Ch.2 The Cell Flashcards
(13 cards)
Histones
one of a number of simple proteins (often found in the cell nucleus) that contains a high proportion of basic amino acids, are soluble in H2O, dilute acids and alkalis, and do not coagulate by heat.
Heterochromatin
- condensed chromatin
- peripheral chromatin
- nucleolus associated chromatin
- gene transcription is suppressed
Euchromatin
- extended chromatin
- nonstaining region
- site of DNA transcription
Nucleolus
- exclusive site for syn of rRNA
- components:
- pars granulosa-light part, rRNA to join with
- pars fibrosa-more dense, location of newly synthesize
- nucleolar organizer regions
Centrioles
small, cylindrical structure w/ 9 bundles of microtubules
- arranged in bundles of three (triplets)
- replicate during cell cycle (G2)
- forms mitotic spindle
2 stages of cell cycle:
- Mitosis (1-1.5 hrs)
- Interphase
- G1 phase: 8 hours
S phase: 7-8 hours
G2 phase 4 hours
Nuclear matrix
karyoskeletal network of fibrils in the interior of the nucleus.
-not generally accepted
Nonmembranous organelles
5
- Ribosome
- Microtubules
- Centrioles
- Cilia and flagella
- filaments
Membranous organelles
10
- Cell membrane
- mitochondria
- rough ER
- Golgi ap
- secretory vesicles
- lysosomes
- coated vesicles
- endosomes
- peroxisomes
- smooth ER
inclusions
- nonliving.
- consists largely of secretory vesicles, pigment granules, neutral fat, other lipid droplets, and glycogen
- for stored foods:
- carbs-glycogen
- fat
- for pigments:
- exogenous
- carotene-orange pigment
- carbon particles - endogenous
- Hemoglobin
- Hemosiderin-brown
- Bilirubin-yellow
- melanin-brown to black
- lipofuschin-wear and tear pigment
- exogenous
microtubules
- slender unbranched tubules of tubulin
- like railroad tracks of cell, along which vesicular movement occurs
- movement of cilia and flagella
- during mitosis and meiosis
- cell elongation and migration
- maintenance of cell shape
- motor proteins: dynein(-) and kinesins(+)
- main structural components of centrioles, mitotic spindles, cilia and flagella
Cytoplasmic filaments (threadlike) 3 classes: 1.micofilaments 2.thick filaments 3. intermediate filaments
- thinner, shorter, more flexible than microtubules
- functions:
- anchorage and movement of membrane proteins
- formation of the structural core of microvilli
- locomotion
- extension of cell processes
- components of contractile elements of muscle cells
1. made up of actin
2. composed of myosin- myofibrils-in muscle cells
- stress fibers-bundles of microfilaments in the superficial zone of cytoplasm just under cell membrane
- microvilli-in absorptive cells, supported by cross-linked bundles of microfilaments
- -keratin -vimentin -desmin -neurofilaments -glial filaments
- structural role in the cytoplasmic link of a tissue-wide continuum of cytoplasmic, nuclear, and extracellular filaments
- rod-shaped
- extend across desmosomes/hemides
Cytoplasmic matrix(cytosol) 2 functional domains
- central domain-few supporting intermediate filaments
2. peripheral domain-dense meshwork of actin microfilaments