Chapter one Flashcards
Significance of Robert Hooke
The first person to assemble a microscrope and test it on a cork screw. He did NOT see any cells.
Significance of Anton Van Leuwenheok
The first person to view a living cell under a microscope.
Significance of Rudolph Virchow
Demonstrated that diseased cells could arise from normal cells in normal tissues.
Three (+1) components of the cell theory
- All living things are composed of cells
- The cell is the basic functional unit of life
- Cells arise from preexisting cells
- Cells carry genetic information in the form of DNA which is passed on to daughter cells
Differences in cellularity and nucleus in prokaryotic cells and eukaryotic cells
PROKARYOTIC - are unicellular and do not contain a nucleus
EUKARYOTIC - are unicellular or multicellular and have a true nucleus enclosed in a membrane
Nucleus
- control center
- contains all genetic material for replication
- surrounded by double-layer nuclear membrane
Nuclear pores
- found in the nuclear membrane
- allow selective two-way exchange of materials between cytoplasm and nucleus
Histones
- linear DNA wound around organizing proteins
- in the nucleus
Nucleolus
- where ribosomal RNA (rRNA) is synthesized
- takes up 25% of volume in nucleus
- darker spot of membrane
Mitochondria
- powerhouse of the cell
- controls metabolic functions (energy)
- can kill the cell by apoptosis; releasing enzymes from electron transport chain
Two layers of the mitochondria
inner membrane
- arranged into numerous foldings called cristae which increase the surface area for electron transport
- inside is called the intermatrix
outer membrane
- barrier between cytosol and inner environment of mitochondria
Semiautonomous organelle
- the mitochondria
- the two layers have their own genes and replicate through binary fission, which is known as extranuclear inheritance
How did the mitochondria originate?
- When an aerobic (oxygen) prokaryotic cell was engulfed by the anaerobic (no oxygen) prokaryotic cell
Lysosomes
- contain hydrolytic enzymes that can break down different substrates (including compounds endocytosis and cellular waste product)
- function in conjunction with endosomes
- can release autolysis enzyme, resulting in apoptosis
Endosomes
- transport, package, and sort cellular material travelling to and from the membrane
- to trans-goli or the lysosomal pathway to break them down
Endoplasmic reticulum
- series of interconnected membranes that border with the nuclear envelope
- double membrane, folded
- lumen is in the center
- rough ER and smooth ER
Rough ER
- studded with ribosomes which permit translation of proteins designed for secretion into the lumen
Smooth ER
- lacks ribosomes
- used for lipid synthesis and detoxification of drugs or poisons
- transports proteins from RER to golgi apparatus
Golgi apparatus
- stacked membrane-bound sacs
- material from ER is transported here from vesicles
- cellular products can be modified by adding carbs, phosphates or sugars
- can introduce signal sequences which direct delivery of package to specific location
Peroxisomes
- contains hydrogen peroxide
- breaks down long chains of fatty acids via beta-oxidation
- participates in synthesis of phospholipids and contains some enzymes involved in the pentose phosphate pathway
Cytoskeleton
- provides structure
- maintains shape
- provides conduit for transport of materials around the cell
Three components of the cytoskeleton
- microfilaments
- microtubules
- intermediate filaments
Microfilaments
- part of cytoskeleton
- made up of solid rods of actin which are organized into bundles that are resistant to compression and fracture (PROTECT)
- can use ATP to generate force for movement by enacting with myosin (like muscle contraction)
- plays a role in cytokinesis
Microtubules
- hollow polymers of tubulin proteins that radiate throughout the cell
- provides pathway for motor proteins like kinesin and dynein
- makes up cilia and flagella
Cilia and flagella
- cilia: projections from cell that are involved in movement of materials along the cell
- flagella: projections of cell that move the cell along itself (like sperm)
- 9 microtubules in outer ring, 2 microtubules in center (9 + 2 structure)
Centrioles
- founded in centrosome
- organizing center for microtubules and structured as nine triplets of microtubules with a follow center
Intermediate filaments
- contains filamentous proteins like keratin, desmin, vimentin, and lamines
- involved in cell-to-cell adhesion and maintenance of cytoskeleton
- can withhold a lot of tension, increasing rigidity
Four tissue types
- unique characteristic of eukaryotic cells
- epithelial
- connective
- muscle
- nervous
Epithelial tissue
- covers the body and lines cavities, providing protection against invasion and desiccation
- involved in absorption, secretion and sensation
- joined by underlaying connective layer, the basement membrane
- constitute the parenchyma, the functional parts of organs
- often polarized, one side facing the lumen and the other side facing the outside world
Three types of layers of connective tissue
- simple epithelium = one layer
- stratified epithelium = multiple layers
- pseudostratified epithelium - appear to have multiple layers, but only has one
Three types of cells (connective tissue)
- cuboidal cells = cube-shaped
- columnar cells = long and thin
- squamous cells = flat and scale-like
