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PCAT > Cell Biology & Molecular Biology > Flashcards

Cell Biology & Molecular Biology Flashcards

1
Q

cell membrane

A
  • encloses the cell, exhibits selective permeability to regulate the passage of materials in and out of the cell
  • PM permeable to small NP molecules (O2) and and small polar molecules (H20)
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2
Q

fluid mosaic model

A
  • cell membrane consists of a phospholipid bilayer w/ proteins embedded throughout
  • lipids/proteins can move freely within the membrane
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3
Q

nucleus

A
  • controls activities of the cell (cell division)
  • contains DNA (composed of structural proteins called histones)
  • nucleolus: dense structure in the nucleus where ribosomal RNA synthesis occurs
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4
Q

ribosome

A
  • sites of protein production
  • synthesized by nucleolus
  • free ribosomes found in cytoplasm, bound ribosomes line ER
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5
Q

endoplasmic reticulum

A
  • involved in transport of materials throughout the cell, particularly those secreted by th cell
  • smooth ER: does not contain ribosomes, involved in metabolism and lipid production
  • rough ER: contains ribosomes and involved in protein synthesis
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6
Q

golgi apparatus

A

-receives vesicles from smooth ER and modifies them (glycosylation), repackages, and distributes to cell surface by exocytosis

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7
Q

mitochondria

A
  • site of aerobic respiration

- supplier of energy (ATP)

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8
Q

cytoplasm

A
  • most of cell metabolic activity occurs here
  • cytosol: fluid contained within the cell membrane
  • cyclosis: transport within the cytoplasm
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9
Q

vacuoles/vesicles

A
  • membrane bound sacs involved in transport and storage of materials
  • vacuoles are larger and more common in plants
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10
Q

centrioles

A
  • involved in spindle organization during cell division

- animal cells have a pair of centrioles that lie in a region called the centrosome

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11
Q

lysosomes

A
  • membrane bound vesicles that contain hydrolytic enzymes involved in digestion
  • break down ingested material
  • autolysis: injured or dying tissue ruptures the lysosome and releasing its enzymes
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12
Q

cytoskeleton

A
  • support, shape, and motility
  • composed of intermediate filaments, microtubules, and microfilaments
  • microtubules: hollow rods made up of tubulin, support and movement (cilia and flagella)
  • microfilaments: solid rods of actin (muscle contraction)
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13
Q

simple diffusion

A
  • movement of particles down their conc gradient (high conc to low conc)
  • passive process, requires no energy
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14
Q

osmosis

A
  • simple diffusion of water from low conc to high conc
  • hypertonic: conc is higher outside cell, shrink (plasmolysis)
  • hypotonic: conc higher inside cell, swell and lyse
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15
Q

facilitated diffusion

A
  • movement of particles down their conc gradient through channels or carrier proteins
  • passive process, no energy required
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16
Q

active transport

A
  • movement of particles against conc gradient

- requires energy

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17
Q

carrier molecules

A
  • energy-independent carriers: facilitate movement along a conc gradient
  • symporters: move 2 ions in same direction
  • antiporter: move in opposite directions
  • pumps: energy-dependent carriers, require ATP
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18
Q

endocytosis

A

-cell membrane invaginates, forming a vesicle that contains extracellular medium bringing it into the cell

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19
Q

pinocytosis

A

-ingestion of fluids of small particles

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20
Q

phagocytosis

A

-engulfing of large particles

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21
Q

exocytosis

A

-vesicle within the cell fuses with the cell membrane and releases contents to the outside

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22
Q

intracellular circulation

A

materials move within a cell by:

  • Brownian movement: KE spreads small particles throughout the cytoplasm
  • cyclosis or streaming: circular motion of cytoplasm
  • ER: network of channels for a passageway from PM to nuclear membrane
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23
Q

extracellular circulation

A
  • diffusion: if in close contact, can serve as a means of transport for food and oxygen from environment; if larger animals, transport b/w cells and interstitial fluid
  • circulatory system: complex animals whose cells are too far from the external environment require this to transport materials
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24
Q

cell division

A

-process by which a cell doubles its organelles and cytoplasm, replicates it DNA, and then divides into 2

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25
Q

interphase

A
  • precedes cell division
  • growth and chromosome replication
  • after replication, chromosomes consist of 2 sister chromatids held together at the centromere
  • consists of 3 parts: G1, S, G2
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26
Q

G1

A
  • initiates interphase
  • active growth phase
  • cells increase in size and synthesizes proteins
  • length of G1 determines length of cell cycle
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27
Q

S

A

period of DNA synthesis

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28
Q

G2

A
  • cell prepares to divide

- grows and synthesizes proteins

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29
Q

Mitosis

A
  • division and distribution of the cell’s DNA to its 2 daughter cells
  • takes place in somatic cells
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30
Q

prophase

A
  • chromosomes condense
  • centriole pair moves to opposite poles, spindle apparatus forms b/w them
  • nuclear membrane dissolves
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31
Q

metaphase

A
  • fibers of the spindle apparatus attach to each chromatid at its kinetochore (location of centromere)
  • chromosomes align at center of the cell forming a metaphase plate
32
Q

anaphase

A
  • centromeres split and sister chromatids separate

- spindle fibers shorten and pull sister chromatids to opposite poles

33
Q

telophase

A
  • spindle apparatus disappears
  • nuclear membrane forms around chromosomes
  • each nucleus contains a diploid number of chromosomes (same as parent)
  • chromosomes uncoil
34
Q

cytokinesis

A
  • cytoplasm divides into 2 daughter cells
  • in animals, cleavage furrow forms and pinches cell into 2 separate nuclei
  • in plants, a cell plate forms
35
Q

meiosis

A
  • process by which sex cells are produced

- results in 4 haploid cells called gametes

36
Q

interphase (meiosis)

A

chromosomes are replicated resulting in 2n number of sister chromatids

37
Q

first meiotic division

A

produces 2 intermediate daughter cells with N chromosomes and sister chromatids

38
Q

prophase 1

A
  • chromatin condenses into chromosomes, spindle apparatus forms, and the nucleoli and nuclear membrane disappear
  • synapsis: homologous chromosomes come together and intertwine
  • tetrad: 2 sister chromatids, 4 chromatids
  • crossing over occurs between homologous chromosomes (at chiasmata)
39
Q

metaphase 1

A

tetrads align at the equatorial plate and each pair attaches to a separate spindle fiber at the kinetochore

40
Q

anaphase 1

A
  • homologous pairs separate and are pulled to opposite poles, called disjunction
  • paternal origin separates from the maternal origin and either can end up in the daughter cell (random)
41
Q

nondisjunction

A

occurs when cells do not separate appropriately, results in incorrect number of chromosomes

42
Q

telophase 1

A

nuclear membrane forms around each nucleus, 2 sister chromatids still joined at a centromere

43
Q

second meiotic division

A
  • chromosomes align at the equator, separate, and move to opposite poles
  • surrounded b a re-formed nuclear membrane with a haploid number of chromosomes
  • 4 gametes produced
44
Q

metabolism

A
  • sum of all chemical reactions that occur in the body

- catabolic (break down chemicals) and anabolic (build up chemicals) reactions

45
Q

absorption

A

passage of nutrient molecules thru the lining of the digestive tract into the body by diffusion or active transport

46
Q

assimilation

A

building up of new tissues from digested food

47
Q

regulation

A
  • control of physiological activities
  • body’s metabolism maintains its internal environment known as homeostasis and includes regulation of hormones
  • irritability: ability to respond to a stimulus
48
Q

respiration

A
  • conversion of the chemical energy in molecular bonds into usable energy
  • uses oxygen to convert glucose into ATP
49
Q

external respiration

A

entrance of air into the lungs and gas exchange b/w alveoli and blood

50
Q

internal respiration

A

exchange of gas b/w blood and the cells

51
Q

fuel molecules

A

carbs and fats (C-H bond is energy rich)

52
Q

dehydrogenation

A
  • high energy hydrogen atoms are removed from organic molecules
  • oxidation reaction
  • reduction part is the acceptance of H by a H acceptor (ETC)
53
Q

glycolysis

A
  • oxidative breakdown of glucose into 2 molecules of pyruvate
  • production of ATP
  • reduction of NAD+ to NADH
  • occurs in cytoplasm
54
Q

fermentation

A
  • NAD+ must be regenerated in order to continue in the absence of O2
  • 2 ATP produced/glucose
55
Q

alcohol fermentation

A
  • occurs in yeast and bacteria

- pyruvate is converted to ethanol, which regenerates NAD+

56
Q

lactic acid fermentation

A
  • occurs in fungi and bacteria, human muscles during strenuous activity
  • pyruvate reduced to lactic acid, NAD+ regenerated
57
Q

cell respiration

A
  • occurs in mitochondria

- 3 steps: pyruvate decarboxylation, CAC, ETC

58
Q

pyruvate decarboxylation

A
  • pyruvate from glycolysis is transported into the mitochondrial matrix and loses a CO2
  • transferred to coenzyme A to form acetyl-CoA
  • NAD+ reduced to NADH
59
Q

citric acid cycle (Krebs cycle)

A
  • 2 C acetyl group from acetyl-CoA combines with oxaloacetate to form a 6 C citrate
  • 2 CO2 released, 2 ATP produced
  • 6 NADH and 2 FADH2 produced and transport e- to ETC
60
Q

electron transport chain

A
  • located in the inner mitochondrial membrane
  • series of carrier molecules (cytochromes) transfer e- to O2
  • each carrier is reduced as it accepts e- and oxidized when it passes them
  • free energy is released which is used to form ATP
  • O2 picks up a pair of H ions to form water
61
Q

substrate level phosphorylation

A
  • forming ATP from the addition of a phosphate to ADP

- 4 ATP (2 form glycolysis and 2 for CAC)

62
Q

oxidative phosphorylation

A
  • transfer of e- fromNADH/FADH2 to O2, 32 ATP
  • 2 NADH of glycolysis yield 4 ATP
  • 8 NADH yield 24 ATP
  • 2 FADH2 yield 4 ATP
63
Q

alternative energy sources where glucose runs low

A

carbs, fats, then proteins

64
Q

carbs

A

disaccharides converted into monosaccharides, which can be converted into glucose

65
Q

fats

A
  • stored in adipose tissue in form of triglycerides
  • hydrolyzed by lipase into fatty acids and glycerol, can be converted into PGAL (a glycolytic intermediate)
  • must be activated in the cytoplasm (requires 2 ATP), transported into mitochondria and converted to acetyl CoA
  • yield greatest number of ATP per gram
66
Q

proteins

A
  • AA undergo transamination reaction in which they lose an amino group, then converted to acetyl CoA, pyruvate, or intermediates
  • oxidative deamination: removes ammonia from AA, fish excrete it, birds/insects convert to uric acid, mammals convert to urea
67
Q

enzymes

A
  • organic catalysts
  • regulate metabolism by speeding up certain chemical reactions, decrease activation energy
  • many are conjugated proteins with a nonprotein coenzyme
  • very selective
68
Q

characteristics of enzymes

A
  • do not alter the equilibrium constant
  • not consumed in the reaction
  • pH and temp sensitive
69
Q

lock and key theory

A

-spatial structure of an enzymes active site is exactly complementary to its substrate (discounted theory)

70
Q

induced fit theory

A

-active site has flexibility of shape

71
Q

enzyme specificity

A
  • as temp increases, rate increases until an optimum temp is reached
  • optimal pH, above and below that enzymatic activity decreases
  • conc low, rate is low; increasing conc increases the reaction rate until all active sites are occupied (then inc in conc doesn’t inc rate, reached Vmax)
72
Q

competitive inhibition

A
  • molecules that are similar to the substrate bind to the active site
  • if sufficient quantities of the substrate are introduced, the substrate can outcompete the competitor
73
Q

noncompetitive inhibition

A
  • substance forms strong covalent bonds with an enzyme and it is unable to bind the substrate
  • cannot be displaced by excess substrate
  • never reach its Vmax
74
Q

allosteric inhibition

A

inhibition takes place at a site other than the active site, changes the structure of the enzyme so the active site is also changed

75
Q

enzymatic activity

A
  • hydrolysis: digest large molecules into smaller ones
  • lactase: hydrolyzes lactase to the monosaccharides glucose and galactose
  • proteases: degrade proteins to AA
  • lipase: break down lipids to fatty acids and glycerol
76
Q

cofactors

A

-nonprotein molecule that is incorporated into an enzyme, can be metal cations (Zn2+ or Fe2+)

77
Q

prosthetic groups

A

cofactors that bind to the enzyme by strong covalent bonds

PCAT (14 decks)

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