CELLS, ORGANELLS, MOVEMENT & SUPPORT

prokaryotic cells

have no membrane bound nucleus nor membrane bound organelles.

• Most are single-celled.

• Examples are bacteria and cyanobacteria

eukaryotic cells

have a membrane bound nucleus and membrane bound organelles.

• Either single-celled or multicellular.

• Organelles are separated by membranes so several processes can be going on at once.

Lynn Marguli’s hypothesis suggests  that eukaryote cells  come from prokaryote cells.

plasma membrane

• This phospholipid bi-layer membrane acts as a selectively permeable gateway for the passage of substances into and out of the cell!

• Boundary between cell and environment.

• Controls materials that enter and exit the cell.

• Example:  oxygen & nutrients IN -wastes OUT

The membrane also contains proteins embedded within its phospholipid layers that act to encourage molecular movement, or as recognition molecules.

cytoplasm

• Jelly-like substance that surrounds organelles.

• Makes up 1/2 of the volume of animal cells.

• Many important chemical reactions occur here.

nucleus

• the command center of the cell.

• Surrounded by a nuclear envelope - double membraned, 4 layers thick.

• Pores in the nuclear envelope allow chemical messages to move in and out of the nucleus.

• Contains DNA - made up of long strands called chromatin threads.

• The nucleolus (inside the nucleus) produces ribosomes.

ribosomes

• The protein synthesis factories (make proteins and enzymes).

• Composed of RNA.

• Non-membrane structures

• Directed by DNA.

mitochondria

• Known as the powerhouse of the cell.

• Site of aerobic respiration.  These organelles capture glucose and use oxygen to release energy for the cell.

• Foldings within the mitochondria are called cristae.

• O₂ + C₆H₁₂O₆ +Mito -----> E + H₂O +CO₂

endoplasmic reticulum

• Bilayer of lipids used for transport within the cell.

2 TYPES:

• Smooth E.R. does not have ribosomes attached and are known to produce lipids.

• Rough E.R. have ribosomes attached and are known for both protein synthesis and lipid synthesis and transport.

smooth endoplasmic reticulum

does not have ribosomes attached and are known to produce lipids.

rough endoplasmic reticulum

have ribosomes attached and are known for both protein synthesis and lipid synthesis and transport.

golgi apparatus

• “Packaging Factory”

• A series of flattened, closely stacked membranous sacs near the nucleus that coats enzymes.

• Lysosomes (“stomachs” of the cell) bud off from the golgi bodies as the cell needs.

• Digest worn out cell parts, food particles and viruses or bacteria.

centrioles

• only found in animal cells.

• These are two small bundles of cytoskeleton arranged at right angles to one another & surrounded by dense cytoplasm.

• aid in cell division in animal cells.

lysosomes

• These small “suicide sacs” are filled with digestive enzymes used to breakdown molecules within the cell.

• As complex molecules enter the cell BLANK surround food and digest it.

vacuoles

• are storage vessels found within the cell.

• Plant cells usually have large BLANK while animals have BLANK that are small or even absent.

• store food, water, or waste products.

• A contractile BLANK is a specialized cell to remove excess water from unicellular aquatic organisms.

chloroplasts

• Only found in plant cells.

• Filled with the green pigment chlorophyll, these organelles function to transform light energy into stored energy (glucose and starch).

• Grana:  stacked membranous sacs.

• Stroma: fluid that surrounds grana.

grana

stacked membranous sacs.

stroma

fluid that surrounds grana.

cell wall

• in plants are protective dead layers of thick cellulose

• Bulk of fiber in diet.

• In fungi - cell walls are made out of a carbohydrate called chitin!

cytoskeleton

• Fibrous, provides support for organelles.

• Maintains cell shape.

• Composed of: Microtubules  and Microfilaments

• Assist organelles to move from place to place.

cilia

 Short, numerous, hairlike

• Beat in a “wave”.  Example:  lungs

flagella

Longer, 1-2 per cell.

• Move in a whip-like motion.

• Example:  sperm cell

multi-cellular organisms

use cilia on cells to move fluids over the surface of tissues.

single-celled organisms

usually depend on cilia or flagella to move.