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BIO 110 > exam 2 (review slides) > Flashcards

exam 2 (review slides) Flashcards

1
Q

what is cell fractionation? how does it work? how are pellets separated based on size? and what is a supernatant?

A

cell fractionation: takes cells apart and separates major organelles and other cell structures from one another

  • done using a centrifuge, tube that spins really fast - components of cell settle at the bottom, forming a pellet
  • higher speed = pellet w smaller components
  • lower speed = pellet w larger components

supernatant: rest of the liquid which is at the top (consists of lighter components that didn’t settle at the bottom - i.e. cytoplasm & other small cell parts)

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2
Q

prokaryotic cells are characterized by having:

A
  • no nucleus
  • no membrane bound organelles
  • DNA in an unbound region called nucleoid
  • cytoplasm bound by plasma membrane
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3
Q

eukaryotic cells are characterized by having:

A
  • DNA in a nucleus that is bounded by a double membrane
  • membrane bound organelles
  • are also much larger than prokaryotic cells
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4
Q

nucleolus

A
  • site of ribosomal RNA (rRNA) synthesis
  • assembles and produces ribosomes
  • “command center” inside the nucleus
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5
Q

function of the nucleus

A
  • control center
  • hold’s cell’s genetic information
  • DNA replication, transcription, and translation happen here
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6
Q

translation vs transcription

A
  • transcription: synthesizing RNA from DNA
  • translation: synthesizing proteins fro the RNA
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7
Q

function of ribosomes + 2 types

A

“protein factories” - site of protein synthesis

free ribosomes: most proteins made on free ribosomes function within cytosol (free ribosomes are not attached to the ER)

bound ribosomes: make proteins destined for insertion into membrane, for packaging within organelles, or for export out of cell (bound to the ER)

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8
Q

what is the endoplasmic reticulum + the 2 types

A
  • cell’s “highway”
  • membrane of interconnected tubules that carry stuff around the cell

two types:

rough ER: synthesis and packaging of proteins
- bumpy because ribosomes are attached to it
- also distributes transport vesicles

smooth ER: has enzymes that help create and package lipids and also detoxifying substances and stores calcium ions

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9
Q

order of where the proteins go after synthesis

A
  1. membranes & proteins produced by the ER move via transport vesicles to the Golgi
  2. The Golgi pinches off transport vesicles and other vesicles that give rise to lysosomes, other types of specialized vesicles, and vacuoles
  3. The plasma membrane expands by fusion of vesicles; proteins are secreted from the cell by exocytosis
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10
Q

what are the 3 destinations for proteins produced by the rough ER

A
  1. shipped to another organelle (enzymes to catalyze reactions)
  2. inserted into plasma membrane (membrane transporters or pumps)
  3. secreted outside of cell (carry messages to other cells - glycoproteins)
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11
Q

what are transport vesicles

A

helps move materials, especially proteins from one organelle to another

  • distributed by the rough er
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12
Q

function of glycoproteins

A

enable cells to recognize another cell as familiar or foreign, which is called cell-cell recognition

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13
Q

cis and trans Golgi apparatus

A

cis: means same
- part of the Golgi apparatus nearest to ER (endoplasmic reticulum), functions primarily in receiving and sorting molecules

trans: means opposite
- part of Golgi farthest from ER, functions in final modifications of proteins before they’re shipped out`

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14
Q

what is the function of the Golgi apparatus?

A

“post office of cell city”

  • processes proteins + packages them before sending them where they need to go via transport vesicles
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15
Q

what are vesicles

A

sacs that little goodies are packaged into

  • used to ship stuff within cell or outside cell
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16
Q

what are lysosomes?

A

sacs of enzymes that break down cellular waste and debris from outside cell to turn into simpler components for inside cell

  • “digestive system of cell”
  • membraneous-enclosed sac of hydrolytic enzyme that can digest macromolecules
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17
Q

what is autophagy?

A

lysosomes use enzymes to recycle the cell’s own organelles and macromolecules

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18
Q

what is the function of the mitochondria?

A

cellular respiration!

  • use oxygen to generate ATP
  • cells that need more power (such as muscle cells) have more mitochondria in them
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19
Q

what is the inheritance pattern for mitochondria?

A

maternal b/c mitochondria self replicates so DNA never mixes with the father’s

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20
Q

what is unique about mitochondria compared to other organelles?

A

acts like its own cell, does its own replication and even has some DNA

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21
Q

3 similarities between mitochondria and chloroplasts

A
  • enveloped by a double membrane
  • contain free ribosomes and circular DNA molecules
  • grow and reproduce somewhat independently in cells
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22
Q

function of the chloroplasts

A

also energy!!

  • sites of photosynthesis
  • found in plants and algae
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23
Q

endosymbiont theory

A

idea that some organelles inside eukaryotic cells (like mitochondria and chloroplasts) were once independent, free-living bacteria

  • bacteria engulfed by larger cells, instead of being digested, formed mutually beneficial relationship with the host cell
  • over course of evolution, host cell and its endosymbiont merged into a single organism
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24
Q

2 main parts of a chloroplast

A

thylakoids: membranous sacs that capture light to turn into ATP solar panels of the cell
- stack to form granum

stroma: internal fluid that contains enzymes to use chemical energy to produce sugar kitchen of the cell, uses products to assemble

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25
Q

do plant cells have mitochondria?

A

yes, they have both mitochondria and chloroplast (chloroplasts are used for photosynthesis only)

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26
Q

how are mitochondria and chloroplasts similar?

A
  • both have double-membrane
  • have their own DNA and manufacture ribosomes
  • grow and divide independently of cell division
  • energy producing organelles
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27
Q

photosynthesis (chloroplasts) vs. cellular respiration (mitochondria)

A
  • photosynthesis builds glucose by capturing energy from the sun and stores the glucose for later use
  • cellular respiration breaks down glucose to ATP and for use within the cell
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28
Q

cilia and flagella

A

microtubule containing extensions that project from some cells

cilia: present in lung + throat cells to push up mucus

flagella: present in sperm cells

protozoans move around using cilia and flagella

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29
Q

tight junctions, gap junctions, and desmosomes (anchoring junctions)

A

tight junctions: “cellular zippers,” connect neighboring tissues tightly to make sure there are no leaks
- ex. present in digestive tract

gap junctions: “communication tunnels,” allow quick communication through openings that allow molecules and ions to pass directly
- ex. present in heart cells

desmosomes: fasten cells together into strong sheets, important in tissues subjected to mechanical stress, like skin and heart muscles

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30
Q

factors that affect membrane fluidity (3 factors + give reasons for why)

A
  • membranes with more unsaturated fatty acids are more fluid (because of the kinks, they cannot pack together as closely)
  • as temperature cools, becomes less fluid and more solid
  • cholesterol molecules embedded in membrane - reduce fluidity but prevent total tight packing (helps because when you reduce temperature, membrane won’t solidify as quickly)

membranes must be fluid to work properly

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31
Q

membranes are held together by ___________________ bonds

A

weak hydrophobic

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32
Q

phospholipids form main fabric of membrane, but ________ determine most of membrane’s functions

A

proteins

  • protein composition of membranes varies among cells within an organism, and among intracellular membranes within a cell
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33
Q

_____________ & ____________, _____________ molecules can enter the membrane easily

A

small & nonpolar, hydrophobic

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34
Q

how does the polarity of a molecule affect its crossing of the cell membrane?

A
  • nonpolar molecules are hydrophobic and have easy time passing through
  • polar molecules are hydrophilic and have difficulty passing (get stuck) or pass really slowly (including water)

proteins that are built into the membrane can help certain things pass

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35
Q

passive transport vs. active transport

A

passive transport: diffusion of substance across membrane with no energy required, goes down concentration gradient (high to low)

active transport: requires energy to move substances, movement against concentration gradient (low to high)

  • if 2 substances in a solute, moves down its OWN concentration gradient, not the overall concentration gradient
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36
Q

2 things that the selective permeability of a membrane is dependent on

A
  • natural permeability of a lipid bilayer (i.e. polar and nonpolar)
  • specific transport proteins built into the membrane
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37
Q

osmosis

A

diffusion but basically only for water

  • high to low water concentration
  • low to high solute concentration
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38
Q

sodium-potassium pump + ratio of Na and K

A
  • example of active transport
  • exchanges sodium for potassium against the electrochemical gradient
  • pumps sodium ions out and potassium ions in
  • ATP is hydrolyzed to ADP
  • carrier protein changes conformational shape
  • 3 Na+ into cell, 2 K+ out
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39
Q

electrogenic pump

A

an active transport protein that generates voltage across a membrane while pumping ions

  • in animals, it is Na+/K+ pump
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40
Q

membrane potential

A
  • all cells have voltages (electric potential energy, separation of opposite charges)
  • inside cell is more negative compared to the outside of the cell
  • pumps regulate this by pumping ions using energy

affects the movement of ions

41
Q

facilitated diffusion

A

speeds transport of solute by providing efficient passageway to go through

still passive bc doesn’t go against the concentration gradient

  • ex. channel proteins
42
Q

what is osmoregulation

A

control of solute concentration and water balance

  • important for organisms that live in very hypo or hypertonic environments
43
Q

bulk transport + 2 types + 3 types of endocytosis

A
  • large molecules, like polysaccharides and proteins, need to cross inside vesicles CAUSE THEY FAT

exocytosis: vesicles transport materials outside of the cell
- ex. nerve cells releasing neurotransmitters

endocytosis: vesicles transport into the cell
- two types: phagocytosis and pinocytosis

phagocytosis: devouring action, engulfs invader and then destroys

pinocytosis: drinking action, cell membrane folds and creates little pocket to bring things in (for fluids and other small substances)

receptor-mediated endocytosis: vesicle formation is triggered by solute binding to receptors, allows cell to acquire bulk quantities of specific substances

44
Q

kinetic energy, potential energy, thermal energy, and chemical energy

A

kinetic energy: energy associated with motion
- ex. water gushing through a dam turns turbines

potential energy: energy stored ready for action, has to do with position or structure
- ex. book on shelf can fall and do work or stretched rubber band
- molecules possess energy due to the arrangement of electrons in bonds between their atoms

thermal energy: associated with heat, the more heat something has = more thermal energy

chemical energy: energy stored in bonds b/w molecules
- ex. potential energy stored in food

45
Q

how to tell if a reaction occurs spontaneously or not?

A
  • by the free energy change

spontaneous: reaction will proceed without an input of energy

*negative ∆G = reaction will be spontaneous

positive ∆G = reaction is NOT spontaneous*

46
Q

entropy

A

∆S

  • measure of disorder in a system (represents dispersion of energy)
  • disordered state = high entropy state
47
Q

enthalpy

A

∆H

  • measure of the total heat content of a system
  • positive = heat is absorbed
  • negative = heat is released
48
Q

Gibbs free energy + equation

A

describes the amount of work that can be done in a system given the thermodynamic environment

∆G = ∆H - T∆S

*temperature in Kelvin

when G is positive = endergonic reaction

when G is negative = exergonic reaction

49
Q

exergonic vs endergonic reactions **

A
  • exergonic: energy out, more energy released than absorbed, products store less free energy than reactants (∆G is negative = so reaction is spontaneous)
  • endergonic: energy in, more energy absorbed than released, products store more free energy than reactants (∆G is positive = nonspontaneous reactions)
50
Q

ATP coupling

A

cells manage their energy resources by energy coupling

  • using energy released from an exergonic reaction to drive an endergonic reaction
  • most energy coupling in cells is mediated by ATP
51
Q

energy is released from ATP by…

A

the phosphate bond being broken by hydrolysis

  • energy comes from the chemical change of system to a state of lower free energy in products (not from phosphate bonds)
52
Q

why does hydrolysis release so much energy?

A

phosphate group has negative charge that causes a lot of repulsions (hence energy) when it breaks

53
Q

in cells, energy from the _____________ is used to drive __________ reactions

(ATP coupling)

A

exergonic hydrolysis of ATP; endergonic

54
Q

activation energy definition + barrier

A

initial energy needed to break the bonds of reactants

  • provides a barrier that determines rate of spontaneous reactions
55
Q

active site

A

region on enzyme, often a pocket or groove, that binds to substrate

56
Q

induced fit (in regards to enzyme-substrate)

A

enzyme changes shape slightly to fit the substrate

  • kinda like how you change grip on hand to shake someone else’s hand
57
Q

noncompetitive (allosteric) vs. competitive inhibitors

A

competitive inhibitors: “molecular rivals” that are competing with the substrate to bind to the active site
- increasing substrate concentration can overcome inhibition
- blocks substrate = reduces enzyme productivity

noncompetitive inhibitors: “molecular blockers” that bind to a different site on the enzyme, changing its shape to make it less effective at catalyzing reaction
- ex. toxins, antibiotics, pesticides

58
Q

allosteric regulation (activator and inhibitor)

A
  • “remote control” - controls from a distance, molecule binds elsewhere and changes function and shape of protein

allosteric activator: “protein cheerleader,” encourages the protein’s activity

allosteric inhibitor: when binds, slows down or blocks protein activity

are mostly bad bc once binded, change the shape forever and the enzyme just becomes useless - ex. toxins, poisons, etc.

59
Q

feedback inhibition

A

“brake system” for controlling a process

  • when product accumulates to a specific level, “feeds back” to inhibit or slow down earlier step in the proces
60
Q

cell cycle consists of _________ & _________

A

Interphase and Mitotic (M) phase

61
Q

interphase + the 3 phases

A

interphase: cell growth & copying of chromosomes in preparation for cell division

G1 phase: (“first gap”) - cell grows

S phase: (DNA synthesis) - chromosome replication

G2 phase: continued growth and preparation for cell division

62
Q

cell grows during all 3 phases of interphase, but chromosomes are only duplicated during what phase?

A

S phase

63
Q

which cell cycle does a cell spend 90% of its time?

A

interphase

64
Q

list the steps of mitosis and a fact about each step (in order)

A

PMAT C

  1. Prophase: chromatin fibers become more tightly coiled, condensing into discrete chromosomes, mitotic spindle begins to form
  2. Metaphase: chromosomes line up along the center of the cell, called the metaphase plate
  3. Anaphase: sister chromatids of each chromosome separate and move toward opposite ends of the pole, each chromatid thus becomes an independent chromosome
  4. Telophase: cell begins to separate but not entirely yet. The nuclear envelope re-forms around each set of chromosomes
  5. cytokinesis: division of the cytoplasm, in animal cells cytokines involves formation of a cleavage furrow, which pinches the cell in 2
65
Q

when a cell is not dividing, and even as it replicates its DNA in prep for cell division, each chromosome is in the form of a ______________

after DNA replication, chromosomes _______

A

long, thing chromatin fiber

condenses (each chromatin fiber becomes densely coiled and folded – chromosomes shorter and thicker)

66
Q

each duplicated chromosome in cell division has _________

A

2 sister chromatids

(joined copies of original chromosome)

67
Q

mitotic spindle

A

a structure made of microtubules that controls chromosome movement during mitosis

  • helps separate chromosomes during cell division (mitosis)
  • begins to form in cytoplasm during prophase
68
Q

at metaphase, chromosomes are all lined up at ____________

A

metaphase plate

(an imaginary plane midway between the spindle’s 2 poles)

69
Q

how is cytokinesis different in plant cells?

A

plants need to create a cell wall

in plant cells, a cell plate forms during cytokinesis – made from vesicles derived from Golgi apparatus move along microtubules to middle of the cell where they combine – site where new cell wall forms

70
Q

2 types of regulatory proteins that are involved in cell cycle control

A

cyclins: “traffic lights” – proteins that regulate progression of cell cycle by turning specific phases on and off

cyclin-dependent kinases (cdks): “drivers of the cell cycle” – enzymes that work with cyclins to activate or deactivate processes in the cell cycle

  • when cyclins bind to CDKs, the green light for the cell to proceed to the next phase.
71
Q

MPF (maturation-promoting factor)

A
  • cyclin and cdk binded together
  • approves cell to go past G2 checkpoint into M phase
72
Q

density- dependent inhibition & anchorage dependence + relation to cancer cells

A

density-dependent inhibition: phenomena in which animal cells stop dividing when they come into contact with each other

anchorage dependence: cells only divide and grow when they are attached to a surface or substrate

cancer cells exhibit neither type of regulation of their division

73
Q

loss of control in cancer cells is caused by what factors?

A
  • cancer cells do not heed the normal signals that regulate cell cycle (do not stop dividing when growth factors are depleted)
  • cancer cells make their own growth factor and may convey growth factor’s signal w/o presence of a growth factor
74
Q

local vs long distance signaling between cells

A

local: animal cells communicate using secreted messenger molecules that travel short distances – paracrine signaling (neighbors chatting over fence)

  • ex. growth factors stimulating nearby target cells to grow and divide or synaptic signaling in neurotransmitters

long distance: plants and animals use hormone molecules

75
Q

GPCRs (G protein-coupled receptors)

A
  • “cellular doorbells”– when rung by signaling molecules, set off a series of events inside the cell to produce a response
  • coupled with G proteins (which are like the “butlers”)

G proteins bind to the energy rich GTP which binds to GPCR

76
Q

Receptor Tyrosine Kinases (RTKs)

A

“cellular radio station”

  • antenna takes the signal outside (membrane receptor) that then
  • radio signal (signaling molecule) carries information inside
  • station receives signal and broadcasts (transmission)

RTK adds “phosphate tag” to certain proteins which triggers responses within the cell

77
Q

ligand-gated ion channel receptors

A
  • contains a region that acts as a gate that opens and closes when receptor changes shape
  • when signal molecule binds as ligand to receptor, the gate allows specific ions, such as Na+ or Ca2+ through a channel in receptor
78
Q

intracellular receptors

A
  • found in cytoplasm or nucleus of target cells
  • small, hydrophobic chemical messengers can readily cross membrane and activate receptors
  • ex. steroid and thyroid hormones in animals, NO (nitric oxide)
79
Q

what is a ligand

A

signaling molecule that works like a messenger

  • binds to specific receptors on cell surfaces and conveys information to elicit a response from the cell
80
Q

ligand binding causes a __________ in receptor

A

shape change

  • directly activates receptor, enabling it to interact with other molecules in or on cell
  • initial transduction of signal
81
Q

“first messenger” & “second messenger” in intracellular receptors

A
  • “first messenger” is the extracellular signaling molecule (ligand) that binds to membrane receptor
  • second messenger is a small, nonprotein that spreads throughout cell by diffusion (initiated by GPCRs and RTKs)
    relays messages in a cell from a receptor to a target where an action within cell takes place
82
Q

2 examples of second messengers

A

cyclic AMP (cAMP) & calcium ions (Ca2+)

83
Q

cyclic AMP pathway (list the steps)

A
  1. ligand binds to GPCR = conformational change in receptor complex occurs
    - activates a G protein that in return activates adenylyl cyclase
  2. adenylyl cyclase breaks down AMP into cAMP
  3. cAMP activates protein kinase A, which phosphorylates various other proteins
84
Q

what is a kinase

A

“cellular switch” that can turn on or off specific activities inside a cell

  • key function is to transfer phosphate group from ATP to another molecule (phosphorylation)
85
Q

an electron _______ potential energy when it shifts from a ______ electronegative atom towards a _______ electronegative one

A

loses

less

more

86
Q

redox reactions that move electrons closer to electronegative O atoms _______ chemical energy that can be put to __________

A

release; work

87
Q

NAD+ functions as an __________ agent during cellular respiration

A

oxidizing

(because it gets reduced)

88
Q

if there is oxygen present then what happens to the pyruvate from glycolysis? what if there is no oxygen present?

A
  • oxygen: continues along cell respiration
  • no oxygen: goes to fermentation
89
Q

goal of fermentation

A

regenerate NAD+ so that glycolysis can continue = so cell can continue to produce ATP

90
Q

which part of cellular respiration starts to produce CO2?

A

pyruvate oxidation

(only 2 times makes CO2 is pyruvate oxidation and Krebs cycle, aka citric acid cycle)

91
Q

how does anaerobic respiration use an ETC?

A

anaerobic respiration uses an ETC but does not use O2 as a final electron acceptor

92
Q

3 points about the evolutionary significance of glycolysis

A
  • early prokaryotes likely used glycolysis to produce ATP before oxygen accumulated in the atmosphere
  • used in both cellular respiration & fermentation – most widespread metabolic pathway on Earth
  • occurs in cytosol without requiring any membrane bound organelles of eukaryotic cells
93
Q

“the versatility of catabolism”

  • its role in carbs, proteins, fats
A

carbs: used in glycolysis

proteins: become intermediates of glycolysis and citric acid cycle

fats: glycerol converted into G3P, fatty acids are broken down by beta oxidation and yield acetyl coA, NADH, and FADH2

94
Q

autotrophs & heterotrophs definition

A

autotrophs: “self feeders” that sustain themselves without eating anything derived from other organisms

heterotroph: obtain organic material from other organisms, consumers

95
Q

the 2 stages of photosynthesis

A

1. light dependent reactions
- in thylakoid membranes
- release O2 as by-product
- reduce NAD+ to NADH
- generate ATP from ADP by photophosphorylation

2. Calvin Cycle, light independent reactions
- occurs in stroma
- makes sugar from CO2, using ATP and NADH generated during light reactions

96
Q

what is unique about the cyclic electron flow compared to the linear electron flow?

A

cyclic electron flow uses photosystem I ONLY

  • produced ATP, but not NADPH or oxygen
97
Q

what are the products of linear electron flow and what are the products of cyclic electron flow during light reactions of photosynthesis?

A

linear: ATP and NADPH

cyclic: ATP

98
Q

where are ATP synthase complexes located in plant cells?

A

thylakoid membrane and inner mitochondrial membrane

99
Q
A

BIO 110 (11 decks)

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