chapter 7: inside the cell Flashcards
prokaryotic cells
archea, bacteria, e coli
- HAS A nucleoid instead of a nucleus which can contain plasmids
- most have a single circular chromosome located in nuceloid
- large # of ribosomes
- can be photosynthetic
-some possess primitive organelles
- have thick cell wall to protect themselves
- have flagella + fimbriae
whats a nuceloid?
irregularly shaped region that stores DNA
prokaryotic dna is found
supercoiled due to the length of DNA relative to the size of the prokaryotic cell
what are plasmids?
segments of circular dna that encode for RNA/ protein but independent of. chromosome
referred to as a auxiliary/ secondary genetic element
what can take up plasmids??
bacteria
prokaryotes having a large # of ribosomes inside their cells represent
machinery that carries out the conversion of RNA to protein
(prokaryotes can be photosynthetic)
cyanobacteria have
thylakoid membranes containing enzymes capable of converting sunlight into energy
(some prokaryotes possess primitive organelles)
some bacterial species have organelles that concentrate carbon dioxide in order to produce…
more complex macromolecules (carboxysomes)
(prokaryotes have thick cell wall to protect themselves)
cytoplasm of most bacteria and archea contains
higher concentration of solutes than the external environment
molecular motor protein that prokaryotes have
flagellum
projections from their surface (prokaryotes) that allow them to move around in evironment
fimibriae
do prokaryotes or eukaryotic cells have specialized organelles?
eukaryotic cells!!
compared to prokaryotic cells, eukaryotic cells are ____ in size
larger but theres a con
as cell size increases
volume increases and surface area decreases (area where diffusion occurs)
diffusion of ions and particles are less efficient in cells with
a small surface area and large volume
diffusion of ions and particles are more efficient in cells with
larger surface are and smaller volume
how do organelles help eukaryotic cells
- increase surface area of a cell to volume ratio
- increase specificity …. serve as area of specialization within the cell (specific cellular processes take place)
- allow for specific chemical reactions to be more efficient
how do organelles allow for chemical reactions to be more efficient in eukaryotic cells?
by concentrating specific enzymes in one location
ex: enzymes needed for ATP production are concentrated more at mitochondria
nucleus is storage site for
genetic information/DNA/ most genes in cells
some genes are also found in the
mitochondria and chloroplasts (mainly nucleus)
nucleus is enclosed by a
double membrane (2 lipid bilayers) = nuclear envelope
nuclear envelope has many pore like openings (nuclear pores) that allow
proteins to enter and exit the nucleus
the nucleolus (inside the nucleus) is responsible for
producing ribosomal RNA molecules
how does RNA enter the cytoplasm after exiting the nucleus
by nuclear pores
what is the site for protein and lipid production?
Endoplasmic reticulum (ER)
endoplasmic reticulum and golgi apparatus both have
membranous sacs and tubules (cisternae)
ER is divided into 2 types
- rough (ribosomes)
- smooth (no ribosomes)
rough er has its name bc the surface is lined with
ribosomes and is a site of protein synthesis
ribosomes are
rna/ protein molecular machines that take mRNA + manufacture protein from it
ribsomes can be found freely in the
cytosol
what type of proteins are made by rough ER?
transmembrane/integral proteins or secreted proteins which are then modified
proteins made in cytosol are
soluble proteins
in ER, what are newly proteins modified with?
carbohydrates which form glycoproteins allowing them to undergo proper folding into tertiary/quaternary structures
why are smooth er called smooth?
due to the lack of ribosomes on its surface
what are smooth er responsible for?
for the synthesis of lipid species (phospholipids and steroids like sex hormones)
smooth er are also a storage site for
calcium ions
in the muscle cells, calcium ions stored in smooth er are released for …
muscle contraction when a nerve stimulates the muscle
where are proteins modified and secreted?
in the golgi apparatus
functions of golgi apparatus
- receive newly made proteins from ER
- modify those proteins w. carbohydrate molecules needed for their proper function (glycoproteins)
- sorts and transports proteins to many locations throughout the cell
cis- cisternae are
closest to nucleus
- mojdifying
trans- cisternae are
closest to plasma membrane
- sorting of proteins then transports them
as proteins move from cis- to trans- cisternae why are they processed in different ways ?
bc of the unique types of enzymes in each cisternae
what are the centers for reduction-oxidation reactions?
peroxisomes
peroxisomes have
enzymes that remove hydrogen atoms from many harmful substances (alc.) and transfer them to oxygen, producing hydrogen peroxide as by-product (neutralizing it)
(has catalase)
catalase
enzymes that break down hydrogen peroxide (H2O2) into water and oxygen…preventing H2O2 from doing any cellular damage.
in peroxisomes oxygen is used to breakdown…
fatty acids into smaller molecules that act as a fuel source for cellular respiration by mitochondria
what are the recycling centers of cell?
lysosomes
lysosomes contain …
hydrolases enzymes that hydrolyze proteins, carbohydrates, lipids, and other macromolecules into their monomers (basic functional units ex is amino acids)
hydrolases require _____ for their proper functioning
acidic environment/ PH
proton pumps on surface of lysosome maintain…
acidic pH inside the lumen of the organelle which depends on ATP hydrolysis
(non spontaneous)
what do lysosome recycle out?
digested broken down material which then goes into the cytosol for the cell to reuse it
mitochondria and chloroplasts both…
supply energy to cells
in animal and plant cells the mitochondria supplies energy to cells by producing…
ATP (adenosine triphosphate)
does the mitochondria have a double membrane?
Yes!!! Outer smooth membrane and inner (consist for many sac like cristae) membrane
enzymes needed to produce ATP are embedded where?
inner membrane
main site of ATP production is where?
in the mitochondria
mitochondria has their own ribosomes and DNA… the dna is known as what
mitochondrial DNA
mitochondrial dna is independent of
nuclear DNA
It used to be a single free organism (mitochondrial dna)
most mitochondrial genes are those that encode rna for…
mitochondrial ribosomes
chloroplasts are found in
plant and algae
what do the chloroplasts carry out?
photosynthesis
what is photosynthesis?
conversion of sunlight into chemical energy (glucose)
chloroplasts have double membrane but have this unique structure…
thylakoids
thylakoids are
membrane bound sacs with enzymes that carryout photosynthesis. it is surrounded by an aqueous fluid (stroma)
stroma contains…
enzymes that convert chemical energy produced by photosynthesis into sugars
what is thought about both chloroplasts and mitochondria?
they are ancestral prokaryotes that were engulfed by larger prokaryotes (eukaryote ancestor)
how were these small prokaryotes kept alive?
due to their ability to produce energy for larger prokaryotes === eventually evolved to form 1st eukaryote cells (endosymbiosis theory)
nuclear pore complex
multi subunit protein complex that has around 30 different proteins interacting
what does the nuclear pore complex do?
it regulates the import + export of molecules into and out of nucleus
does dna exit or enter the nucleus?
does rna? do proteins?
DNA does NOT
rna and proteins do but require active transport.
what can freely diffuse through nuclear pores?
nucleotides
nuclear localization sequence/ nuclear export sequence
molecular zip codes/sequences that allow proteins to enter/exit nucleus respectively
RNA molecule are bound to what part of a protein to aid in export out of nucleus ?
bind in 5’ end and 3’ end, assisting in the rna passage
what is the cells trafficking system?
endomembrane system
what does the endomembrane system do?
sort and deliver cargo (like proteins) needed for normal cell function throughout the cell
what is part of the endomembrane system?
ER, golgi, endosomes, mitochondria, plasma membrane etc.
what is the secretory pathway responsible for
production and trafficking of newly synthesized proteins
in the secretory pathways, newly made proteins go from er to golgi thennn brought into
vesicles and then delivered to locations throughout the cell (plasma membrane for examples, etc.)
what did the pulse chase experiment track?
protein movement
what is the network of fibers that provide structural support for cells
cytoskeleton
how many types of filaments make up the cytoskeleton and what are they
3 types
1. actin filaments
2. intermediate filaments
3. microtubules
how are the 3 types of filaments distinguished?
by size, structure, and type of protein subunit
actin filaments (microfilaments)
structure is two coiled strands (7nm) with actin subunits
function is to maintain cell shape by resisting tension/pull. Move cells via muscle contraction/cell crawling. Divide animal cells into 2. Move organelles + cytoplasm in plants, fungi, and animals.
intermediate filaments
structure is fibers wound into thicker cables (10 nm)
has subunits of keratins and lamins, etc.
function is to maintain cell shape by resisting tension/pull. Anchors nucleus and other organelles.
microtubules
structure is a hollow rod (25nm)
subunits of alpha and beta tubulin dimers
function is to…
maintain cell shape by resisting compression (push). Move cells via flagella / cilia. Move chromosomes during cell division. Assist formation of cell plate during plant cell division. Provide tracks for intracellular transport.
AIDS IN CELLULAR MOVEMENT
are microtubules constructed from related protein subunits?
yes, alpha tublin and beta tublin which interact to form a heterodimer
similar to actin, tubulin dimers polymerize in a
minus to plus end fashion… alpha to beta direction forming protofilaments
protofilaments interaction forms
the actual microtubule
are microtubules or actin larger?
microtubules are much larger
where do microtubules originate from?
from the structure, microtubule organizing center (MTOC)
in most animal cells, where are MTOC located near?
the nucleus known as the centrosome which consists of 2 centrioles
what do centrioles consist of ?
9 sets of triplet microtubules arranged in a ring (microtubules flow from)
microtubules work with
motor proteins (kinesin and dynein)
microtubules play huge role in what?
separating chromosomes during mitosis and meiosis ALSO cell motility and vesicle trafficking
in vesicle trafficking, what happends?
vesicles are transported to destinations along microtubules with help of motor proteins (dynein and kinesin)
dynein and kinesin hydrolyze what?
ATP to ADP and during this it undergoes conformational changes that allow them (and associated vesicles) to move across microtubules
anything dynein or kinesin do requires hydrolysis of ATP so its…
non spontaneous (requires energy)
flagella
whip like projections that aid in cell movement
cilia
many tiny hair like projections aid in cell movement
structure of both flagella and cilia have…
axoneme
what is a axoneme?
a ring of 9 microtubule pairs surrounding 2 central microtubules
where does the axoneme originate from?
from basal body (equivalent of the centriole but distinct) which is anchored in the cell underneath plasma membrane
the use of dyneins that are attached along each outer microtubule pair is used in what movement?
flagella and cilia
hydrolysis of ATP causes microtubule pairs to …
oscillate
actin filaments are long strands of
actin monomers bound to one another, which coil to form a helical structure
has a plus and minus end
plus end of actin filaments is associated with
faster polymerization
minus end of actin filaments is associated with
slower polymerization
can actin monomers be recycled?
yes by depolymerization process
what does the depolymerization process do
allows actin monomers to be reused for additional polymerization reactions
what does treadmilling mean?
net growth at plus end and net disassembly at minus end
theres net polymerization at the ____ end
plus
theres net depolymerization at the ____ end
minus
actin works with what motor protein?
myosin
cytokinesis
cell division
cytoplasmic streaming
movement of cytoplasm
actin plays major role in … (3 things)
- motility (movement)
2.cytokinesis
3.cytoplasmic streaming
myosin hydrolyzes ATP to ADP and in the process creates….
mechanical energy
during ATP hydrolysis myosin undergoes what?
conformational changes causing head region to extend and attach to actin and then pull itself… resulting in contraction of actin- myosin bundle
both actin and myosin interaction causes….
movement
