Chapter 5: Eukaryotic Cell Structure Flashcards
Eukaryotes have a wide variety of _____ and have
evolved to live in numerous → _____
shapes ; habitats
Eukaryotes are ___ than bacterial and archaeal cells
larger
Eukaryotic cells have
membrane compartments in
the form of →
organelles
organelles
These are internal cell
structures that perform
specific functions for the
cell
Organelles allow for
different functions to act
independently from one
another
The large volume of these
cells requires adequate
regulation, metabolic
activity, and transport
Eukaryotic cell membrane include a phospholipid bilayer
with a high amount of →
sterols
• Cholesterol and ergosterol
These sterol impact the ___ and ____of the
membrane
fluidity ; permeability
They can respond to low or high temperature changes
to maintain the membrane
Eukaryotic plasma membranes contain microdomains
(lipid rafts)
• Areas that differ in protein and lipid composition
• Thought to help in cellular processes like signal
transduction, viral assembly and release, and →
endocytosis
Membrane also have carbohydrate chains that can form →
glycocalyx
glycocalyx
carbohydrate chains
What is the most common type of transport
system?
Facilitated diffusion
Some eukaryotic microbes have
cell walls
Cell walls of photosynthetic algae have
cellulose,
pectin, and silica
Cell walls of fungi consist of
chitin and glucan
Protists that form cysts are mode of multiple layers of
chitin
Cytoplasm
consists of liquid cytosol and many organelles
cytosol
liquid fluid in cell
Cytoskeleton
vast network of interconnected filaments
within the cytoplasmic matrix
Cytoskeleton
vast network of interconnected filaments
within the cytoplasmic matrix
• Filaments that form the cytoskeleton: microfilaments
(actin), microtubules, intermediate filaments, and
motor proteins
• Play a role in both cell shape and cell movement
Actin filaments
small protein filaments
• Scattered within cytoplasmic matrix or organized into
networks and parallel arrays
• Composed of → actin protein
• Involved in cell motion and shape changes
Intermediate filaments
diverse elements of the
cytoskeleton
• Role in cell is unclear, may play structural role
• Some shown to form→ nuclear lamina
• Others help link cells together to form →tissues
Microtubules
shaped like thin cylinders and are made of
α- and β- → tubulin
• Help maintain → cell shape
• Involved with microfilaments in cell → movements
• Participate in intracellular transport processes
Secretory Endocytic Pathway
• Intricate complex of membranous organelles and vesicles
that move materials into the cell from outside, from inside
to outside, and within the cell
• Endoplasmic reticulum (ER)
• Golgi apparatus
• Lysosomes
Endoplasmic reticulum (ER)
membrane network of →
tubules
Functions:
• Transports proteins, lipids, and other materials within
cell
• Major site of cell membrane → synthesis
Rough ER
studded with → ribosomes
• Involved in protein synthesis
Smooth ER
lacks ribosomes
• Produces → lipids
Golgi apparatus
flattened saclike network, packages
materials and prepares them for → secretion
Lysosomes
contain digestive enzymes that allow this
organelle to perform intracellular digestion of
macromolecules
• Found in → animal cells
• Lysosomes contain hydrolases, enzymes which hydrolyze
(break down) molecules and function best under slightly
acidic conditions
• Maintain an acidic environment by pumping protons
into their interior
There are lysosome like organelles in protists and fungi,
which function in storage in addition to intracellular
digestion
Secretory Pathways
Process that moves materials like proteins and lipids to
their → proper location
Transport vesicles leave the Golgi with modified and
packaged proteins
• Takes them either to the plasma membrane or outside
of the cell
“Quality assurance mechanism”
• Unfolded or misfolded proteins
are secreted into cytosol,
targeted for destruction by
ubiquitin polypeptides
• Proteasomes destroy targeted
proteins
Endocytosis
used to bring material → into the cell
• Cells take up material by
enclosing them in vesicles
made from the → plasma
membrane
• Performed by → all
eukaryotes
• Not found in bacteria or
archaea
• Pinocytosis – liquid or small particle intake
• Phagocytosis – large particle intake
Pinocytosis
liquid or small particle intake
Phagocytosis
large particle intake
involves the formation of pseudopods
from the cell surface that surround and bring in a particle
• Forms a phagosome
receptor-mediated
endocytosis is when endocytosis is trigger by the
binding of a molecule called a
___ to a ____
ligand ; receptor
Concentrates the ligand before
it is brought into the cell
Clathrin-dependent endocytosis
clathrin protein-coated pits are used to
internalize hormones, growth factors,
iron, and cholesterol
Caveolin-dependent endocytosis
may
play role in signal transduction and
transport of small molecules such as
folic acid as well as macromolecules
Autophagy
lysosomes of
eukaryotes selectively isolate and
destroy bacteria, viruses, aggregated
proteins, and mitochondria
• Helps cell maintain homeostasis or
destroy pathogens that may have
entered the cell by endocytosis
Nucleus
membrane bound structure that houses
eukaryotic cell genetic material
• Contain one or more chromosomes in the form of →
chromatin
chromosomes
take the form of chromatin inside the nucleus
Chromatin
condensed structure of DNA and
proteins wound around→ histones
• Form a nucleosome “beads on a string
Nuclear envelope
surrounds the nucleus
• Has an inner and outer lipid bilayer and is continuous
with the → ER
Nuclear pores
go through the nuclear envelope allow
small molecules to move between the → nucleus and
the cytoplasm
Nucleolus
found in the center of the nucleus
• Forms ribosomes in eukaryotes
• Directs synthesis and processing of → rRNA
• Directs assembly of rRNA to form partial →
ribosomal subunits
• Ribosomes mature in → cytoplasm
Ribosomes are larger in which cell domain?
Eukaryotic
80S in size: 60S + 40S subunits
• Found free in the cytoplasm or
bound to → RER
• Still responsible for → protein
synthesis
Mitochondria
“powerhouse of the
cell” performs metabolic processes that
generates ATP when oxygen is available
to the cell
• Site of tricarboxylic acid cycle activity
• Site where ATP is generated by
electron transport and oxidative
phosphorylation
Hydrogenosomes
• Small energy conservation organelles in
some anaerobic protists
• ATP is generated by fermentation
process rather than respiration
• CO2
, H2
, and acetate are products
Plastids
organelles of photosynthetic protists and plants
• Most common type are→ chloroplasts
chloroplasts
• Contain chlorophyll and use energy from sunlight to
change CO2
and water to → carbohydrates and O2
Cilia
short, hair-like fibers
• Beat like oars through
surrounding fluid, propelling
organisms
Flagella
long, hair-like fibers
• Beat from base to end,
pushing the cell along
