y3.1: bacteria and viruses 🦠

Question 1

what are the modes of life of bacteria?

Answer 1

• saprophytic (decaying organic matter)
• parasitic (living within other cells)
• autotropic (can manufacture their own food)

Question 2

what is the mode of reproduction by bacteria?

Answer 2

dividing into two by binary fission

Question 3

what is the role of bacteria in biology?

Answer 3

• dieseases
  => crop plants, food producing animals, humans
  => Cholera, tubercolosis, and STIs
• decay
  => recycling of nutrients
  => food spoilage, tooth decay
• production of food (cheese) and useful enzymes and hormones (insulin (more in DNA !!))

Question 4

comparison between prokaryotic and eukaryotic cells: definition

Answer 4

prokaryotic (bacteria and archaea)
- lack membrane-bound nucleus
eukaryotic (cells from other kindgdoms)
- contain membrane-bound nuclei

Question 5

comparison between prokaryotic and eukaryotic cells: similarities

Answer 5

• DNA as genetic material
• Cell membrane
• Ribosome

Question 6

comparison between prokaryotic and eukaryotic cells: differences

Answer 6

Eukaryotes Prokaryotes
nucleus: present vs absent
membrane-bound organelles: present vs absent
size: larger vs smaller
composition of cell wall: cellulose vs peptidoglycan
location of DNA: nucleus vs cytoplasm nucleoid region

Question 6

what are the characteristics of viruses?

Answer 6

• smallest disease-causing particles
• genetic materal
  => surrounded by a protein coat - capsid
  => surrounded by an evelope derived from the host cell’s membrane
• specific to cell types

Question 6

what is the mode of life of viruses?

Answer 6

• incapable of carrying out normal living processes outside a living cell
• take control of a living cell (host cell)
• releases genetic material of the virus and viral proteins => across cell membrane of the host cell into cytoplasm

Question 7

why are viruses not considered living?

Answer 7

• smaller and simpler than bacteria
• lack metabolic enzymes and equipment to making proteins (ribosomes)
• !! cannot reproduce or carry out metabolic activities outside of a host cell !!

Question 8

what are the characteristics of bacteria?

Answer 8

• no nucleus
• genetic material
  => single bacterial chromosome consisting of coiled-up, circular strand of DNA
  => may have smaller rings of DNA called plasmids
• peptigoglycan cell wall
• cytoplasm may contain food stores
  => glycogen
  => lipids
• structures it may possess
  => thread-like structure called flagella
  => slime capsule

Question 9

how does viral genetic material take over body cells?

Answer 9

=> takes over the host cell’s biochemical machinery
=> make new copies of itself using the host’s resources
=> release themselves by lysing the host cell
=> viral particles go on to infect other healthy cells