MCB U1 Exam

prokaryotes & main one we talk about in class

lack of nucleus & independent

EX: bacteria

unique features of prokaryotes

1. free floating DNA

2. walls are sturdy

3. no organelles

coccus — bacterial shape

spherical shape

bacillus — bacterial shape

rod/cylindrical shape

wide shape

curved — bacterial shape

comma shaped

spirillum — bacterial shape

spiral & rigid

spirochete

spiral & flexible

appendages of bacteria

1. flagella — tail & used as movement

2. fimbria — attachement hairs used for attachment & est. infection

3. pilus — tube structure, used for connection

what is conjugation pili

pilus that has a transfer of DNA from one cell to another by connecting it

2 surface coverings of bacteria

1. slime layer — loose shield that protects bacteria from loosing water

2. capsule — thick layer focused on protection from human immune system recognizing it

what are encapsulated bacteria

more likely to cause pathogenesis because capsules protect the bacteria against phagocytosis

bioflim of bacteria

slime layer

mixed community of bacteria & other microbes & makes it difficult to get rid of bacteria

cytoplasmic membrane of bacteria

inner membrane

• contains lipid bilayer

• transport things in and out

cell wall of bacteria

strong, structural support

keeps their shape (rigid)

protects from LYSIS (cell wall failing & collapsing)

what is bacterias cell wall made up of

peptidoglycan

negative gram stain: which one

the one on the left

• dyes PINK

• 3 layers — outer membrane, cytoplasmic membrane, + thin peptidoglycan cell wall washes away

positive gram stain: which one

the one on the right

• dyes PURLE

• 2 layers — membrane + THICK peptidoglycan cell wall that dyes purple

what is LPS & is it located on gram - or gram +

LPS — lippolysaccharide that causes fevers

ON GRAM NEGATIVE

benefits of outer membrane for gram - bacteria

extra barrier

makes them resistant to antibiotics

harder to kill off

exceptions to nontypical cell walls (3)

1. arent characterized as either gram +/-

2. dont have a cell wall

3. are too small for the stain

bacterial chromosomes v. plasmids

bacterial chromosomes — essential pieces of DNA (a single circle strand of DNA)

plasmids — nonessential pieces of DNA

T/F: do prokaryotic and eukaryotic ribosomes differ in size

TRUE: prokaryotic are smaller

bacterial endospores

dormant bodies produced by bacteria

can survive the HARSHEST conditions

sporulation of bacteria

process where bacteria form endospores

not reproduction, only 1 is made

germination of bacteria

endospore is in FAVORABLE environment and bacteria will return to its vegatative state

eukaryotes

has nucleus + organelles

protozoa, fungi, helminths

extracellular matrix — eukaryotes

helps protect, adhere, & receive signals

cell wall

chitin & all fungi have cell walls

structural support + shape

cell membrane

phospholipid bilayer + sterols (proteins)

nucleus

chromatin + nuclear envelope

lysosomes v. vacuole

lysosome — break things DOWN thru phagocytosis

vacuole — stores waster & nutrients

mitochondira

generates ATP

2 types of fungal cells & difference (shape, # cells, colonies)

1. yeast — round/oval shaped, UNIcellular, colonies = smooth/creamy

2. mold (hyphae) — long, threadlike cells, MULTIcellular, colonies = soft/hairy

dimorphic

fungi can take on 2 forms and transition between yeast and mold depending on growth conditions

mycelium

mass of hyphea in mold

septate v. nonseptate hyphae

1. septate hyphae — separate cells/segmented

2. nonseptate hyphae — no sepraration

morphology of molds (2)

1. vegetative hyphae — growth phase/phase when it lands on substance

2. reproductive hyphae — reproduction phase/produces spores

how does yeast reproduce

budding (asexually)

how does yeast reproduce

spores

importance of fungal spores

fungi make spores for a chance to TRAVEL to new places via wind

fungal nutrition

• saprobes — eating DEAD substances

• parasites — eating LIVING substances

acellular pathogens: viruses & prions

viruses: macromolecules

prions: 1 protein

describe the relative scale of microbes: largest → smallest

helminths > fungi > protozoa > bacteria > viruses > prions

what are the 3 viral components of VIRUS

1. genome (DNA/RNA)

2. capsid (protein)

3. viral attachment proteins

what do viral attachment proteins do & how does it relate to TROPISM

uniquely bind to a specific host receptor proteins for attachment & entry

• tropism — which cells can be infected

shapes of capsids & describe what a capsid is

capsid — protect the genome from damage

1. helicial

2. icosahedral

3. complex

what is the purpose of a viral envelope

protection & disguises the virus from host immune system

• second layer of virus

• not all viruses have this

2 types of viral envelope

1. naked — no envelope

2. enveloped

genome of viruses (4)

1. RNA or DNA

   1. negative sense RNA: cannot be read by ribosomes

   2. positive sense RNA: can be read by ribosomes

2. single stranded (ss) or double stranded (ds)

3. linear or circular

RDRP viruses

RNA → RNA copying

“rna dependent rna polymerase”

RT viruses

RNA → DNA

“reverse trasncriptase”

viral life cycle

AERAR —> All Edgars Run Addiction Rings

1. attachment

2. entry

3. replication

4. assembly

5. release

how do viruses replicate when in a host

virus uses your cells machinary (nucleic acids/ribosomes) to create viral protein etc.

DNA virus → nucleus

RNA virus → cytoplasm

what is integration in viruses

when viruses insert their DNA into the host’s DNA & stay there

what type of viruses require RT

RNA viruses that INTEGRATE need RT

what type of viruses require RDRP

negative-sense RNA need RDRP

what are prions & how are they transmissable

misfolded proteins

all normal proteins will fold incorrectly due to 1 misfolded one

is it easy or hard to get rid of prions

EXTREMELY difficult to get rid of them

are protozoans unicellular/multicellular?

do they have cell walls?

UNICELLULAR

no cells bc they need to move around

how do protozoa move

1. cilia

2. flagella

3. pseudopods

what are the 2 main life cycles a protozoa goes through & describe them?

which cycle do most infect humans?

1. trophozoites — feeding/growing stage

   1. CAUSE DISEASE

2. cyst — dormant/resting stage & able to survive harsh environments

   1. CYST INFECT HUMANS

2 types of helminths

1. nematodes = flatworms

2. round worms

   1. cestodes — cylindrical/tape worms

   2. trematodes — flat/FLUKES

scolex in helminth

feeding & attachment

proglottid helminth

reproduction (segments)

ventral sucker

in flukes/trematodes

• USED FOR ATTACHMENT

cuticle

used in roundworms

• PROTECTION

life cycle of a helminth & which stages do humans get infected?

1. egg — humans get infected

2. larva — humans get infected

3. adult — egg develops into a larva

difference between intermediate & definitive host

1. intermediate — larva + egg

2. definitive — adult + sexual reproduction

how do worms reproduce

sexually

what is binary fission

2 daughter cells created from 1 parent cell

• cell splits in half

stages of growth curve

1. lag phase

2. exponential growth phase

3. stationary phase

4. death phase

whats happening in the lag phase

cell is aclimating to the environment

whats happening in the exponential growth phase

growing & reaching max rate of division

whats happening in the stationary phase

nutrients are diminishing

whats happening in the death phase

whole population dies

more death cells > fewer living cells

what is turbidity & how does it relate to population growth

indication of microbial growth

GREATER turbidity = LARGER population

what environmental factors make it impactful to microbes

1. temp — cannot control own temp

2. gas conditions

3. pH — require specific pHs

4. pressure

5. symbioses — need other substance to live

what are microbial aerobes (X1)?

can use O2 in metabolism

OBLIGATE AEROBES — cannot grow w/o O2

• growth is usually at top of tube

what are microbial anaerobes (X3)?

1. obligate anerobes — cannot grow in an O2 environment

   1. usually at bottom of tube

2. facultative anaerobes — use O2 if its there, but can function w/o it

   1. choice

3. aerotolerant anarobes — don’t use O2, but can process O2

3 major catabolic pathways

1. aerobic respiration (MOST energy)

2. anaerobic respiration

3. fermentation (LEAST energy)

why might a microbe use fermentation

independence from O2

adaptability to many environments

what do polyribosomal complexes do

help bacteria replicate quickly

1. translation of mRNA can begin while transcription is still occuring

2. multiple ribosomes read the same mRNA

how do bacteria control which genes are turned into proteins (2)

1. operons — sequence of genes that are expressed together

2. phase variation — gene is expresssed in a way to alter the phenotype

expressed v. silenced genes

expressed: translated into protein

silenced: not translated

how does the lactose operon work when silenced/expressed

silenced: aeorbic respiration

expressed: anaerobic respiration

how do bacteria share genes thru conjugation

how does this related to plasmids

2 cells must have direct connection thru a PILUS

resistance plasmids — antibiotic resistance genes that is EASILY shared thru conjugation

how do bacteria share genes thru transduction

viruses can pick up DNA from donor cells and release it into the receiving cell

how can viruses control which genes get turned into protein

1. gene order — genes at the start of a strand get translated more compared to at the end

2. overlapping genes — store genetic information efficiently because 1 nucleic acid → per 2 protein messages

how do viruses create genetic diversity (2)

• RDRP high mutation rate, RNA viruses mutate rapidly

  • antigenic DRIFT — small variation overtime, happens to the antigens so that the antibodies cant dectect them

• segmented genomes, more than 1 piece

  • antigenic SHIFT — easily swap genes

3 different types of symbioses & what do they mean

1. mutualism — both parties benefit

2. commensalism — microbe benefits, human is not affected

3. parasitism — microbe benefits, human is harmed

what is antigonism

species compete for resource/habitat

what is a polymicrobial community?

OPTIONAL relationship between +2 species that they both benefit

how do microbes communicate?

communicate thru quorum sensing w/ each other using AI signals

microbe

living thing that is too small to be seen

pathogen

cause of disease

infectious disease

resulting disease from pathogen

difference between prokaryotes v. eukaryotes

prokaryotes — small, no nucleus & organelles, free floating DNA

eukaryotes — bigger, nucleus & organelles, DNA

how do you properly write names in binomial nomenculture

Genus (capitalized) + species name (not capitalized)

louis pasteur

germ theory; that they make you sick