Outcome 1 Flashcards
Which structures and organelles are membrane bound?
nucleus, mitochondria, the e.r, the gogli complex and lyosomes
Function of cell wall
located outside and around the cell membrane
are present in prokaryotic and plant/algae cells
Function of the nucleus
enclosed in a double membrane known as the nuclear envelope
the envelope is lined by the NPC (nuclear pore complex)
contains DNA and RNA
Function of the mitochondria
continually use and replace ATP
ATP is produced here
only present in eukaryotic cells
ATP produced via cellular respiration
Function of ribosomes
are the site in which proteins are made
proteins are made from amino acids
ribosomes are attached to the e.r.
Function of ER
interconnected system of membrane enclosed flattened channels
only rough e.r. has ribosomes connected to it
both involved in transportation within cells.
Function of rough ER
involved in transporting proteins to various locations within the cell
Function of smooth ER
stores and transports lipids i.e. fats
involved in manufacturing substances, detoxifying harmful products and storage of substances
Function of golgi complex
exports proteins that are intended for use outside the cells where they are formed
is a multilayer structure composed of stacks if membrane-lined channels
Functions of lyosomes
a sac filled with fluid containing digestive enzymes
in plant cells vacuoles carry out a similar function
digests macromolecules, breaks down non functional cell organelles and breaks down substances such as bacteria
Function of peroxisomes
single membrane boundary
contains a large number of enzymes
breaks down long chain fatty acids
carries out several functions in cellular metabolism
Functions of chloroplasts
photosynthesis occurs here
are green due to the light trapping chlorophyll
each chloroplast is enclosed in two membranes
the third membrane is flattened to create an intricate structure of layers of grana
are not present in all plant cells
Function of the cytoskeleton
supplies support and strength for the cell
determines the shape of the cell
moves chromosomes during cell division and facilitates movement of cell organelles within a cell
Function of flagella
present in unicellular organisms
sometimes found in animals although very rare to be found in a plant cell
are long and only one maybe two can be present in one cell
have long “tails” for movement
i.e. human sperm have a flagellum that enables them to move
Function of cilia
are smaller than the flagella but multiple can occur in a cell
i.e. the combined effort of many cilia move mucus up the trachea
Key differences between an optical and electron microscope
optical microscopes operate at a lower level of resolution although images are usually colored unlike an electron microscope, living cells can be viewed on an optical microscope
Functions of the plasma membrane
is an active and selective boundary
denotes cell identity
receives external signals
transports materials
Explain cell identity
glycoproteins on the outer plasma membrane functions as cell surface markers
i.e. in mammals, these markers enable the immune system to identify these cells as ‘self’ and distinguish them from foreign cells
Define an impermeable, permeable and selectively permeable barrier
impermeable: no substance can cross it
permeable: any substance can cross it
selectively permeable: allows some substances to cross and can block others
Explain simple diffusion
the means of transport of small lipophilic substances
from a region of high concentration to low concentration
going down a concentration gradient, therefore, doesn’t require an input of energy
Explain osmosis
the movement of solvents (water)
the water moves across a semipermeable membrane that is permeable to water but not solute molecules
moves up the concentration gradient
doesn’t require an input of energy
Define solute, solvent and solution
Solute: substance that is dissolved
Solvent: liquid in which a substance dissolves
Solution: liquid mixture of solvent and solute
Define hypotonic, hypertonic and isontic
Hypotonic: having a lower solute concentration than the cell contents
Hypertonic: having a high solute concentration than the cells contents
Isontic: having an equal solute concentration than the cell contents
Explain facilitated diffusion
protein-mediated transport
doesn’t require an input of energy and moves substances down their concentration gradient
enables molecules that cannot diffuse across the phospholipid bilayer to move across through protein transporters
Function of a channel proteins
has a central water-filled pore in which dissolved substances can pass down their concentration gradient
specific for charged particles and polar molecules
creates a hydrophilic passage across the plasma membrane that bypasses the bilayer
Function of carrier proteins
are specific for the molecule they transport
after binding to its molecule the protein changes shape as it delivers its cargo to the other side of the membrane
diffusion of hydrophilic uncharged substances
Explain active transport
moving substances across a plasma membrane against the direction they would travel by diffusion
can only occur with input of ATP
from a region of low concentration to a region of high concentration
proteins transport specific substances
moves polar molecules and ions
protein changes shape during the process
some pumps can transport two substances simultaneously
Explain endocytosis
the process of bulk transport into a cell
if the material is food it is called phagocytosis
requires an input of ATP
pinocytosis - a form of endocytosis that involves material in a solution
Explain exocytosis
bulk transport out of the cell
requires an input of ATP
vesicles formed within a cell fuse with the plasma membrane before the contents of the vesicles are released from the cell
Define hydrophilic
water-loving molecules dissolve readily in water
Define lipophilic
substances dissolve readily in organic solvents such as benzene
Define hydrophilic
water fearing molecules are usually lipophilic (lipid loving)
What are the two major components of the plasma membrane?
Phospholipids and proteins
What is a glycoprotein?
protein with a carbohydrate attached
What is a glycolipid?
lipid with a carbohydrate attached
What is cholesterol?
holds the phospholipid bilayer together
What are integral proteins?
are embedded in the plasma membrane
What are peripheral proteins?
are either anchored or attached to the exterior of the plasma membrane
