AP BIO Unit 2: Cell Structure and Function

amphipathic

polar/hydrophilic on one side and nonpolar/hydrophobic on other

functions of plasma membrane

-outlines cells borders

-determines how it interacts with env

-carries markers allowing for recognition of pathogens

properties of plasma membrane

-receive signals for effectors and growth factors

-flexible so things can fit through

-semipermeable

fluid mosaic model

phospholipids reorganize themselves like fluid

what type of phospholipids are more flexible in membrane

unsaturated fatty acids

carbs in plasma membrane (10% of mass)

-only on exterior surface

-glycolipids and glycoproteins

-used as cell markers for communication

lipids in plasma membrane (40% mass)

-phospholipids and cholesterol

role of cholesterol in membrane

buffers fluidity agaisnt temp changes

-in warm temperatures, molecules want to spread apart and cholesterol keeps them connected

-in cold temperatures molecules want to stay close and cholesterol helps separate it

amount of proteins in membrane

50% of mass

integral proteins

attach completely into membrane

r groups on membrane region are nonpolar

r groups that protrude and contact extracellular fluid are polar

peripheral proteins

either attached to integral proteins or phospholipids

what kind of molecules CANT pass through the cell membrane because of the nonpolar lipid intermembrane

large nonpolar, or polar molecules

ex glucose and amino acids

passive transport

movement down concentration gradient (high to low concentration)

no energy needed

natural

simple diffusion

small uncharged molecules can easily pass through

(nonpolar and lipid soluble)

how does steepness of the concentration gradient impact diffusion

steeper/bigger difference means diffusion will happen faster

how does mass of molecule impact diffusion

bigger molecules are slower at passing through the membrane

how does temp impact diffusion

hotter means more energy so faster

how does solvent density impact diffusion

higher density means slower diffusion

facilitated diffusion

still part of passive so no energy

uses transport protein: channel or carrier

channel proteins

aquaporin for water

ion channel for ions

gated ion channel only allows to pass sometimes

carrier proteins

changes shape to move the molecule down membrane (bound molecules)

active transport

always facilitated but uses energy

moves against concentration gradient

electrochemical gradient

combined conc gradient + electrical charge that affect ion movement

electrical gradient

difference of charge across plasma membrane in volts

cell has negative charge compared to outside

pumps

use of ATP to move substances against gradient

primary active transport

direct use of ATP to move ions across membrane and create charge difference

secondary active transport

no direct atp use

uses energy stored in electrochemical gradient

proton pumps

sends H+ ions outside to create difference in charges

can create higher acidity which is specific to certain proteins

uniporter

carrier protein for active transport

goes down one way

symporter

carrier protein for active transport

sends two things down same way

antiporter

carrier protein for active transport

sends two things down in opposite directions

sodium potassium pump

NA+ -K+ ATPase

found in all animal cells

pumps 3K+ in and 2NA+ out for each ATP

pumps high concentrations of sodium outside the cell

activated when phosphate is taken from ATP

maintains high concentration of sodium outside neurons and potassium inside neurons

endocytosis

active transport moves large particles or other cells into cell

membrane pinches off and creates new vesicle

phagocytosis

takes in large particles by endocytosis

pinocytosis

takes in extracellular fluid by endocytosis

exocytosis

expels material by vesicle fusing with plasma membrane

osmosis

diffusion of water molecules according to concentration gradient

can be simple (but takes long)

usually facilitated with aquaporin

ways that water moves

high water concentration to low water concentration

low solute concentration to high solute concentration

high pressure to low pressure

tonicity

extracellular solution changes cell volume by affecting osmosis

osmolarity

total solute concentration

osmoregulation

ability of cells to regulate solute concentration and maintain cell balance

hypertonic solution

higher osmolarity

higher solute

water moves towards hypertonic side

if outside cell, cell will shrivel from water loss

plasmolysis

occurs in hypertonic solutions

vacuole shrinks and plasma membrane moves away from walls

hypotonic

lower osmolarity/lower solute

water moves AWAY from

water will move into cell and lyse

isotonic

net water movement of 0 bc moves in and out at same time

optimal condition for plant cells

hypotonic solution, cell wall prevents lyses

what happens to plants in isotonic conditions

vacuole doesnt exert enough pressure so they wilt

what happens to plants in hypertonic solutions

cells will shrivl and die due to plasmolysis

water potential

measures potential energy of water in pressure units

predicts direction of flow

how does water move based on potential

high water potential to low water potential

ion constant to know for solute potential formula

glucose=1

NaCl=2

domains in prokaryotes

bacteria and archaea

organisms included in eukaryotes

animals, plants, fungi, protists

who was first to discover cell existence

robert hooke in 1665

when were microscopes invented

1590s

components of cell theory

1. every living thing is made up of 1+ cell

2. the cell is the structural unit of all organisms

3. the cell is the smallest unit of life

4. living cells come from pre-exisiting cells

5. cells contain hereditary material that passes to offspring

6. cells are individually alive

4 common components of ALL cells

1. plasma/cell membrane

2. cytoplasm

3. dna

4. ribosomes

prokaryote

pro-before kary-kernel

no nucelus

why is presence of ribosomes in all organisms significant

strong evidence for common ancestry

components of prokaryotes

nucleoid region-contains genetic material

capsule-helps stick to surfaces

pili-exchange genetic material during conjugation

fimbriae: on surface of bacteria, attaches to host cell

what is prokaryotic cell wall made of

peptidoglycans, usually permeable so dissolved solvents can enter

where can you find flagellum

prokaryotes + animal cells

plasmids

usually only prokaryotes, small chunks of DNA that contain genes that are easily shared with other bacteria

relationship between archaea and bacteria

archaea are closer to humans than bacteria

why is it helpful than prokaryotes are smaller than eukaryotes

ions and organic molecules diffuse quicker to other parts of the cell

why is surface area important to cells

greater surface area means more interactions/transport

cell size relation SA:V

as cells increase, SA:V decreases

what happens as cells grow

become less efficient as SA:V decreases

how do cells increase surface area

folding cell membrane

becoming flat or thin

elongated

developing organelles for specific tasks

unique to eukaryotes

membrane bound nucleus

organelles

chromosomes

compartmentalization

unique to eukaryotes, focus of organelles with specific functions

purpose of compartmentalization

too many tasks, so they have to be split up esp with different surface areas to speed interactions

plasma membrane

both

phospholipid bilayer with proteins

controls passage of organic molecules, ions, water, and oxygen into and out of cell

cytoplasm

both

region between plasma membrane and nuclear envelope

made up of cytosol gel

nucleus

houses DNA

envelope: double membrane structure

chromosomes: made of dna and proteins

chromatin-unwound protein/chromosome complex

ribosomes

conduct protein synthesis to make proteins from DNA code

made of protein and rRNA

two types of ribosomes

free: make cytoplasmic protein

bound: ribosomes in ER make membrane/excretory proteins

mitochondria

make ATP through aerobic respiration

inner membrane folds to increase surface area + chemical reactions

cristae-inner folds

matrix-innermost area stores enzymes, proteins, ribosomes, and DNA

chloroplasts

carry out photosynthesis to make glucose

contain thylakoid stacks called grana, stroma liquid, ribosomes, and DNA

vacuole in animal cells

helps sequester waste

large central vacuole

plants only, occupies most of cell volume by regulating water/turgor pressure

cytoskeleton

structural protein filaments throughout whole cell

extensions of cytoskeleton

cilia & flagella

endomembrane system

group of membranes and organelles working together to modify, package, and transport proteins and lipids

rough er

has bound membranes

conducts protein synthesis

ribosomes transfer proteins to RER lumen (inside) and RER membrane

could end up in ER membrane or any organelle membrane

where could proteins made in rough er lumen end up

secreted

in a membrane

in a vacuole

smooth er

packages proteins into vesicles, but some stay to turn into enzymes, vesicles for golgi apparatus

synthesizes carbs, lipids, and steroid hormones

what organelle detoxifies medications and poisons (drugs and alcohol/inorganic)

smooth er

what type of ions are smooth er known for storing

calcium

golgi apparatus

sorts, modifies, and distributes lipids and proteins

can be sent to excrete or turned into lysosome

golgi cis face

faces ER, receives transport vesicles

trans face

modified proteins packaged into secretory/transport vesicles budding from golgis trans face

vesicles

small sacs that transport around cell

secretory vesicles

fuse with cell membrane to deliver membrane proteins or release secretory proteins in exocytosis

lysosome

animal only

made by golgi

contains hydrolytic enzymes

recycles organelles + pathogens

breaks down macromolecules

peroxisome

break down amino/fatty acid

type of vesicle formed from fusing vesicles from mitochondria and rough er together

mostly in animals liver

in plants found in seeds

oxidation reactions

transport vesicle

small container that breaks off from larger organelle

transports materials from one organelle to another

made of phospholipids

how do molecules move around cells

motor proteins walking along tracks

centrosomes

made of centrioles, organize microtubules

endosymbiotic theory

eukaryotes developed from endosymbiotic relationship between bacterium and archaean