Microbiology

Question 1

how is a virus different from bacteria

Answer 1

not living
lack organelles or nucleus
substantially smaller

Question 2

what is a bacteriophage

Answer 2

any virus that infects bacteria

has a head with genetic material and tail to attach to surface of bacterium

Question 3

viral life cycle

Answer 3

attach to host cell and enter
bacterial ribosomes replicate and transcribe viral DNA
new viruses are formed and released by cell lysis

Question 4

how do most animal viruses enter the cell

Answer 4

receptor mediated endocytosis

Question 5

retrovirus life cycle

Answer 5

enter host cell by fusion and use reverse transcriptase to form DNA from RNA
the DNA is integrated into the host genome and exists by budding

Question 6

difference between lytic and lysogenic cycle

Answer 6

lytic - active/virulent producing viral components that can infect other cells
lysogenic - dormant/temperate inserted into host cell allowing it to be replicated. will enter the lytic cycle when host chromosome is stressed

Question 7

organisms are classified by how they acquire carbon and energy, what are the different groups

Answer 7

autotroph- can fix carbon
heterotroph - rely on autotrophs to synthesis organic compounds
photo - uses light for energy
chemo - uses chemical energy

Question 8

difference between archaea and bacteria

Answer 8

archaea have no nucleus or organelles and live in extreme environments

Question 9

3 bacteria shapes

Answer 9

cocci - sphere
bacilli - rod
spirilli - spiral

Question 10

what is the DNA in bacteria and where is it located

Answer 10

single circular chromosome of double stranded DNA

localized in the nuclei region because there is no membrane bound nucleus

Question 11

do prokaryotes have ribosomes

Answer 11

yes

Question 12

what are plasmids

Answer 12

extra chromosomal Dna that may contain genes for antibiotic resistance (r factors )

Question 13

how do bacteria reproduce

Answer 13

binary fission (asexual) where the circular DNA is replicated and grows. divides into two cells that are genetically identical 
** exponential growth

Question 14

what are flagella

Answer 14

made of flagellin to help bacteria move *bacteria only

Question 15

describe the cell wall of a bacteria

Answer 15

bacteria have a plasma membrane which is surrounded by a cell wall and sometimes a capsule. the cell wall prevents the protoplast (plasma membrane + everything inside) from bursting

Question 16

staining in gram negative vs positive bacteria

** where is the peptidoglycan located

Answer 16

positive - thick peptidoglycan wall on the outside of the cell = purple
negative - thin wall located between two membranes = pink

Question 17

binary fission has no genetic recombination , what are the 3 ways bacteria undergo genetic recombination

Answer 17

conjugation
transformation
transduction

Question 18

describe bacterial conjugation

Answer 18

F+ plasmid has the sex pilius and attaches to the recipient cell
a single strand of DNA is transferred to the recipient and both synthesize the double stranded circular plasmid and produce new pili

Question 19

what is an R plasmid

Answer 19

contain gene for sex pills but they bestow different types of antibiotic resistance to their recipient cells

Question 20

what is bacterial transformation

Answer 20

bacteria incorporate dna plasmids from external environment into their genome

Question 21

what is bacterial transduction

Answer 21

bacteria accidentally encapsulates host DNA fragment then infects a new bacterium with some of that DNA
the virus that mediates this is called a vector

Question 22

difference between bacterial conjugation, transformation, and transduction

Answer 22

conjugation is like sex, transformation gets DNA from external environment, transduction gets DNA from a host cell then a the virus brings it to new host cells

Question 23

what are transposons

Answer 23

genetic elements that can jump around by inserting or deleting themselves from the genome. contain a gene for transposes protein

Question 24

3 different types of transposons

Answer 24

IS elements - transposes gene flanked by inverted repeated sequences
complex -
composite - two transposes sequences
this is dumb

Question 25

what is the lac operon

Answer 25

codes for enzymes that allow ecoli to import and metabolize lactose when glucose isn’t available
has a operator, promoter, and genes for mRNA

Question 26

how does lactose regulate lac operon activity **

Answer 26

when lactose is not present a lac repressor protein binds to operator and prevents expression of lac genes.
when glucose is not present and lactose is the lactose prevents the repressor from working and transcription of lac genes can proceed