BIOL 2P93 Lecture Notes - Lecture 2: Chlorophyceae, Pyrenoid, Bryophyte
4 May 2018
School
Department
Course
Professor
BIOL 2P93 Spring Lecture 1: Chapter 15 Part 2 03/05/2018
• Algae: Morphology
o Body Plan
▪ No specialization of body into root/stem
▪ Photosynthetic portion is a thallus while
attachment part is made up of hair-like rhizoids
o Lack of Embryo
▪ Most algae, sperm & eggs fuse in open water
▪ Zygotes develop into new plant unprotected
o Reproductive Structures
▪ Gametes produced w/n single cell
▪ No protective jacket of sterile cells
• Green Algae Morphology
o ~17,000 species
o Most are aquatic
▪ Some are found on snow, tree trunks, soil and in
symbiotic associations w/ lichens
o Microscopic
▪ But…arie speies suh as Codium magnum can be 8+ meters in length and 25 cm
in width
o Morphological similarities b/n Green Algae (GA) and Embryophytes (Bryophytes &
Vascular Plants)
▪ These 3 groups of plants are the only ones that contain the following
• Chlorophylls a and b
• Store starch (food reserve) inside plastids
▪ GA are similar to Bryophytes & Vascular Plants
• Have firm cell walls made of cellulose, hemicelluloses and pectic substances
o Classification traditionally relied on structural appearance
▪ Not 100% since related GA cannot always be recognized by this manner
o Classification now substantiated by ultrastructural studies of mitosis, cytokinesis, reproductive
cells
o Important to know the precise natural of molecular variation amongst groups
• Characteristics of 3 Major Groups of Green Algae
o Indicates physical & molecular characteristics
find more resources at oneclass.com
find more resources at oneclass.com
BIOL 2P93 Spring Lecture 1: Chapter 15 Part 2 03/05/2018
• Class Chlorophyceae (Chlorophytes)
o Somewhat similar but there are subtle variations b/n species
o Some are unicellular & nonmotile
▪ Chlorococcum echinozygotumas
▪
o Some are colonial
▪ Algae in which cells form large elaborately interconnected groups
▪ Motile or nonmotile
• Hydrodictyon reticulatum
o Nonmotile & colonial
o
• Volvox carteri
o Motile & colonial
o Forms a hollow sphere known as a spheroid which is made of a single layer of 500-
600,000 individual cells
o
o Filamentous algae
▪ Single cells reproduce & join in long hair-like strands or colonies
▪ Oedogonium sp.
• Unbranched & filamentous
o
o Generally live in freshwater
▪ Few are terrestrial, living under snow
• Gree “o ourrig just elo the surfae uder tree aopies
o
find more resources at oneclass.com
find more resources at oneclass.com
BIOL 2P93 Spring Lecture 1: Chapter 15 Part 2 03/05/2018
• Chlamydomonas spp.
o
o Motile & unicellular freshwater algae
o Model system for molecular studies of genes regulating photosynthesis
o Morphology
▪ Propelled by 2 equally sized flagella
▪ Have a chloroplast w/
• photosensitive red eyespot or stigma which aids in light detection.
• Pyrenoid which is a protein body involved in starch synthesis & deposition surrounded
by a starch shell
▪ Uninucleate protoplast surrounded by think glyocproteinaceous (carb protein) cell wall,
inside which is the plasma membrane
▪ Cell wall has no cellulose
▪ At the anterior end of the cell
• 2 contractile vacuoles that function to collect excess water and discharge it from cell
▪ Internal morphology
•
o Asexual Reproduction
▪ Absorbs its flagellum
▪ Haploid nucleus undergoes mitosis 2-3 times
• Produces up to 16 haploid, identical, flagellated daughter cells (zoospores) w/n parental
cell wall
o Zoospore secretes enzyme breaking down parental wall -> allows them to escape
o Some fully formed zoospores are retained w/n parent cell wall for some time
find more resources at oneclass.com
find more resources at oneclass.com
