Structure and Functions of the Cell and its Organelles

Eukaryotic cells have what type of nucleus

membrane bound

are euakaryotic cells less or more complex than prokrayotic

more

what does a eukrayotes cytoskeleton allow for

support and to maintain cellular structure

size of nucleus

5-7um

what stored in nucleus

genetic information

how is DNA divided in eukrayotes

multiple linear chromosomes

why are chromosomes folded in a double helix

storage large amounts of information in small places

most eukaryotic cells possess what?

a single nucleus

what is the nucleolus

region where rRNA synthesis takes place

what are ribosomes responsible for

protein synthesis

what is the nucleur envelope composed of

2 phospholipid bilayers (7-8nm)

what does the nuclear pores do

control passage in and out

ribosomes are composed of

-rRNA

-mRna

-tRNA

function of RER

synthsises proteins to be secreted

SER function (3)

synthesis, caclium storage, detoxification

what is the golgi apparatus

flattened stack of interconnected membranes

function of golgi apparatus

packaging and distribution of molecules synthesised at one location and used at another

what do golgi appartus contain

cis and trans faces

function of vesicles

transport molecules to their destinations

vesicle fluid are enclosed by what

lipid bilayers membrane

when are vesicles formed

exocytosis, phagocytosis, and endocytosis

what are vesicles used for

transporting materials within the cytoplasm

what are vesicles involved in (3)

-metabolism

-transport

-enzyme storage

what are lysosomes

small membrane bound digestive vesicles

where do lysosomes arise from

Golgi apparatus

lysosomes function

destroy cells or foreign matter engulfed by phagocytosis

what are lysosomes involved in

autophagy

mitochondria is the site of

oxidative metabolism

name 3 fibers that cytoskeleton is composed of

-microfilaments, microtubules, intermediate filaments

what is microfilaments involved in

movements such as contraction, crawling, and pinching

what is microtubules purpose

facilitate movement of cells and materials within cells

what are microtubules composed of

dimers of alpha and beta tubulin subunits

intermediate filaments are very what?

stable

size of intermediate filaments

between the size of actin filaments and microtubules

what are specialised units of centrosomes called

centrioles

purpose of centrosomes

microtubule organising centre

what type of cells lack centroioles

plant and fungi

how thick are cell membranes

4nm thick

what do cell membranes do

supports the cell

list 3 compositions of membranes

-phospholipids, proteins,cholestrol

how are phospohlipids arranged

bilayer

list 2 type of protein

integral and peripheral

what does cholestrol do

reduces permeability to hydrophilic molcules

fatty acid compisition and temperature affect what?

fluidity

active transport definition

uses energy (ATP) to move materials against a concentration gradient

what is active transport involved in

carrier proteins/cells channels

definition of osmosis

net diffusion of water across a membrane toward a higher solute concentration

when does osmosis occur

when a membrane separates solutions with different concentration of solutes

hypertonic solution definition

higher solute concentration

hypotonic solution definition

lower solute concentration

isotonic solution

equal osmotic concentration

what happens to cells in hypotonic solution

swell

some cells use extrusion, why?

to eject water to maintain osmotic balance

isomotic regulation keeps what?

cells isotonic with their enviroment

p-type ATPases

transport Na+, K+, Ca2+ through phosphorylation

f-type ATPases

proton transporters in mitochondria and bacteria

v-type ATPases

located in lysosomes

ABC transporters

transports ions, metabolites, and drug molecules

what is the sodium potassium pump

active transport mechanism using ATP

process of sodium potassium pump

moves 3Na+ out and 2K+ into the cell against concentration gradients

how much cellular energy does the sodium potassium pump use

significant

coupled transport uses ATP how?

indirectly

symporter meaning

used for transporting two molecules in the same direction

endocytosis

movement of substances into the cell

name 3 endocytosis

phagocytosis, rinocytosis, receptor mediated endocytosis

phagocytosis

cell takes in partculate matter

pinocytosis

cell takes in fluid

receptor mediated endocytosis

specefic molecules taken in after binding to a receptor

exocytosis

movement of substances out of the cell; requires energy

b-barrel

cylinder of beta sheets in the protein secondary structure

interior is polar or non polar?

poalr

how are membrane lipids distrubruted

asymmetrically

uniporters

move one molecules at a time

symporters

move two molecules in the same direction

antiporters

move two molecules in the opposite direction

stages of sodium potassium pump

1. 3 x Na+ bind to cytoplasmic side of the protein → conformation change

2. Protein binds 1 x ATP → ADP and phosphate (Pi). ADP released, but Pi is linked to protein. The protein is phosphorylated

3. Protein phosphorylation → conformational change. This translocates the 3 x Na+ outwards across the membrane. The 3 x bound Na+ break away and diffuse into the extracellular fluid

4. The new conformation has a high affinity for K+ - 2 x K+ bind to the extracellular side of the protein

5. → conformational change again, and hydrolysis of the phosphate group

6. Protein is dephosphorylated and reverts to its original shape - 2 x K+ enters the cytoplasm. The original conformation has a high affinity for Na+. When these ions bind, they initiate another cycle