Topic 4 - Specific organelles of the plant cell Flashcards Preview

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Flashcards in Topic 4 - Specific organelles of the plant cell Deck (43)
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1
Q

Plant specifications

A
  1. Cell wall
  2. Non-living cells are part of the body
  3. Tiny connections between cells (plasmodesmata) - all cells interconnected
  4. Plastids
  5. Vacuoles
  6. Inclusions
2
Q

Cell size

A
Micrometer (bacteria) 
↓
Millimeter (nettle hair) 
↓
centimeter (hemp fibers)
3
Q

Cellular compartments

A

Surrounded with a double phospholipid membrane, differences in function, interaction

4
Q

Cell membranes

A

Function: separation and transport

Double phospholipid layer
Unit membrane hypothesis → fluid mosaic membrane
Plasma membrane (plasmalemma), tonoplast (vacuoles)

5
Q

Function of membrane proteins

A
Receptor proteins
Channel proteins
Carrier protein
Transport proteins
Filaments of cytoskeleton
pH regulation (vacuoles) 
Excretion (dictyosome)
6
Q

The cytoplasm

A

Cytosol and cytoskeleton

7
Q

Cytosol

A
o	Soluble proteins
o	RNA
o	Water
o	Ions
o	Caarbohydrates
o	Fatty acids
8
Q

Cytoskeleton

A

Spiral protein filaments
Mechanical resistance, migration of cell organelles
Play role in cell

9
Q

Plant specific organelles

A
The vacuole system
Plastids
The cell wall 
Incrustations
Adcrustations
Plasmodesmata
10
Q

The vacuole system

A

A Chamber bounded with tonoplast membrane storing solid or fluid compounds and gases

Minor importance in animal cells

11
Q

Provacuole

A

Vesicles or ER and dictyosomes

12
Q

Central vacuole

A

Three provacuoles fused into a larger one

13
Q

Major functions of the vacuole system

A
Storage (isolating materials)
Cell lysis
Maintaining hydrostatic pressure (tugor) and pH
Dispersal 
Protection
14
Q

Types of vacuoles

A

Lysosomes
Vegetative (storage) vacuoles
Inclusions
Crystals

15
Q

Lysosomes (vacuole)

A

Thick membrane

Hyrdolytic enzymes in the middle - autophage

16
Q

Vegetative (storage) vacuoles

A

Diluted water solution, mildly acidic pH 5-6
Ions (e.g. high salt habitats)
By-products (important products for plant life: essenctial oils, paints, flavours)
Waste products (e.g.: glycosides, alkaloids)
Nutrient storage (protein, carbohydrates)

17
Q

Inclusions

A

o Non constant, but not essential substances
o No metabolic activity, no membranes
o Protein inclusions: in pulse grains or aleurone layer, globoid or chrystalloid forms homogeneous/heterogeneous
o Carbohydrate inclusions: mainly starch
o Oil inclusions: small droplets of oil in the cytoplasm

18
Q

Crystals

A

o Accumulation of inorganic compounds
o Oxalates, carbonates, silicates
o Digestion problems, irritation

19
Q

Plastids

A

Assimilation, synthesizing metabolic processes, storage functions
Double phospholipid layer, chloroplast DNA
Coloured plastids: chloro- and chromoplastids
Colourless plastids: leucoplastids
Originated from prokaryotes

20
Q

Development of plastids

A

Plastid initial (meristematic cell) → proplastid

Etioplastid: in cotyledons and plants have not been exposed to sunlight

Light → chloroplastid, synthesis of membrane proteins and pigments

21
Q

Types of plastids

A

Leucoplastid
Chromoplastids
Chloroplastids

22
Q

Leucoplastid

A

Colourless plastids in organs not exposed to sunlight

Storage function

The plant uses stored nutrients and plastids can turn into green ones (potato)

Globular or fusiform shape

23
Q

Types of leucoplastids

A

Amiloplastids - starch
Elaioplastids - oil, fatty acids
Proteinoplastids - protein

24
Q

Amiloplastids

A

Starch

In ground tissues, roots, modified stems, endosperm of seeds
Chrystalline center (hilum) → amorphous and crystalline regions
Simple and compound starch
25
Q

Elaioplastids

A

Oil, fatty acids

Stored nutrients in different organs
Essential for germination
Drying (linseed, poppy), semi-drying (sunflower) and non-drying (castor bean) oils

26
Q

Proteinoplastids

A

Protein

Simple or compound
In modified stems, seeds

27
Q

Chromoplastids

A

Originated from proplastids or amiloplastids or chloroplastids (ripening, ageing leaves)

Less developed inner membranes

Carotenoid pigments: carotene, xanthophylls

Globular, fibrillary or crystalline forms

In flowers, fruits, leaves, roots

Pollination, dispersal

28
Q

Chloroplastids

A

Thylakodis

Stroma

29
Q

Structure and function of thylakodis

A

Outer membrane similar to cell membrane

Photosystems: integral proteins and pigments

Electron transport chain: proteins

ATP and NADPH production photosynthesis (light dependent reactions)

30
Q

Compounds and functions of stroma

A

RuBisCO enzyme (protein complex)

Photosynthesis (light independent reaction) – production of glucose and intermediate products

31
Q

Plastids of C3 and C4 plants

A

For C4 plants mesophyll cells has a granum structure, but it’s absent form the bundle-sheath cells

32
Q

the cell wall

A

Similar in fungi cell but with different composition

Importance in everyday life
    Woods
    Fibers
    Cooking quality
    Nutrients
    Cell wall proteins - hay fever
33
Q

Major functions of the cell wall

A

Protection (environmental stress, pathogens, water loss)
Gives a definite shape
Enables transport information to the exterior
Helps in osmotic-regulation, prevents water loss
Transport processes
Ion exchange, mineral uptake (root hairs)

34
Q

Skeletal substances in the cell wall

A

Cellulose

1,4 linked ß-D-glucose chain
Synthesised by the rosette enzyme of the plasma membrane

Primary cell wall
Web of microfibrils + auxin → loosened structure, formation of new fibrils → increasing cell wall surface

Secondary cell wall
New transverse layers of cellulose fibrils (increased strength)

Cellulase enzymes → decomposition of cell wall (secretory ducts, transport vessels)

35
Q

Matrix substances

A

Pectins (soluble fiber) – linear chain of galacturonic acid polymers: high proportion in fruits and storage organs

Hemicellulose (glucose chain + oligosaccharides): cross-link between pectins and cellulose (e.g. arabinoxylan)

Proteins
Soluble (hydrolitic enzymes, peroxidases)
Insoluble (= extensins) – web-like structure

36
Q

Incrustations

A

Lignin (wood)
Suberin (cork)
Pigments
Mucilage - storage of water, gelling effect
Inorganic compounds - in plant hairs → irritation

37
Q

Lignin

A

Phenolic polymers consists of
Coumaryl alcohol
Coniferyl alcohol
Sinapyl alcohol

Mainly in the secondary wall (lignification)
Increase rigidity
Decrease digestibility

38
Q

Suberin

A

Polymers of aromatic and aliphatic compounds
Waterproof layer, decreasing evaporation
Decreasing digestibility

39
Q

Adcrustations

A

On cell wall surface
Wax, cutie
Water insulators, decreasing evaporation

40
Q

Plasmodesmata

A

Channels traverse the cell walls - smooth ER tubes and protein filaments
Direct transport between cells
Large number in young cells, later decreasing abundance

41
Q

The secondary wall

A

After the end of cell growth

Generally in mature cells with no cytoplasm (e.g.: fibers)

Increasing amount of incrustations decreasing digestibility

42
Q

Outer (centrifugal) thickening

A

In case of spores and pollens

Spikes, grains, appendages

43
Q

Inner (centripetal) thickening

A

Strengthening, protection (e.g.: transport tissues)

Total – complete cell wall (sclerenchyma)

Local – some part of a cell wall (e.g.: tracheids)

Partial – some of the cell wall (collenchyma)

General – whole cell wall except plasmodesmata