cell structure

• DNA • nucleus • plasma membrane (phospholipid bilayer)

• 70S ribosomes (50S+30S subunits) • cell wall • lack nucleus/no true nucleus • have a single loop of dna in the cytoplasm (nucleoid) • non compartmentalised (organells are not membrane bound) • naked dna (not wrapped around histone proteins) ----- • exceedingly small (about the size of individual organelles found in eukaryotes)

• 80S ribosomes (60+40 subunits) • mitochondria • nucleus (double membrane structure)

• process by which cells become specialized, when some genes and not others are expressed in a cell’s genome • cell division is very often restricted to unspecialized cells

• largest organelle of eukaryotic cells • controls and directsthe activity of the cell

• semi-permeable barrier that controls what goes in and out of a cell • contains the cytoplasm • it is where cell is identified by surrounding cells

site of protein synthesis

• fluid that fills each cell and is enclosed by the plasma membrane. • site of all metabolic reactions

• organisms that have a nuclear membrane surrounding their genetic material • (they have a true nucleus)

• unicellular organism without a true nucleus • (they have a loop of naked DNA)

plant cells have a large central vacuole

bacteria and cyanobacteria (a group of bacteria that can photosynthesize)

• pili • capsule (polysaccharid coat) as additional protection • plasmid • infolded cell membrane (ex. mesosome, lamellasome) • flagellum • food granules

enable attachment to surface of other bacteria which allows conjugation to take place

• the genetic material • a single loop of naked DNA of about 4000 gees

protects cell from rupture caused by osmosis and possible harm from other organisms

bring about movement of the bacterium

eu = linear, many contained in each cell pro = singular, form a loop (circular) within the nucleoid region of the cell

all the biochemical reactions of life are collectively known as metabolism

a chemical substance involved in metabolism

• a double layered membrane • a lipid bilayer surrounding the genetic material of the cell

• protein-lined channel in the nuclear envelope • regulates the transport of molecules between the nucleus and the cytoplasm. --- • pores increase sa:vol ratio • suggests that communcations bw nucleus and cytoplasm are imp

• one or more my be present in the nucleus • sub-units of ribosomes are synthesized here --- • tiny, rounded, darkly stained body

only visible if stained with certain dyes