Chapter 4: General Features of Cells Flashcards
prokaryotes
simple cell structure, no nucleus
eukaryotes
more complex cells, DNA enclosed within membrane-bound nucleus, internal membranes from organelles
cytoplasm
contained within plasma membrane (everything found within the cell)
cytosol
everything outside the cell organelles but inside the plasma membrane
nucleoid region (bacteria)
where DNA is located
ribosome
synthesizes proteins, not an organelle
cell wall
provide support and protection
glycocalyx (bacteria)
traps water, gives protection, helps evade the immune system
appendages (bacteria)
pilli (attachment), flagella (movement)
organelles
membrane-bound compartments, each has unique structure and function
variety
shape, size, and organization of cells vary considerably
chloroplast
site of photosynthesis
central vacuoles
site that provides storage and regulation of cell volume
cell wall
structure that provides cell support
cytoskeleton
network of three types of protein filaments: microtubules, intermediate filaments, actin/microfilaments
microtubules
hollow and composed of protein tubulin; functions in cell shape, organization of organelles, intracellular cargo movement, cell mobility
intermediate filaments
twisted filaments and can be composed of different proteins; function in cell shape, cell strength, anchoring of cell, nuclear membrane
actin/microfilaments
spiral-shaped composed of intertwined strands of actin; function in cell shape, cell strength, muscle contraction, cell movement, cytokinesis in animal cells
cytokinesis
step in cell division when a cell splits into two
motor proteins
use ATP as a source of energy for movement
motor protein movement
- carries cargo along filament
- motor protein remains fixed, filament moves
- motor protein and filament remain fixed, filament bends
flagella
usually longer than cilia, present singly or in pairs
cilia
often shorter than flagella, tend to cover all or part of the cell surface
propagation of a bend
flagella/cilia movement begins at the base and moves toward the tip
endomembrane system
enclosing the nucleus, endoplasmic recticulum, golgi apparatus, lysosomes, vacuoles, and plasma membrane
nuclear envelope
double-membrane structure enclosing nucleus, outer membrane is continuous with ER membrane
nuclear pores
provide passageways into the nucleus
chromosomes
composed of DNA and proteins
chromatin
complex of DNA and proteins
euchromatin
loosely distributed, transcriptionally active
heterochromatin
densely packed, transcriptionally inactive
nuclear matrix
filamentous network, organizes chromosomes
nucleolus
where ribosome assembly occurs
endoplasmic recticulum
network of membranes that form flattened, fluid-filled tubules or cisternae
ER lumen
single compartment created by the ER membrane
rough endoplasmic recticulum
studded with ribosomes, involved in protein synthesis and sorting
smooth endoplasmic recticulum
lacks ribosomes, detoxification, carbohydrate metabolism, calcium balance, synthesis, and modifications of lipids
golgi apparatus
stack of flattened membrane-bound compartments
vesicles
transport materials in the cell
pulse-charge experiments
used by George Palade to trace the path of radioactive proteins
lysosomes
contain acid hydrolase that promotes hydrolysis, breaks down carbohydrates, nucleic acids, and lipids
autophagy
recycling of worn-out organelles through endocytosis
central vacuoles
used for storage and support in plants
contractile vacuoles
used to expel excess water in protists
phagocytic vacuoles
used for degradation in protists and white blood cells
perozisomes
catalyze certain reactions that break down molecules by removing hydrogen or adding oxygen
catalase
breaks down dangerous hydrogen peroxide into water and oxygen
plasma membrane
boundary between the cell and extracellular environment
membrane transport
in and out of the cell with selective permeability
cell signaling
using receptor
semiautonomous organelles
mitochondria and chloroplasts
mitochondria
primary role is to make ATP, also involved in the synthesis, modification, and breakdown of several types of cellular molecules
mitochondrial matrix
inner folded part that allows for more reactions to make ATP
chloroplasts
perform photosynthesis
photosynthesis
capture light energy and use some of that energy to synthesize organic molecules like glucose
thalakoid membrane
surrounds the compartment where photosynthesis occurs
evidence of mitochondria and chloroplasts being descended from bacteria
different ribosomes, contain circular DNA, similar structure to bacteria
protein sorting
how eukaryotic proteins are sorted to the right destination
co-translational sorting
begins in cytosol during translation, ER signal sequence binds signal recognition particle (SRP) and associates with ER channel
- for: ER, golgi apparatus, lysosomes, vacuoles, plasma membrane, and secreted proteins
post-translational sorting
synthesized in cytosol and taken up by target organelles; short amino acid sequence directs the protein to its target where its taken up from the cytosol
-for: nucleus, mitochondria, chloroplasts, and peroxisomes
