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Bio 1 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Cell Theory

A

Unifying principle of biology:
- Cells are fundamental unit of life
- All organisms are made of cells.
- All cells come from preexisting cells
- Modern cells evolved from a common ancestor

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2
Q

Site of cellular transport of nutrients and waste for all cells

A

Cell membrane

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3
Q

Cellular intake of nutrients and release of waste products happens faster when what ratio is higher

A

Surface area to volume

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4
Q

What limits how big a cell can get

A

Surface area

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5
Q

Components of all cells

A
  • Cell Membrane: Outer boundary of every cell; phospholipid bilayer with embedded proteins
  • Cytoplasm: Everything in cell (except nucleus if applicable)
  • Cytosol: Fluid cytoplasm not contained inside other compartment.
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6
Q

What organelles do prokaryotic cells have that eukaryotic cells don’t

A

Nucleoid, cell wall, capsule (not in all prokaryotes)

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7
Q

Prokaryotic cell walls are polymers of

A

Peptidoglycan

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8
Q

Difference between gram negative and positive bacteria

A

Gram negative bacteria have a thin peptidoglycan cell wall surrounded by a polysaccharide-rich outer membrane (rod-shaped) vs positive bacteria that have no outer membrane but have layers of thick peptidoglycan cell wall (spherical)

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9
Q

Hairlike structures that help bacteria adhere to other cells

A

Pili

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10
Q

Used by prokaryotes to swim, made from protein flagellin

A

Flagella

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11
Q

Function of slimy capsule that some bacteria have outside their cell wall

A
  • Prevents detection by host immune cells
  • Keeps cells from drying out
  • Sometimes help with adhesion to other cells
  • Mostly made of polysaccharides
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12
Q

Steps of cell fractionation

A
  • Break cells open through homogenization; amphipathic cells could do this
  • Separate homogenate using centrifugation; organelles with greatest density would fall first (nuclei first)
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13
Q

Nucleus in DNA

A
  • Stores DNA
  • Site of DNA replication, transcription, ribosome assembly
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14
Q

How is DNA packed in the nucleus?

A

Chromatin+chromosomes (compacted chromatin)

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15
Q

Chromatin

A

DNA and the histone proteins it wraps around

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16
Q

Where is DNA stored in prokaryotes

A

Nucleoid

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17
Q

Where does transcription and translation occur in prokaryotes

A

In cytoplasm (happens at the same time and place)

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18
Q

Mitosis

A

Process of nuclear division in eukaryotic cells

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19
Q

How did nucleus form

A

Through invagination of the cell membrane

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20
Q

Mitochondria

A
  • Powerhouse of cell
  • Uses glucose to produce ATP
  • Next dense organelle after nucleus
  • Many layers of membrane
  • Has own DNA and can divide separately from cell division but can’t divide or grow outside cell
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21
Q

Which cells have the most mitochondria

A

Cells that require a lot of ATP (e.g muscle cells)

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22
Q

Endosymbiotic Theory

A

Some eukaryotic organelles are a result of our ancestors engulfing from ancient bacteria

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23
Q

Chloroplasts

A
  • Helps provide plants cells with energy
  • Has own DNA and can divide separately from cell division but can’t grow outside of cell
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24
Q

Plant Vacuoles

A

May provide structure, hold pigment, aid in digestion, and/or store water or waste

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25
Q

Thylakoids

A

Located in the inner membrane of the chloroplast; harvests light for photosynthesis

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26
Q

Endoplasmic Reticulum

A

Where some new proteins are made, modified, and sent off to specific locations

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27
Q

Immunofluorescence

A

One technique for finding locations and relative abundance of specific proteins; allows us to see multiple cell structures at the same time

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28
Q

Cytoskeleton

A

The dynamic network of varied proteins that gives cell structure and facilitates movement

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29
Q

Roles of the cytoskeleton

A
  • Supports and maintains cell shape
  • Holds organelles in position
  • Moves organelles
  • Involved in cytoplasmic streaming
  • Interacts with extracellular structures to hold cell in place
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30
Q

Microfilaments

A

One of the three filaments that make up the cytoskeleton; long chains of the monomer actin

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31
Q

Roles of microfilaments

A
  • Maintain cell shape by resisting tension (pull)
  • Move cells via muscle contraction or crawling
  • Divide animal cells in two
  • Moves organelles and cytoplasm in plants, fungi, and animals
  • Has distinct plus/minus ends
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32
Q

How do microfilaments move?

A

Via cytoplasmic streaming; actin and the motor protein myosin interact to cause movement; myosin head attaches to actin and uses ATP to move, causing filament to slide

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33
Q

Intermediate filaments

A

One of the three filaments that make up the cytoskeleton; tough rope-like structures that maintain cell shape by resisting tension and anchor cell structures (nuclei) in place (many different compositions like keratin)

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34
Q

Microtubules

A

One of the three filaments that make up the cytoskeleton; long hollow cylinders (polymers) made of dimers of the a and b tubulin

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35
Q

Roles of microtubules

A
  • Forms a rigid internal skeleton
  • Maintains cell shape by resisting cell tension (push)
  • Can change length rapidly by adding or losing dimers at plus or minus ends
  • Acts as train tracks for motor proteins; moves cells via flagella or cilia and moves chromosomes during cell division
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36
Q

What are eukaryotic flagella and cilium made of

A

Microtubules in “9+2” array called an axoneme

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37
Q

Kinesin

A

The motor protein that uses ATP to move cargo along a microtubule

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38
Q

What bonds to microtubule doublets and allows cilia and flagella to slide past each other to facilitate movement

A

Dynein

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39
Q

Evolution of mitochondria/ chloroplasts in a eukaryotic cell probably occurred through endosymbiosis, but that of nucleus/ ER/ Golgi was likely through

A
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40
Q

Nuclear Envelope

A

Comprised of 2 layers of protein studded membrane that protects the DNA in the nucleus and regulates entry and exit of other molecules

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41
Q

Endoplasmic Reticulum

A

Network of tubes where some proteins are made, modified, packaged, and sent to specific locations

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42
Q

Where are ribosomal proteins synthesized

A

RER; Proteins made in the RER are destined to become embedded in the membrane, end up in the lysosome, or leave the cell

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43
Q

Does the smooth ER contain ribosomes

A

No

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44
Q

Smooth Endoplasmic Reticulum

A

Another site of protein modifications but has other functions including
- Chemically modifying small molecules such as drugs
- Site of glycogen degradation in animal cells
- Synthesis of lipids and steroids
- Stores calcium ions

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45
Q

What are all new proteins routed through

A

ER and Golgi (secretory pathway)

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46
Q

What do proteins leave the ER in to go to the Golgi Apparatus

A

COPII-coated transport vesicles

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47
Q

What happens to proteins in the Golgi Apparatus

A

They’re further modified, packaged, and sorted

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48
Q

Order that cargo travels in vesicles in secretory pathway in Golgi

A

cis –> medial –> trans; from there could end up in lysosome, membrane, or outside cell

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49
Q

The endomembrane system is an interconnected system of membrane-enclosed compartments including

A

Nuclear envelope, ER, golgi apparatus, lysosomes, and cell membrane

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50
Q

Fluid Mosaic Model

A

Describes membrane structure; phospholipids form a liquidy bilayer which is like a lake in which some proteins float

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51
Q

How does fatty acid saturation affect membrane fluidity

A

Saturated (straight) = Rigid
Unsaturated = Fluid

52
Q

How does fatty acid chain length affected membrane fluidity

A

Long = Rigid
Short = Fluid

53
Q

How does cholesterol/lipid composition affect membrane in fluidity in animal cells

A

Low = Fluid
High = Rigid (more van der waals forces)

54
Q

How does temperature affect membrane fluidity

A

Low (low kinetic energy) = Rigid
High = Fluid

55
Q

What does a rigid membrane mean for permeability of a cell

A

More rigid = less permeability

56
Q

What are biological membranes comprised of

A

Phospholipids and proteins

57
Q

Steps for protein co-translation into the RER membrane

A
  • ER signal sequence is synthesized by ribosome
  • ER signal sequence binds to signal recognition particle (SRP) and halts synthesis
  • SRP binds to receptor in ER membrane
  • SRP is released; protein synthesis continues; protein enters ER through the translocon
  • ER signal sequence is removed; protein synthesis then proceeds to completion
58
Q

Glycosylation of a protein

A

Occurs in RER by glycosyltransferase protein; essential for a proteins folding/function, stability, cell-cell communication, and transport

59
Q

What determines where a protein goes after they leave the trans face of the Golgi in their vesicles?

A

Proteins carry tags in the endomembrane system that serve as zip codes for different destinations

60
Q

ER Signal Peptides

A

Example of zip code for protein targeting; stops translation until docked at ER; detected by SRP during translation; detected co-translationally

61
Q

KDEL

A

Example of zip code for protein targeting; tells protein to stay in the ER lumen

62
Q

Nuclear Localization Sequence

A

Example of zip code for protein targeting

63
Q

Peroxisomal Targeting Signal

A

Example of zip code for protein targeting

64
Q

Mannose-6-Phosphate

A

Example of zip code for protein targeting; tells protein to go to the lysosome

65
Q

Integral Membrane Proteins

A

One of the three types of membrane proteins; at least partially embedded in the bilayer; some are transmembrane and extend all the way through the bilayer

66
Q

Anchored Membrane Proteins

A

One of the three types of membrane proteins; covalently attached to fatty acids or other lipids inside the membrane

67
Q

Peripheral Membrane Proteins

A

One of the three types of membrane proteins; lacks exposed hydrophobic regions, are noncovalently attached to the membrane and don’t penetrate the bilayer

68
Q

Homotypic Cell Adhesion

A

The same molecule sticks out from both cells and binds to each other (less common)

69
Q

Heterotypic Cell Adhesion

A

The cells have different proteins that bind together (more common)

70
Q

Cell Junctions

A

Specialized structures comprised of many different proteins that hold cells together

71
Q

Tight Cell Junctions

A

Forms a tight seal (barrier) between cells, which helps ensure directional movement of materials

72
Q

Gap Cell Junctions

A

Forms tunnels called channels so that adjacent cells can communicate by exchanging small molecules, electrical impulses, etc

73
Q

Desmosome Cell Junction

A

Holds cells together like velcro; also allows materials to move around in the intercellular space

74
Q

Cells can move within a tissue by the binding and reattaching of adhesion receptors to the

A

Extracellular matrix

75
Q

Integrals

A

One type of adhesion receptor that can facilitate movement through binding/reattaching to extracellular matrix

76
Q

Extracellular Matrix

A

Macromolecule-rich gel outside of cells

77
Q

Diffusion

A

Process of random movement of solute from a region of higher to lower concentration

78
Q

Diffusion works better over

A

Short Distances

79
Q

Molecules move across permeable membrane in diffusion until

A

Concentration is equal on both sides

80
Q

What factors affect the rate at which substances diffuse

A
  • Concentration gradient
  • Size and mass of particles
  • Temperature of solution
  • Density of solution
  • Area and distance
81
Q

Osmosis

A

Process by which water diffuses across membrane

82
Q

Isotonic

A

Equal solute concentration inside and outside cell

83
Q

Hypotonic

A

Lower solute concentration outside of cell

84
Q

Hypertonic

A

Higher solute concentration outside cell

85
Q

Passive Transport

A

Process by which substances can cross membranes without energy input

86
Q

Aquaporins

A

Channels made of transmembrane tunnels made of protein through which water moves across membrane (example of facilitated diffusion)

87
Q

Facilitated Diffusion

A

Carried out by protein channels or carriers that increase the ……

88
Q

Ion Channels

A

Penetrate the membrane and have hydrophilic pores (facilitated diffusion)

89
Q

What stimulates the protein of an ion channel to open

A
  • A chemical signal (ligand)
  • An electrical charge (voltage gated)
  • A mechanical signal (force)
90
Q

Carrier Protein

A

Transports specific polar molecules, like glucose, across membrane in both direction (facilitated diffusion)

91
Q

What is it called when glucose transporters are all occupied

A

Saturated

92
Q

Active Transport

A

Requires energy; movement against concentration gradient

93
Q

Three kinds of proteins that active transport involves

A
  • Uniporter: One molecule in one direction
  • Symporter: Two in one direction
  • Antiporter: Two in different directions
94
Q

Primary Active Transport

A

Requires direct hydrolysis of ATP (ex: sodium-potassium pump)

95
Q

Secondary Active Transport

A

Energy comes from an ion concentration gradient that is established by primary active transport

96
Q

Endocytosis

A

Process where eukaryotic cells may take up and release fluids, large molecules, particles, and smaller cells (way that larger molecules can cross membrane)

97
Q

Phagocytosis

A

Type of endocytosis; molecules/entire cells are engulfed; a food vacuole or phagosome forms, which fuses with a lysosome where the contents are digested

98
Q

Pinocytosis

A

Type of endocytosis; vesicle forms to bring small dissolved substances or fluids into a cell; vesicles are much smaller than in phagocytosis

99
Q

Receptor-Mediated Endocytosis

A

Type of endocytosis; uses proteins

100
Q

How do cells process info from the environment

A

A ligand binds to a receptor in a specific binding site; cells must have a specific receptor molecule that can detect it

101
Q

How do chemical signals differ in their source and distribution (mode of delivery)

A
  • Autocrine Signaling: On same cell
  • Juxtacrine: Not far, touching cells
  • Paracrine: Across extracellular space
102
Q

Hormones

A

Travels to distant cells via the circulatory system; circulating signals are transported by the circulatory system

103
Q

Signal Transduction Pathway

A

A signal from outside the cell is relayed through a series of internal messengers that can cause short or long term changes in the cell

104
Q

Short terms changes from signal transduction pathways

A

Enzyme activation, cell movement

105
Q

Long term changes from signal transduction pathways

A

Altered DNA transcription

106
Q

Agnonists

A

Type of drug; has the same effect as ligand when binding to a receptor

107
Q

Antagonists (inhibitors)

A

Type of drug; prevents ligand from binding but doesn’t trigger a response when binding to receptor

108
Q

Ion Channel Linked Receptor

A

Type of eukaryotic membrane receptor; allows ions to enter or leave a cell; signal binding results in change in shape of the channel protein, and the channel opens

109
Q

Protein Kinase Receptors

A

Type of eukaryotic membrane receptor; When ligand is present at the extracellular ligand binding domain, PKR catalyzes phosphorylation of themselves and/or other proteins to change their shapes/functions

110
Q

What does phosphorylation of a protein do?

A
  • Changes shape of protein
  • Alters its catalytic activity
  • Affects its activity with other proteins
111
Q

G Protein Coupled Receptor

A

Type of eukaryotic membrane receptor; activates a special protein called a G protein, which then activates an effector

112
Q

When are G proteins active

A

When connected to a GTP; not GDP

113
Q

Intracellular Receptors

A

Responds to signals such as light or small molecules that can cross the cell membrane; many are transcription factors, which alter gene expression

114
Q

What are the three amino acids that can be phosphorylated by protein kinase activity

A

Serine, threonine, and tyrosine

115
Q

In a protein kinase cascade

A
  • The signal is amplified at each step
  • Info that arrived at the cell membrane is communicated to the nucleus
  • Different target proteins provide variation in the response
116
Q

Cyclic AMP (cAMP)

A

A 2nd messenger that amplifies and distributes a signal

117
Q

Second Messengers

A

Nonprotein signaling molecule that increase in concentration inside a cell in response to a signaling molecules that binds at the surface

118
Q

How is Protein Kinase A activated

A

By a high concentration of cAMP

119
Q

Epinephrine (adrenaline)

A

Mediates the fight or flight response

120
Q

IP3 and DAG

A

Second messengers made from hydrolysis of PIP2 by phospholipase C

121
Q

CA2+ Channel role

A

IP3 binds to and activates a CA2+ channel in the ER membrane; the activated CA2+ channel releases stores of CA2+ from ER; the increased CA2+ helps activate protein kinase C; with CA2+ bound, PKC binds and becomes fully activated by DAG; activated PKC phosphorylates other proteins to stimulate a cellular response

122
Q

How do cells respond to signals

A
  • Opening ion channels
  • Changing enzyme activity
  • Differential gene expression
123
Q

NO Gas

A

A 2nd messenger between acetylcholine and the relaxation of smooth muscle in blood vessels, allowing more blood to flow

124
Q

What determines the cellular response to a signal

A

The balance between enzymes that activate and enzymes that inactivate transducers

125
Q

How are signal transduction pathways turned off/regulated

A
  • Kinases can be inactivated by phosphatase enzymes which removes phosphate groups
  • GTPases inactivate G proteins by hydrolyzing GTP (becomes GDP)
  • 2nd messengers can be broken down (ex: phosphodiesterases degrade cAMP to AMP or cGMP to GMP)

Bio 1 (8 decks)

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