L.1 H.Biology (T) ”Virology - Algae” Dr.Riad (1).pdf

Albayan University ‫ﺗﺤﻠﯿﻼت‬ H. Biology 1st year 14th & 151th lec. F2 Dr. Riad 2020-2021 1-6-2021 2023-2024 Virology Algae  ALGAE INTRODUCTION TO ALGAE  Algae are a diverse group of aqua...

Albayan University ‫ﺗﺤﻠﯿﻼت‬ H. Biology 1st year 14th & 151th lec. F2 Dr. Riad 2020-2021 1-6-2021 2023-2024 Virology Algae  ALGAE INTRODUCTION TO ALGAE  Algae are a diverse group of aquatic organisms that have the ability to conduct photosynthesis. Certain algae are familiar to most people; for instance, seaweeds (such as kelp or phytoplankton), pond scum or the algal blooms in lakes.  The term "algae" covers many different organisms capable of producingoxygen through photosynthesis which is the process of harvesting light energy from the sun to generate carbohydrates.  Algae lack true roots, stems and leaves, and a vascular system to circulate water and nutrients throughout their bodies. Second, many algae are unicellular.  They also occur in a variety of forms and sizes. They can exist as single, microscopic cells; they can be macroscopic and multicellular; live in colonies; or take on a leafy appearance as in the case of seaweeds such as giant kelp and algae are found in a range of aquatic habitats, both freshwater and saltwater.  All types of algae are eukaryotes except prokaryotic organisms — cyanobacteria, also known as blue-green algae which classified as algae but they are prokaryotes not eukaryotes.  cyanobacteria are gram-negative bacteria General characteristics  The majority of algae lives in aquatic habitats and can thrive in freshwater lakes or in saltwater oceans. They can also endure a range of temperatures, oxygen or carbon dioxide concentrations, acidity and turbidity. For example, giant kelp are found more than 200 meters below the polar ice sheets ," while the unicellular green algal species Dunaliella salina is found in very salty, or hypersaline, environments such as the Dead Sea.  Free-floating, mostly unicellular algae that live within illuminated regions of water are known as planktonic.  Also able to survive on land. Some unexpected places where they grow are tree trunks, animal fur, snow banks, hot springs.  they can also form symbiotic relationships with a variety of non-photosynthetic organisms including ciliates, sponges, mollusks and fungi (as lichens). Nutrition  As a general rule, algae are capable of photosynthesis and produce their own nourishment by using light energy from the sun and carbon dioxide in order to generate carbohydrates and oxygen. so algae are autotrophs or more specifically, photoautotrophs, while others are heterotrophic which apply a variety of heterotrophic strategies to acquire nutrients from organic materials. Reproduction  Algae are capable of reproducing through asexual or vegetative methods and via sexual reproduction.  In asexual reproduction involves the production of a motile spore, while vegetative methods include simple cell division by mitosis to produce identical offspring and the fragmentation of a colony but in Sexual reproduction involves the union of gametes by meiosis. Importance  Most important contribution of algae to our environment and well-being is the generation of oxygen through photosynthesis.  Algal biofuels are a promising replacement for fossil fuels. All algae have the ability to produce energy-rich oils and several microalgal species naturally accumulate high levels of oil in their dry mass. Algal blooms  Algae, in the form of algal blooms, get a bad rap for creating toxic conditions in oceans and lakes. "Algal blooms" refers to the rampant growth of certain microalgae, which in turn leads to the production of toxins, disruption of the natural aquatic ecosystems and increases the costs of water treatments.  the main toxin producers in oceans are certain dinoflagellates and diatoms.  In freshwaters, cyanobacteria are the main toxin producers.  main cause of algal blooms is a phenomenon called nutrient pollution. With nutrient pollution, there is an excess of nitrogen and phosphorus, which can reduce algeal growth so this lead to produce the toxins. This due to a variety of human activities such as fertilizers used in agriculture and animal manures which rich in nitrogen. THANK YOU