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Plant molecular biology > test 1 > Flashcards

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1
Q

Nucleolus: _______

A

is the ribosome factory

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2
Q

what does amphipathic mean to membrane lipids?

A

each lipid has a hydrophilic head (usually containing a phosphate group) and hydrophobic tails.

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3
Q

How does the lipid bilayer serve as a general permeability layer?

A

Because, polar molecules (water soluble) cannot traverse its nonpolar interior.

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4
Q

How do cells optimize the fluidity of their membranes by controlling lipid composition?

A

Adjusting the ratio of saturated to unsaturated fatty acids, cholesterol content, and fatty acid chain length, to maintain the right balance between rigidity and flexibility. This is dependent on temperature

Super Cool Flowers (saturated vs unsaturated, cholesterol, and fatty aci

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5
Q

Chloroplasts function?

A

photosynthesis

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6
Q

Nucleus does what?

A

contains most cells genetic information and is the center of regulatory activity.

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7
Q

Golgi apparatus is?

A

a carbohydrate factory

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8
Q

all plastids are developmentally related to?

A

proplastids

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9
Q

T/F: Membrane sterols in lipid bilayers behave somewhat differently from phospholipids. This is because the hydrophobic domain of a sterol molecule is much larger than an uncharged polar head group.

A

true

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10
Q

T/F: chloroplasts, similar to mitochondrion and nucleus, has a double membrane and it contains its own DNA.

A

True

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11
Q

What processes are involved to get external materials and expel unneeded internal materials in a plant cell, describe how.

A

Endocytosis: cell membrane engulfs external materials to form a vesicle, which then transports the materials into the cell.
Exocytosis: Expels unneeded internal materials by fusing vesicles containing these materials with the cell membrane, releasing their contents to the outside.

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12
Q

Without the cell wall, protoplasts would be…?

A

spherical

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13
Q

The difference between an animal cell and plant cell?

A

PLant cells contain a cell wall.

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14
Q

____ are building blocks of the cell wall?

A

sugars

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15
Q

new cell walls are born in the ___

A

cell plate

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16
Q

Monosaccharides linked into the cell wall polymers are derived from

A

glucose

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17
Q

The two major cross linking glycans of all primary cell walls of flowering plants are

A

Xyloglucan and glucuronoara binoxylans

XYG and GAX

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18
Q

Two fundamental constituents of pectin are

A

Hg and RG1

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19
Q

T/F: the plant cell wall is a dynamic compartment, changing throughout the life of the cell.

A

True

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20
Q

What is happening in Arabidopsis murus1 mutant and why does adding boron rescue the mutant phenotype?

A

dimers do not form which alters side chain structure to not bind to born. (stature and strength reduced) Spraying with excess boron causes cross-linking of the cell wall which is essential for its function and stability. this will help it.

No dimers, no boron. Add boron creates cross-link which saves.

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21
Q

What are pectin functions?

A

Determine porosity, provide charged surfaces, regulate cell-cell adhesion, recognition molecule, effect wall growth by access of wall loosening enzymes.

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22
Q

Compare type 1 and II cell walls

A

BOTH- show the molecular interaction between cellulose, but in different ways.
Type 1- XyG pectins, and wall proteins
Type II- GAX pectins, and aromatic substances.

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23
Q

What are five classes of polymers that structural complexity of plant cell walls can involve?

A

Cellulose, glycans, pectins, proteins, and lignins.

Creatures Gather Pumpkins Preparing Lanterns

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24
Q

Explain cell wall biosynthesis, and list what cell organelles are involved and their functions.

A

It is forming cellulose microfibrils at the plasma membrane after mitosis, requiring coordination for cellulose production at the plasma membrane,
rough ER synthesizes proteins and wall-modifying enzymes
golgi synthesizes non cellulosic polysaccharides.

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25
Q

how does brown-midrib mutants of sorghum SPP or Z mays result in improved nutrition in ruminant animals?

A

by reducing lignin content, brown-midrib mutants enhances ruminant nutrition. This improves digestion and the availability of energy and proteins.

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26
Q

T/F: many transporters are selective for the substrate being transported and their activities are regulated.

A

True

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27
Q

T/F: most plant transporter genes are members of the multigene families that show developmental and tissue-specific expression.

A

True

28
Q

Pumps transport___

A

protons

29
Q

Channels transport___

A

ions

30
Q

Cotransporters transport___

A

solutes

31
Q

Membrane transport underlies many essential cell biological process, what are they?

A

nutrient acquisition, metabolite distribution and compartmentalization, energy transduction, turgor generation, waist excretion, and signal transduction

Naughty - Nutrient acquisition
Mice - Metabolite distribution and compartmentalization
Eat - Energy transduction
Tasty - Turgor generation
Waffles - Waste excretion
Slowly - Signal transduction

32
Q

Pumps, channels, and cotransporters are components of membrane transport systems. What are their differences?

A

pumps: catalyze active transport, coupling the energy through hydrolysis of ATP. THis is to transport specific molecules against an electrochemical gradient
Channels and cotransports: facilitate passive transport
Cotransporters: (carriers) transport specific molecule through/against an electrochemical gradient

Pumps Are Transporters
Channels Pass
Carriers Move Together

33
Q

what are the F-Type ATPase and the P-Type PM H+ATPase? WHat is their difference?

A

Ftype- at the inner mitochondrial and thylakoid membranes are H+ pumps and they synthesize ATP.
P-type covalently binds the y-phosphate of ATP during catalysis.located in plasma membrane of plant cells.
Difference- one f-type harnesses pmf to drive ATP synthesis; P-type generates pmf to hydrolyze atp

F- pumps synthesize atp @ mitochondrial and thylakoid
First Synthesize Power at Mitochondria and Thylakoid
P-binds y-phosphate of ATP during catalysis
difference: F-type: harnesses pmf to drive ATP,
P-type: generates pmf to hydrolyze.

34
Q

What does AKT1 gene encode for? What is going on in AKT1 arabidopsis plants from genotype, function, and phenotype?

A

AKT1 encodes K+ influx channel, for K+ intake in roots. In arabidopsis akt1 plants.
Genotype- AKT1 gene was knocked out
function- uptake of 86Rb+ by roots of arbidopsis akt1-1 mutant plants was decreased.
Phenotype- arabidopsis akt1-1 mutant plants have diminished growth in comparison with WT. The difference in growth rates is pronounced at limited concentrations of K+

AKt1 encodes for influx of K+, genotype explains AKT1 was knocked out making its function of uptaking 86Rb+ decreased resulting in a phenotype of shorter plants due to limited concentration of K+.

35
Q

why can water not traverse the membrane lipid bilayer? How does water move across the membrane lipid bilayer?

A

The lipid bilayer has a hydrophobic interior which repels water/polar molecules. Aquaporins allow water to pass across the membrane layer.

36
Q

what are 1, 2, and 3. How can you tell?

A
  1. (in vacuole) Cotransporter: passive transport 2 molecular species
  2. (golgi) pumps: active transport, driven by ATP hydrolysis
  3. (plasma membrane) Channels: passive, one molecular species, forming aqueous pores in the membrane.
37
Q

peptide address labels for targeting mitochondria is called?

A

presequence

38
Q

To remain in the chloroplast stroma, proteins is folded with the help of a class III chaperone called____

A

chaperonin

39
Q

protein import to peroxisomes requires not only a peroxisomal targeting signal but also ____

A

atp

40
Q

T/F: transport of proteins into chloroplasts involves a removable transit peptide, but after proteins enter a mitochondrion, their peptide address labels are not cleaved

A

false

41
Q

transport of proteins into chloroplasts involves a removable transit peptide, but after proteins enter a mitochondrion, their peptide address labels are_____

A

cleaved.

42
Q

T/F:targeting proteins to the vacuole depends on short vacuolar sorting signals

A

True

43
Q

T/F: molecular chaperones increase the yield of correct tertiary structures and the rate of protein folding.

A

false.

44
Q

Chaperones increase the yield of correct tertiary structures but NOT____

A

the rate of protein folding.

45
Q

T/F:most polypeptides destined for the nucleus have address labels, called nuclear localization signals. The position of the NLS is within the amino acid sequence of a protein varies, and they are cleaved from nuclear proteins after translocation.

A

False

46
Q

NLS’s are __________ from nuclear proteins after translocation

A

NOT CLEAVED

47
Q

T/F: the rough ER is abundant in cells that specialize in proteins secretion or protein storage.

A

true

48
Q

T/F:The three functions of promoting correct folding, retaining proteins until they are correctly structured and degrading defective proteins are collectively termed ER quality control

A

True

49
Q

T/F: proteins targeted to mitochondria have an amphipathic polypeptide helix with charged amino acids on one side and hydrophobic amino acids on the other side.

A

True

50
Q

T/F: most proteins destined for the secretory pathway are cotranslational.

A

True

51
Q

Actin binds and hydrolyzes____

A

ATP

52
Q

Plants contain 2 kinds of filaments, one from protein, actin, usually called actin ____ and the other built from the protein, tubulin, called ____

A

filaments, microtubules

53
Q

The phragmoplast coordinates the depositon of ____ for the new wall

A

polysaccharides

54
Q

____ and ____ are NOT superfamilies of motor proteins

A

filaments and microtubules

55
Q

Transmembrane domains of membrane proteins are usually ____ the loops are _____

A

Hydrophobic, hydrophilic

56
Q

T/F: The mitotic spindle comprises balanced forces and rapid microtubule turnover.

A

True

57
Q

T/F: actins are encoded by multigene families, but tubulins are not.

A

false

58
Q

Both actin and tubulin are encoded for by______

A

multigene families.

59
Q

T/F: intracellular movements of cytoplasm and organelles depends on microtubules.

A

false

60
Q

intracellular movements of cytoplasm and organelles depends on ____

A

actin filaments

61
Q

what are the 3 types of motor proteins. What are the differences and what are their likenesses

A

myosin, kinesin, and dynein:
differences: myosin moves along ACTIN FILAMENTS, while kinesin and dynein move along microtubules; kinesin transports toward the + end, dynein toward the - end and they do not bind the same polymers or transport the same cargo.
commons: all use ATP hydrolysis, contain a globular ATP-binding domain and a rod-shaped tail for cargo binding, and function as dimers.

motor proteins: My Kite Dances
common: All Great Runners are Determined
Think “My Act” for Myosin and Actin.
Associate Kinesin with Kinetic energy – moving toward the + end (forward movement)
Associate Dynein with “Downward” – toward the - end.

62
Q

cytoskeleton is a network of interconnected fibrous polymers that run throughout the cell within the cytosol. What are its functions?

A
  1. provies structural stability to the cytoplasm, anchoring proteins and other macromolecules. Also supports organelles during and after their synthesis.
  2. gives cells the property of motility, both internal and external. Cellular components can move actively within the cell.
  3. participates in processing cellular information
  4. many elements consist of symmetric subunits so that the polymers themselves are like an arrow, and provide directional cues within the cell.
63
Q

What is endocytosis? After endocytosis, what may happen to the materials? (hint: 2 possible pathways)

A

process that engulfs external materials by enclosing them in vesicles derived from the cell membrane. Post endocytosis materials may be degraded by vesicles fused with lysosomes, or recycled back to the plasma membrane or other parts of the cell to be reused.

64
Q

The cytoskeleton provides the machinery that separates the replicated chromosomes at mitosis and that partitions the daughter cells at cytokinesis. What is the machinery at mitosis, and what is the machinery at cytokinesis?

A

mitosis: the mitotic spindle which separates chromosomes.
cytokinesis: phragmoplasts that builds a wall between daughter cells. Phragmoplasts orchestrates the intense secretory activity needed to build the forming cell plate

65
Q

List at least one example of a protein and its function from the topics studied: 1. membrane structure and membranous organelles 2. the cell wall 3. membrane transport 4. protein sorting and vesicle traffic 5. the cytoskeleton

A
  1. transmembrane signaling receptors are essential for cell communication and for mediating interactions with the environment.
  2. cellulose synthase- synthesizes cellulose, which is a key component of the plant cell wall, providing structural support and protection.
  3. proton pump (H+ ATPase)- pumps protons out of the cell creating a proton gradient that drives nutrient uptake
  4. SNARE proteins- mediate the fusion of vesicles with target membranes
  5. actin- actin filaments are involved in various cellular processes including cell shape maintenance, intracellular transport, and cytokinesis during cell division.

Plant molecular biology (1 decks)

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