Bio - Cell structures and transport

exocytosis

process by which cells move materials from within the cell into the extracellular fluid

endocytosis

process by which cells take in substances from outside of the cell by engulfing them in a vesicle

diffusion

movement of molecules from an area of high concentration to low concentration

amphipathic

having both a hydrophillic region and hydrophobic region (ex. phospholipid)

hypotonic

a solution that when surrounding a cell will cause it to take up water - more water potential than the cell

hypertonic

a solution that when surrounding a cell will cause it to loose water - less water potential than the cell

isotonic

a solution that when surrounding a cell causes no net movement of water into or out of the cell - equal water potential?

tonicity

the ability of a solution surrounding a cell to cause that cell to gain or lose water

osmosis

diffusion of water molecules across a selectively permeable membrane

glycoproteins

a protein molecule with a carbohydrate attached to it

plasmolysis

a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment.

occurs when the cell loses water to a hypertonic environment.

cytoskeleton

helps maintain cell shape, structure, and internal organization

What are 3 differences between prokaryotic eukaryotic cells?

eukaryotic cells are usually bigger, has a nucleus and are multicellular unlike prokaryotic cells

What is the cell membrane made of?

phospholipids, proteins, cholesterol

How does the composition of the cell membrane create hydrophobic and hydrophilic regions?

The phospholipid bilayer has the hydrophilic heads on the outside of the membrane with the hydrophobic tails in the inside of the membrane.

How does the phospholipid molecule change and affect the membrane fluidity relative to temperature?

In cold temps the cell membrane contains more unsaturated phospholipid tails that are kinked, keeping it fluid

In hot temps the membrane is full of saturated phospholipids, keeping from becoming too fluid

How does cholesterol affect the membrane fluidity at body temp and in low temps?

At body temp the cholesterol makes the membrane less fluid by restricting phospholipid movement

Cholesterol also hinders from close packing of the phospholipids and lowers the temp for solidification.

resists changes in fluidity as temp changes

What are the 6 membrane proteins?

Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix

What is the difference between active and passive transport?

passive transport - the diffusion of a substance across a membrane without the use of energy

active transport - the diffusion of a substance across a membrane with the use of energy

What is the biggest factor limiting cell size?

surface area to volume ratio

How does the surface area to volume ratio affect the rate of diffusion?

The higher the surface area is to volume there is a higher rate of diffusion.

What factors affect water potential?

solute potential and pressure potential

How does water potential determine the direction of where the water moves?

Water potential tells us what way the water is going. if the water potential number is higher it will move to the lower number.

What three factors affect membrane permeability?

small size, nonpolar charge, fat soluble molecules that can dissolve in lipids

How does concentration gradient affect diffusion?

diffusion happens from High concentration and goes to low concentration

what is the role of transfer proteins in facilitated diffusion?

Allow for hydrophilic substances to diffuse through the membrane

How are channel and carrier proteins different?

Channel proteins have channels that are hydrophilic while carrier proteins hold on to the substance and change shape to move them across the membrane

What are 2 examples of active transport?

exocytosis and endocytosis

what are the 3 different types of endocytosis?

phagocytosis (cellular eating), pinocytosis(cellular drinking), receptor-mediated endocytosis

How are the molecules brought into the cell by the 3 types of endocytosis?

By forming vescles from the membrane.

How does the sodium-potassium pump create a difference in charge across the cell membrane?

3 na+ move out of the cell while 2 k+ come into the cell. Which causes the outside of the cell to become more positive and the inside move negative (membrane potential). The differences in charges causes thing to move.

How does carbohydrates help in cell-cell recongnition?

carbohydrates on the extracellular side of the plasma membrane function as makers that distinguish the cells. The carbohydrates vary in location.

Name the three kinds of endocytosis and the kinds of molecules they bring into a cell

phagocytosis - "cellular eating" - engulfs particle by packaging within membranous sac called food vacuole

pinocytosis - "cellular drinking" - gulps droplets of extracellular fluid into tiny vesicles

receptor-mediated endocytosis - solutes bound to receptors in coated pits that form vesicles

Is it better to have a small or large surface area-to-volume ratio? Why?

Its better to have a large surface area to volume ratio because its quicker for molecules to diffuse. The volume doesn't make it take so long and the surface area allows it to have all the orgenelles to be comfortable in the cell.

electrochemical gradient

The combination of forces that acts on membrane potential to move ions

Uniporter

A carrier protein that transports a single molecule across the plasma membrane.

Symporter

transporter that carries two different ions or small molecules, both in the same direction

Antiporter

A carrier protein that transports two molecules acrss the plasma membrane in opposite directions.

primary active transport

Active transport that relies directly on the hydrolysis of ATP.

secondary active transport

uses an electrochemical gradient created by primary active transport to move a different substance against its concentration gradient

Osmolarity

measure of total concentration of solute particles

bulk transport

transports large molecules and solid clumps of materials by movements of the cell membrane usually with the need of energy

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells- cell eating

Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes- cell drinking

receptor-mediated endocytosis

extracellular matrix (ECM)

intricate network of polysaccharides and proteins produced by and surrounding many eukaryotic cells

interstitial fluid

fluid in the spaces between cells located in the extracellular matrix

Fibroblasts

In connective tissue, cells that secrete the proteins and fibers that make up the extracellular matrix

intercellular junctions

Intercellular junctions are structures between cells that allow neighboring cells to form strong connections with each other, prevent passage of materials, or establish rapid communication between adjacent cells.

Plasmodesmata

channels through cell walls of plant cells that connect the cytoplasm of adjacent cells

tight junctions

watertight seals between animal cells that prevent materials from leaking between cells

Desmosomes

short proteins in the plasma membrane (cadherins) that act as spot welds

gap junctions

a protein-lined pore that allows water and small molecules to pass between adjacent animal cells