzymes involved w/ the oxidation of fatty acids

  • hydrogen peroxide prod. as byproduct— rendered useless by catalase

vacuoles

• membrane bound structures typically found in plants

• various func. depending on cell type

• central vacuole in PLANTS

• storage vacuole in PLANTS

  • contractile vacuole in some FUNGI AND PROTISTS

mitochondria

• found in all types of eukaryotic cells

• bound by membranes

• intermembrane space

• inner membrane shaped into folds called cristae

• matrix

• has proteins that carry out oxidative metabolism (on surface of inner membrane and embedded)

• have their own DNA

chloroplasts

• organelles present in cells of plants and some other eukaryotes

• surrounded by 2 membranes

  • has chlorophyll for photosynthesis

• has thylakoids

• has grana

• has their own DNA

thylakoids

membranous sacs within the inner membrane

grana

stacks of thylakoids

endosymbiosis theory

• some preset day eukaryotic organelles evolved by a symbiosis betw. 2 free-living cells

• a prokaryote was engulfed by and became a part of another cell, which was the precursor of modern eukaryotes

• mitochondria and chloroplasts have similarities to prokaryotic cells

cytoskeleton

• network of protein fibers found in ALL eukaryotic cells

• supports shape of cell

  • keeps organelles in fixed locations

dynamic system

constantly reforming and disassembling

microfilaments (actin filaments)

• 2 protein chains loosely twined together

  • movements like contraction, crawling, “pinching”

microtubules

• largest of the cytoskeletal elements

• has dimers of alpha and beta tubulin subunits

  • facilitate mvmt of cell materials within cell

intermediate filaments

• between the size of actin filaments and microtubules

  • very stable, usually NOT broken down

centrosomes

• surrounds centrioles in almost all animal cells

• has microtubule organizing center

microtubule organizing center

nucleate the assembly of microtubules

centrioles

• involved in development of spindle fibers in cell division

• animal cells and most protists have (usually in pairs)

• plants and fungi dont have

cell movement

• movement of actin filaments, microtubules, or both help cells move

• some crawl using actin microfilaments

eukaryotic cell walls

• present in plants, fungi, and some protists

• differ from prokaryotic cell walls structurally and chemically

• plant and protist cell walls: cellulose

• fungi cells: chitin

  • plant cells have primary and maybe secondary cell walls

extracellular matrix

• animal cells lack cell walls

• an elaborate mixture of glycoproteins into space around them

• collagen is abundant

• forms protective layer over cell surface

• influence cell behavior

glycolipids

most tissue specific cell surface markers

MHC proteins

recognition of self vs nonself cells by immune system

adhesive junctions

mechanically attaches cytoskeletons of neighboring cells to ECM

septate/tight junctions

• connect plasma membranes of adjacent cells in sheet

• no leakage

communicating junctions

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

plasmodesmata

• plant cells have these

• specialized openings in cell walls

• cytoplasm of adjoining cells connected

• similar to gap junction in animal cells