samealike standing staying greater concentration lesser concentration diffusion
TRANSCRIPT
TWO CRITERIA FOR OSMOSIS:
1. SUBSTANCE MUST BE WATER
2. SUBSTANCE MUST PASS THROUGH A SELECTIVELY PERMEABLE MEMBRANE
A. solution in which the number of water molecules inside the cell is equal to the number of water molecules outside the cell
B. the number of solute molecules inside the cell is equal to the number of solute molecules outside the cell
water molecules
solute molecules
solute molecules and water molecules constantly move into and out of the cell, but the rates of movement are equal
a cell in an isotonic solution is a cell in homeostasis!
O = water molecules X = solute molecules
X X
X
X
X
O
O
O
OO
O
X
PLANT CELL IN AN ISOTONIC SOLUTION
water entersthe cell at thesame rate as it leaves the cell
solute entersthe cell at thesame rate asit leaves the cell
normal shape and pressure
A. solution in which the number of water molecules inside the cell is less than the number of water molecules outside the cell; net movement of water is into the cell
watermolecules
greater concentrationoutside the cell
move into the cell
B. the number of solute molecules inside the cell is greater than the number of solute molecules outside the cell; net movement of solute molecules is out of the cell
solutemolecules
move out of the cell
greaterconcentrationinside the cell
C. in animal cells, it results in cytolysis (bursting of the cell due to turgor pressure – pressure that exists in a cell due to the presence of water
D. in plant cells, it results in wilted plants becoming rigid (due to gain of turgor pressure); presence of the cell wall. prevents cytolysis
cytolysis
cell membrane breaks
E. in some protists, organelles called contractile vacuoles collect water coming into the cell, then contract, and squeeze the water out of the cell through the cell membrane; prevents cytolysis
contractile vacuole
collects water coming in and contracts it out of the cell
under
PLANT CELL IN A HYPOTONIC SOLUTION
water moleculesmove into the cell
solute moleculesmove out of the cell
water molecules are smaller than solute molecules and diffuse more rapidly
plant cells swellin a hypotonic solution
X
X
X X
X
X
X
XO
O
O
O
O
O
O
O
more solute molecules inside the cell
solute move out of the cell
more water molecules outside the cell
water moves into the cell
A. solution in which the number of water molecules inside the cell is greater than the number of water molecules outside the cell; net movement of water is out of the cell
watermolecules
move out of the cell
greaterconcentrationinside the cell
B. The number of solute molecules inside the cell is less than the number of solute molecules outside the cell; net movement of solute molecules is into the cell
solutemolecules
move into the cell
greater concentrationoutside the cell
C. results in plasmolysis (shrinking of the cell due to loss of turgor pressure
above
X
X
X
X
X
XX
O
O
O
O
O OO
O
O
more solute molecules outside the cell
solute moves into the cell
more water molecules inside the cell
water moves out of the cell
PLANT CELL IN A HYPERTONIC SOLUTION
water moleculesmove out of the cell
solute moleculesmove into of the cell
plant cell loses turgor pressure and shrinks
plasmolysis occurs plant wilts
the movement of particlesacross the plasma membrane without the expenditure of energy
Examples of passive transport:
1. diffusion
2. osmosis
3. facilitated diffusion
greater concentration
lesser concentration
greaterconcentration
lesserconcentration
carrierprotein
energy
the movement of materials across a membrane against the concentration gradient and requiring the expenditure of chemical energy
1. channel proteins – form channels that allow specific molecules to flow through; movement is with the concentration gradient and requires no energy input from the cell
channel protein
2. carrier proteins – proteins that change the shape to allow a substance to pass through the plasma membrane; movement is with the concentration gradient and requires no energy input from the cell
carrier protein
process of endocytosis in which fluid materials are engulfed into the cell; forms a vacuole
process of endocytosis in which large particles are engulfed into the cell; forms a vacuole
to drink
to eat
CELL’S DNA
most cells are uninucleated – contain only one nucleus tomanage all of the cell’s processes
DNA deoxyribonucleic acid “master molecule of the cell”
1. chromatids each of the two identical halves of a chromosome; sometimes called “sister chromatids”
2. centromerethe point of attachmentof the sister chromatids
center
portion share
3. upper arm the part of a chromosomelocated above the centromereknown as the “p” arm (petite)
4. lower armthe part of the chromosomelocated below the centromere;known as the “q” arm
upper arm is always the smallestarm if the centromere is not in the center
5. allelesgenes for the same traitthat may have differingexpressions and locatedat the same location on sister chromatids
shape of nosestraight, pug, roman
hair colorred, blonde, black, brown
genetic diseasenormal, diseased
22 pairs or 44
1 pair or 2
X and X sex chromosomes = female
X and Y sex chromosomes = male
23 pairs or 46
2. period of division
A. mitosis = division of the nucleus
B. cytokinesis = division of the cytoplasm
1. the busiest phase of the cell cycle
2. G phase (gap 1 phase) – rapid growth and metabolic activity 1
G phase 1
interphase
G = growth
2. chromatin coils and becomes visible as chromosomes
chromosomes
each chromosome consists of two sister chromatids
3. the nuclear envelope and nucleolus disintegrate
disappearing nuclear envelope
nucleolus disintegrated
5. in animal cells, the spindle begins to form
spindle fibers
spindle fibers are microtubules that form from centriole to centriole
2. the doubled chromosomes become attached to the spindle fibers by their centromeres
each sister chromatid is attached to its own spindle fiber
spindle fibers
centromere
sister chromatids
3. the chromosomes are pulled by the spindle fibers and begin to line up on the midline, or equator, of the spindle
equator
one sisterchromatidis attached to the spindle fiber at one pole
the other sister chromatidis attached to the spindle fiber at the other pole
2. the centromeres split apart and the chromatid pairs separate from each other
the chromatids are pulled apart by the shortening of the microtubules in the spindle fibers
chromatids
2. chromatids reach opposite poles of the cell
pole of the cell
pole of the cell
chromatids chromatids
3. chromosomes unwind and elongate into chromatin
6. the spindle fibers break down and disappear
4. the nuclear envelope reforms around the chromatin
5. the nucleolus reappears
7. cytokinesis occurs
8. two daughter cells are formed
division of the cytoplasm
twoidenticaldaughter cells
1. animal cells – cytokinesis begins during early anaphase when the plasma membrane begins pinching in from the outside to the inside to form the cleavage furrow until the cell divides into two identical daughter cells
2. plant cells – vesicles formed by the Golgi apparatus fuse at the equator of the cell forming the cell plate which grows from the inside to the outside until the cell divides into two identical daughter cells; the cell plate forms into the cell wall
1. guarantees the continuity of life, resulting in the production of two new cells with chromosome sets that are identical to those of the parent cell
2. unicellular organisms remain as single cells – produces two complete new organisms
3. multicellular organisms result in cell growth and reproduction which provides new tissues, organs, and organ systems
1. set of proteins that control the cell cycle
2. proteins that attach to the cyclin and become activated
a malignant growth resulting from uncontrolled cell division
Possible causes of cancer:
1. genetic factors – predisposition in the family; genes inherited
2. environmental factors – smoking; air and water pollution
3. viral infections – that damage the genes