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BIO130 > Test 2 (Exam) > Flashcards

Test 2 (Exam) Flashcards

1
Q

ECM

A

Extracellular matrix: specialized material outside the cell, found in animal cells

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2
Q

Saccharomyces cervevisiae

A

Single-celled model organism
- animal cell
- has a cell wall

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3
Q

Lysosome

A

Deagradation of cell components that are no longer needed (animal cells)

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4
Q

Vacuoles, two types

A
  1. Degradation, like animal lysosome
  2. Storage for small molecules and proteins
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5
Q

Chloroplast

A

Site of photosynthesis

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6
Q

Cytoplasm

A

Contents of the cell outside the nucleus, includes organelles, ribosomes, cytoskeleton

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7
Q

Cytosol

A

Aqueous part of cytoplasm, does not include the membrane-bound organelles, DOES include ribosomes and cytoskeleton

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8
Q

Lumen

A

Inside of organelles
- for nucleus, space between two membranes of nucleus
- mitochondria includes whole organelle

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9
Q

Phospholipid basic structure

A

Hydrophilic head group

Two hydrophobic tails

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10
Q

Amphipathic

A

Two different biochemical properties on different sides
Ex. Polarity of phospholipid

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11
Q

Membranes are composed of three types of lipids

A
  1. Phospholipids
  2. Sterols
  3. Glycolipid
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12
Q

Phosphoglyceride general composition

A

A type of phospholipid, many different types of phosphoglyceride

  1. Different group and phosphate make head group
  2. GLYCEROL
  3. Hydrophobic tail
    - 12-14 carbon atoms long, can be saturated or unsaturated
    - if tail has a kink it is unsaturated, contains cis double bond
    - single bonds means it is saturated
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13
Q

In aqueous environment, phospholipids…

A

Spontaneously associate into bilayer
- hydrophilic heads interact with water, hydrophobic tails face in away from water

Will then form sphere because it is more energetically favourable

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14
Q

Liposomes

A

Artificial lipid bilayer, used for drug delivery

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15
Q

Phospholipid movements

A

Phospholipids within each leaflet
- diffuse laterally
- rotation
- flex

They rarely flip flop, or move from one leaflet to another on their own

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16
Q

Factors affecting membrane fluidity

A
  1. Temperature
    - lower temperatures make it more viscous, less fluid (not good)
  2. Composition changes that can increase mobility if it’s too cold
    -cis-double bonds increase fluidity at lower temperatures (give kink to tail)
    - shorter hydrocarbon tails increase fluidity at lower temperatures (lipid tails interact less)
    - additional of cholesterol in animal cell membranes, stiffens membrane and makes it less permeable to water
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17
Q

Sterols

A

In animals, mainly cholesterol
- decreases mobility of phospholipid tails (stiffens membrane)
- plasma membrane is less permeable to polar molecules

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18
Q

Lipid movement to the other leaflet

A

Scramblase catalyzes flip flops in ER membrane randomly
- needed since phospholipids are synthesized in cytosolic leaflet of ER, would become lopsided without flip flop since the only grow on one leaflet (one side of bilayer)

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19
Q

Asymmetry of the lipid bilayer

A

Noncytosolic face
Cytosolic face (always faces cytosol)

Membranes bulge, form vesicles and fuse, no flip flop, to form membranes of organelles
-maintains two distinct faces throughout this process

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20
Q

Flipases - enzyme in the Golgi membrane

A

Catalyzes flip flop of specific phospholipids to the cytosolic leaflet

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21
Q

Enzymes in the Golgi membrane

A

Flip lipids from one leaflet to another
- flipase

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22
Q

Glycolipids and glycoproteins

A
  • formed by addition of sugars to lipids and proteins on luminal face of golgi
  • end up on plasma membrane, inside some organelles - GLYCOPROTEIN FACES NONCYTOSOLIC FACE
  • protect membrane from harsh environments
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23
Q

4 Types of membrane proteins

A

Transmembrane
- protein passes through entire lipid bilayer

Monolayer-associated
- associate with one leaflet

Lipid-linked
- attached to lipids which insert into the membrane

Protein-attached
- associated non-covalently to proteins which are inserted

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24
Q

3 types of integral membrane proteins

A

Proteins that insert in some way directly into the membrane
1. Transmembrane
2. Monolayer-associated
3. Lipid-linked

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25
Q

Peripheral membrane proteins

A

Associate with membrane or integral membrane proteins non convalently
- protein-attached or lipid-attached

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26
Q

Extraction methods for integral membrane proteins

A

Use detergents, lipid bilayer will be destroyed but proteins will remain

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27
Q

Extraction methods for peripheral membrane proteins

A

Gentle extraction methods, lipid bilayer and protein both remain intact

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28
Q

Transmembrane proteins hydrophilic and hydrophobic regions

A

Hydrophilic domains interact with cytosol and extracellular space

Hydrophobic domains span the membrane
- about 20 hydrophobic amino acids

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29
Q

Two techniques for identifying protein structure

A
  1. X-ray crystallography determines 3D structure
  2. Hydrophobicity plots
    - segments of 20-30 hydrophobic amino acids which can span lipid bilayer as an alpha helix
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30
Q

Monolayer-associated membrane protein characteristics

A

Anchored on cytosolic face by an amphipathic, horizontal alpha helix

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31
Q

Lipid-linked membrane protein synthesis and anchoring

A

Synthesized in ER lumen, end up on cell surface (don’t flip flop)

Have a GPI anchor

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32
Q

T/F Proteins can’t flip flop

A

TRUE

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33
Q

Extraction of membrane proteins by detergent addition

A

Integral membrane proteins
- Triton X-100 detergent has hydrophobic head and hydrophilic tail
- hydrophobic tails interact with tails of phospholipid
- hydrophilic heads interact with water
- protein can then be purified, phospholipids can be added to reform lipid bilayer and remove detergent

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34
Q

FRAP (fluorescent recovery after photobleaching) method

A

Some proteins can’t move laterally
- protein labelled with green fluorescent protein
- photobleach an area white
- measure how quickly protein can recover (become green again) to see how much the protein can diffused laterally
- quicker recovery = more lateral diffusion

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35
Q

A faster FRAP time corresponds to…

A

Faster lateral movement

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36
Q

Permeable and impermeable molecules across a lipid bilayer

A

Permeable: small nonpolar molecules, small uncharged polar molecules

Impermeable: large uncharged polar molecules, ions

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37
Q

Permeable

A

Movement via simple diffusion through the lipid bilayer
- high to low concentration gradient, down the gradient
- more hydrophobic or nonpolar have faster diffusion across lipid bilayer

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38
Q

Impermeable molecules and ions require…

A

Membrane proteins for transport
- each transport protein is selective as to what it will transport

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39
Q

Two main classes of membrane transport proteins

A
  1. Channel
    - binds weakly to transported molecule
    - does not change much in conformation
    - selectivity based on size and charge
  2. Transporter
    - binds strongly to transported molecule
    - undergoes conformational change during transport
    - selectivity based on binding site
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40
Q

Passive transport

A

Down concentration gradient
- does not directly require energy

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41
Q

Active transport

A

Against concentration gradient
- does directly require energy

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42
Q

Electrochemical gradient =

A

Concentration gradient + Membrane potential (difference in charge)

Electrochemical gradient is stronger when voltage and concentration gradients work in the same direction

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43
Q

Channel proteins only do _____ transport

A

Passive

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44
Q

T/F Transporter proteins can do both passive and active transport

A

True

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45
Q

Channel proteins

A
  • hydrophilic pore across membrane
  • most are selective based on ion size and electrical charge
  • faster type of passive transport
  • interactions with solute are transient
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46
Q

Two types of ion channels

A
  1. Non-gated ion channels, always open
    - K leaks out of the cell, generates resting membrane potential
  2. Gated ion channels
    - some signal is required for channel opening
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47
Q

Four types of gated ion channels and their signals

A
  1. Mechanically-gated
    Signal: mechanical stress
  2. Ligand-gated (extracellular signal)
    Signal: ligand (ex. neurotransmitters)
  3. Ligand-gated (intercellular ligand)
    Signal: ligand (ex. ion, nucleotide)
  4. Voltage-gated
    Signal: change in voltage across membrane
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48
Q

Transporter proteins

A
  • binds to a specific solute
  • goes through conformational change
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49
Q

Passive transport by transport proteins: Uniport

A

Uniport means one solute passes, direction of transport is reversible (if concentration becomes reversed, but will always remain down the electrochemical gradient)

Ex. GLUT Uniporter transports glucose passively down the electrochemical gradient
- can work in either direction

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50
Q

Active transport by transporter proteins and examples

A

Against the electrochemical gradient, so needs energy (but not necessarily in the form of ATP)

Ex. Gradient driven pump: first solute down gradient, makes energy, second solute against gradient, uses energy
Ex. ATP driven pump use ATP hydrolysis to move solute against its gradient
Ex. Light driven pump in bacteria uses light energy to move solute against its gradient

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51
Q

Two types of gradient driven ports

A

Symport
- both solutes move in the same direction

Antiport
- two solutes move in opposite directions

Both use free energy from first solute moving down electrochemical gradient to move second solute against electrochemical gradient

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52
Q

Symport example

A

Sodium glucose symporter
- sodium ion moves down its electrochemical gradient to provide energy to move glucose against its concentration gradient
- both are moving into the cell

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53
Q

Antiport example

A

Na+ H+ exchanger
- use energy from Na going down electrochemical gradient to move H against electrochemical gradient out of the cell
- regulates pH of cytosol
- drop in cytosolic pH makes transporter activity increase

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54
Q

How is Na+ electrochemical gradient maintained?

A

Na+ K+ pump
- plasma membrane ATP driven pump
- both moved against electrochemical gradient
- 3 Na out for every two K in
- low cytosolic Na+, high cytosolic K+ gradients

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55
Q

Three types of ATP driven pumps

A
  1. P type pump
    - always phosphorylates itself during pumping cycle
    - generate and maintain electrochemical gradients
    Ex. Na K pump in animals, H+ pump in plants
  2. ABC transporter
    - use 2 ATP to pump small molecules across cell membranes
    Ex. Toxins
  3. V type proton pump
    - use ATP to pump H+ into organelles to acidify the lumen
    - in lysosome, plant vacuole
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56
Q

What is Na+ gradient used for

A

Transporting nutrients like glucose into the cell (Symport), maintains pH (Antiport)

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57
Q

Pumping cycle of Na+ K+ pump

A
  • 3 Na+ bind
  • pump phosphprylates itself, hydrolysing ATP
  • phosphorylation triggers conformation change, Na ejected out of cell
  • 2 K+ bind
  • pump dephosphorylates itself
  • goes back to original conformation, K goes into cell
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58
Q

V type pump VS F type ATP synthase

A

V type proton pump:
uses ATP to pump H+ against electrochemical gradient

F type ATP:
synthase uses the H+ electrochemical gradient to produce ATP (reversible)

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59
Q

Two cellular processes regulated by transport proteins

A
  1. Trans cellular transport of glucose by transporters
  2. Generation of membrane potentials
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60
Q

Generation of membrane potentials is done by

A
  • channel proteins
  • transporter proteins: passive and active
  • active transport by transporter proteins includes gradient driven pumps (Symport and Antiport) and ATP driven pumps (P type, V type, ABC)
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61
Q

K+ leak channel

A

Outward flow of K+

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62
Q

Electrogenic

A

Net charge
Ex. Sodium potassium pump net +1 charge outside cell

  • a bit more positive on outside membrane than inside, varies from -20 to -200 mV
  • this number is always measured from inside the cell
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63
Q

Ions in extracellular space vs cytosol

A

Extracellular space: high Na+, low K+, high Cl-

Cytosol: low Na+, high K+, low Cl-, cell’s fixed anions (nucleic acids, proteins, cell metabolites)

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64
Q

Plant cell membrane potential

A

Plasma membrane P type pump
- H+ pump generates H+ electrochemical gradient
- -120 to -160 mV inside cell
- used to carry out active transport, electrical signalling, regulate pH

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65
Q

How much of the cell volume is the cytosol, role of cytosol

A

50%
- volumes differ for different cells

Role: protein synthesis and degradation, many metabolic pathways, cytoskeleton

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66
Q

Rough ER

A
  • membrane bound ribosomes
  • synthesis of soluble proteins and transmembrane proteins for the endomembrane
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67
Q

Smooth ER role

A

Phospholipid synthesis, detoxication

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68
Q

Are there more membranes in the cell or around it

A

More in the cell

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69
Q

Rough ER and Smooth ER make up about ____% of membranes

A

50%

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70
Q

Organelles that are not membrane bound examples

A

Nucleolus, centrosome

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71
Q

Protein sorting overview

A
  • mRNA arrives in cytoplasm, translation start on ribosomes in cytosol
  • cytosolic protein have no sorting signal
  • proteins that are sorted have a signal sequence
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72
Q

Signal sequence

A
  • a couple of amino acids that are part of the protein (not something separate added on)
  • directs protein to the correct compartment
  • specifies specific destination in cell
  • recognized by sorting receptors
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73
Q

Sorting receptors

A

Recognize signal sequences and take proteins to their destinations

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74
Q

Protein sorting two options

A

Post-translational sorting
OR
Co-translational sorting

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75
Q

Post-translational sorting

A
  • proteins are fully synthesized in cytosol before sorting (nuclear encoded)
  • folded before sorting: nucleus and peroxisomes
  • unfolded during sorting: mitochondria, plastids
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76
Q

Co-translational sorting

A
  • nuclear encoded
  • proteins have ER signal sequence, associated with ER during protein synthesis
  • protein synthesis in the cytosol
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77
Q

Peroxisomes

A
  • contain enzymes for oxidative reactions
  • detoxify toxins, break down fatty acid molecules
  • enzymes imported into the peroxisome through a transmembrane protein complex
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78
Q

Proteins are unfolded for import to the mitochondria and the chloroplast by _____

A

hsp70 chaperone proteins

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79
Q

Why do proteins sort to the ER?

A

Entry point to the endomembrane system

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80
Q

Sorting proteins to the ER

A
  • cotranslational sorting
  • proteins are nuclear encoded and have an ER signal sequence
  • associated with ER during synthesis in the cytosol
  • ER signal sequence is hydrophobic
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81
Q

Protein sorting to the ER steps

A
  • mRNA arrives in cytoplasm, translation starts on ribosomes in the cytosol
  • ER signal sequence causes half made protein to be inserted into the ER as translation continues (CO-TRANSLATIONAL TRANSLOCATION)
  • proteins entering ER are soluble proteins (go into lumen) and transmembrane proteins
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82
Q

Co-translational translocation steps

A
  1. Translation starts
  2. ER signal sequence recognized by SRP, elongation stops
  3. SRP-ribosome complex gets taken to the SRP receptor and then to the translocon
  4. Translocation protein opens
  5. Protein synthesis resumes with protein transfer into ER lumen
  6. Signal peptidase cleaves ER signal sequence which is hydrophobic so found in lipid bilayer (eventually degraded)
  7. Protein released into ER lumen
  8. Translocon closes
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83
Q

SRP

A

Signal recognition particle, takes ribosome to ER membrane

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84
Q

Co-translational Translocation of TRANSMEMBRANE proteins

A

Steps 1-5 the same
6. Stop-transfer sequence enters translocon
7. Protein transfer stops and transmembrane domain is released into lipid bilayer
8. Signal peptidase cleaves ER signal sequence and translocon closes
9. Protein synthesis completed and signal sequence is degraded

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85
Q

Constitutive exocytosis pathway

A
  • all eukaryotic cells
  • continual delivery of proteins and lipids to plasma membrane
  • includes constitutive secretion of soluble proteins (ex. Collagen for ECM)
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86
Q

Two secretory pathways (two types of exocytosis)

A
  1. Constitutive exocytosis pathway
  2. Regulated exocytosis pathway
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87
Q

Regulated exocytosis pathway

A
  • in specialized cells
  • stored in specialized secretory vesicles
  • extracellular signal (ex. Hormone, neurotransmitter etc.) needed for vesicle to fuse with plasma membrane and release contents
    Ex. Insulin released when blood glucose increases in pancreatic beta cells
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88
Q

Golgi apparatus role

A

Receives proteins and lipids from the ER, modifies them, dispatches them to other destinations in the cell

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89
Q

Protein glycosylation

A
  • starts in the ER: one kind of oligosaccharide is attached to many proteins
  • Golgi apparatus: complex oligosaccharide processing occurs, multistage processing unit (different enzymes in each cisterna), glycosylation modifications for proteins and lipids
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90
Q

Endosomes and what they mature into

A
  • membrane-bound organelles
  • contain material ingested by endocytosis
  • early endosomes fuse with vesicles to eventually mature into late endosomes
  • late endosomes mature into lysosomes
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91
Q

Lysosomes

A
  • membrane-bound organelles
  • contain hydrolysis enzymes to digest worn-out proteins, organelles, waste
  • containing forty hydrolytic enzymes
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92
Q

Main site of intracellular digestion

A

Lysosomes

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93
Q

Lysosomes are acidified by

A

H+ pump, acidity needed for hydrolytic enzymes

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94
Q

Lysosomal membrane proteins and their protection

A

Need to be protected from proteases in the lysosome, this is accomplished by glycosylation

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95
Q

Transport proteins in lysosomal membrane role

A

Transfer digested products to cytosol (amino acids, sugars, nucleotides)

96
Q

3 components of cytoskeleton

A
  1. Actin filament
  2. Microtubules
  3. Intermediate filaments
97
Q

Components of cytoskeleton important for internal organization

A

Microtubules
- organelles, vesicle transport

98
Q

Cytoskeleton components involved in cell division

A

Actin filament, Microtubules
- chromosome segregation, divide cell in two

99
Q

Cytoskeleton component involved in large scale movements

A

Actin filament
- crawling cell, muscle contraction

100
Q

Microscopy techniques to look at cytoskeleton

A

Light microscope too small
- can use fluorescence microscopy, labels added to detect specific proteins
- MOST USEFUL: transmission electron microscope, uses beams of electrons

101
Q

Immunofluorescence microscopy

A

Used to determine location of proteins
- cells are dead
- primary antibody binds to protein of interest
- fluorescent marker (secondary antibody) attached to primary antibody
- use fluorescence microscope to visualize

102
Q

How are cytoskeleton filaments held together

A

Noncovalent interactions

103
Q

Actin filaments

A

Smallest filament, made of actin

104
Q

Intermediate filaments

A

Medium size, made of intermediate filament proteins

105
Q

Microtubules

A

Largest of three components, made of tubulin

106
Q

Intermediate filament function

A
  • structural support, provides mechanical strength
  • form nuclear lamina
107
Q

Four categories of intermediate filaments

A

Cytoplasmic
1. Keratin in epithelial cells
2. Vimentin is tissue, muscle
3. Neurofilaments in nerve cells

Nuclear
4. Nuclear lamins in all animal cells (just under nuclear membrane)

108
Q

Two IMF monomers

A

Coiled coil dimer

109
Q

Two IMF dimers

A

Staggered antiparallel tetramer

110
Q

8 IMF tetramers

A

Associate side by side to make a filament

111
Q

Where are keratin filaments in epithelial cells anchored

A

Cell-cell junctions (desmosomes)
- provides mechanical strength

112
Q

Microtubules flexibility

A

Inextensible — non elastic, does not extend

113
Q

Microtubules structure

A

Long hollow tubes
- made up of individual tubulin heterodimers (alpha and beta tubulin) bound to GTP
- gives Microtubules polarity at plus end (beta) and minus end (alpha)
- 13 parallel protofilaments make up a hollow tube

114
Q

Which ends are beta and alpha

A

Minus end alpha, plus end beta

115
Q

Growth and disassembly of Microtubules can occur ____ but is more rapid at _____

A

Can occur at both ends, more rapid at plus end

116
Q

Dynamic instability and MTOCs

A

Microtubules Organizing Centres
- minus ends stabilized at MTO
- plus ends grow out and shrink
- needed for remodelling
Ex. Centrosome

117
Q

Dynamic instability — growing

A

Free aB tubulin dimers bound to GTP on plus end
B tubulin hydrolyzes GTP to GDP

If addition of dimers is faster than hydrolysis, GTP cap forms which stabilizes plus end and facilitates growth

118
Q

Dynamic instability — shrinking

A

Slower addition of aB tubulin dimers
- slower than GTP hydrolysis in newly added dimers
- GTP cap lost
- now GDP is at plus end, causes weaker binding
- ends curl, microtubules disassembles

119
Q

Nucleating sites

A

Sites for microtubule growth in MTOC
Ex. Gamma tubulin ring complex

120
Q

Microtubules and intracellular transport

A

Done by motor protons of microtubules
ex. Neurotransmitter transport from ER to axon terminal

121
Q

Kinesins

A

Move towards plus end

122
Q

Dyenins

A

Move towards minus end

123
Q

Kinesin-1 and cytoplasmic dyenin are

A

Dimers
- use ATP hydrolysis for movement
- heads move along microtubules, tails transport cargo

124
Q

Actin filaments aka

A

Microfilaments

125
Q

Myosins found in which filament

A

Actin filaments, move towards plus end of actin filaments

126
Q

Actin filament structure

A

Helical filament made of repeated actin monomers
- 2 protofilaments twisted in helix
- has polarity
- growth faster at plus end
- actin monomers have an ATP cap

127
Q

Treadmilling

A

Occurs in actin filaments
- needs continuous ATP
- continuous rates of addition and loss of actin monomers, so length stays constant

128
Q

Cell crawling

A

Actin filaments, example treadmilling
- rapid assembly and disassembly to push cell forwards

129
Q

Junctions in epithelial cells in order from apical to basal (TADGH)

A

Tight
Adherens
Desmosome
Gap junction
Hemidesmosome

Top three hold sheets of cells together

130
Q

The two Cell-cell anchoring junctions and what they link

A

Adherens junction and desmosomes
- link cytoskeletons of neighbouring cells

131
Q

Cell-ECM anchoring junction

A

Hemidesmosomes
- link cytoskeleton to basal lamina

132
Q

Adherens junctions form

A

Adhesion belts

133
Q

Tight junctions

A
  • create a tight seal between cells
  • prevents mixing of extracellular environments
  • acts as fence in the membrane to prevent mixing of membrane proteins
134
Q

Tight junctions are composed of two transmembrane proteins

A

Claudin and Occludin
- required in both cells
- extracellular domain in one cell interacts with extracellular domain of neighbouring cells
- occludin-occludin and claudin-claudin pairings

135
Q

What transmembrane adhesion protein do adherins have?

A

Cadherins

136
Q

What cytoskeleton filament do Adherens junctions attach to?

A

Actin filament

137
Q

What do desmosomes and hemidesmosomes link to?

A

Intermediate filaments
- these filaments provide structural strength

138
Q

What do desmosomes link to?

A

Keratin filaments and connect to a neighbouring cell

139
Q

What do hemidesmosomes link to?

A

Anchor keratin filaments to the basal lamina

140
Q

Is a hemidesmosomes equal to half a desmosomes?

A

No, they are made of different proteins

141
Q

Desmosome transmembrane proteins

A

Cadherin family members
Ex. Desmoglein, desmocollin

142
Q

Hemidesmosome transmembrane adhesion protein

A

Integrins
- binds to laminin in the basal lamina

143
Q

What do gap junctions do?

A

Allow for communication between cells

144
Q

Gap junction structure (numbers of each sublevel)

A

1 subunit = connexin
6 connexins = connexOn (hemichannel)
2 connexons = intracellular channel (hollow)

12 subunits in one intracellular channel

145
Q

What can/cant pass through gap junctions

A

Can: Ions and metabolites, nucleotides, glucose, amino acids (anything less than 1000 daltons)

Can’t: macromolecules, proteins, nucleic acids

146
Q

Which junction is gated

A

Gap junctions
- open and closed state dictated by extracellular signals (if one cell leaks, gates will close)

147
Q

Intracellular junctions in plant cells

A

Not needed due to cell wall serving function
- plasmodesmata instead

148
Q

Plasmodesmata

A

Intercellular junction in plant cells
- allows for communication between cells
- cytoplasmic channels with continuous plasma membrane and ER across plasmodesmata
- allow sugars, ions, nutrients pass (less than 1000 daltons)
- gated by protein and regulatory RNA (ex. Can control callose passage)

149
Q

Animal tissue composition

A

EPITHELIAL TISSUE

BASAL LAMINA

CONNECTIVE TISSUE

150
Q

Cell association in epithelial tissue vs connective tissue

A

Epithelial tissue: closely associated cells
- cells attached to each other
- limited ECM (thin basal lamina)
- cytoskeletal filaments resist mechanical stress

Connective tissue: cells are rarely connected
- cells are attached to the matrix
- plentiful ECM
- ECM resists mechanical stress

151
Q

3 major classes of macromolecules in ECM

A
  1. Glycosaminoglycans (GAGs) and proteoglycans
  2. Fibrous proteins (collagens, elastin)
  3. Glycoproteins (laminin, fibronectin)

Different composition can give tissues different properties

152
Q

GAGs (glycosaminoglycans) structure charge and role

A

Disaccharide
- highly negatively charges
- synthesized inside the cell, released by exocytosis
- form hydrated gels which are space filling and resist compression
Ex. Hyaluronan

153
Q

Hyaluronan

A

Simple GAG
- long chain of repeating disaccharide units up to 25k
- spun directly from cell surface by a plasma membrane complex

154
Q

Proteoglycans

A

Subclass of glycoproteins
- protein with at least one sugar side chain that is a GAG
- 95% sugar

155
Q

Collagen (makes up connective tissue ECM)

A

Fibrous protein
- provides tensile strength, resist stretching
- three chains form triple helix, assemble into polymers to form fibrils, fibrils pack into fibers

156
Q

Collagen is secreted as

A

Procollagen
- once secreted outside the cell it is assembled into collagen

157
Q

Connective tissue cells that secrete collagen bind to it in the ECM through

A

Integrin and fibronectin

158
Q

Fibronectin

A

Binds collagen and integrin in different domains

159
Q

Integrin collagen interaction

A

Binds fibronectin with extracellular domain and adaptor proteins (actin filaments) with intracellular domain

160
Q

Elastin

A

Fibrous protein, gives tissues elasticity
- provides strength and prevents from excessive stretching

161
Q

Basal lamina (epithelial tissue ECM)

A
  • underlies all epithelial, thin
  • secreted by epithelial cells
  • influences cell polarity
  • separates epithelia from underlying tissue, allows immune cells to pass
162
Q

Basal lamina anchored by

A

Hemidesmosomes, organized by laminin
- links Integrin to type IV collagen

163
Q

Plant cell wall components

A

More rigid than ECM
- cellulose and pectin

164
Q

Cellulose microfibrils provide…

A

Provide tensile strength in cell wall

165
Q

Pectin

A

Space filling, provides resistance to compression

166
Q

Where are cellulose chains synthesized?

A

Plasma membrane at the cellulose synthetase complex
(Other cell wall components synthesized at Golgi and exported by exocytosis)

167
Q

Which type of molecule moves faster across the lipid bilayer (diffusion)

A

Nonpolar, more hydrophobic molecules

168
Q

Symport

A

Gradient driven pump where both solutes move in the same direction

169
Q

Antiport

A

Gradient driven pump where solutes move in opposite directions

170
Q

Xray crystallography

A

Determines 3D protein structure

171
Q

Where are phospholipids synthesized?

A

Smooth ER

172
Q

Three main steps of cell cycle

A
  1. Cell growth and chromosome duplication
  2. Chromosome segregation
  3. Cell division
173
Q

Phases of cell cycle

A

M (mitosis)
G1
S
G2

174
Q

M phase

A
  • nucleus and cytoplasm divide
  • mitosis and cytokinesis
175
Q

Mitosis definition

A

Nuclear division

176
Q

Cytokinesis definition

A

Cytoplasmic division

177
Q

Interphase

A

The period between cell divisions
- G1, D, G2

178
Q

Cells that divide on an ongoing basis

A

Epithelial stem cells and hematopoietic

179
Q

Cells that do not divide are in _____

A

G0
Metabolically active, just not dividing (nothing wrong with them)

180
Q

Start transition signal

A

Is environment favourable

181
Q

G2/M transition signal

A

Is all DNA replicated and undamaged

182
Q

Metaphase to anaphase signal

A

Are all chromosomes attached to mitotic spindle

183
Q

What triggers entry to the next phase of the cell cycle?

A

M-Cdk : cyclin dependant protein kinases

184
Q

Interphase is compromised of two phases

A

G1 phase
S phase

185
Q

What happens during prophase

A
  • replicated chromosomes condense
  • mitotic spindle assembly starts and requires duplicated centrosomes
186
Q

Cohesin

A

Hold sister chromatids together

187
Q

Condensins role

A

Condense DNA in each sister chromatid

188
Q

Centrosome structure

A
  • pair of centrioles organized at right angles
189
Q

Centriole composition

A

Nine fibrils of three microtubules each

190
Q

When is centrosome duplication initiated and completed

A

Initiated G1, completed by G2

191
Q

What do the duplicated chromosomes form

A

Poles of mitotic spindle

192
Q

What phase does mitotic assembly start

A

Prophase (M phase)

193
Q

Why does the nuclear envelope break down?

A

So DNA is available to mitotic spindle

194
Q

When does nuclear envelope breakdown occur

A

Between prophase and prometaphase

195
Q

What breaks down nuclear enevelope

A

Phosphorylation of lamins and nuclear pore proteins
- triggers disassembly into small membrane vesicles

196
Q

Prometaphase

A
  • nuclear envelope now disassembled
  • mitotic spindle assembly can be completed
  • kinetichore microtubules in mitotic spindle attach to duplicated chromosomes
  • chromosome movement begins
197
Q

What does the mitotic spindle require for assembly and function

A
  • microtubule dynamics
  • microtubule motor protein activity
198
Q

Astral microtubules

A

Position mitotic spindle, has cytoplasmic dyenin

199
Q

What direction does cytoplasmic dyenin walk

A

Towards the minus end

200
Q

Non-kinetochore microtubules

A

Cross linked microtubules throughout the mitotic spindle
- kinesin-5 and other microtubule associated proteins

201
Q

What direction does kinesin-5 walk along the non-kinetochore microtubules

A

Towards the plus end

202
Q

Kinetochore microtubules role

A

Attach duplicated chromosomes to the spindle poles

203
Q

Where are kinetochores located

A

Centromeres of chromosomes

204
Q

When does the cell move to metaphase

A

When all chromosomes are aligned in the middle

205
Q

Tubulin flux is an example of

A

Treadmilling

206
Q

What maintains the metaphase spindle

A

Tubulin flux

207
Q

When does anaphase start

A

Chromosomes aligned on metaphase plate

208
Q

Anaphase (what is activated, what does it cleave)

A
  • seperase activated, cohesin complex cleaved
  • anaphase A and B
209
Q

Anaphase A

A

Chromosomes pulled polewards
- kinetochore microtubules shorten to drag chromosomes towards poles

210
Q

Anaphase B

A

Poles are pushed and pulled apart
- sliding force kinesin
- pulling force cytoplasmic dyenin

211
Q

What starts to assemble during telophase

A

Contractile ring starts to assemble

212
Q

Nuclear envelope reassembly

A

Desphosphorylation of nuclear pore proteins and lamins

213
Q

Cytokinesis marks

A

The end of M phase

214
Q

Cleavage furrow

A

Where cytoplasm divides

215
Q

Contractile ring of actin and myosin filaments role

A

Divides cytoplasm in two

216
Q

Cytokinesis requires

A

Dymanic actin and myosin filaments

217
Q

Mitosis in a plant cell has no ____

A

Centrosome

218
Q

Cytokinesis in plant cells

A

Telophase
- phragmoplast forms
Cytokinesis
- cell plate forms
G1
- cell wall turns into plasma membranes and cell wall between daughter cells

219
Q

Meiosis produces

A

4 haploid cells

220
Q

How many rounds of DNA replication in meiosis and mitosis

A

1

221
Q

How many rounds of cell division in meiosis

A

2

222
Q

Claudin and occludin make up

A

Tight junctions

223
Q

Separase

A

Cleaves cohesin complex during anaphase

224
Q

Proteins that are folded before sorting head for

A

Nucleus and peroxisome

225
Q

Proteins that are unfolded before sorting head for

A

Mitochondria and plastids

226
Q

How many subunits in a gap junction connexin

A

1

227
Q

How many connexins in a gap junction connexon/hemichannel

A

6

228
Q

How many connexons and connexins in an intercellular channel/gap junction

A

2 connexons, which means 12 connexins

229
Q

What motor protein provides the sliding force in anaphase B

A

Kinesin

230
Q

What motor protein provides the pulling force in anaphase B

A

Cytoplasmic dyenin

231
Q

What forms the nuclear lamina

A

Intermediate filament

232
Q

Are internal ER signal sequences removed

A

No

233
Q

Are N terminal signal sequences removed

A

Yes, by signal peptidase

234
Q

What type of proteins sort to the ER

A

Soluble proteins, transmembrane proteins

235
Q

Transport of vesicles, organelles, or molecules to the plus end of a microtubule is done by

A

Kinesin

236
Q

Flippase

A

Flips phospholipids from the extracellular leaflet to the cytosolic leaflet

237
Q

Cell-cell junctions (TADG)

A

Tight, Adherens, desmosomes, gap

BIO130 (2 decks)

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