Chapter 7 - Cell Structure and Function Flashcards
Surface area to volume ratio
inversely proportional
-the smaller the volume of a cell, the larger the surface area to volume ratio
Examples of cells that have exceptional dimensions
1) Nerve cell
- glial cells support and nourish them
2) Muscle cell
- has transverse tubule (T-tubule)
Sedimentation order by weight (differential centrifugation) of plant cells
Central vacuole => Nucleus => Chloroplast => Mitochondria => Endomembrane System => Plasma membrane => Ribosome
Sedimentation order by weight (differential centrifugation) of animal cells
Nucleus => Mitochondria => Endomembrane system => Plasma membrane => Ribosome
Genetic material of prokaryotic cells
Bacterial chromosome
-major genetic information
Plasmid
-accessory genetic information
Prokaryotic capsule
- jelly-like
- composed of polysaccharides to avoid host cell’s immune response
e. g. smooth and rough type - smooth are pathogenic as they are difficult to detect
Mesosome
- infoldings/invagination of the plasma membrane in bacteria
- role: DNA replication, cell division, excretion
Eukaryotic chromatin
30nm fiber
Nuclear lamina
- cytoskeleton with net-like array on the inner membrane
- made of intermediate filament (Structural support)
- damage causes progeria (extreme aging in children)
Plant vs. animal cells
Plant
- cell membrane + cell wall
- organelles of chloroplast and central vacuole
Animal
- only cell membrane
- organelles of lysosomes and centrioles are present
Double membrane organelles
1) Nucleus
2) MItochondria
3) Chloroplast
Nucleolus
- densely stained region within the nucleus
- non-membranous organelle
- role: ribosomal assembly
Ribosome
- made of rRNA + proteins
- has large and small subunit
- free or membrane-bound
Bound ribosome
- attached to rER
- produces secretary proteins (digestive enzymes, hormones)
- chemical modification off proteins (glycosylation)
Free ribosome
- freely floating in cytoplasm
- synthesizes cytoplasmic proteins (e.g. enzymes)
Endomembrane system
- extensive network of membranous organelles
- includes: nuclear envelope, endoplasmic reticulum (rER, see), Golgi apparatus, lysosome, vesicles, plasma membrane
- role: translocation and modification of molecules (nucleic acid, carbs, proteins, lipids) in and out of cells
Transitional ER
- end of smooth & rough ER
- exit site of proteins leaving the ER => go to Golgi apparatus for modification and packaging
Rough ER
- single membrane, has bound ribosomes
- role: produce and modify secretory protein
Smooth ER
-single membrane, no ribosomes
-role:
lipid biosynthesis (steroid, triacylglycerol)
chemical modification of secretory protein
Ca2+ storage in muscle cell
Detoxification of toxic materials and drugs
Golgi apparatus
- stacks of cisternae (flattened sacs)
- role: post office - receive proteins on cis side and sort/ship them through trans side, produces lysosome , polysaccharide biosynthesis
Types of vacuoles
1) Central vacuole
- storage of waste materials (trash can)
2) Food vacuole
- produced by phagocytosis of WBC
- fuses with lysosome for food hydrolysis
3) Contractile vacuole
- regulates osmolarity in paramecium
Peroxisome
- membrane-bound organelle
- role: catabolism of long chain fatty acids and detoxify hazardous byproducts (hydrogen peroxide)
Glyoxysomes
specialized peroxisome in plant seeds
-stores fat and lipid germination
Types of cytoskeleton
1) Microtubule (thickets)
2) Intermediate filament
3) Microfilament (thinnest)
Microtubule
- thickest (25nm)
- hollow tube
- composed of tubule (dimer of alpha- and beta- tubule monomers)
Role
- maintenance of cell shape
- motility
example:
1) centrosome - non-motile microtubule (9+0)
2) cilia - motile microtubule (9+2), trachea
3) flagella - motile microtubule (9+2), sperm
Intermediate filaments
- middle size (10nm)
- fibrous proteins coiled into cable
- found in laminae and keratin (hair)
Role:
- maintenance of cell shape
- anchorage of nucleus
Microfilaments
- thinnest (7nm)
- two intertwined strands of actin
Role:
- ameboid movement - crawling found in pseudopodia of phagocytosis
- cytoplasmic streaming in plant cells (circulation)
- structural support of microvilli
- cleavage furrow in animal cell
Animal cell’s extracellular matrix (ECM)
1) Proteoglycan
2) Collagen
3) Fibronectin
4) Integrin
3 types of cell junction
1) tight junction
2) desmosome
3) gap junction
