Cell Ultrastructure and Cytoskeleton Flashcards
2 major categories of organisms
prokaryotes
eukaryotes
prokaryote examples
monera, cyanobacteria
eukaryotes examples
single-celled protists, protozoa, multicelled metazoans
metazoans
multicellular organisms
Is is present or absent in prokaryotes and eukaryotes?
nucleus with nuclear envelope
prokaryotes: absent
eukaryotes: present
Is is present or absent in prokaryotes and eukaryotes?
membrane bound organelles
prokaryotes: absent
eukaryotes: present
Is is present or absent in prokaryotes and eukaryotes?
histones
prokaryotes: absent
eukaryotes: complex with DNA
Is is present or absent in prokaryotes and eukaryotes?
DNA
prokaryotes: circular
eukaryotes: organized into chromosomes
Is is present or absent in prokaryotes and eukaryotes?
flagella
prokaryotes: lack axoneme
eukaryotes: axoneme present
Is is present or absent in prokaryotes and eukaryotes?
cell wall
prokaryotes: unique
eukaryotes: absent in animals, present in plants and fungi
protoplasm
~70-85% water, electrolytes, proteins, lipids, carbs
chromatin
DNA complexed with nucleoproteins
chromatin is packaged into
chromosomes
individual chromosomes contain
genes
genes
segments of DNA coding for particular traits
alleles
different forms of the same gene
inmost eukaryotic cells, chromosomes exist as
homologous pairs
diploid in humans
2n=46
haploid
n=23
karyotyping
sorting of chromosome pairs according to size and shape
heterochromatin
e- dense, darkly staining, inactive DNA and nucleoproteins
Barr body
permanently inactive DNA found in females
represents degenerates X chromosomes, only 1 of pair active, other degenerates
euchromatin
dispersed DNA active in transcription (RNA synthesis)
cells active in translation will have prominent
nucleolus and abundant euchromatin
why do we have RNA?
DNA is trapped in the nucleus and the machinery is in the cytoplasm. the DNA cannot exit the nucleus, however the RNA can
most chromatin in the nucleus is
inactive heterochromatin
only a small % active at any one time is euchromatin
lamp brush chromatin
active portions of chromosomes unravel to become visible
histones assist with
DNA folding chromatin organization into chromosomes
nucleosomes
segments of DNA wrapped around several histones
regulate DNA activity
non histones
additional category of nucleoproteins; may also be involved in regulation of gene activity
nuclear envelope separates
nucleoplasm from cytoplasm
two layers of the nuclear envelope
inner and outer nuclear membrane separated by perinuclear cisterna
nuclear lamina
inner nuclear membrane associated with network of lamin filaments
outer membrane is studded with ribosomes
continuous with eER
inner and outer nuclear membranes are connected by a
nuclear pore complex
nucleoproteins
ring of proteins which surrounds the nuclear pore complex
nuclear envelope regulates the exchange of
macromolecules between the nucleus and cytoplasm
ribosomes are bipartite, meaning
two subunits
40s and 60s
=80
ribosomes contain
protein
rRNA
ribosomes are synthesized and assembled in the
nucleolus
ribosomes are found
free in the cytoplasm and attached to rER and outer nuclear membrane
polyribosomes/polysomes
aggregates of ribosomes and mRNA, frequently attach to ER
if ribosomes attach to ER, it becomes
rER
ribosomes are the site of
protein synthesis (translation)
mitochondria produce energy (ATP) via (2)
krebs cycle
oxidative phosphorylation
mitochondria vary greatly in
size, shape, and number within the cell
oblong to oval, move
freely within the cytosol
mitochondria are present in all cells, except (2)
rbc
keratinocytes
(limits their life span because they dont have an energy source)
mitochondria membranes
inner and outer
microchondrial inner membrane is
pleated to form folds, known as cristae
cristae are lined with
elementary particles that contain enzymes for oxidative phosphorylation
mitochondrial outer membrane is
permeable, containing pore-forming protein, porin
inner cavity of the mitochondria is filled with
amorphous matrix material
matrix also contains
dense grandules
dense granules are thought to be
binding/storage sites for Ca
mitochondrial DNA is
circular
mitochondria replication
self replicating
reproduce by binary fission, similar to bacterial division
mitochondrial ribosomes are similar to
bacterial ribosomes
mitochondria are inherited
maternally
mitochondria are similar to
prokaryotes
cells depend on energy derived from
cellular respiration
energy released from chemical breakdown of organic molecules from diet (proteins, carbs, fat)are stored in the form of
ATP
cell respiration begins in the cytosol where glucose is
converted to pyruvic acid
pyruvic acid then diffuses into the
mitochondria
mitochondria is the site of
aerobic respiration
mitochondria matrix contains enzymes of the
krebs cycle
pyruvate=co2+h2o+ATP
the most ATP is produced during
oxidative phosphorylation by cytochromes of the ETC
cytochromes
enzymes on the inner membrane of cristae
krebs cycle and oxidative phosphorylation within the krebs cycle both require
o2
aerobic respiration
rER has surface receptor molecules for
ribosomal attachment
rER specializes in
protein synthesis
sER function in (5)
lipid synthesis transport of proteins from rER to golgi membrane formation recycling synthesis of cholesterol and steroid hormones
sER is the principle organelle involved in
detoxification and conjugation of drugs and toxins
coated vesicles
surround and coat proteins for transport, bud off sER, transport proteins between sER and golgi and between golgi and cell
golgi functions in
post-translational modification, packaging, and sorting of proteins synthesized in the rER
examples of post-translational modification
sulfation
phosphorylation
glycosylation
convex golgi vs concave golgi
forming face
maturing face
convex golgi is where
proteins arrive from rER in coated transfer vesicles
cis
concave golgi is where
proteins packaged into clathrin-coated vesicles are secreted
trans
glogi curvature is from
vesicles constantly budding off and arriving
vesicles bud off maturing face as
condensing vacuoles, sorted into secretory vesicles for extracellular export via exocytosis or as membrane-bound vesicles for internal use, or as secretory granules for long term storage
membrane trafficking
during exocytosis and secretion, large amounts of intracellular membrane incorporated into outer cell membrane- recycled by golgi
lysosomes
membrane-bound vesicles containing hydrolytic enzymes
ex. acid phosphatase
1’ lysosome
newly formed lysosomes produced by rER and golgi
phagolysosome/2’ lysosome
when 1’ lysosome fuses with phagocytic vesicles
hydrolytic breakdown results in the production of
3’ lysosome/ residual body
3’ lysosome may either be
excreted or remain in cells for life
lysosomes and apoptosis
lysosomes used to degrade organelles and cells with finite lifespans during apoptosis (autophagy)
endosomes
endocytic vesicle with acid pH in lumen
endosomes have an acid pH because
proton pumps in the membrane, which pump H+ into the interior, acidifying its contents
peroxisomes (microbodies)
membrane bound organelles containing oxidative enzymes (oxidases)
peroxisomes resemble
lysosomes
peroxisomes contain (2)
catalase
peroxidase
peroxisomes use enzymes, free radicals, and hydrogen peroxide to
oxidize toxic metabolites
peroxisomes are seen in
kidney and liver cells which digest toxins from the environment
non-living components of the cell include (5)
neutral fat droplets lipids glycogen secretory granules pigment granules
viral inclusions can be (2)
intracytoplasmic or intracellular
melanin
black, brown, granular pigment; produced by melanocytes, transported to other cells
lipofuscin
gold-brown granules; frequently seen in neurons; sometimes called “old age pigment” (accumulates in older cells)
mammals have limited pigment bc of
melanin
