MLB ST 1

CELL theory

1. fundamental units of life

2. all living organisms are composed of cells

3. all cells come from pre exsisting cells

4. evolved from common anchestor

cytoplasm

everything inside cell exept nucleus

Cytosol

the fluid component of the cytoplasm

cell membrane functions

acts as selectively permeable barrier

allows cell to maintain constant internal environment

broundry from outside wall

has proteins protruding into the bilayer that aid in transport and communication.

surface/area solutions

increase infoldings

size increase in 1 dimension

nerve cells become thin and elongated

increase rate of substance transport across membrane

nucleus

region of cell where DNA is located

ribosomes

complexes of RNA and protein that synthesize proteins in cytoplasms

features found in some PROKARYOTIC CELLS

• cell wall

• internal mebranes

• flagella and pili

• cytoskeleton

• no nucleus

plant cell vs animal cell

PC - plasmodesmata, cell wall, plastids (e.g. chloroplasts)

AC - cell membrane, other cell junctions, no plastids

Endomembrane system

a group of interrelated organelles

endomembrane system includes

1. cell membrane

2. nuclear envelope

3. endoplasmic reticulum

4. golgi aparatus

5. lysosomes

golgi apparatus vesicle movement

ER→ cis-Golgi → medial-Golgi→ trans-Golgi

kinesins

move materials to the ‘plus’ end

dyneins

moves materials toward the ‘minus’ end

Plant cell wall

1. provides support for cell & plant , remain regid

2. acts as barrier to infection

3. contributes to plant form

fluid mosiac model

‘fluid’ → the components can move freely

‘mosiac’ → made up of many discrete components

fluidity of membrane affected by

1. lipid composistion

2. chain length

3. saturation

4. cholestrol

5. tempreture

glycolipid

consists of a carbohydrate covelently bonded lipid

glycoprotein

consists of one/more short carbohydrate chains covelenly bonded to a protein

tight junctions

prevent substances from moving through the spaces between cells

desmosomes

hold neighboring cells tightly together , acting like spot welds

gap junctions

channels that run between membrane pores in adjacent cells

homeostasis

• all of cells of body share an internal environment that is made up of extracellular fluids

• the maintenance of this narrow range of conditions

passive transport

Do not require input of chemical-bond energy

active transport

driven by chemical-bond energy

2 types of diffusion

1. Simple diffusion through phospholipid bilayer

2. facilitated diffusion via channel proteins or carrier proteins

diffusion

a NET movement of dissolved molecules from one region of higher concentration to region of lower concentration

speed of diffusion relies on 5 factors

1. size & mass of molecules or ions

2. tempreture of solutions

3. density of solution

4. concentration gradient in system

5. area of which substance diffuses and distance

osmosis

movement of h2o molecules through membrane from region with lower solute concentration to region with higher solute concentration