Bio U3

Ribosomes

make proteins according to mRNA sequence

comprised of rRNA and protein

are in all forms of life —> used as evidence of common ancestry

cytosol

gelatin liquid stuff inside cell membrane of cells

membrane-bound organelles

unique to eukaryotes

golgi apparatus

vacuole

ribosomes attached to the Rough ER are membrane bound

nucleus

Smooth ER and Rough ER

mitochondria

lysosomes

chloroplasts

smooth endoplasmic reticulum

involved with detoxification (ex. breaks down alcohol) and lipid synthesis

series of folded membranes and is associated with lipid formation

makes steroids

breaks down carbohydrates

regulates calcium ion concentration inside the cell

rough endoplasmic reticulum

ribosomes float around in the cytoplasm —> ribosomes will have mRNA and feed through it and start to make a protein —> ribosomes will then attach to the rough ER and then make the protein inside the ER

Rough ER will make the proteins and then the proteins will be packed into vesicles

golgi apparatus (golgi body)

membrane-bound structure that consists of a series of flattened membrane sacs

polypeptides made from the ribosomes in the Rough ER will go to the golgi apparatus

functions

• correct folding & chemical modification of newly synthesized proteins

• packaging for protein trafficking

the vesicle that is sent out from the golgi could be retained within the cell that contains digestive (hydrolytic) enzymes that become lysosomes in a cell

vesicles made from the golgi could fuse with the plasma membrane which could then release the proteins outside the cell

communicates with the ER to package up proteins

vacuoles

membrane-sac that plays many different roles

in plants a specialized large vacuole can serve many functions

vacuoles can store starch or food and water

to regulate solute and water balance there can be a contractile vacuole

when water diffuses into a cell because it is in a hypotonic solution to prevent the cell from bursting because it does not have rigid cell walls it will use a contractile vacuole to squeeze out excess water from the cell

lysosomes

when the golgi sends out a vesicle that can be retained in the cell which contains digestive enzymes that become lysosomes

membrane-enclosed sacs that contain hydrolytic enzymes

lysosomes can fuse with food vesicles and break them down

autophagy

• lysosome may fuse with dead or non functioning mitochondria & the lysosomes will fust with it and break it down

nucleus

membrane bound organelle that contains a cell’s chromosomes and genetic information

cell wall

do not exist in animal cells

in plant cells they have a rigid elastic cell wall

cell walls prevent the cell from bursting in hypotonic solutions

offers protection against the environment (ex. stress from water influx)

plasma (cell) membrane

Fluid Mosaic Model of cell membranes

• made of different components

• fluid structure with various proteins embedded in or attached to a double layer (bilayer) of phospholipids

• made of proteins and phospholipid bilayer

• the middle part is hydrophobic fatty acids which means that it is nonpolar and water can not stick to it

phospholipids

are made of hydrophobic nonpolar fatty tails (lipids) and hydrophilic polar heads

glycoproteins

involved with cell recognition and cell communication

with unfinished glycoproteins there is communication between the ER and golgi body to package up the protein

the vesicles go to the inside of the cell membrane which they fuse to and open up which allow the glycoproteins to go to the cell surface or the other molecules to be secreted

the glycoproteins can stay on the outside of the cell to help with cell recognition

channel proteins

also known as transport proteins

uses passive transport

• solute is going from a high concentration to a low concentration

helps move molecules across the membrane through a channel

the inside of the channel protein be hydrophilic and have side chains that would be chemically like water- they have a charge

water can grab hold of the charged side chains and diffuse through the membrane through the channel protein

solute can also bind to the channel protein and then the protein opens up to let the solute through —> example of a carrier protein

aquaporins

channel proteins that transport water

diffusion

when solutes go from a high concentration to a low concentration —> diffusion

goes with the concentration gradient

no ATP needed

osmosis

water moves via osmosis from an area of higher water potential (more water molecules, less solute) to an area of lower water potential (less water, more solutes)

movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules through a cell’s partially permeable membrane

water potential

measure of the differences in potential energy between a water sample with solutes and pure water

selective permeability

certain molecules can pass through the phospholipid bilayer

lipids can diffuse across because they are chemically similar to the cell membrane

passive transport

solute is going from a high concentration to a low concentration

also known as facilitated diffusion

no ATP needed

transport along a concentration gradient (diffusion) which requires no energy from the cell

facilitated transport

polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane

still passive transport —> no ATP

active transport

transport proteins that pump against a concentration gradient

requires work by the cell because it forces a more ordered system

requires ATP

endocytosis

process in which substances are brought into cells by the enclosure of the substance into a membrane-created vesicle that surrounds the substance and escorts it into the cell

exocystosis

process in which substances are exported out of the cell (reverse of endocytosis)

a vesicle escorts the substance to the plasma membrane —> causes it to fuse with the membrane —> ejects the contents of the substance outside the cell

so the vesicle functions like the trash chute of the cell

hyptertonic

lots of solute

not much water

hypotonic

no solute

pure 100% water

isotonic

equal amounts of solute inside and outside (ex. contact solution)

what happens to animal and plant cells in different solutions

In animal cells

• cell is about 70% water

• in hypotonic solutions

  • pure water will move into the cell because it is moving along the concentration gradient

  • causes the cell to burst because there is no elastic cell wall

• isotonic solution

  • water will go in and out of the cell

  • will not burst

  • nothing will change

  • ideal condition for animal cells

• hypertonic solution

  • lots of water will leave the cell

  • shriveled cell

In plant cells

• plants have a rigid elastic cell wall

• in hypotonic solutions

  • water will diffuse in but the elastic cell wall will prevent it from bursting

  • ideal condition for plant cells

• in isotonic solutions

  • the plant cells will shrivel a bit and become flaccid

• in hypertonic solutions

  • the cell membrane will peel away from the cell wall (plasmolysis)

  • leads to the plant’s leaves to shrivel up and causes the plant to die

homeostasis

self-regulating process by which biological systems maintain stability while adjusting to changing external conditions

process for an organisms to keep all its parts in equilibrium to survive

state of steady internal physical and chemical conditions maintained by living systems

osmoregulation

active regulation of the osmotic pressure of an organism’s body fluids to maintain homeostasis of the organism’s water content

it maintains the fluid balance in the body

an example of this is through contractile vacuoles

concentration gradient

going from a high concentration to a low concentration

tonicity

ability of an extracellular solution to make water move into or out of a cell by osmosis

ex. hypotonic (hypotonicity)

ex. hypertonic (hypertonicity)

endomembrane system

group of membranes and organelles in eukaryotic cells that work together to modify package and transport lipids and proteins

composed of different membranes that are suspended in the cytoplasm within a eukaryotic cell —> these membranes divide the cell into functional structural compartments - organelles

vesicles

proteins can be packed into vesicles

involved with endocytosis and exocytosis

transport vesicles

can contain proteins which can be secreted outside of the cell

can help move materials like proteins from one part of a cell to another

ex. after rough ER makes proteins —> vesicles can carry these proteins to the golgi apparatus for packaging

phagocytosis

when food enters a cell and turns into a food vacuole

basically when cells ingest other particles and turns them into a vacuole

eukaryotic cell

have double membranes

animals

plants

fungi

protists

larger than prokaryotes

• have bunch of membranes (ex. ER, golgi body, nuclear membrane)

all eukaryotes have mitochondria

mitochondrial DNA is similar to bacterial DNA

evolution of eukaryotes through

• natural selection (divergence)

• endosymbiosis (convergence)

Bigger than prokaryotes b/c of compartmentalization —> increases SA:V ratio —> allows specialization (different parts of the cell does different jobs and do not mess with each other)

prokaryotic cell

smaller than eukaryotes

bacteria and archaea

endosymbiotic theory

ancestral cells engulfed mitochondria and chloroplasts which lived inside the cell and split when the cell split and evolved into modern day cells

reason for double membranes

this is the theory for how organelles came about

there was an ecological relationship that could have been parasitism in which a bacterium infected a cell and got inside of it and could survive on its own and would divide each time the cell divided

helped evolve eukaryotes

leads to convergence and fusion in the tree of life

SA:V ratio

greater SA:V ratio means more diffusion of materials

reason why so many organelles have folded membranes —> increase SA:V ratio

more places for enzymatic reactions to occur

What side chains are polar?

SNO

sulfur

nitrogen

oxygen

makes cells hydrophilic and polar

osmolarity

concentration of a solute in water

greater osmolarity means more solute

lower osmolarity means less solute