prokaryotic organisms 1.3 Flashcards
do bacteria have a nucleus?
no, they don’t, as they are prokaryotes
where is the genetic material of a bacteria stored?
the genetic material is in the cytoplasm in the form of a single circular chromosome
are bacteria multicellular or single-celled?
bacteria are single-celled, small organism
example of bacteria:
lactobacillus - breaks down milk sugars and is used in yoghurt production, rod-shaped
pneumococcus - is a pathogenic and is one of the causes of pneumonia (lung infection), spherical shape
structure of bacteria cells:
what do bacteria cells have?
cell membrane - controls what enters and leaves the cell
cell wall - made of peptidoglycan (complex molecule of sugars and proteins) which maintains and protects the cell
cytoplasm - contains the circular chromosome and where chemical reactions take place
a slime capsule - outside cell wall and providing more protection
plasmids - small circles of DNA containing extra genes
a flagellum - allowing the bacteria to move
what are viruses made of?
a strand of genetic information surrounded by a protein coat
are viruses alive?
no - they are not cells and not alive, they do not respire, or carry out any processes taking places in living organisms
how do viruses reproduce?
- they have to enter a host cell
- take over the ribosomes and enzymes in the cell to make new virus particles
- when many new viruses have been made the cell dies and the viruses are released to infect new cells
examples of viruses:
tobacco mosaic virus - causes discolouration of leaves, causing brown patches by stopping the production of chloroplasts
influenza - infects humans causing a cough and temperature
how do some bacteria feed?
saprotrophic nutrition = the secretion of extracellular digestive enzymes onto an organism to break down food and then absorb the nutrients
