AP Bio- Unit 2

parts of cells, transports, cell membrane stuff, and isotonicity j bc idk if the last part is being tested on or not

Two distinct types of cells:

Prokaryotic and Eukaryoti

What do organisms under domains Bacteria and Archaea consist of?

prokaryotes

Certain basic features all cells share:

Bounded by selective barrier (plasma/cell membrane), have cytosol, chromosomes, and ribosomes

cytosol

semifluid portion of the cytoplasm

major difference between eu and pro

location of DNA

eukaryotic cell

has mem enlcosed nucleus and organelles

prokaryotic cell

no mem enclosed nucleus and organelles

nucleoid

non membrane enclosed region in a prokaryotic cell where its chromosome is located

fimbriae

attachment structures on the surface of some prokaryotes (not visible on TEM)

glycocalyx

outer coating of many prokaryotes, consisting of a capsule or a slime layer

flagella

locomotion organelles of some prokaryotes

cytoplasm

contents of cell enclosed by plasma mem, portion exclusive of the nucleus in eukary

LARGER ORGANISMS DO NOT GENERALLY…

HAVE LARGER CELLS (j more cells)

flagellum

motility structure present in some animal cells, composed of a cluster of microtubules within an extension of the plasma membrane

microvilli

projections that increase cells SA

plasmodesmata

cytoplasmic channels thru cell walls that connect the cytoplasms of adjacent cells

nucleus

organelle of a eukaruotic cell that contians the genetic mat in form of chromosomes (made up of chromatin)

nuclear envelope

in an eukaryotic cells, double membrane that surrounds nucleus, perforated w pores that regulate traffic w the cytoplasm. outer mem continuous w the endoplasmic reticulum

nuclear lamina

netlike array of protein filaments (animal cells, called INTERMEDIATE filaments) that maintains shape of nucleus

Compartmentalization in organelles allows for…

different metabolic reactions to occur in different locations

• Increases surface area for reactions to occur

• Prevents interfering reactions from occuring in the same location

endomembrane organelles:

endoplasmic reticulum (ER), Golgi complex, lysosomes, and vacuoles

nucleoulus

• Dense region of the nucleus where ribosomal RNA (rRNA) is synthesized

  • rRNA is combined with proteins to form large and small subunits of ribosomes

  • Subunits exit via nuclear pores

ribosomes

Comprised of ribosomal RNA and protein

function of ribosomes:

synthesize proteins

locations of ribosomes

1. Cytosol 

   • Proteins produced here generally function within the cytosol (ie enzymes)

2. Bound to the endoplasmic reticulum or nuclear envelope

   • Proteins produced here can be secreted from the cell

     • Leave via transport vesicles

ER

network of membranous sacs n tubes

ER functions

• Synthesizes membranes

• Compartmentalize the cell to keep proteins formed in the rough ER separate from those of free ribosomes

Rough ER

• Contains ribosomes bound to the ER membrane

Smooth ER

• Contains no ribosomes

• Synthesizes lipids, metabolizes carbohydrates, and detoxifies the cell

• stores calcium

glycoproteins

secretory proteins w carbo cov bonded to them

trasnport vesicles

small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules prodced by cell

golgi

Contains flattened membranous sacs, called cisternae

• Separate the sacs from the cytosol

• Each cisternae is not connected

• Has directionality

CIS golgi

• Receives vesicles from the ER

TRANS golgi

• Sends vesicles back out into cytosol to other locations or to the plasma membrane for secretion

golgi function

• Receives transport vesicles with materials from the ER

• Modifies the materials (Ensures newly formed proteins are folded correctly or modified correctly)

• Sorts the materials

• Adds molecular tags

• Packages materials into new transport vesicles that exit the membrane via exocytosis

lysosomes

Membranous sac with hydrolytic enzymes

lysosome function

• Hydrolyzes macromolecules in animal cells

  • Autophagy: lysosomes can recycle their own cell’s organic materials

    • Allows the cell to renew itself

peroxisomes

sim to lysosomes, Membrane bound metabolic compartment 

• Catalyze reactions that produce H₂O₂

  • Enzymes in peroxisomes then break down H₂O₂ to water

vacuoles

large vesicles, stem from ER and golgi, selective in transport

food vacuole

Form via phagocytosis (cell eating) and then are digested by lysosomes

contractile vacuole

Maintain water levels in cells

central vacuole

• found in plants

  • Contains inorganic ions and water

Important for turgor pressure

endosymbiont theory

An early eukaryotic cell engulfed a prokaryotic cell

• Prokaryotic cell became an endosymbiont (cell that lives in another cell)

  • Became one functional organism

evidence of endosymbiont theory

1. Double membrane 

2. Ribosomes 

3. Circular DNA

4. Capable of functioning on their own

flaws w endosymbiont theory

-Evolution of today’s mammalian ribosomes from prokaryotes requires major mutation and selection events

-Computer simulations with yeast and human genomes have shown that natural selection is unable to create new beneficial structures from random mutational events.

-Experiments introducing minor changes in the RNA and protein sequences of ribosomes have also demonstrated that these changes are deleterious and lead to decreased fitness. 

mitochondria

site of cell res.

mitochondria double mem structure

• Outer membrane is smooth

• Inner membrane has folds called cristae

  • Divides the mitochondrion into two internal compartments and increases the surface area

    1. Intermembrane: space between inner and outer membrane

    2. Mitochondrial matrix: enclosed by inner membrane

    • Location for the Krebs cycle

    • Contains: 

      • Enzymes that catalyze cellular respiration and produce ATP

      • Mitochondrial DNA

      • Ribosomes

number of mitochondria in cell…

correlates w metabolic activity (direct relationship)

chloroplast

Specialized organelles in photosynthetic organisms

• Site of photosynthesis

• Contains the green pigment chlorophyll

thylakoid

• Membranous sacs that can organize into stacks called grana

  • Light dependent reactions occur in grana

stroma

fluid around thylajoids, location for calvin cycle, has chloroplast dna, ribosomes, and enzymes

cytoskeleton

Network of fibers throughout the cytoplasm

• Give structural support 

  • Especially for animal cells

• Mechanical support

  • Anchor organelles

  • Allow for movement of vesicles and organelles and/or the whole cell

    • Movement occurs when the cytoskeleton interacts with motor proteins

types of fibers in cytoskel

microtubuls, microfilaments, intermediate filaments

microtubules

Hollow rod-like structures made of the protein tubulin

• Grow from the centrosome

  • Assist in microtubule assembly

function of microtubules

• Serve as structural support (think: tracks) for the movement of organelles that are interacting with motor proteins

• Assist in the separation of chromosomes during cell division

• Cell motility

  • Cilia and flagella

microfilaments

Thin solid rods made of the protein actin

microfilaments function

• Maintain cell shape

  • Bear tension

• Assist in muscle contraction and cell motility

  • Actin works with another protein called myosin to cause a contraction

• Division of animal cells

  • Contractile ring of the cleavage furrow

intermediate filaments

Fibrous proteins made up of varying subunits, Permanent structural elements of cells, not assembled and broken down at the rate of microtubules and microfilaments

IF functions

• Maintain cell shape

• Anchor nucleus and organelles

• Form the nuclear lamina

  • Lines the nuclear envelope

phagocytosis

type of endocytosis in which large particulate substances/ small organisms are taken up by a cell

cristae

infolding of the inner membrane of a mitochondrion, houses elctron transport chains and molecules of enzyme catalyzing the synthesis of ATP (ATP synthase)

plastid

one of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts, found in cells of photosyntehtic eukaryotes.

motor protein

protein that interacts w cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell

centrosome

structure present in the cytoplasm of animal cells that functions as a microtubule organizng center n is important during cell division, has two centrioles

cilia

short appendage containing microtubules in eukaryotic cells

dynein

in cilia and flag, a large motor protein extending from one microtubule doible to adjacent oiblet. ATP hydrolysis drives changes in dynein shape that lead to bending of cilia and flagella

primary cell wall

in plants, a relatively thin and flexible layer that surrounds plasma membrane of a young cell

middle lamella

in plants, thin layer of adhesive Extracellular material, primarily pectins, found between primary walls of adjacent young cells.

secondary cell wall

often deposited in several laminated layers, has a strong and durable matrix that affords the cell protection and support.

ECM

meshwork surrounding animal cells, consisting of glycoproteins, polysacchs, and proteoglycans synthesized and secreted by cells.

collagen

forms strong fibers, found extensively in conective tissue and bone

proteoglycan

consists of a small core protein with many carbohydrate chains covalently attached; it may be up to 95% carbohydrate

fibronectin

ECm glycoprotein secreted by animal cells that helps them attach to ECM

integrins

cell-surface receptor proteins, span the membrane and bind on their cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton, in a position to transmit signals between the ECM and the cytoskeleton and thus to integrate changes occurring outside and inside the cell.

why is ECM important?

regulate cells behavior

CONCEPT:

cellular metabolism depends on cell size, At a certain size, it begins to be too difficult for a cell to regulate what comes in and what goes out of the plasma membrane

CONCEPT: size of cell will dictate function

Cells need a high surface area-to-volume ratio to optimize the exchange of material through the plasma membrane

CONCEPT: cells tend to be small

small cells have a HIGH SA:V, optimizes exchange of mats at plasma mem

phospholipids are…

amphipathic, Hydrophilic head and hydrophobic tails, Forms a bilayer

selective permeability

The ability of membranes to regulate the substances that enter and exit

Hydrophilic heads oriented

TOWARD aqueous environments

Hydrophobic tails are facing

inwards AWAY from aqueous environments

fluid mosaic model

model to describe the structure of cell mem

fluid:

• membrane is held together by weak hydrophobic interactions and can therefore move and shift

  • Temperature affects fluidity

  • Unsaturated hydrocarbon tails help maintain fluidity at low temps

    • Kinked tails prevent tight packing of phospholipids

cholesterol…

• helps maintain fluidity at high and low temps

  • High temp: reduces movement

  • Low temp: reduces tight packing of phospholipids

mosaic:

comprised of many macromolecules

integral proteins

• embedded into the lipid bilayer

  • aka transmembrane proteins 

  • Amphipathic

peripheral proteins

• Proteins that are not embedded into the lipid bilayer

  • Loosely bonded to the surface

membrane carbo…

important for cell to cell recognition

glycolipids

carb bonded to lipids

transport proteins

transmembrae protein that helps a certain substance or class of closely relarted substances to cross the membrane

channel proteins

hydrophilic channel that certain molecules or atomic ions use as a tunnel thru the mem

aquaporins

type of channel protein in the plasma mem of a plant/animal/microorganism cell that specifically facilitaates osmosis

carrier proteins

holds onto their passengers and change shape in a way that shuttles them across the membrane

CONCEPT: transport protein is specific for the substance it translocates (mvoes)

this allows only a certain substance to cross membrane

diffusion

random thermal motion of particles of liquids, gases, or solids. (in conc, net movement of a substance from a region where more conc to less conc)

concentration gradient

region along which the density of a chemical susbtance inc. or decr.

passive transport

no energy required

tonicity

the ability of an extracellular solution to cause a cell to gain or lose water,depends on the concentration of solutes that CANNOT PASS thru the cell mem

osomoregulation

cells must be able to regulate their solute concentrations and maintain water balance