LO 3 Flashcards
Human cells ______ in size and shape
Vary considerably - 200 types and 100 trillion cells in the body
What is the basic composition of all human cells?
Cytoplasm, plasma membrane, organelles, nucleus
Describe the plasma membrane
It encloses the cytoplasm and forms the outer boundary, phospholipid bi-layer, selectively permeable, contains specialized proteins on surface
Describe cytoplasm
Internal ‘living’ material of cells, between plasma membrane and nucleus, contains cytosol (intracellular fluid), contains organelles
What are ribosomes responsible for?
Creating proteins (ribosomes often found on ER)
Describe the endoplasmic reticulum
Network of connecting sacs that carry substances through the cytoplasm
Describe golgi apparatus
Group of stacked, flattened sacs near the nucleus
Recieve substances from smooth ER via vesicles, then package, process, and transport substances to plasma membrane for release
Describe the mitochondria
Composed of inner and outer membranes, is the site if cellular respiration, contains one DNA molecule
Describe lysosomes
Membranous-walled organelles, resemble small sacs, contain digestive enzymes that can destroy microbes,
Describe centrioles
Fine, rod-shaped tubes that exist in a pair (at right angles) near the nucleus - vital in cell division
Describe microvilli
Finger-like projections on cell membrane that increase surface area
Describe cilia
Fine hair-like extensions on free or exposed surfaces of some cells - propel a cell or move substances (e.g mucus)
Describe flaggelum
Single projection extending from cell surface that creates propulsive movement (sperm)
What are the 4 layers of the nucleus?
- Nuclear membrane
- Nucleoplasm
- Nuleolus - produces ribosomes
- Chromatin granules - package DNA in a smaller volume to fit cell
What are the 2 methods of transportation across the cell membrane?
- Passive transport
- Active transport
Define passive transport?
Form of transport that does not require additional energy - results from movement down a concentration gradient (diffusion and filtration)
What are the 2 types of diffusion?
- Osmosis - diffusion of water when some solutes can’t cross membrane
- Dialysis - diffusion of solutes
Define osmotic pressure
The minimum pressure that must be applied to a solution to halt the flow of solvent molecules through a semipermeable membrane (osmosis)
Define isotonic
A solution with the same osmotic pressure as body fluids - no net movement
Define hypertonic
A solution with higher osmotic pressure than body fluids - water flows out of cell
Define hypotonic
A solution with lower osmotic pressure than body fluids - water flows into cell
Define filtration
Movement of water and small solutes through a membrane (high pressure to low pressure). High pressure on one side of membrane -hydrostatic pressure
Define hydrostatic pressure
The pressure exerted by a fluid at equilibrium at any point of time due to the force of gravity (e.g. during formation of urine by kidneys)