BIOL235 Unit 1 Ch 3

Cells

basic, living, structural and functional units of the body

internal environment

everything inside cell

external environment

everything outside cell

Plasma Membrane

forms flexible outer surface of cell seperating internal and external environment

Cytoplasm

consists of all cellular contents between the plasma membrane and the nucleus

Cytosol

fluid portion of the cytoplasm aka intracellular fluid

organelles

little organs within cells with charactersics shapes and specific functions

Nucleus

large organelle that houses most of the cells DNA

fluid mosaic model

model where the molecular arrangement of the plasma membrane resembles a sea of lipids with a moasic of floating proteins

lipid bilayer

2 back to back layers of phospholipids, cholesterol and glycolipids that form the plasma membrane

75

percentage of the lipid bilayer made up of phospholipids

20

percentage of the lipid bilayer made up of cholesterol

5

percentage of the lipid bilayer made up of glycolipids

amphipathic

molecules with polar and nonpolar components are

outward

The polar phopholipid head, cholesterol OH- group and Glycolipid carbohydrate groups are all _______ facing in a lipid bilayer

inward

The tails of phospholipids and glycolipids and the seteroid rings of cholesterol are all ______ facing in a lipid bilayer

Integral Proteins

proteins that extend into/through the lipid bilayer and are firmly embedded in it

Transmembrane proteins

integral proteins that span the entire lipid bilayer protruding into cytosol and ECF

Ion channels, Carriers, Receptors, Enzymes, Linkers, Glycoproteins

Types of Integral proteins

Glycoproteins

Integral proteins with crabohydrate groups on the end that protrude into the ECF (exclusive)

Glycocalyx

extensive sugary coat on outside surface of cell formed by glycolipids and glycoproteins

Peripheral Proteins

proteins attatched to polar heads of phospholipids or integral proteins allong the surfaces of the lipid bilayer

cell identity markers

the cariation between cells glycocalyxs allows them to enable cellular recognition as ______________

increases

membrane fluidity ________ with double bonds in fatty acid chains

decreases

membrane fluidity ________ with increased percentage of cholesterol in lipid bilayer at body temperature (opposite in cold)

Permeable

when a structure permits paasage of substances through it it is __________

Impermeable

when a structure doesnt permit paasage of substances through it it is __________

Selective permeability

when the permeability for some substances is easier than others

gasses and other small uncharged nonpolar molecules (steroids)

The lipid bilayer is highly permeable to (2)

small uncharged polar molecules

The lipid bilayer is moderately permeable to

ions, large uncharged molecules

The lipid bilayer is impermeable to (2)

Concentration Gradient

difference in concentration of chemical between ECF and ICF

negative

typically within the cell there is more ________ charge

posiive

typically surrounding a cell there is more _________ charge

electrical gradient

the difference in electrical charges between 2 regions

membrane potential

the electrical gradient across the plasma membrane

electrochemical gradient

combined influence of concentration gradient and electrical gradient on the movement of a specific ion

passive

processes where ions move down their concentration or electrical gradient with only their own kinetic energy are considered ________

active

processes where energy is used to drive ions against their concentration or electrical gradient are considered _________

Vesicles

tiny spherical membrane sacs by which some substances may enter or leave cells

Diffusion

passive process in which random mixing of solution occurs where substances move down their concentration gradient until the gradient is balanced

increases

diffusion rate ________ when the steepness of the concentration gradient increases

increases

diffusion rate ________ when temperature increases

decreases

diffusion rate ________ when mass increases

increases

diffusion rate ________ when surface area of the membrane being diffused through increases

decreases

diffusion rate ________ when the diffusion distance (thickness of membrane being diffused through) increases

simple diffusion

passive process where diffusion of substances occurs freely through lipid bilayer of plasma membranes without transport proteins

Facilitated diffusion

passive process where diffusion of substances is mediated by integral membrane proteins that allow specific substances to cross the membrane

channel-mediated diffusion

form of facilitated diffusion where solutes move down their concentration gradients through a membrane channel

Gated

when part of the channel acts as a plug until channel changes shape to open it is considered ______

carrier-mediated diffusion

form of facilitated diffusion where solutes are transported down their concentration gradients

transport maximum

upper limit on diffusion rate through carrier mediated diffusion based on how many carrier are available

saturation

when the concentration of a substrate is higher than the transport maximum allows for a carrier protein

GluT

Carrier protein for glucose diffusion

Insulin

hormone that increases the transport maximum for glucose by increasing the number of GluT proteins inserted into the cell membrane

Osmosis

type of diffusion in which there is a net movement of a solvent though a selectively permeable membrane

simple diffusion, aquaporins

means by which osmosis can occur (2)

Aquaporins

integral proteins that function as water channels

Hydrostatic Pressure

force exerted by fluid on surface due to gravity

Osmotic Pressure

minimum pressure required to prevent a solvent from passing though a membrane

increases

high solute concentration on the opposite side of the membrane _______ osmotic pressure

Tonicity

measure of solutions ability to change the shape or volume of cells by altering their water content

Isotonic

Solution that maintains normal shape and volume of cell

Hypotonic

Solution that has lower concentration of solutes than within cell causing cell to swell and burst

Hemolysis

when red blood cells burst from exposure to a hypotonic solution

lysis

when any cell bursts from exposure to a hypotonic solution

hypertonic

Solution that has higher concentration of solutes than within cell causing cell to shrivel

Crenation

shrinking of cells in hypertonic solution

Active Transport

When energy is required for carrier proteins to move solutes across a plasma membrane against their concentration gradient

Primary Active Transport

form of active transport that hydrolyses ATP for energy

Pumps

carrier proteins that mediate primary active transport

Sodium Potassium Pump (ATPase)

Most prevalent primary active transport mechanism

sodium

The sodium potassium pump pumps this out of the cell

potassium

The sodium potassium pump pumps this into the cell

Secondary active transport

form of active transport that uses energy stored in concentration gradients of sodium and hydrogen ions to drive other substances against their concentration gradient through simultaneous binding mechanisms that cause both substances to cross the membrane at the same time

Symporters

Secondary active transport proteins that move substance in same direction as Na+/H+

Antiporters

Secondary active transport proteins that move substance in opposite direction as Na+/H+

endocytosis

when materials move into a cell via a vesicle formed by the plasma membrane

Receptor mediated endocytosis

highly selective form of endocytosis where only specific ligands that bind on plasma membrane are endocytosed

Clathrin

plasma membrane protein that facilitates the structural formation of vesicles in receptor mediated endocytosis before being returned to the membrane with the receptor

Phagocytosis

form of endocytosis in which cell engulfs large solid particles

Phagocyte

Type of cell that can perform phagocytosis

Macrophage, Neutrophil

Phagocytes (2)

Bulk-Phase endocytosis (pinocytosis)

form of endocytosis where droplets of ECF are taken up

Exocytosis

when materials move out of a cell via fusion of a vesicle to the plasma membrane

Transcytosis

when vesicles undergo endocytosis on one side of the cell then cross over the cell before undergoing exocytosis

55

percetage of total cell volume that is cytosol

cytoskelaton

network of protein filaments that extend through the cytosol to form scaffold for cell shape and organisation while also aiding in movement

microfilaments

thinnest elements of the cytoskelaton, help generate movement and provide mechanical support

actin + myosin

proteins that microfilaments are made of

microvilli

non motile projections of plasma membrane formed by microfilaments that increase cell surface area

Intermediate filaments

medium sized elements of the cytoskelaton, exceptionally strong, found in spots of high mechanical stress, stabilize organelle positions and help attach cells to one another

Microtubules

largest elements of the cytoskelaton, long unbranced hollow tubes that are assembled in the centrosome, that help to determine shape and enable cell movement

Tubulin

protein that microtubules are made from

Cilia and Flagella

motile projections of the cell surface that are comprised of microtubules

Centrosome

Organelle that is the center of microtubule organization

Centrioles

cylindrical stuctures each composed of 9 clusters of 3 microtubulrs aranged in a circular pattern

right angle

the 2 centrioles are aligned with each other at a

pericentriolar matrix

hundreds of tubulin ring shaped complexes surrounding the cntrioles that act as organizing centers for growth of mitotic spindle

cilia

numerous short motile hair like projections comprised of 20 microtubules each