Lecture 12: Unique plant structures

Question 1

What is the protoplast?

Answer 1

A plant cell minus the cell wall.

Question 2

What are plasmodesmata?

Answer 2

Narrow channels between two cell walls.

Question 3

How many membranes surround the vacuole?

Answer 3

One.

Question 4

What is the tonoplast?

Answer 4

The single membrane around the vacuole. It is highly selective.

Question 5

How many vacuoles do plant cells usually have?

Answer 5

Young plant cells often have many small vacuoles, but mature plant cells typically have one large vacuole.

Question 6

How are vacuoles produced?

Answer 6

Vacuoles are produced by the golgi associated endoplasmic reticulum.

Question 7

What are the three main functions of a vacuole?

Answer 7

Storage - Primary and secondary metabolites
Breakdown of macromolecules and organelles
Regulation of cell turgor

Question 8

Where are metabolites stored in plant cells?

Answer 8

In the vacuole.

Question 9

Which metabolites are growth associated?

Answer 9

Primary metabolites are growth associated, Secondary metabolites are not growth associated.

Question 10

The tonoplast is a __________ membrane that controls the movement of substances into and out of the vacuole.

Answer 10

The tonoplast is a selective membrane that controls the movement of substances into and out of the vacuole.

Question 11

What are the 6 main primary metabolites in vacuoles?

Answer 11

Inorganic ions
Organic acids
Sugars
Amino acids
Proteins
Lipids

Question 12

Can water pass through the tonoplast freely?

Answer 12

Yes.

Question 13

What are two types of secondary metabolites?

Answer 13

Molecules for defence

Molecules for signalling

Question 14

What are 3 examples of defence molecules?

Answer 14

• Rubber tree (Hevea brasiliensis)
• Raphides in vacuoles (Raphides are needle shaped crystals of calcium oxalate)
• Alkaloids. Have a toxic effect on animals. Used in drugs e.g., cocaine, morphine, codeine, quinine

Question 15

What is an example of signalling molecules?

Answer 15

Catharanthus roseus pigment. Used in Vincristine &/or Vinblastine

Question 16

How are plant cells produced artificially?

Answer 16

Using a cell culture (can be genetically modified). Economical (efficient) and ecological benefits.

Question 17

What is Anthocyanin?

Answer 17

A pigment used for attracting animals and pollinators to plants.

Question 18

Where are anthocyanins stored?

Answer 18

In the vacuole.

Question 19

Where are organelles and macromolecules digested in a plant cells?

Answer 19

In the vacuole. (Digestion of cytoplasmic constituents)

Question 20

Vacuoles are ALKALINE/ACIDIC and contain ________ enzymes similar to the lysosomal enzymes of animal cells

Answer 20

Vacuoles are acidic and contain hydrolytic enzymes similar to the lysosomal enzymes of animal cells

Question 21

What decides what enters and exits the vacuole?

Answer 21

The tonoplast. Tonoplast control can vary depending on the environment and cell type.

Question 22

Because they contain water and
make up such a large portion of the
protoplast, vacuoles can play a role
in the ____________ __ _____ _______.

Answer 22

Because they contain water and
make up such a large portion of the
protoplast, vacuoles can play a role
in the regulation of cell turgor.

Question 23

How is turgor developed?

Answer 23

High concentrations of solutes in the vacuoles have a negative osmotic potential, resulting in water up take. The plant cell wall enables water up
take without bursting.

Question 24

Loss of water from vacuoles _________ turgor pressure

Answer 24

Loss of water from vacuoles decreases turgor pressure

Question 25

What is wilting?

Answer 25

A loss of turgor pressure.

Question 26

What the 4 steps in the plastid origin theory?

Answer 26

1. Non-photosynthetic eukaryote 2. Engulfing of Photosynthetic prokaryote 3. Chloroplast becomes a semi-autonomous organelle 4. Photosynthetic eukaryote

Question 27

What is the DNA in chloroplasts called and what shape does it have?

Answer 27

ctDNA, circular.

Question 28

``` Although _______ contains information for the formation of many chloroplast proteins, some proteins found in the chloroplast are encoded by genes present in the _______ of the cell. ```

Answer 28

``` Although ctDNA contains information for the formation of many chloroplast proteins, some proteins found in the chloroplast are encoded by genes present in the nucleus of the cell. ```

Question 29

What is the function of chloroplasts?

Answer 29

photosynthesis: Capture light energy and convert it to chemical energy

Question 30

What is the function of chromoplasts?

Answer 30

synthesis and storage of coloured pigments

Question 31

What is the function of leucoplasts?

Answer 31

storage of assimilates (starch)

Question 32

What is the function of proplastids?

Answer 32

precursors to the other plastids

Question 33

What are 4 similarities between chloroplasts and mitochondria?

Answer 33

- bounded by two membranes - contain nucleic acids - outer membrane highly permeable - inner membrane more selective

Question 34

What is a unique feature of chloroplasts in terms of its membranes?

Answer 34

It has a third membrane system.

Question 35

Where are the thylakoid membrane systems found?

Answer 35

In the chloroplast.

Question 36

Where are lumens found?

Answer 36

Inside of thylakoid

Question 37

What are the 3 membranes of the chloroplast?

Answer 37

Inner, out, thylakoid

Question 38

What are the 3 compartments of the chloroplast?

Answer 38

Stroma, thylakoid space, and intermembrane space.

Question 39

Where do dark reactions take place in the chloroplast?

Answer 39

In the stroma.

Question 40

Where do light reactions take place in the chloroplast?

Answer 40

On the thylakoid membranes.

Question 41

As fruit ripens _____________are converted to __________.

Answer 41

As fruit ripens chloroplasts are converted to chromoplasts.

Question 42

What are the major structural differences between chloroplast and chromoplasts?

Answer 42

Chromoplasts have increased carotenoids (pigments) and decreased thylakoid membranes.

Question 43

What do leucoplasts store?

Answer 43

Pigments, protein, lipids or starch.