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BIMM 121 > W1/2 material > Flashcards

W1/2 material Flashcards

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1
Q

define eukaryote

A

single celled or multicellular.

an organism whose cells have a nucleus enclosed by a membrane.

contain membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum).

animals, plants, fungi, and protists.

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2
Q

define prokaryote

A

a unicellular organism lacking a nucleus.

no membrane-bound organelles.

bacteria and archaea.

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3
Q

define unicellular. provide examples (3)

A

a single cell that performs all life functions.

Ex: include bacteria, archaea, and some protists.

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4
Q

define multicellular. provide examples (3)

A

multiple cells that work together, often specializing in different functions.

Examples include animals, plants, and fungi.

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5
Q

define colonial. what are they composed of? do they live in groups? can they survive independently?

A

organisms composed of multiple genetically identical cells that live together in a group but can often survive independently

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6
Q

define protist

A

a diverse, mostly unicellular eukaryotic organism that aren’t animals, plants, or fungi

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7
Q

define protozoa. unicellular or multicellular? heterotorphic or not? how do they move?

A

unicellular, heterotrophic protists that move using cilia, flagella, or pseudopodia.

often motile and can be free-living or parasitic

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8
Q

define algae. multicellular of unicellular?where do they live? what can they produce?

A

photosynthetic protists that can be unicellular or multicellular.

They live in aquatic environments and produce oxygen

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9
Q

define Archaea

A

unicellular prokaryotes that thrive in extreme environments

have unique cell membranes and genetic features distinct from bacteria.

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10
Q

define bacteria

A

unicellular prokaryotes with cell walls, no nucleus, and diverse metabolic abilities.

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11
Q

define fungi

A

eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds, mushrooms).

heterotrophic

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12
Q

define yeast

A

unicellular fungi that reproduce by budding or fission (sometimes)

budding - daughter cell is smaller

fission - parent + daughter cell same size

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13
Q

what is a definition

A
  1. It is not a list of organisms
  2. It is not an encyclopedia entry
  3. It includes all organisms that are in the group
  4. It excludes all organisms that are not in the group
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14
Q

what do eukaryotes and prokaryotes have in common?

A
  1. both have a plasma membrane
  2. both have a cytoplasm
  3. both utilize DNA as genetic material
  4. both have ribosomes
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15
Q

five differences between eukaryotes & prokaryotes

A

Prokaryotes
1. DNA is naked, circular, no introns
2. No nucleus, No membrane-bound organelle
3. Binary fission, haploid
4. Smaller
5. always single celled

Eukaryotes
1. DNA bound to protein, linear, w/ introns
2. Nucleus, membrane bound
3. Mitosis + meiosis, diploid
4. Larger
5. single celled or multicellular

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16
Q

Which organisms have cell walls? What are the cell walls made of?

A

plants - cellulose
fungi - chitin
bacteria - peptidoglycan
algae - cellulose

NOT ANIMALS

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17
Q

how many variables should you change in an experiment at a time? Why?

A

One at a time, to ensure any observed changes are directly attributed to that variable

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18
Q

what is a control variable? why do we do controls?

A

Where conditions are kept constant

Used to validate experimental design

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19
Q

what type of controls are there? how do you know what type a control is?

A

postive control + negative control
——-> yk the outcome in advance
***when you know EXACTLY the outcome it should be, if the outcome is different from the expected, it means something is wrong w/ the experiment

baseline control
——-> you don’t know what to expect
***dont know the default

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20
Q

A1 control(s)? B1 control(s)?

A

b1: static with no additive replicates

a1: baseline control - unwashed produce

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21
Q

what is a controlled variable?

A

A variable that could affect the outcome, so it is kept constant across all groups.

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22
Q

explain how a controlled variable is NOT related to a control? why do controlled variables matter?

A

A controlled variable is kept constant to prevent interference, while a control is a separate test group used for comparison.

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23
Q

what was the controlled variable in A1? B1?

A

a1: Type of produce

b1: static condition

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24
Q

what are biofilms? why are they significant?

A

a collection of microorganisms where cells stick to each other or to surfaces via an EPS matrix

important bc it increases antibiotic resistance

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25
What is the experimental design of the biofilm experiment ? Why? Explain the strategy
4 experimental controls = used to measure the effect of the independent variable on the dependent variable 2 control vials = to validate experimental design 1 baseline = bc we dont know what to expect, a reference used to compare against the experimental controls 1 blank = control for aseptic technique
26
what is the purpose of microcosm experiment?
to examine phenotypic and genotypic diffrences across bacteria grown under different conditons.
27
how do you determine what volume is a particular percentage of a total volume? provide the equation
(% / 100)*(total volume) = desired volume
28
What is the point of aseptic (or sterile) technique? How do you achieve aseptic technique? (methods of sterilization, methods of inoculation)
to prevent contamination autoclaving, dry heat, flaming, and chemical disinfectants like ethanol. Inoculation Methods: 1. Work in the cone of stability 2. Sterilize tools before and after use 3. Flame tube lips before and after opening 4. Avoid unnecessary cap handling 5. Use proper transfer techniques.
29
Why do we store plates up-side-down?
to prevent condensation from dripping onto bacterial colonies
30
Why might we seal a plate with parafilm?
if culture is pathogenic, if plate will be stored for a long time
31
What is the “cone of sterility?”
created by a Bunsen burner’s heat to minimize airborne contamination.
32
Where might you find bacteria that could contaminate your pure cultures?
anywhere
33
in the lab environment, what is sterile and what is not?
sterilized tools and media unsterilized bench tops, gloves, clothing, air etc.
34
What is MacConkey agar? Why might we use it? (What is it for?) What bacteria might be differentiated using this medium? What does it look like? What category(ies) of media does this fall into? How does TSA compare?
selective, via inhibiting gram positive bacteria, and differential, via distinguishing lactose fermentors from non lactose fermentors, medium used to isolate and differentiate Gram-negative bacteria contains bile salts and crystal violet, thus its reddish-pink color TSA/Kings's B is non-selective, non-differential medium meaning it supports wide range of bacterial growth without differentiating
35
What would you learn about your bacteria by plating them on MacConkey? Why? What is in the agar?
gram negative bacteria bc of the bile slats and crystal violet which inhibit gram positive lactose fermenting bacteria bc of the lactose and neutral red (pH indicator) that turn pink due to acid production, a byproduct of fermentation
36
Explain the difference between “Gram positive” and “Gram negative” bacteria. Why do they have these names?
Gram-positive bacteria - a thick peptidoglycan layer in their cell wall, retains crystal violet stain, causing them to appear purple. Gram-negative bacteria - a thin peptidoglycan layer and an outer membrane. Ccrystal violet stain is washed away, appearing pink. come from the Gram stain method which differentiates bacteria based on their cell wall characteristics.
37
What is the point of streaking for isolated colonies? What essential steps in the streak plate technique ensure that this will happen?
to obtain pure colonies dilution via sterilizing loop between streaks
38
Would you be able to isolate bacteria by inoculating them into a broth culture? Why or why not? What if you streak a broth culture on an agar plate?
no bc bacteria will grow together in the liquid yes bc streaking spreads bacteria across surface
39
Why does a streak plate produce the best isolation in the later sectors rather than the first?
bacteria more isolated in later sectors bc of dilution
40
If you wish to make a T-streak, do you need to dilute the culture first?
No
41
What are the characteristics of a good streak plate?
Isolated Colonies, Distinct Colony Morphology, No Overlap
42
Can you tell if your bacterial culture on an agar plate is contaminated, just by looking at it?
yes based on the way colonies look
43
What characteristics are used to describe bacterial colonies?
Size, color Shape/edge - circular, irregular, filamentous, rhizoid texture - creamy, hard, mucoid, dry surface appearance - glistening, dull, wrinkeld evolution - flat, convex, pulvinate, umbonate
44
Distinguish between agar slants, agar deeps, agar plates
Agar Slants – Tubes w/ solid agar tilted at an angle to increase the surface area. Used for long-term culture storage and bacterial growth observation. Agar Deeps – Tubes w/ solid agar hardened in an upright position. Used to test oxygen requirements and motility. Agar Plates – Petri dishes w/ a thin layer of solid agar. Provide a large surface area for isolation, colony morphology observation, and microbial testing.
45
What is agar? Advantages?
mixed polysaccharides derived from seaweed Not broken down by bacteria, nutrients nutrients are not usable by most bacteria melts @ high temps, solid @ temps used for bacterial growth
46
Why would you shake a broth culture during incubation?
provides aeration - increases oxygen availability, promoting faster growth, especially for aerobic bacteria.
47
How would you determine the “optimal” temperature for growing a microbe?
by figuring out the temp they like to grow in
48
Spell the organism we have been using. What is the taxonomy? What is the strand name? What temp do they grow best @? Are they aerobes? Motile rods? Gram - or +? When do they turn yellow? What medium do they grow in?
Pseudomonas fluoresens Bacteria SBW25 28°C Yes Gram (-) When in King's B + high cell density LB and KB
49
How are the sizes of prokaryotes and eukaryotes related?
prokaryotes always smaller than eukaryotes bc eukaryotes have a more complex structure
50
What does a bacterium look like in the view at 100X? at 40X?
100x - small specks 40x - prokaryotic bacteria not visible
51
Describe these parts of a light microscope and how they work: focus knobs, substage condenser, two controls for the light
Focus Knobs – Coarse and fine adjustments move the stage up/down to focus the image. Substage Condenser – bends and directs light toward the sample on stage light switch; brightness control dial
52
Explain resolution, depth of focus, parfocal
resolution: ability of the microscope to clearly distinguish 2 very small objects places close together as 2 separate entities depth of focus: the range of distances for which the specimen (object) is imaged with an acceptable sharpness on the image plane parafocal: a specimen in focus at 1 magnification will be in focus at the other magnification
53
What is “brightfield” microscopy? When would you use it?
used to see colored or stained samples.
54
When observing slides under a microscope, can you distinguish between a eukaryote and a prokaryote? Explain
for wet mounts - generally yes based on size, shape, and motility. Stained slides provide clear identification based on overall cell structure, especially when using differential stains for bacterial classification
55
What is the point of phase contrast microscopy? When should you use it?
Phase contract is used to obtain precise info on cell size, shape, and motility used to view live or transparent, unstained cells via wet mounts
56
How do you prepare a wet mount? What defines a good wet mount? Why should it be fresh?
by adding 20 microliters of water, add cells, cover mount using a cover slip A good wet mount is one without too and not adding too many cells and little to no air bubbles fresh to ensure living specimens remain motile although movement does not mean they are motile
57
Which lenses can utilize phase contrast optics?
40 and 100
58
If you have bacteria on the slide, what should you focus on at low power? (Do you need to focus on anything at low power?)
a sharpie dot
59
Advantages and disadvantages if staining cells? (compared to wet mounts)
Advantages: Preserves cells for extended study, can see cell structures, differentiate bacteria based on cell wall structure Wet mounts: Good for general shape and movement, not cell structures Disadvantages: Kills living cells, Time-consuming
60
What is ecological opportunity why is bacteria a great model for evol? In a niche, is there a higher proportion of evolved morphs? What type of environments can you get environmental differences to create different niches for variants who are better adapted to survive in ? can we expect evolutionary trade-offs with diversification? Can you have more mutants in a larger pop? Can variation correlate with environmental heterogeneity? what type of reproduction keeps genotypes pure?
availability of new/underutilized resources or niches that can drive evolutionary diversification bc they have a short evolutionary time scale Yes. Heterogenous environments Yes Yes YES Asexual

BIMM 121 (4 decks)

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