Fungi are microscopic/macroscopic eukaryotic and heterotrophic organisms exhibiting growth on various natural and synthetic substrates and are capable of continuing their function almost indefinitely. Unlike other microorganisms such as algae, fungi lack the chlorophyll necessary for photosynthesis and must therefore live as parasites or saprobes. About 80 000 to 1,20,000 …
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Fungi: Asexual Reproduction & Reproductive Structures
The fungi constitute a group of living organisms devoid of chlorophyll. They resemble simple plants in that, with few exceptions, they have definite cell walls, they are usually nonmotile, although they may have motile reproductive cells, and they reproduce by means of spores. A spore (Gr. spora = seed, spore) …
Read More »Pollination: Introduction, Types and Conditions
Pollination is a very significant process of reproduction in plants. Creating offspring for the next generation is one of the major goals of every organism. Plants are indifferent too. One of the ways that plants can produce offspring is by making seeds, i. e., by sexual reproduction. Seeds contain the …
Read More »Malthus’ Law & How It Catalyzed Darwin’s Thought
Five years with nature aboard, the Beagle destroyed Darwin’s faith in the fixity of species. In July, 1837, shortly after the voyage, he started his first notebook on “transmutation.” Already convinced that evolution had occurred, Darwin sought a theory to explain its mechanism. After much preliminary speculation and a few …
Read More »ATP Synthase: World’s Smallest Motor
Ever wondered that your very own body might contain a motor like the one we use to run any machine? And it is not just any motor, but a motor recorded to be the world’s smallest one. This motor is commonly known as ATP synthase. Every one of the 50 …
Read More »Endoplasmic Reticulum: Discovery, Structure, & Function
The ER is the most extended organelle in plenty of eukaryotic cells: on average it occupies 10% of the cellular volume (Eelco and Roberto, 2016). The endoplasmic reticulum (ER) is a large, continuous organelle that extends throughout the entire cell (Eelco and Roberto, 2016). The ER not only is the …
Read More »Restriction Enzymes: An Introduction to Biological Knives
The first step in sequencing a genome is to divide the individual chromosomes (in eukaryotes) or whole DNA (in prokaryotes) in an ordered manner into smaller and smaller pieces that ultimately can be sequenced. That is, one begins by creating a genomic library of fragmented DNA parts. However, at some …
Read More »Organization of Nuclear DNA in Eukaryotes
Each eukaryotic nucleus encloses a fixed number of chromosomes which contain the nuclear DNA. During most of a cell’s life, its chromosomes exist in a highly extended linear form. Prior to cell division, however, they condense into much more compact bodies which can be examined microscopically after staining. The duplication …
Read More »Genome Structure in Viruses & Prokaryotes
The genomes of viruses and prokaryotes are very simple structures, although those of viruses show remarkable diversity (for a review see Dimmock et al. 2001). Most viruses have a single linear or circular genome but a few, such as reoviruses, bacteriophage φ6 and some plant viruses, have segmented RNA genomes. …
Read More »DNA Reassociation Kinetics & Sequence Complexity
When double-stranded DNA in solution is heated, it denatures (‘melts’) releasing the complementary single strands. If the solution is cooled quickly the DNA remains in a single-stranded state. However, if the solution is cooled slowly reassociation/reannealing i. e. spontaneous realignment of two single DNA strands to re-form a DNA double …
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