3.2.1.2 - structure of prokaryotic cells and of viruses

prokaryotic cells are m____ s_________ than eukaryotic cells.

prokaryotic cells are much smaller than eukaryotic cells.

in a prokaryotic cell’s cytoplasm, are there any membrane-bound organelles?

no

what type of ribosome do prokaryotic cells have

70s ribosomes (smaller than the ribosomes (80s) in eukaryotic cells)

• do prokaryotic cells have a nucleus?

• what do they have instead?

• no

• a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins (learn this wording - straight from spec!)

what does the single loop of DNA contain

genetic info for an organism’s characteristics, development, growth, function + reproduction

• do prokaryotic cells have a cell wall?

• what is this made of?

• what is this?

• yes

• murein

• a glycoprotein

some prokaryotes (not all, mainly bacterium) contain one or more plasmids. what are these?

small rings of DNA

what do plasmids DO

• carry genes that provide bacteria with advantages so they can survive in harsh environments

• e.g. resistance to antibiotics / toxins

some plasmids contain g_____ that enable bacteria to c______ d_________ by producing t______ that help them i______ h____ c_____

some plasmids contain genes that enable bacteria to cause disease by producing toxins that help them infect host cells

some prokaryotes (not all) have a slime capsule. 

this provides extra protection from…

…being engulfed by phagocytes, viruses (and drying out!)

the slime capsule also helps the cell s_____ t__ s_________ (e.g. the h____ c____)

stick to surfaces (e.g. the host cell)

what can the slime capsule help trap

nutrients for the bacteria

some prokaryotes (not all) can have one or more of a tail-like structure. what is this called

flagella (plu.)

what is the function of the flagella

helps w/ mobility / movement, esp. through liquids

viruses are a_________ and n___- l________. 

viruses are acellular and non-living.

why are viruses non-living

because they are not cells, they are more like biological parasites. they are only active when they invade a host cell

why is a virus not a cell

• unlike a cell —→ has no complex cell structures and functions

• no metabolism —→ can’t produce energy / carry out chemical reactions on its own

• cannot reproduce on its own —→ requires a host cell

are viruses bigger or smaller than bacteria

much smaller

what are the 3 structural properties the most basic viruses have?

• genetic material

• capsid (protein coat)

• attachment proteins

what does the capsid do

surrounds and protects the genetic material from the environment

• where do attachment proteins protrude from?

• what do they allow the virus to do?

• the surface of the capsid (or if the virus has an additional, optional envelope, then that)

• attach to specific receptors on the host cell

some viruses MAY have a lipid envelope. what is this?

an outer membrane contaning viral proteins and phospholipids