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MCAT > Bio 4 > Flashcards

Bio 4 Flashcards

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MCAT flashcards
1
Q

What colour are Gram-negative bacteria?

A

light pink

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2
Q

What colour are Gram-positive bacteria?

A

dark purple

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3
Q

Describe the cell wall of Gram-positive bacteria

A

thick layer of peptidoglycan

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4
Q

Describe the cell wall of Gram-negatice bacteria

A

thin layer of peptidoglycan in the periplasmic space with an outer membrane with endotoxin outside it

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5
Q

How can endotoxins cause septic shock?

A

when bacteria die inside us and their disintegrated outer membranes are released into circulation

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6
Q

How is the prokaryotic flagellum different from a eukaryotic flagellum?

A

different structure
has a filament, hook, basal structure and rod (eukaryotic is 9+2 MTs)
requires large amounts of ATP to rotate rod

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7
Q

What are fimbriae?

A

like pill, but smaller

they are involved in adhering to surfaces

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8
Q

What are pilli?

A

long projections on the surface of bacteria that are used for attaching to different surfaces i.e. the sex pilus is used for conjugation

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9
Q

What are mesophiles?

A

like 30 degrees (i.e. us)

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10
Q

What are thermophiles?

A

survive at temperatures up to 100 degrees C

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11
Q

What are psychrophiles?

A

thrive at temps near 0 degrees C

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12
Q

What are autotrophs?

A

use CO2 as their carbon source

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13
Q

What are auxotrophs?

A

bacterium which cannot survive on minimal medium

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14
Q

What is a plaque in a bacterial lawn?

A

a clear area where the bacteria have died from lytic viruses or toxins

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15
Q

What is a facultative anaerobe?

A

use oxygen when its around, but don’t need t

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16
Q

What is a tolerant anaerobe?

A

can grow in the presence of oxygen, but don’t use in it their metabolism

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17
Q

What is an obligate anaerobe?

A

poisoned by oxygen

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18
Q

What is anaerobic respiration?

A

using something other than O2 as an electron acceptor i.e. SO4- or NO3-

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19
Q

What are endospores?

A

some Gram-positive bacteria can form tough, thick external shells made of peptidoglycan under unfavourable growth conditions
can survive above 100 degrees C

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20
Q

What is metabolic reactivation of endospores called?

A

germination

21
Q

Are bacteria that possess the F factor male or female?

A

male

22
Q

How can conjugation with an Hfr cell transfer other genes?

A

since it is integrated into the genome, when it is replicated replication can continue into other genes and then they will be transferred too

23
Q

What is the nuclear matrix or nuclear scaffolding?

A

insoluble mesh of protein left behind if you treat a nucleus with DNase and detergent

24
Q

Which RNA polymerase makes rRNA?

A

RNA polymerase 1

25
Q

What is a nuclear localization sequence?

A

sequence of basic amino acids that targets proteins larger than 60kDa to allow them through nuclear pores

26
Q

What is a signal sequence?

A

N-terminal amino acid sequence on proteins that targets them to the rough ER via an SRP
on all proteins except the ones going to the nucleus, mitochondria, peroxisomes etc

27
Q

What is the “default” pathway for proteins that go through the secretory pathway?

A

the plasma membrane

28
Q

What is a targeting signal?

A

amino acid sequence on proteins that need to go somewhere other than the PM in the secretory pathway i.e. Golgi, ER or lysosome

29
Q

What is a localization signal?

A

amino acid sequence on proteins that are made in the cytoplasm and need to be sent to an organelle that is not part of the secretory pathway i.e. nucleus, mitochondria, peroxisomes

30
Q

What is crinophagy?

A

lysosomal degradation of unneeded secretory products

31
Q

What is special about the mitochondrial inner membrane?

A

higher concentration of proteins than lipids

32
Q

Where is glycosylation found?

A

on the extracellular surface of membranes only

33
Q

What is molality? Why is it useful for measuring properties that involve temperature?

A

mol of solute / kg of solute

because it does not change with temperature

34
Q

What do colligative properties depend on?

A

number of solute particles in the solution instead of the type of particle

35
Q

What is vapour pressure? What happens to it as you add more solute to a solution?

A

the pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of the liquid
higher vapour pressure = evaporates easier
adding more solute will decrease its vapour pressure (raises the boiling point)

36
Q

Describe boiling-point elevation

A

boiling point is directly related to the number of particles in solution, more particles the higher the boiling point is
delta T = kbim
kb=solvent’s boiling point elevation constant

37
Q

Describe freezing-point depression

A

more particles in a solution, lower freezing point
delta T = kfim
kf=solvent’s freezing-point depression constant

38
Q

What is osmotic pressure?

A

the pressure it would take to stop osmosis from occurring
van’t Hoff equation:
osmotic pressure = MiRT
Note: M is the osmolarity of the solution (not osmolality)

39
Q

What are porins?

A

polypeptides that form pores in cell membranes

40
Q

What does the Na+/K+ ATPase move in one cycle?

A

3 Na+ out of the cell and 2 K+ into the cell

hydrolyzes ATP to do this

41
Q

What are the 3 types of endocytosis?

A

phagocytosis
pinocytosis
receptor-mediated endocytosis

42
Q

What is the secondary messenger used for epinephrine and glucagon?

A

cAMP

43
Q

When is the alpha subunit of a G-protein-coupled-receptor active?

A

when bound to GTP it will dissociate and activate or inhibit adenylyl cyclase or other enzymes

44
Q

How large is the diameter of microtubules?

A

25nm

45
Q

What is the diameter of intermediate filaments?

A

10nm

46
Q

What is the diameter of microfilaments?

A

7nm

these are actin filaments

47
Q

What do desmosomes do?

A

hold cells together tightly, but don’t form a seal like tight junctions would
are found in the epithelial cells in the skin
anchored to the PM by keratin, attach to the intermediate filaments of the cytoplasm

48
Q

What is another name for tight junctions?

A

occluding junctions

49
Q

What do gap junctions allow the exchange of?

A

ions, amino acids and carbs

NOT polypeptides or organelles

MCAT (15 decks)

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