Test 3. Lecture 26 Flashcards

1
Q

choloroplasts are a type of __________.

Plastids have the same genome as chloroplasts, but differ in structure and
function.
Chloroplasts are specialized for photosynthesis; other plastids are involved in
other aspects of plant metabolism.
Other plastids have a double-membrane envelope but lack thylakoid membranes
and other components of the photosynthetic apparatus.

A

plastid

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2
Q

plastid are classified based on the pigments they contain

_______ contain chlorophyll
________ contain carotenoids, resulting in yellow, orange, and red color of flower and fruits

____________ store A VARIETY OF ENERGY sources in nonphotosynthetic tissues

______ and __________ are leucoplasts that STORE STARCH AND LIPIDS

A

chloroplast

chromoplasts

leucoplasts

amyloplasts and elaioplasts

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3
Q
  1. All plastids develop from ___________ , small undifferentiated organelles in rapidly dividing cells
  2. some mature plastids can change from one type to another. Chromoplasts develop from chloroplast during fruit ripening
  3. Devlopment of plastids is controlled by
    ______________-
    _____________
  4. in the photosynthetic cells of leaves, protplastids develop into chloroplasts in the prescence of light
A

proplastids

environmental signals
intrinsic developmental signals

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4
Q

if kept in the dark, development of protoplastids is arrested at an intermediate stage (_____________)

an array of tubular interal membrane has formed, bu chlorophyll has not been synthesized

if moved into the light, etioplasts devlop into choloroplast

A

etioplasts

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5
Q

_______________: SINGLE-MEMBRANE - enclosed organelles containing enzymes involved in many metabolic reactions

A

peroxisomes

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6
Q

peroxisomes do not have their own ____________

most peroxisomal proteins are synthesized on free ribosomes and imported as completed polypeptides

A

genomes

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7
Q

perioxomes can replicate by division but can also be regenerated even if entirely lost

Peroxins are typical eukaryotic proteins ( many mitochondrial and plastid proteins resemble those of prokaryotes)

________________ are broken down by ___________ reactions in peroxisomes, which leads to the production of HYDROGEN PEROXIDE

A

many substance

oxidative reactions

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8
Q

_________________ converts hydrogen peroxide to water or uses i to oxidize another organic compound

A

catalase

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9
Q
  1. Peroxisomes are also involved in synthesis of lipids

In animal cells, ____________ and ______________ are synthesized in peroxisomes and in the eR.

In the liver, peroxisomes are involved n synthesis of bile acids from cholesterol

peroxisome have enzymes for synthesize of _________-_________ with one hydrogcarbon chain joined to glycerol by an ether bond rather than an ester bond

plasmalogens are important membrane components in some tissues

A

In animal cells, cholesterol and dolichol are synthesized in perosomes and in the ER

peroxisomes have enzymes for synthesis of plasmalogens-phospholipids

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10
Q

In seeds, peroxisomes convert fatty acids to carbohydrates via the _______________ ( variant of the CAC)

THis provides energy and raw materials for the germinating plant

the peroxisomes are sometimes called __________-

A

glyoxylate cycle

glyoxysomes

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11
Q

Cytoskeletons (general information?)

A

The cytoskeleton is a network of protein filaments extending throughout the
cytoplasm of eukaryotic cells.

• It provides a structural framework that determines cell shape, positions of
organelles, and general organization of the cytoplasm.

• The cytoskeleton is also responsible for movement of entire cells, and internal
transport of organelles and other structures.

• It is not rigid, but is a dynamic structure that is continually reorganized as cells
move and change shape.

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12
Q

the cytoskeleton is composed of three main types of protein filaments?

____ polymerizes to form actin filaments (_________)

A
  1. actin filament
  2. microtubules
  3. intermediate filaments

ACTIN polymerizes to for actin filaments (MICROFILAMENTS)

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13
Q

________________regulate assembly and disassembly of actin
filaments, cross-linking into bundles and networks, and associations
with other cell structures.

A

actin-binding proteins

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14
Q

 All the actin monomers are oriented in the same direction, so actin
filaments have ________.
 This is important in their assembly and in establishing the direction of
myosin movement relative to actin.
 __________is the first step of actin polymerization—a trimer is formed, and
monomers are then added to either end.
 Actin polymerization is _______; the filaments can be broken down when
necessary.

A
  • polarity
  • nucleation
  • reversible
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15
Q

Actin is very abundant (5 to 10% of total protein) in all types of eukaryotic cells.
Mammals have______ genes: 4 are expressed in ________ cells and 2 in ______

A
  • 6 actin genes
  • 4 expressed in MUSCLE CELLS
  • 2 in NONMUSCLE CELLS
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16
Q

Each actin monomer (________) has tight binding sites that mediate head-to-tail
interactions with two other actin monomers, to form filaments (____________).

A

globular [G] actin

filamentous [F] actin

17
Q

TREADMILLING:

The barbed end of a filament grows 5–10 times faster than the pointed end.
Actin bound to ________ associates with _______, and the ATP is then hydrolyzed
to ADP.
______is less tightly bound than ATP-actin and ______________
Treadmilling is critical in regulating actin filaments within the cell.

A

ATP

the barbed ends

ADP-actin

dissociates at the pointed end.

18
Q

Actin-binding proteins: (KNOW)

_________ bind ATP-actin and nucleate INITIAL POLYMERIZATION of long
unbranched actin filaments.

_________ binds actin monomers and stimulates EXCHANGE OF BOUND ADP for ATP, increasing the local concentration of ATP-actin.

A

FORMINS

PROFILINS

19
Q

(KNOW)
______________(actin-related proteins): initiate growth of branched actin
filaments, important in driving cell movement at the plasma membrane

A

Arp2/3 complex

20
Q

(KNOW)
_____________ stabilize actin filaments by binding lengthwise along the
groove of the filament.
Capping proteins stabilize actin by binding to the barbed or pointed ends

A

Tropomyosins

21
Q

(KNOW)
Other actin-binding proteins remodel or modify existing filaments.
_______________ severs filaments, generating new ends which are then available for
polymerization or depolymerization.

A

Cofilin

(The actin-binding proteins act together to promote rapid turnover of filaments and
remodeling of the cytoskeleton needed for cell movements and changes in cell shape.
Their activities are controlled by signaling mechanisms in response to environmental
signals.)