C2: Eukaryotic Cells Flashcards
Class 2
what is the function of the nucleus?
holds the genome, transcription takes place here
what is the function of the nuclear envelope?
it is inside the nucleus, separates its contents into distinct compartments
what is the function of the nucleolus?
a ribosome factory
what is the function of the mitochondria?
produces ATP via cell respiration, contains mitochondrial DNA
what is the function of the chloroplast ?
photosynthesis, contains chloroplastic DNA
what is the function of the ribosomes?
translation
what is the function of the centrosome?
- what is it made up of?
anchors the mitotic spindle
- 2 centrioles and some proteins
what is the function of the cytoskeleton?
- what 3 things is it composed of?
structural support of the cell, transport around the inside of the cell, movement of the cell
- microtubules, intermediate filaments, microfilaments
what is a microtubule composed of?
- what is a microtubule organizing center?
- what does the MTOC contain?
2 globular proteins, alpla tubulin and beta tubulin which form an alpha beta tubulin dimer which allows the microtubule to elongate
- the end of the microtubule that does NOT elongate
- a pair of centrioles
what is a microfilament composed of?
- what are they responsible for?
rods formed in the cytoplasm from the polymerization of the globular protein actin
- amoeboid movement: changes in the cytoplasmic structure that cause the rest of the cell to flow in one direction
what is the function of cilia and flagella?
- how are they arranged?
- how are they anchored to the plasma membrane?
move fluids past the cell surface
- 9 + 2 arrangement of microtubules, each one bound to its neighbor by dynein
- basal body
what is the only flagellated cell in eukaryotes?
sperm cells
what is the function of intermediate filaments?
provide strong cell structure
what is the function of the rough ER?
translation of proteins in secretory pathway
what is the function of the smooth ER?
steroid biosynthesis, calcium storage, detoxification and glycogen breakdown
what are the 3 functions of the golgi body/ apparatus?
- modification and sorting of proteins made in the RER
- sorting/ sending proteins to their correct destination
- synthesizing certain macromolecules
what is a constitutive secretory pathway?
when proteins are sent in vesicles from the Golgi immediately to the cell surface
what is a regulated secretory pathway?
- where is this pathway present?
when specialized secretory cells store secretory proteins in secretory vesicles and release them only at certain times, usually in response to a change from the extracellular environment
- Golgi apparatus
what is the function of lysosomes?
degradation, contains acid hydrolases that digest various substances and stores hydrolytic enzymes
what is autophagy?
- phagocytosis?
- crinophagy?
- in what cell structure do these processes occur?
self-eating
- cell eating
- digestion of unneeded secretory products
- lysosome
what are the enzymes responsible for degradation in lysosomes?
acid hydrolases
what is the function of peroxisomes?
degradation (lipids) and detox, contains catalase
what is the function of the vacuole?
sacs of water with organic or inorganic solutes, storage (especially water), help isolate harmful substances
what is the largest organelle found in plant cells and what is its function?
central vacuole, used for water storage
all membranes of the cell are composed of ….
lipid bilayer membranes
what are the 3 most common lipids in eukaryotic membranes?
- of these 3 which are the most abundant?
phospholipids, glycolipids, cholesterol
- phospholipids
plasma membranes are composed of…
phospholipids, glycolipids, cholesterol, proteins, carbohydrates
what are cell surface receptors?
- where are they synthesized?
bind extracellular signaling molecules such as hormones and relay these signals into the cell so it can respond accordingly
- in the rough ER
what are intracellular enzymes and where are they synthesized?
proteins synthesized in the cytoplasm
what is a ligand?
the molecule that serves as a key for a given cell surface receptor
what is signal transduction?
the signal that is triggered by the binding of a ligand to its receptor on the extracellular surface of the plasma membrane
what are the 3 types of signal transduction cell surface receptors?
- ligand gated ion channels
- catalytic receptors
- g protein linked receptors
in cell surface receptors,
what is the function of a ligand gated ion channel?
opens an ion channel upon binding a particular neurotransmitter
in cell surface receptors,
what is the function of a catalytic receptor?
- what enzyme helps with this?
have an enzymatic site that is initiated by ligand binding at the extracellular surface
- kinase
in cell surface receptors,
what is the function of a g protein linked receptor?
does not directly transduce its signal, transmits it into the cell with the help of a second messenger
what are the 2 types of g protein linked receptors?
- Gs: stimulatory
- Gi: inhibitory
what is the most important second messenger?
- what hormones does it serve?
- what do these hormones cause?
cyclic AMP (cAMP)
- epinephrine and glucagon
- energy mobilization
what are channel proteins?
selectively allow ions or molecules to cross the membrane
what are integral membrane proteins?
- peripheral membrane proteins?
proteins actually embedded in the membrane, held there by hydrophobic interactions
- not embedded in the membrane, stuck to integral membrane proteins, held there by hydrogen bonding and electrostatic interactions
what is the fluid mosaic model?
says that the membrane is seen as a mosaic of lipids and proteins that are free to move back and forth fluidly
the membrane is said to have ….
polarity
a solute will always diffuse ____ its concentration gradient, which means from ____ to ____ concentration
down; high; low
what is osmosis?
a special type of diffusion in which solvent diffuses rather than solute
in diffusion, ____ moves towards equilibrium and the membrane is permeable to ____. in osmosis, ____ moves towards equilibrium and the membrane is permeable to ____
solute; both solvent and solute; solvent; solvent but impermeable to solute
within osmosis,
what does isotonic mean?
the solute concentration is the same inside and outside
within osmosis,
what does hypertonic mean?
a solution that has more total dissolved solutes than a cell
within osmosis,
what does hypotonic mean?
a solution that has less solute on the outside of the cell compared to the inside of the cell
what is osmotic pressure?
the tendency of water to move down its concentration gradient and possibly cause the cell to explode
how do molecules travel via passive transport?
- does this form of transport require energy?
- down concentration gradient
- no
what are the 2 types of passive transport?
facilitated diffusion and simple diffusion
how do molecules travel via facilitated diffusion?
what are 2 examples?
solute goes through a protein
- water and glucose since they are hydrophillic
how do molecules travel via simple diffusion?
what is an example?
solute goes through without a protein
- small hydrophobic molecules (steroids, cholesterol, fatty acids)
what are the 2 types of facilitated diffusion?
channels and carriers/ports
within a membrane,
what is a pore?
a tube through the membrane that is so large it is not selective for any particular molecule, any molecule may pass
how do molecules travel via channels?
narrow opening, surrounded by protein
how do molecules travel via carriers/ports?
solute binds one side and comes out other side
what are the 3 types of channels?
unregulated, ligand- gated, voltage- gated
what is an unregulated channel?
open all the time, leak channels, aquaphorins
what is a ligand- gated channel?
open in response to ligand binding
what is a voltage-gated channel?
open in response to changes in plasma membrane potential
what are the 3 types of carriers/ports?
- what does each one mean?
uniport, symport, antiport
- uniport: 1 thing being transported
- symport: 2 things being transported in the same direction
- antiport: 2 things being transported in opposite directions
how do molecules travel via active transport?
- does this form of transport require energy?
up a concentration or electrochemical gradient
- yes
what are the 2 types of active transport?
primary and secondary
what is primary active transport?
- what is an example?
ATP is used directly
- sodium potassium pump
what is secondary active transport?
- what is an example?
ATP is used to make a gradient, transport is coupled to this gradient
- Na+ glucose symporter
what is the Na+/K+ ATPase?
- what does it do?
a transmembrane protein in the plasma membrane of all cells in the body
- pumps 3 Na+ out of the cell, 2 K+ into the cell, and hydrolyzes 1 ATP to drive the pumping of these ions against their gradients
in a sodium potassium pump,
what is a potassium leak channel?
when potassium ions that are pumped into the cell are able to leak back out
in a sodium potassium pump,
what is the resting membrane potential?
as potassium leaves the cell through the leak channels, the movement of positive charge out of the cell creates an electric potential across the plasma membrane with a net negative charge on the interior of the cell
what is exocytosis?
a process to transport material out of the cell
what is endocytosis?
materials are taken in by the cell
what do macrophages do?
engulf large particles in phagocytosis
what is pinocytosis?
cell drinking
what is receptor- mediated endocytosis?
- what is an important example?
the site is marked by pits coated with clathrin (inside the cell) and receptors that bind to a specific molecule (outside the cell)
- the uptake of cholesterol from the blood
what is a centromere?
what chromosomes have near the middle to ensure that newly replicated chromosomes are sorted properly during cell division, one copy to each daughter cell
what is a telomere?
with the help of telomerase (a DNA polymerase), maintain the ends of the linear chromosomes during DNA replication
what are the 5 phases of the cell cycle?
G1, G0, S, G2, mitosis
describe the G1 phase of the cell cycle?
cell growth, metabolism, make organelles
describe the G0 phase of the cell cycle?
not all cells go through this phase, the cells are still alive but exit the cell cycle and are non-dividing
describe the S phase of the cell cycle?
synthesis of the genome, DNA replication
describe the G2 phase of the cell cycle?
similar to G1, prep for mitosis
describe the mitosis phase of the cell cycle?
- what are the las 2 stages of mitosis called?
PMAT: prophase, metaphase, anaphase, telophase
- cytokinesis
in mitosis,
what happens during prophase?
chromosomes condense, nuclear envelope degrades, mitotic spindle appears, centrosomes move to the ends of the cells
in mitosis,
what happens during metaphase?
chromosomes line up on metaphase plate, spindle fibers attach to centromeres of chromosomes
in mitosis,
what happens during anaphase?
homologous chromosomes separate, sister chromatids move to opposite ends of the cell, number of chromosomes double because you go from X shaped chromosomes to linear ones
in mitosis,
what happens during telophase?
- what specific feature is present within this phase?
opposite of prophase, cytokinesis, ends with 2 cells and each is diploid but the chromosomes are linear
- cleavage furrow made of microfilaments that pinches the cell into 2
what are oncogenes?
mutated genes that induce cancer
what do homologous chromosomes have in common?
- different?
- where do they come from?
- where are they located within the cell cycle?
same length and genes
- different sequence and alleles
- 2 chromosomes, 1 from mom 1 from dad
- G1 phase
what are sister chromatids?
- where are they located within the cell cycle?
- where do these chromosomes come from?
they are completely identical since they are the product of DNA replication. same length, genes, sequence, alleles
- G2 phase
- 2 chromosomes, 1 from mom 1 from dad BUT have double the amount of DNA since DNA replication has already been completed
what is the role of microtubules during a cell cycle?
pull apart the sister chromatids during anaphase
a chromosome is made up of 2 ____
sister chromatids
within chromosome structure, what is a telomere?
the end of a chromosome, helps with stability and cell aging/ lifespan. are consumed and shorten during each cell division
when telomeres become too short and reach a length where a chromosome can no longer replicate, they can do 1 of 3 things….
- activate DNA repair pathways
- enter a senescent state (where they are alive but not dividing)
- activate apoptosis
what is the hayflick limit?
the # of times a normal human cell type can divide until telomere length stops cell division
many age related diseases are linked to ____
telomere shortening
within chromosome structure, what is a mitotic spindle fibre?
made of microtubules, connected to the centromere
within chromosome structure, what is a kinetochore?
complex of proteins, associated w centromere, attach to spindle fibres
cells stained for kinetochore proteins have ____ visible punctae at the beginning of ____and 92 at the end of ____
46; anaphase; anaphase
there are ____ kinetochores per tetrad and ____ kinetochores in each cell at the end of ____
4; 23; telophase II
within chromosome structure, what is a centromere?
part of chromosome where sister chromatids are connected, divides into chromosome arms
what are the little arm and long arm called within a chromosome (respectively)?
p and q
eukaryotic DNA is ____ around ____ proteins and packaged into ____
wrapped; histone; chromatin
what are introns?
regions of eukaryotic DNA that are transcribed into RNA but ultimately spliced out during mRNA processing and thus never translated into a protein
what are exons?
the regions between the introns that are translated and therefore have also been transcribed
how many different human chromosomes are there?
- humans and most animals are ____, they have ____ copies of each chromosome (except ____ chromosomes which are ____ and ____)
46 (23*2); diploid; 2; sex; X; Y
what is the endosymbiotic theory?
mitochondria originated as independent unicellular organisms living within larger cells
mitochondria exhibit ____ inheritance, which means ….
maternal; mitochondria are inherited only from the mother
what are the 2 sites of protein synthesis in a eukaryotic cell?
ribosomes free in the cytoplasm or ribosomes bound to the rough ER
proteins that are synthesized in the rough ER will end up in 1 of 3 ways ….
- secreted into extracellular environment
- as integral plasma mem. proteins
- in the membrane or interior of the ER, golgi apparatus or lysosomes
how do epithelial cells prevent things from moving freely within the body?
tight junctions
what do desmosomes do?
make sure epithelial cells in the skin are held together tightly but do not form a complete seal
what do gap junctions do?
- what type of cells contain these?
allow ions to flow back and forth in specialized cell types
- heart muscle cells
what is the eukaryotic cell wall made up of?
cellulose or chitin
both prokaryotes and eukaryotes translate proteins in the ____
cytosol
____ is located in the cytoplasm and therefore has no ____ sequence or ____ domains
hexokinase; signal; transmembrane
all living things are composed of ____
organic molecules
