ch. 3 cellular form and function Flashcards
inclusions
two kinds of inclusions
stored cellular products
* glycogen granules, pigments, fat droplets
foreign bodies
* viruses, intracellular bodies, dust particles, and other debris phagocytized by a cell
never enclosed in a unit membrane
NOT ESSENTIAL FOR CELL SURVIVAL
development of the cell theory 2
cell theory
all organisms composed of cells and cell products
cell is the simplest structural and functional unit of life
an organism’s structure and functions are due to activities of cells
cells come only from preexisiting cells
cells of all species exhibit biochemical similarites
cell shapes and sizes 1
about how many types of cells in human body with varied shapes
200
cell shapes and sizes 1
squamous
thin, flat, scaly
cell shapes and sizes 1
cuboidal
squarish looking
cell shapes and sizes 1
cuboidal
taller than wide
cell shapes and sizes 1
polygonal
irregulary angular shapes, multiple sides
cell shapes and sizes 1
stellate
star like
cell shapes and sizes 1
spheroid to ovoid
round to oval
cell shapes and sizes 1
discoid
disc shaped
cell shapes and sizes 1
fusiform
thick in middle tampered towards the ends
cell shapes and sizes 1
fibrous
thread-like
cell shapes and sizes 2
human cell size
most cells about 10-15 micrometers
ex. egg cells (very large) 100 micrometer diameter
some nerve cells over 1 meter long
cell shapes and sizes 2
human cell size limit on cell size
an overly large cell cannot support itself may rupture
for a given increase in diamete, volume increases more than surface area
volume proportional to cube of diameter
surface area proportional to square of diameter
basic components of a cell 2
plasma (cell) membrane
surrounds cell
defines boundaries
made of proteins and lipids
basic components of a cell 2
cytoplasm
organelles
cytoskeleton
inclusions (stored or foreign particles)
cytosol (ICF, intracellular fluid)
basic components of a cell 2
extracellular fluid (ECF)
fluid outside of cells includes tissue (interstitial) fluid
the plasma mebrane 1
plasma membrane
border of the cell
the plasma mebrane 1
plasma membrane appears as pair of
dark parallel lines when viewed with electron microscope
has intracellular and extracellular faces
the plasma mebrane 1
plasma membrane functions
defines cell boundaries
governs interactions with other cells
controls passage of materials in and out of cell
membrane lipids 1
98% of membrane molecules are
lipids
membrane lipids 1
phospholipids
- 75% of membrane lipids are phospholipids
- amphipatic molecules arranged ina bilayer
- hydrophilic phosphate heads face water on each side of membrane
- hydrophobic tails-are directed toward the center, avoiding water
- drift laterally, keeping membrane fluid
membrane lipids 2
cholesterol
- 20% of the membrane lipids
- holds phospholipids still and can stiffen membrane
membrane lipids 2
glycolipids
- 5% of the membrane lipids
- phospholipids with short carb chains on extracellular face
- contributes to glycocalyx-carb coating on cell surface
membrane proteins 1
membrane proteins
2% of the molcules but 50% of the weight of membrane
membrane proteins 1
integral proteins-penetrate membrane
- transmembrane proteins pass completelt through
- hydrophilic regions contact cytoplasm, ECF
- hydrophobic regions pass through lipid of the membrane
- some drift in membrane, others are anchored to cytoskeleton
membrane proteins 1
peripheral proteins
- adhere to one face of the membrane (do not penetrate it)
- usually tethered to the cytoskeleton
membrane proteins 2
functions of membrane proteins include
- receptors
- second messenger systems
- enzymes
- channels
- carriers
- cell-identity markers
- cell-adhesion molecules
membrane proteins 3
receptors
bind chemical signals
membrane proteins 3
second messenger systems
communicate within cell receiveing chemical message
membrane proteins 3
enzymes
catalyze reactions including digestion of molecules production of second messagers
membrane proteins 3
channel proteins
allow hydrophilic solutes and water to pass through membrane
some are always open, some are gated
* ligand-gated channels-respond to chemical messengers
* voltage-gated channels-respond to charge changes
* mechanically-gated channels-respond to physical stress on cell
CRUCIAL TO NERVE AND MUSCLE FUNCTION
membrane proteins 4
carriers
bind solutes and transfer them across membrane
* pumps-carriers that consume ATP
membrane proteins 4
cell identity markers
glycoproteins acting as identification tags
membrane proteins 4
cell-adhesion molcules
mechanically link cell to extracellular material
second messengers
chemical first messenger (epinephrine) binds to a
surface receptor
second messengers
receptor activates G protein
an intracellular peripheral protein that gets energy from guanosine triphosphate (GTP)
second messengers
G protein relays signal to
adenylate cyclase which converts ATM to cAMP (second messenger)
second messengers
cAMP activates
cytoplasmic kinases
second messengers
kinases add phosphate groups to
other enzymes turning some on and others off
second messengers
up to 60% of drugs work through
G proteins and second messengers
the glycocalyx
fuzzy coat external to
plasma membrane
* carbohydrate moieties of glycoproteins and glycolipids
* unique in everyone but identical twins
the glycocalyx
functions
- protection
- immunity to infection
- defense against cancer devlopment
- transplant compatibility
- cell adhesion
- fertilization
- embryonic
microvilli 1
extensions of membrane (1-2 micrometers)
- gives 15-40 times more surface area
- best developed in cells specialized in absorption
microvilli 1
on some absorptive cells they are very dense and appear as a fringe
“brush border”
some microvilli contain actin filaments that are tugges toward the center of cell to milk absorbed content into cell
cilia 1
cilia
hairlike processes 7-10 micrometers
cilia 1
single, nonmotile primary cilium found on nearly
every cell
* “anntenna” for monitoring nearby conditions
* helps with balance in inner ear: light detection in retina
cilia 1
multiple nonmotile cilia
found on sensory cells of nose
cilia 1
ciliopathies
defects in structure and function of cilia
cilia 1
motile cilia
respiratory tract
uterine tubes
ventricles of brain
ducts of testes
50-200 micrometers
beat in waves sweeping material across a surface in one diretion
power strokes followed by recovery strokes
cilia 2
axonene-core of motile cilium
- has 9+2 structure of microtubules
- two central microtubules surrounded by ring of nine pairs
- ring of nine pairs anchors cilium to cell as part of basal body
- dynein arms “crawl” up adjacent microtubule, bending the cilium
uses energy from ATP
cilia 4
cilia beat freely within a saline layer at cell surface
chloride pumps pump into ECF
and follow
mucus floats on top of saline layer
cystic fibrosis
cystic fibrosis
hereditary disease in which cells make chloride pumps but fail to install them in the plasma membrane
chloride pumps fail to create adequate saline layer on cell surface
cystic fibrosis
thick mucus plugs
pancreatic ducts and respiratory tract
- inadequate digestion of nutrients and absorption of oxygen
- chronic respiratory infections
- life expectanct of 30
flagella
tail of a sperm
only functional flagellum in humans