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ISCI1A24 > LifeSci (Winter Exam 2024) > Flashcards

LifeSci (Winter Exam 2024) Flashcards

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1
Q

most extremophiles are _____. why?

A

bacteria and archaea, due to diverse metabolic pathways.

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2
Q

name four main types of extremophiles

A

anaerobe - absence of oxygen
halophile - high conc. salt
thermophile - 40 deg. or higher
xerophile - low water

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3
Q

describe cell theory (4 main points)

A

1) all living things are made of cells
2) cells are a basic unit of structure
3) cells contain info that is passed down from cell to cell
4) all cells come from preexisting cells

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4
Q

describe the central dogma of biology

A

genetic information flows in specific directions: DNA to RNA to protein

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5
Q

what are the two genetic origin ‘perspectives’?

A

top down approach: RNA and ribosome first (RNA world)
bottom up approach: chemical chimera, composed of RNA/DNA building blocks

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6
Q

why does research support the chimera model of genetic origin?

A
  • increased surface area
  • increased molecular stability
  • greater probability of RNA/DNA synthesis
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7
Q

describe endosymbiosis

A

the theory that organelles began by ancestral eukaryotic cells engulfing prokaryotes, forming small ‘cell components’ within

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8
Q

describe secondary endosymbiosis

A

a cell that has gone through primary endosymbiosis in engulfed by another cell, forming an ancestral organelle

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9
Q

describe the water cycle concisely.

A

more precipitation falls on land than evaporates/transpires, excess leave as runoff. less precipitation falls on the ocean that evaporates/transpires, ocean export water via atmosphere

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10
Q

what is a carbon flux?

A

the amount of carbon exchanged between two carbon pools: eg. the ocean and land

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11
Q

in terms of carbon fluxes: human causes fluxes are _________, larger fluxes are _________ and _________.

A

1) Small but persistent
2) Land plants and atmosphere
3) ocean and atmosphere

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12
Q

where are the largest oxygen fluxes? where is the greatest oxygen reservoir?

A

1) plants & atmosphere
2) lithosphere

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13
Q

why is nitrogen the most abundant atmospheric element?

A

nitrogen cycle: key biogeochemical cycle

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14
Q

what is nitrogen fixation?

A

the process in which nitrogen gas (N2) is converted into ammonia (NH3)

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15
Q

what are the four conceptual pillars of physiology (according to Chad)?

A

1) function based on structure
2) evolution
3) homeostasis
4) feedback loops

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16
Q

what is the definition of homeostasis? how does the body maintain it?

A

“the ability of an organisms to main internal equilibria by adjusting physiological processes against external fluctuation”. positive/negative feedback loops.

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17
Q

name and describe 6 methods of intercellular communication

A

AUTOCRINE - act on same cell
PARACRINE - acts on neighbors
ENDOCRINE - hormones, fluid carry (distant cells)
NEURAL - short diffusion, neurons
NEUROENDOCRINE - neuron, fluid carry (distant cells)
PHEROMONES - released into environment, act on a different individual

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18
Q

what are the MAIN two method of intercellular communication? give examples.

A

endocrine signals: eg. hormones
neural signals: eg. neurotransmitters

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19
Q

what is a neurotransmitter?

A

chemical released between two nerve cells (presynaptic to postsynaptic nerve), affects electrical potential of receiving nerve

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20
Q

describe the Na+/K+ pump.

A

The Na+/K+ pump actively transports 3 Na+ out of the cell and 2 K+ ions into the cell, maintaining the electrochemical gradient essential for cell function. It uses ATP to power changes in the pump protein, allowing the ions to move against their concentration gradients.

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21
Q

what is a hormone?

A

chemicals released by a cell/gland in one part of the body that affects cells in other parts of the organism. receiving cells must have receptors for the hormone to be affected.

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22
Q

what is an agonist?

A

chemical that binds to a to a cell receptors and TRIGGERS A RESPONSE (mimics natural action)

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23
Q

what is an inverse agonist?

A

chemical that binds to a to a cell receptors and TRIGGERS AN INVERSE RESPONSE (mimics opposite of natural action)

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24
Q

what is an antagonist? are they reversible?

A

chemical that binds to a receptor site and prevents the binding of an agonist. can be reversible OR irreversible

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25
describe mode vs method of action.
mode - general mechanism of action (eg. receptor antagonist) method - specific interaction (eg. extracellular, lipid-soluble)
26
how does conditioning (classical AND operant) tie into addiction?
classical conditioning: substance becomes linked with specific triggers, such as places, people, or emotions, leading these cues to evoke cravings operant conditioning: substance's rewarding effects, like euphoria or stress relief, reinforce the behavior
27
describe the form and function of the nucleus
double membrane (nuclear envelope), chromosomes attached to nuclear lamina, NE studded with nuclear pores, contains nucleolus (with chromosomes regions encoding ribosomes)
28
describe the form and function of the ribosome
protein synthesis, composed of RNA/protein
29
describe the form and function of the rough endoplasmic reticulum
membrane is continuous with nuclear envelope, proteins are folded and processed, multiple types of proteins made (eg. enzymes, membrane transport proteins)
30
describe the form and function of the smooth endoplasmic reticulum
lacks ribosomes, processes lipids (and stores lipids), is a reservoir for Ca2+
31
describe the form and function of the golgi apparatus
made of flat sacs (cisternae), has cis/trans polarity (cis is facing nucleus), proteins from Rough ER are processed/packaged here (released in vesicles)
32
describe the form and function of the lysosome
stores/degrades/recycles solid waste, lumen is acidic, has 40 different enzymes to target substrates
33
lysosomes are involved in what three processes?
phagocytosis, autophagy, and receptor-mediated endocytosis
34
describe phagocytosis
Cell membrane surrounds and engulfs smaller cell or food particle, phagosome is delivered to lysosome
35
describe autophagy
Damaged organelle surrounded by a membrane & taken to lysosome
36
describe receptor-mediated endocytosis
a selective process where cells internalize specific molecules by binding them to receptors on the cell membrane, forming protein-coated vesicles for transport into the cell
37
describe the form and function of the peroxisome
single membrane, grows/divides INDEPENDENT of other organelle, is the center for oxidation
38
describe the form and function of the mitochondria
synthesizes ATP, has a double membrane, grows/divides independently, has chromosomes that code unique proteins
39
describe the form and function of the chloroplast
double membrane, thylakoids/grana, independent circular chromosome, stores chlorophyll for photosynthesis
40
describe the form and function of the cytoskeleton
network of protein fibers, gives shape/stability
41
describe the form and function of the cell wall
made of cellulose/lignin, provides structure/protection in plants, algae, and fungi
42
what is the endomembrane system?
proteins are synthesized in the Rough ER, move to the golgi for processing, then travel to the cell surface
43
why is the endomembrane system important?
movement of proteins is energy demanding
44
what is the signal hypothesis, in summary?
The signal hypothesis explains how proteins are sent to the right place in a cell. A special tag, called a signal peptide, on the protein helps guide it to the endoplasmic reticulum (ER). There, the protein is processed and sent to where it’s needed.
45
explain step 1 of the signal hypothesis
postal code (ER signal sequence) direct growing polypeptide, binds to signal recognition particle (SRP) that then binds to an SRP receptor in the ER membrane
46
describe steps 2+3 of the signal hypothesis
proteins transported from the ER to the CIS face of golgi using vesicles, enzymes attach carbohydrate chains, proteins pass through cisternae to TRANS face.
47
describe steps 4+5 of the signal hypothesis
carb. chains act as molecular 'tag', places protein in particular transport vesicle. each transport vesicle is tagged for its destination.
48
how are proteins imported into the nucleus?
using the signal hypothesis/endomembrane system. nuclear localization signal is 17 amino acids long! molecules move through the nuclear pores.
49
what is a tight junction?
type of cell-cell attachment composed of specialized plasma membrane proteins, proteins line up and bind, forming a watertight seal and 'stitching' two cells together
50
what is a desmosome?
proteins that link the cytoskeletons of adjacent cells (ANIMAL)
51
what are the plasmodesmata?
gaps in the cell wall (PLANT) where the plasma membranes, cytoplasm, and smooth ER of two cells connect
52
what is a gap junction?
a cell-cell gap that connects adjacent animal cells to allow the flow of small molecules
53
what is a signal receptor?
receptor proteins that change shape/activity after binding to signaling molecule
54
what is a receptor protein?
a protein that dictates which cells can respond to particular hormones
55
signal receptors that bind to _______ are located inside the cell. most signal receptors are located in the _______.
steroid hormones, plasma membrane
56
_________ hormones cannot diffuse across the plasma membrane
hydrophilic
57
how to hydrophilic hormones convey signals?
signal transduction
58
what are g proteins?
membrane proteins located INSIDE the cell, associated with transmembrane signal receptors
59
when are g proteins activated? when are they deactivated?
activated when they bind GTP, deactivated when they hydrolyze GTP to GDP.
60
g-protein-activated enzymes can _______ the production of intracellular signaling molecules called _____________
catalyze, second messengers
61
how do g proteins work? (3 steps)
1) G protein binds GDP. signal arrives, binds to receptor 2) signal-receptor complex changes conformation, g protein bindings GTP and splits into 2 3) enzyme catalyzes reaction that produces second messenger
62
how does signal deactivation happen? why is this process important?
automatic/rapid mechanisms within the cell. allow cells to remain sensitive to changes in hormone concentration/activity of signal receptors.
63
describe bioconcentration
the process by which a chemical substance accumulates in an organism's tissues from its surrounding environment, such as water or air, at a rate faster than it is metabolized or excreted
64
describe bioaccumulation
the process by which a substance, such as a pollutant, builds up in an organism over time, from both its environment (like water, air, or soil) and through its diet
65
describe biomagnification
the process by which the concentration of a substance, such as a toxin or pollutant, increases as it moves up the food chain
66
what is the net trophic transfer efficiency?
the percentage of energy or biomass transferred from one trophic level to the next in an ecosystem. usually ~10%
67
cortisol is linked to the ________ system
stress response
68
cortisol is controlled through a ______ feedback loop that involves what three main endocrine glands?
negative feedback - hypothalamus (CRH), pituitary gland (ACTH), adrenal glands (cortisol)
69
what are three main functions of cortisol?
'fight or flight', managing how nutrients are used (carbs, fats, etc.), regulating blood pressure/glucose
70
what are some effects of long-term high cortisol?
impairment of memory (hippocampus), genesis of increased dose dependence (over time, less cortisol is produced), increased stress/anxiety
71
consider the statement: humans are more evolved than slime molds. Is it true or false, and why?
false, both are extant.
72
define a diuretic
A chemical that decreases water reuptake
73
define a metabolite
A metabolite is any substance produced or consumed during metabolism, which is the set of chemical reactions that occur within a living organism to maintain life.
74
what is cognitive dissonance
actions and thoughts/beliefs don't align (eventually one will have to change and match the other)
75
what is groupthink
in a big group, you will go along with the majority - more likely to have pushback or action when individual or one-on-one
76
what is the bystander effect
the presence of others discourages action by an individual
77
difference between plasmodesmata and desmosomes?
plasmodesmata are in plants, desmosomes + gap junctions in animals. same basic function
78
gap junctions are an example of _____________ communication
paracrine
79
describe signal transduction
Triggered by G-proteins responding to extracellular stimulus, gives an intracellular response using the phosphate bond energy (GTP → GDP)
80
describe the secretory pathway hypothesis
The secretory pathway hypothesis describes how proteins are synthesized on ribosomes bound to the rough ER, where they enter the lumen for folding and modifications. They are packaged into vesicles, transported to the Golgi apparatus for further processing and sorting, and then directed via vesicles to their final destinations, such as the plasma membrane, lysosomes, or secretion outside the cell.
81
what is weathering
erosion - can be chemical or physical
82
____________ leads to the bystander effect
Diffusion of responsibility
83
explain classical conditioning (simply)
Neutral stimulus + unconditioned stimulus → conditioned stimulus + conditioned response
84
explain operant conditioning
Behavior → consequence (reinforcement or punishment) → increases or decreases behavior
85
describe biogenesis vs abiogenesis
Biogenesis: Life arises from pre-existing life Abiogenesis: Life originates from non-living matter
86
describe the hadean eon's oceans. what was happening?
active mantle plumes occurring, extremophiles living in and around
87
what is the significance of the Miller-Urey experiment (1953)?
first demonstration of abiogenesis
88
what is the Oparin-Haldane hypothesis?
life was created through abiogenesis
89

ISCI1A24 (9 decks)

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