Lecture 12

Question 1

What are the vacuoles produced by?

Answer 1

Produced by the Golgi associated endoplasmic reticulum

Question 2

What is the structural feature of the Vacuole? (1)

Answer 2

It is enclosed by a single membrane called the tonoplast

Question 3

What are the three main differences between a plant cell and an animal cell?

Answer 3

1. Cell Wall
2. Chloroplasts
3. Central Vacuole

Question 4

How many vacuoles per plant?

Answer 4

Depends. Mature plant cells typically have a single large vacuole and younger plants have many small vacuoles.

Question 5

What are the functions of the vacuole?

Answer 5

Storage
Breakdown of macromolecules
Regulation of Cell Turgidity

Question 6

What are the type of substance that vacuoles store? What are each of their characteristics?

Answer 6

Primary Metabolites - growth associated

Secondary Metabolites - Not growth associated

Question 7

What are some examples of Primary metabolites?

Answer 7

Inorgainc ions
Organic acids
Sugars
Amino acids
Proteins
Lipids

Question 8

What are some the two sections of Secondary metabolites?

Answer 8

Molecules for Defence

Molecules for signalling

Question 9

What are some examples of molecules for defence?

Answer 9

Small latex containing vacuoles - rubber tree
Specialised cells called Raphides
Alkaloids- nitrogen containing bases

Question 10

What are Raphides?

Answer 10

Needle shaped crystals of calcium oxalate

Question 11

Whats the tonoplast?

Answer 11

It’s a selective membrane that controls the movement of substances into and out of the vacuole (has proteins in the membrane eg transport proteins)

Question 12

Molecules for signalling? - explain

Answer 12

Pigments to attract animals for seed dispersal to give petals colour/attract insects e.g. anthocyanins - purple dots are concentrated areas of anthocyanins and light purple is vacuole

Question 13

Secondary metabolites can now be produced in ___ ___ Why is it better to produce it in these conditions?

Answer 13

Cell cultures- this way it is more efficient than extracting it form harvested material and ecologically less damaging.

Question 14

Vacuoles: Degradation

1. What it is described to be?
2. What characteristics does the vacuole have to help degradation?

Answer 14

1. Digestion of cytoplasmic constituents

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

Question 15

Why do vacuoles play a large part in regulation of cell turgor?

Answer 15

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 16

What are the pathways that cause the cells to lose/gain turgor pressure?

Answer 16

1. Due to this high solute concentration within the vacuole, this means that there is a NEGATIVE OSMOTIC PRESSURE, resulting in the WATER UPTAKE.

The plant cell wall enables the uptake of water without bursting.

2. Loss of water means the decrease in turgor pressure, and thus will result in WILTING.

Question 17

What are plastids?

Answer 17

Plastids are double membrane bound organelles found inside plants, which are responsible for activities related to making and storing food.

Question 18

Describe the origin of Plastids

Answer 18

1. A non-photosynthetic eukaryote engulfs a photosynthetic prokaryote.
2. The prokaryote forms a relationship between the eukaryotic cell.
3. The prokaryote then becomes semi-autonomous. (The prokaryote cannot survive without the host cell fully)
4. The non-photosynthetic eukaryote then turns into a photosynthetic eukaryote cell.

Question 19

What are the main features of Chloroplast DNA?

Answer 19

• Chloroplast DNA is circular
• Most of the genome encoding for chloroplast proteins are in the chloroplast DNA, some of the genes that code for chloroplast proteins are also in the nucleus of the cell.

Question 20

What are the functions of the chloroplasts? Which reactions take place where?

Answer 20

The function of the chloroplasts are to capture of light energy and convert it to chemical energy.

The dark reactions take place in the stroma
The light reactions take place in the thylakoid membranes

Question 21

What are the 4 features that chloroplasts have in common with mitochondria?

Answer 21

• Both bounded by two membranes
• Contains nucleic acids
• Outer membrane is highly permeable
• Inner membrane is more selective.

Question 22

What is the unique feature about the chloroplasts that differs from the mitochondria?

Answer 22

There is a third membrane system in the thylakoid membrane.

Question 23

What is the thylakoid lumen (space) used for?

Answer 23

Used to build up gradients of molecules for ATP.

Question 24

What are the structures of the Chloroplasts?

Answer 24

1. 3 membranes (thylakoid, inner, outer)
2. There are three compartments (stroma, thylakoid space, inter membrane space)
3. These compartments and the membranes that separate them are for isolation of different photosynthetic reactions.

Question 25

What do chromoplasts do?

Answer 25

They attract animals - give colour to many flowers and fruits. They have increased carotenoids (pigments) and decreased thylakoid membranes.

Question 26

What is the conversion of chromoplasts as fruit ripens?

Answer 26

Chloroplasts are converted to chromoplasts.

Question 27

What do leucoplasts store?

Answer 27

Pigments
Protein
Lipids
Starch

Question 28

What are proplastids?

Answer 28

All plastids are derived from proplastids. I.e the proplastids can differentiate and turn into any of the 3 plastids (leucoplasts, chromoplasts, chloroplasts)