BIOL 110 Lecture Exam 2
What is diffusion?
The movement of molecules across the membrane from an area of high concentration to an area of low concentration. (does not require cell energy)
The plasma membrane acts as a barrier that defines the cell and regulates the important process of ______________.
transport regulation
Polysaccharides found in the plasma membrane
what do they do?
Lysosome
An organelle containing digestive enzymes
Over time, hybrid cells show increasingly _______________ ________________.
intermixed proteins
Steps of determining what the membrane is mad of:
1. Counted RBCs 2. Calculated total SA 3. Destroyed the cells and collected the membrane phospholipids (chemical separation) 4. Placed the phospholipids into a chamber of liquid where they would form a floating monolayer 5. Measured the total SA of the phospholipids in the chamber, and compared it to the total SA of RBCs
Photobleaching Experiment
1. Labeled membrane proteins with fluorescent dye 2. Target an area of a plasma membrane and hit the cells with a laser, laser would destroy or bleach out the dye on an area of the membrane 3. See what happens
cell fusion experiment
1. The membrane proteins of humans and mice were stained with fluorescent dyes 2. Fused the cells together 3. Watched the colors over time, if the colors mixed or stayed locked in place
What is the ratio of a nuclear envelope membrane?
4:1
cytoplasm
A jellylike fluid inside the cell in which the organelles are suspended
flagellum
A long, hairlike structure that grows out of a cell and enables the cell to move.
cell wall
A rigid structure that surrounds the cell membrane and provides support to the cell
plasma membrane
A selectively-permeable phospholipid bilayer forming the boundary of the cells
pilus
A short, thick hair-like protein structure that allows a bacterium to attach to other bacteria and surfaces.
Chromatin
Clusters of DNA, RNA, and proteins in the nucleus of a cell
capsule
Covers the cell wall in prokaryotes.
If the membrane is a static structure and everything is locked into place, what would happen after lasering?
Everything would stay in place.
What was found with photobleaching experiments?
Fluorescent labeled molecules diffuse into bleached area.
look back at slides here
LOOK BACK AT SLIDES HERE
Cells are at a lower temp, how does PM change?
Membrane becomes less fluid, FA chains are shorter and more unsaturated.
Cells are at a higher temp, how does PM change?
Membrane becomes more fluid, FA chains are longer and more saturated.
Evert Gorter's experiment with red blood cells demonstrated what?
Membranes are composed of a phospholipid bilayer
Are things static in the plasma membrane?
No, they are dynamic structures.
Cell fusions experiments demonstrated what?
Plasma membranes are fluid.
endomembrane system includes
SER, RER, Golgi Complex, Vesicles
function of chloroplast
Site of photosynthesis, light energy is converted into usable chemical energy
inside the macrophage, ...
TB multiplies, kills and devours it, and spreads to infect more cells
What is active transport (anti-diffusion)?
The movement of molecules across the membrane from low concentration to high concentration. (requires cellular energy)
What was the most important reason that Dr. Gorter used red blood cells for his experiment?
They are uniform and identical, easy to get in large quantities, and easy to count.
How does the cell control membrane fluidity?
They change the fatty acid chains of phospholipids in two ways (happening simultaneously).
what do prokaryotes have that eukaryotes don't?
a cell wall
Cholesterol
a fluidity buffer of the membrane
fluid mosaic model of membrane structure
a model that describes the phospholipid bilayer as fluid and proposes that integral membrane proteins float freely in the lipid bilayer
structure of endoplasmic reticulum
a network of tubules and vesicles, walls composed of a lipid bilayer, space inside is the lumen
What is exocytosis?
a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane. ex: insulin secretion
2 types of prokaryotic cells
archaea and bacteria
peripheral proteins
bound to the outer and inner surface of the membrane
How do we know that membranes are fluid?
cell fusion experiment (Johns Hopkins University)
both prokaryotes and eukaryotes have
cell membrane, cytoplasm, ribosomes
What do plant cells have that animal cells don't?
cell wall and chloroplasts
prokaryotes have a ________ _______ made of...
cell wall, peptidoglycans
DNA bound to protein (histones)
chromatin
the most distinctive feature of eukaryotic cells is their
compartmentalization
a semi solid gel (cytosol) contains all the cells internal components
cytoplasm
prokaryotes are small but they are the dominant life forms on earth in terms of
diversity and biomass
how does the nuclear envelope differ from plasma membrane?
double lipid bilayer
chloroplast structure
double lipid bilayer, enclosed within are internal membranes stacked into disks
mitochondria structure
double lipid bilayer, inner membrane is extensively infolded, fold are cristae, "liquid center" called the matrix
The plasma membrane is ____________ and cells can ______________.
dynamic, adjust
Primary lysosomes can digest material from outside the cell by fusing with an _________ or material from within the cell by fusing with an _________.
endocytic vesicle, phagosomes
outer bilayer is connected to
endomembrane system
Mitochondria function
energy metabolism: ATP production
Endocytosis is a process by which materials ______ a cell and Exocytosis is a process by which materials _____ a cell.
enter, exit
bacteria aka
eubacteria
cells that contain a membrane bound nucleus and an internal membrane system
eukaryotes
archaea aka
extremophiles
extracelluar fluid
fluid outside cells
secondary lysosome
fused with damaged organelle, digestive enzymes activated, toxic chemicals isolated
series of flattened sacs
golgi apparatus
stick of thylakoids
granum
Change 2: The cells can generate phospholipids that have...
have much longer or shorter fatty acid chains.
A major barrier for molecules crossing a plasma membrane is the _________________ ______________.
hydrophobic interior
For every cell type, there is an ______________ amount of fluidity.
ideal
The smooth and the rough ER are
interconnected with each other and the outer bilayer of the nuclear envelope
The plasma membrane's most basic function is
it acts as a barrier, keeping the outside out and the inside in
If the membrane is too solid...
it will not permit integral proteins to flex and carry out their functions.
If the membrane is too fluid...
it will not serve as a boundary and will fall apart.
What is simple diffusion?
jjj
Impermeable to what kind of molecules?
large polar molecules, ions
A saturated fatty acid chains means __________ fluidity.
less
The phospholipids with short FA chains are going to be packed _________ tightly. (more fluid)
less
What were the two possible outcomes for the lipid layer of the membrane?
lipid monolayer (1:1 ratio), lipid bilayer (2:1 ratio)
function of smooth ER
lipid synthesis, cholesterol and steroid synthesis, fatty acid desaturation
inactive insulin is
made in the rough ER
what is endocytosis?
material entering the cell, plasma membrane surrounds contents from around the cell, trapping it in an endocytosis vesicle
compartments are
membrane bound
Why are mitochondria and chloroplasts thought to have once been independent prokaryotic organisms?
mitochondria cannot arise from other mitochondria, circular dna, cellular division (endosymbiotic theory)
Endosymbiotc Theory
mitochondria only arise from pre-existing mitochondria
The extracellular matrix is made of
molecules secreted from cells
An unsaturated fatty acid chain means _____________ fluidity.
more
The phospholipids with long FA chains are going to be packed _________ tightly. (less fluid)
more
Change 1: The cells can generate phospholipids that have...
more or fewer unsaturations in the fatty acid chains.
primary lysosomes
newly formed lysosomes
Permeable to what kind of molecules?
nonpolar (and hydrophilic)
a double lipid bilayer membrane that surrounds the nucleus
nuclear envelope
endomembrane system includes
nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles and the plasma membrane.
Parts of the nucleus
nuclear envelope, nucleolus, chromatin
passages through the nuclear membranes that regulate transport
nuclear pores
an area in the nucleus where ribosome complexes are assembled
nucleolus
What do prokaryotes lack?
nucleus and membrane bound organelles
compartments are called
organelles
Cells can change the ____________________ ___ ______________________ with saturated or unsaturated fatty acid chains.
percentage of phospholipids
Cell membranes are a ________________________ ___________________.
phospholipid bilayer
In the 1920's scientists knew that membranes were composed of ________________________.
phospholipids
functions of plasma membrane
physical barrier, transport regulation
A newly formed lysosome is referred to as a _______ lysosome and once it fuses with an endocytic vesicle or organelle the structure is referred to as a _______ lysosome.
primary, secondary
What does the cytoskeleton do?
protein fibers maintain the cells shape and can move the cell membrane
function of rough ER
protein synthesis bound for export from cell, or for use in the endomembrane system
function of golgi apparatus
proteins and other molecules may be modified and are sorted by eventual destination, packaged into vesicles
ribosomes are made of
rRNA and protein
cis face
receiving side of golgi apparatus
what important function occurs in the nucleolus
rewrite ribosomal rna
enzyme complexes that are considered organelles, non-membrane bound
ribosomes
the universal organelle, responsible for building proteins
ribosomes
trans face
shipping side of golgi apparatus
function of ribosomes
site of protein synthesis
ribosomes
site of protein synthesis
LESS permeable to what kind of molecules?
small polar molecules (size matters)
Endocytosis can be:
specific, using receptors, or passive, taking up water and nutrients
Functions of the nucleus
stores genetic info, site of ribosomes assembly, and RNA production
soluble material around granu
stroma
3 main functions of cytoskeleton
structural support, transport within the cell, help the cell move
Functions of the ECM
support (strengthens and cushions cartilage and bone), adhesion (hold cells together in tissue), movement, regulation (filters material between cells, ex: kidneys)
Integral (transmembrane) proteins
the majority of proteins; they extend entirely through the membrane
Red blood cells are _____________ in size.
the same
Tuberculosis bacterium survive and affect so many because
they are able to prevent phagosome/lysosome fusion, thus surviving and living in the cell.
single disks within the DLB of chloroplast
thlakoid