A+P 1.3 Organization of cells Flashcards
Name the three main parts of a cell
plasma membrane, cytoplasm, nucleus
DESCRIBE the plasma membrane
- plasma membrane : flexible outer surface; regulates flow of materials into and out of cell; plays key role in communication among and between cells and external environment
DESCRIBE cytoplasm
- consists of all the cellular contents between the plasma membrane and the nucleus
- divided into two components; cytosol and organelles
DESCRIBE cytosol and organelles
- cytosol : liquid portion of cytoplasm; consists mainly of water with dissolved solutes particles
- organelles : found within the cytosol; membrane-bound structures with specific structures and functions
DESCRIBE the nucleus
- the largest organelle of a cell
- acts as the control center of the cell because it contains the organisms genes the control cell structure and activities
DEFINE the function of the plasma membrane
- flexible, sturdy barrier consisting mainly of lipids and proteins
- Lipid bilayer : two tail-to-tail layers made up of three types of lipids: phospholipids, cholesterol, glycolipids
- two types of membrane proteins
- integral; extend into or through the lipid bilayer
- peripheral; loosely attached to the interior or exterior surface of the membrane; glycoproteins are peripheral proteins attached to carbohydrates
Cell membrane function
Selective Permeability
- allows some substances to move into and out of the cell but restricts others
cell membrane function of
lipid portion
- permeable to water and nonpolar lipid soluble molecules
membrane function of integral proteins
may form ion channels through which ions such at potassium(K+) can move into and out of cells
membrane function of other proteins
act as carriers which change shape as they move a substance from one side to another
membrane function
large molecules
unable to pass through the plasma membrane except by transport within vesicles
membrane function
integral proteins - receptors
recognize and bind specific molecules; some integral proteins are enzymes speeding up specific reactions
membrane function
glycoproteins and glycolipids
often serve as identity markers to recognize its own growing tissues or respond to dangerous outside cells
transport across the plasma membrane
- movement of materials across the plasma membrane is essential to the life of a cell
- substances move into the cells to support metabolic reactions
- cells produce waste and must be moved out of the cell
Intracellular Fluid (ICF)
- fluid found inside body cells
- makes up about 2/3 of the fluid found in the body
Extracellular Fluid (ECF)
- fluid outside of the cell
- between cells = interstitial
- in blood vessels = plasma
- in lymphatic vessels = lymph
Define solute
material dissolved in a fluid
define concentration
amount of solute dissolved in a solvent
define concentration gradient
the difference between high and low concentration
DEFINE passive transport
kinetic energy moves molecules from areas of high concentration to low concentration ; simply diffusion
DEFINE active transport
cellular energy (ATP) is used to push the substance against the concentration gradient ; from low to high
EXPLAIN passive transport
- involves only kinetic enery (energy of motion) ; does not require ATP
- ex. simple diffusion, facilitated transport, osmosis
EXPLAIN Simple diffusion
- movement of a substance through the lipid bilayer, from an area of high concentration to low until equilibrium is reached
- pass through lipid bilayer if lipid-soluble; oxygen, carbon dioxide, fatty acids, steroids
- polar molecules such as water and urea also pass through
EXPLAIN facilitated diffusion
- some molecules bind to integral proteins on one side of the membrane and are released on the other side after the protein carrier undergoes a change in shape
Ion channels
ion channels in the membrane allow specific ions to pass through
Osmosis
- diffusion of water from an area of higher concentration to lower
isotonic solution
- concentration of water and solute is the same on both sides of membrane
- water enters and leaves cell at the same rate
- cell maintains normal shape
Hypotonic solution
- low concentration of solute, high concentration of water outside the cell in ECF
- water enters the cell at a faster rate than it leaves
- the swells or ruptures (hemolysis)
Hypertonic solution
- high concentration of solute and low concentration of water outside cell in ECF
- water leaves the cell at a faster rate than it enters
- cell shrinks (crenation)
Two types of active transport
- pumps involving carrier proteins
- transport within vesicles
Major/most important pump for active transport
- sodium-potassium pump; critical for nerve and muscle function
Methods transport in vesicles
- Endocytosis
- phagocytosis
- bulk phase endocytosis
- Exocytosis
Endocytosis
- substances are surrounded and enclosed by a piece of the plasma membrane
- this forms a vesicle that is brought into cell
two types of endocytosis
- phagocytosis “cell eating” large plasma membrane projections called pseudopods surrounds and ingest bacteria and other foreign particles
- bulk phase endocytosis “cell drinking” ingestion of tiny droplets of ECF (pinocytosis)
Exocytosis
moving substances out of a cell by fusing vesicle membrane with plasma membrane resulting in excretion into ECF
Nucleus
- spherical or oval structure
- surrounded by nuclear envelops with nuclear pores
Nuclear pores
small openings in the nuclear envelope which control movement in and out of the nucleus
nucleolus
structure of the nucleus that makes ribosomes that pass into cytoplasm through nuclear pores
somatic (body) cells
- 46 chromosomes
- 23 from each parent
genome
the total genetic information carried in a cell or organism
Average human adult
cell number and type
composed of nearly 100 trillion cells consisting of about 200 different cell types
cell measurements
- measured in micro meters (1/1000 meter)
oocyte
- largest cell
- diameter of about 140 micrometer; barely visible to the unaided eye
Red blood cells
- diameter of 8 micrometer
shapes of cells
- round, oval, flat, cube-shaped, column-shaped, elongated, star-shaped, cylindrical, or disk-shaped
sperm cell shape
-has a long whip like tail (flagellum) that it uses for motion
red blood cell shape
- disk shape
- the large surface are enhances its ability to pass Oxygen to other cells
