Characteristics of Bacillariophyceae (diatoms)

Question 1

structure

Answer 1

unicellular often forming chains or colonies

Question 2

main pigments

Answer 2

• chlorophyll a and c
• fucoxanthin
• diatoxanthin
• diadinoxanthin

Question 3

storage products

Answer 3

chrysolaminaran (b-1,3-linked glucan)
oil (lipid)
used for buoyancy control

Question 4

flagella

Answer 4

single, hairy flaggellum in male gametes

Question 5

unique features of diatoms

Answer 5

• Frustule formation: has a silica-based external wall (frustule)
• Storage Product: Chrysolaminarin (β-1,3-linked glucan)
  serves as the primary energy storage compound.
• Silica Uptake: Require dissolved silicic acid for frustule
  formation, making them key players in the silica cycle.
• • Ecological Importance: Frustules contribute to
    diatomaceous earth deposits, widely used in filtration,
    insulation, and abrasives.

Question 6

cell wall covering

Answer 6

siliceous wall in form of a box with an overlapping lid (frustle)
providing protection

Question 7

plastids

Answer 7

thylakoids stacked in 3’s with girdle lamella, chloroplast DNA in ring genopore

Question 8

what are the 2 types of valves in diatoms

Answer 8

epivalve - larger upper valve

hypovalve - lower valvefitting inside the spivalve

Question 9

what are the 2 different orders of diatoms?

Answer 9

centrales - circular cylindrical

pennales- elongated or boat shaped

Question 10

reproduction of diatoms

Answer 10

Asexual (main)
- Mitosis/bianary fission
- May occur rapidly

Sexual- different in pennate and centric
- Centric diatoms
* Oogamous
* Male gametes are the only flagellate stage
– Pennate diatoms
* Isogamous
* Male and female gametes without flagella
- Dcreases in size (asexual)
- Leads to sexual production
Asexual reproduction (binary fission/mitosis) most common

Question 11

process of asexual reproduction for diatom

Answer 11

Asexual reproduction (binary fission/mitosis) most common
Process:
- The parent cell divides, each daughter cell inherits one original valve (either epivalve or hypovalve)
- Each daughter cell synthesizes a new smaller valve inside of the existing one
-
- Daughter cell gradually shrinks over generations
- This is why we need sexual reproduction eventually to retore the siz e of the cell