specialized structures in cells used to carry out various functions. Only in eukaryotes
the cell membrane is semi-permeable, consising of a double layer of phospholipids, which have a hydrophilic phosphate head and a hydrophobic fatty acid tail. Heads on outside, tails on inside
four major phospholipid types in mammalian cells
phosphotidylcholine, sphingomyelin, phosphotidylserine and phosphotidylethanolamine. All have neutral charge except with serine
lipid that is essential in cell signaling, used to convert nonsteroid hormone messages into "second messages" sent into the cel cytoplasm
an example of a glycolipid in cell membrane. May aid in electrical impulses along cel membranes and cell-to-cell recognition
What do most proteins/phospholipids associated with the plasma membrane have associated with them?
carbohydrate groups/sugars. The plasma membrane is extremely sugar rich
What is the most favorable configuration for the amino acid region that crosses within the hydrophobic membrane interior?
alpha helix because it allows the protein to "hide" the polar peptide bonds that link the amino acids, which causes the nonpolar amino acid side chains to stick out, which works well with hydrophobic fatty acid tails.
the protein- and carbohydrate-rich coating on the cell surface
What are two factors that determine whether or not a molecule will be able to pass through a cell's membrane?
size and polarity. Those that are small and nonpolar will have easiest time getting through
What are three transport mechanisms for molecules through the cell membrane?
simple difussion, facilitated diffusion and active transport
movement of particles from higher concentration to lower concentration. No energy required!
Examples of molecules that can move through layer via simple diffusion
water, carbon dioxide, oxygen
simple diffusion when it occurs with water. Higher water concentration (low salt) to lower water concentration (high salt)
where salt concentration is high compared to surroundings (water rushes in) causes swelling
where salt concentration is low compared to surroundings (water rushes out) causes shrinking
when there an equal salt concentration compared to surroundings
uses channels, aka passive transport
what type of charge does the cytoplasm have? what ions are favored to move by facilitated diffusion
negatively charged, positively charged ions
combination of solute concentration and electrical gradient
use energy of ATP to change conformation in membrane so molecules can be brought into and out of cell AGAINST concentration gradients.
provide maintenance of unequal concentrations of cetain ions across the lipid bilayer
example of an active transport
sodium-potassium ATPase membrane pump. uses the energy of ATP breakdown to pull in 2 potassium ions and kick out 3 sodium ions
one molecule goes in, another goes out
two molecules go in/out at same time
Where is calcium stored in the cell?
It is in high concentration in endoplasmic reticulum, and low concentration in cytoplasm
in the ER membrane, actively transport calcium to ER
What can the calcium gradient in the ER be used for?
by muscle cells to regulate muscle contraction
endo and exocytosis
used to move large molecules through the cell membrane. Invagination of cell membrane to make vesicle
what are the three types of cell junctions?
tight junctions, desmosomes, gap junctions
aka occluding junctions. so tight that nothing can diffuse between the cells or past the junction. Privide barrier to transport
example of a useful place for tight junction
intestines because cells absorb nutrients from one side of cell and transport them out to the other side, tight junctions prevent the nutrients from leaving the cell once inside
what types of cells use anchoring junctions?
cells subjected to stress
hold cells together
an example of cells with anchoring junctions
desmosomes in epithelial/heart cells
what is another name for communicating junctions
what types of proteins form gap junctions?
connexins, form tubes between cells cytoplasms
what types of signals are transmitted with gap junctions?
undisrupted and very fast signal transmission
examples of cells with gap junctions
ex. heart, muscle contraction, fish tail flip
complex of many connexin proteins
glant cells equivalent of gap junctions, allow flow of nuclei from one cell to another.
what can plant viruses do?
exploit plasmodemata, virus particles can spread rapidly from one section to another
largest organelle of animal cell.
separates the nucleus from the rest of the cell. Double membrane with nuclear pores for communication. very selective
what allows proteins to enter nucleus
special sequences in protein
assembles ribosomal RNA (rRNA) whcih is taken to cytoplasm for protein synthesis
what process is not done in nucleus?
involved in protein production. One large and one small subunit
where are ribosomes made?
where can you find ribosomes
free ribosomes in cytoplasm and bound ribosomes in the outermembrane of ER
which organelles have their own ribosomes for protein synthesis?
mitochondria and chloroplasts. They more closely resemble prokaryotic ribosomes
has ribosomes lining outer surface, invoved in protein synthesis
the interior of the ER between membrane layers, at some points its continuous with nuclear envelope
no ribosomes, involved in lipid synthesis and drug detoxification
what types of proteins are made by ribosomes in the rough ER?
proteins that are secreted, found in the cell membrane, the ER or the Golgi
what type of amino acid sequence on the amino terminus of proteins determines its fate?
a hydrophobic sequence of amino acids
what is special about proteins that will be secreted?
they have one hydrophobic signal sequence, they will be inserted into the ER lumen when synthesized and then released from cell later
what is special about proteins that are destined to be membrane bound?
They have hydrophobic transmembrane domains that are threaded through the rough ER membrane as protein is synthesized
what is another function of ER membrane besides protein synthesis?
budding off to form vesicles that have newly synthesized proteins, they head for golgi
location of golgi apparatus
located between the ER and plasma membrane
location of cis golgi
stacks of golgi apparatus closest to ER
location of trans golgi
stacks of golgi farthest from ER, closest to plasma membrane
What part of golgi do vesicles from ER fuse to?
fuse with cis golgi
Give an example of a role of the golgi
carries out postranslational modification of proteins through glycosylation (adding sugar groups to proteins) so they can go to plasma membrane
how do proteins move from stack to stack in cis golgi?
they are packaged in vesicles and as they move, they fuse with the stack and release contents.
what happens to proteins in trans golgi?
they are sorted into vesicles bsed on signals on the proteins that indicate their destination
contain hydrolytic enzymes that break down the various biological molecules to their building blocks to be used in new synthesis
What is the pH inside the lysosome?
slightly acidic, pH 5, optimal for enzymes. This is kept separate by lysosome membrane
what is special about peroxisomes?
contain oidative enzymes that catalyze reactions where hydrogen peroxide (toxic) is created and then destroyed.
what do peroxisomes break down?
fats into small molecules to be used for fuel, in liver used to detoxify alcohol
source of energy and site of aerobic respiratin
What is special about mitochondria phospholipid bilayer membrane?
it has many pares that allow some molecules to enter on the basis of their size
the internal compartments formed by the inner membrane of a mitochondrion
matrix of mitochondria
the area bounded b the innermembrane, site of reactions involved in cell respiration (electron transport, krebs cycle and ATP production)
What is unique about mitochondria?
They contain their own circular DNA and ribosomes, both of which resemble those of prokaryotes. They can self-replicated through binary fission
the theory that mitochondria developed from prokaryotic cells, providing energy to host cell and protection from environment (symbiosis)
what is one major organelle that animal cells have but plant cells do not?
only in plant cells and protist. Function in photosynthesis, have their own DNA and ribosomes
membrane sacs inside chloroplast
the stacks in the thylakoids tht are derived from the inner membrane
the floid inside the chloroplast surrounding the grana
Where is the chlorophyll of the cell located?
in the thylakoid membranes
What are the specialized plant organelles?
chloroplasts, large vacuoles, cellulose cell wall
membrane-enclosed sacs within cells. In plants, they can take up to 90% of the cell volume. Store waste products
What is the difference between genome in prokaryotes and eukaryotes?
pro- small, circular, no histones. Euk- large segmented chromosomes with histones, packaging
where does ATP production occur in prokaryotes v eukaryotes?
pro- plasma membrane, euk- mitochondria
what is the difference between flagella in prokaryotes vs eukryotes?
pro- unique structure, euk- with microtubules
What is the diff between RNA processing in prokaryotes vs eukaryotes?
pro- no splicing, euk- 5-cap, poly-A tail, mRNA splicing
Where does transcription and translation occur in pro- vs euk-?
pro- together in cytosol, euk- separate
Difference between cytoskeleton of pro- and euk-?
pro- do not have cytoskeleton, euk- do have one