GROUP 7GROUP MEMBERS

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CONTENT

INTRODUCTIONCLASSIFICATIONSTRUCTURAL COMPLEXISITYREPRODUCTION

INTRODUCTION 680 generas 4000-6000 species Habitats:-

• In marine• In tropical• In warm water• In cooler regions• In fresh water

Eukaryotic

Nutrition mode• Autotrophic

Cell organizationUnicellular - CyanidiumMulticellular - Polysiphonia , Laurencia , Geledium

• Thalliopenly branching filamentsFleshy and foliose erect thalliEncrusting thalli (calcarious forms )

thallus

Crystal structure of Cyanidium

Geledium

CLASSIFICATION

KINGDOM- PROTISTA

DIVISION-RHODOPHYTA

CLASS-RHODOPHYCEAE

ORDER ORDER ORDER ORDER ORDER Nemalionales Cereniales Gelediales Cryptonemales Gigantinales

GENUS GENUS GENUS GENUS GENUSBatrachospermum Polysiphonia Geledium Jania Gracillaria

STRUCTURE

Cell wall• Rigid

• Inner componentCelluloseAnother polysaccharide

•Outer mucilaginous layerSulfated polymer of galactose – agar or carrageenan

•Some deposit calcium carbonate - family –

Corallinaceae (Coralline algae)

Cell structure

Absence of flagella and centrioles

Floridean starch as a storage product

Chloroplast• unstacked plastids in thylakoids•PigmentChlorophyll a,phycoerithrin,phycocyanin allophycocyaninpresence of the phycobilin or phycoerithin

STRUCTURAL COMPLEXISITY OF Gracillaria

From of thalli•Often fleshy thalli•Cylindrical or terete•Compressed or flattened•Foliose

Branching•Alternate•Di or trichotomous•Secund•Irregular

Constriction of branches • frequently Gracilaria shows a constriction at the point where a lateral branch joins a main axis.

Branch apex•Attenuate•Rostrate•Tapering•Apiculate•Obtuse•Blunt

Types of spermatangial conceptacles•Chorda type-superficial•Textorii type-shallow cavity•Verrucose type-deep pot like cavity•Polycavernosa type-compound verrucosa type

Characteristics of cystocarps•Form•Basal constriction•With or without rostum

Anatomy of cystocarp•Pericarp•Gonimoblast cells•Carposporangia•Absorbing filament

Types of cystocarps

Order – Nemalionales

Filamentous or uniaxial multicellularStem like thalli often dichotomously branched and gelatinous in texture

Batrachospermum

Order – Cereniales

SlenderFilamentous or uniaxial bush like plantsMore complex reproductive structure is characteristic of this order

Polysiphonia

Order- Gelediales

Thalli is cylindrical and wiry or flattened Usually pinnately branched Usually pseudo-parenchymatous

Order - Cryptonemales

Plants formDichotomously branched structureGrowing in tangledSmall clumpsBranches composed of rigidCylindrical segments with flexible joints

Order- Gigantinales

Crustose to fruticoseFoliose types with thin, broad fronds fruticose types with flattened Usually dichotomously branched Often fleshy thalliTissues as in cryptonemiales

REPRODUCTION OF

RHODOPHYTA

REPRODUCTION

SEXUAL REPRODUCTION ASEXUAL REPRODUCTION

ASEXUAL REPRODUCTION

Discharging Spores – monosporesIf condition are suitable monospores may attach to a substrate. By mitosis they produce new seaweeds.

Sexual reproductionWidely among the multicellular red algae.Alternation of generation.

Life Cycle of Polysiphonia

Isomorphic

Gametophytes:-•heterothallic•male gametophytes•female gametophytes

Spermatia:-•unite with the tricohogyne

spermatangia

Zygote:-•oogamous•auxillary cell become zygote•grows in a carposporophyte

Carpospores:-•type of mitospores•produce by carposporophyte•settle out of water column•grow in to tetrasporophyte

carcosporangia

Tetrasporsphytes:-•Isomorphic to gametophyte•Produce tetrasporangia in which meiosis takes place

Tetraspores:-•produce by meiosis•shed to the water•settle out of the water column•grow up in to gametophytes

Tetrasporangia

Sexual Reproduction ofPolysiphonia

REPRODUCTON OF Gracillaria

Isomorphic generation Gamitophyte

• Male-spermatangia• Female-carpogonia• Fertilization structure-cystocarp

Cystocarp•Carposporangia-carpospores

Germinate to tetrasporophytesFormation of tetrasporangium-tetrasporesGerminate to new thalli

Sexual Reproduction ofGracillaria

Order-Nemalionales

Mostly haplonticUsually no auxiliary cellsNurse cells perform similar functionNurse cells and auxiliary cells form prior to fertilization

Sexual Reproduction ofBatrachospermum

Order-Gigantinales

Three phase diplohaplonticA vegetative cell serves as auxiliary cellDeveloping prior to fertilizationSecondary pit often elongated in to an ooblast

Order-Gelediales

Three phase diplohaploticNo auxiliary cells

Gellidium

Life Cycle of Gellidium

Order-Cryptonemales

Three phase-DiplohaplonticAuxiliary cell in special filament growing from a vegetative cellSecondary pits elongated to an ooblast forming prior to fertilization

Order-cerenialesSlenderFilamentous or unisexual bush like plants lacking clear cut differentiation of cortex and medulla tissuesSimpler anatomy accompanied by more complex reproductive structure is characteristic of this order

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