Chapter 3 & 4 — Cellular Form and Function/Genetics Flashcards
development of the cell theory
robert hooke = naming cells in 17th century
theodor schwann = all animals are made of cells in 19th century
louis pasteur = cells only arise from other cells in 1859
sex cells contain __ chromosomes
23
somatic cells contain __ chromosomes
46
__ are the simplest structural and functional unit of life
cells
there are about __ types of cells in the human body with varied __
200; shapes
most cells are __-__ micrometers in diameter
10-15
types of microscopes
light = used in lab
transmission electron = surface features
scanning electron = 3d
the plasma (cell) membrane is…
an oily film of lipids with diverse proteins embedded
plasma (cell) membrane functions
defines cell boundaries
governs interactions with other cells
controls passage of materials in and out of cell**
plasma (cell) membrane composition
lipids (phospholipid bilayer)**
proteins
carbohydrates
__% of cell membrane molecules are lipids
- __% phospholipids
- __% cholesterol
- __% glycolipids
98%
- 75%
- 20%
- 5%
phospholipid bilayer
hydrophilic head face water on each side
hydrophobic tails are in the center to repel water back into the cell
drift laterally to keep membrane fluid
membrane cholesterol
holds phospholipids still and can stiffen membrane
membrane glycolipids are…
phospholipids with short carbohydrate chains on the extracellular face
membrane proteins are __% of the molecules but __% of the weight of the membrane
2; 50
*this means they are big
integral (transmembrane) proteins are…
able to pass completely through the cell membrane and can drift freely in the phospholipid film; most are glycoproteins
peripheral proteins are…
bound to the membrane surface either inside or outside and are anchored to the cytoskeleton
list membrane protein functions
receptors enzyme ion channel gated ion channel cell-identity marker cell-adhesion molecule
membrane channel proteins are __ proteins with pores that allow __ and __ to pass through the membrane
transmembrane; hydrophilic solutes; water
ligand-gated channel proteins respond to __ to open
chemical messengers
voltage-gated channel proteins respond to __ to open
charge changes
mechanically-gated channel proteins respond to __ to open
physical stress on the cell
membrane channel proteins are important in __ and __
nerve signal; muscle contraction
microvilli are…
stationary extensions of the membrane
the function of microvilli is…
to increase the surface area exposed to the extracellular environment; best developed in specialized cells for absorption
cilia are…
motile hairlike processes
the function of cilia is…
to move material across cell surface; they beat in waves of power strokes followed by recovery strokes
have sensory functions in the inner ear, retina, and nasal cavity
__, __ cilium found on nearly every cell
single, nonmotile
flagella are…
whiplike structures with axonemes identical to cilium, though they are much longer than cilium
the function of flagella is…
to move the cell
the only functional flagellum are on __
sperm cells
permeability
the ease with which dissolved materials can cross a membrane
the plasma membrane is __ __– allowing some things through, but preventing others from passing
selectively permeable
__ transport requires no ATP
passive
*molecules bounce off each other until spread out almost evenly
__ transport requires ATP
active
passive transport
- movement down the concentration gradient (high –> low)
- filtration, simple diffusion, and osmosis
active transport
- movement against the concentration gradient
- vesicular transport
filtration
- passive transport
- the process in which particles are driven through a selectively permeable membrane by hydrostatic pressure (force exerted on a membrane by water)
- molecules that are small enough will go through, but won’t if too big
simple diffusion
- passive transport
- movement of particles from an area of high concentration to area of low concentration due to their constant, random motion (bouncing off each other
- down the concentration gradient
there are two ways an ion or molecule can cross the cell membrane: diffusion through __ or diffusion through __
lipid bilayer
- nonpolar, hydrophobic substances diffuse through lipid layer
channel proteins
- water and charged hydrophilic solutes diffuse through channel proteins
osmosis
- passive transport
- diffusion of water through a membrane from an area of more water to an area of less water
- the more solutes/particles, the less water because they take up more space
tonicity
ability of a solution to affect fluid volume and pressure within a cell; depends on the concentration and permeability of the solute
hypotonic solutions
- solute concentration less than that of the cell cytoplasm
- high water concentration
- cells absorb the water, swell, and may burst (hemolysis)
hypertonic solutions
- solute concentration greater than that of the cell cytoplasm
- low water concentration
- cells lose water and shrivel (crenation)
aquaporins
channel proteins specialized for passage of water
isotonic solution
- equal solutes and water
- normal saline