The endosymbiosis theory proposes that cyanobacteria may have evolved into the chloroplasts that exist in plant cells today (Gault and Marler, 2009)
Cyanobacteria don't have chloroplasts. Instead, the chlorophyll is stored in thylakoids in their cytoplasm.
Diazotrophs are able to conduct nitrogen fixation.
Cyanobacteria can convert inert, atmospheric nitrogen into an organic form (e.g. nitrate or ammonia) that other organisms, including plants, can use.
'True plants' are not able to do this. They can only use the organic form of nitrogen and have to rely man-made fertilisers or form a symbiotic relationship with diazotrophs (nitrogen-fixing bacteria).
The nitrogen cycle:
Nitrogen is cycled through an ecosystem by both plants and animals.
Decomposers break down dead organisms and their waste products to release ammonia in a process called ammonification.
Organisms called nitrifying bacteria convert this ammonia into nitrates in a process called nitrification.
These nitrates can be used by plants to make amino acids.
The process of converting nitrogen in the atmosphere to ammonia is called nitrogen fixation.
This process is carried out by bacteria that live in the soil and in plant roots.
Plants can absorb both ammonia and nitrates from the soil, but animals cannot.
Animals obtain nitrogen by eating plants and other organisms and then digesting the proteins they contain.
Nitrogen is needed for proteins and for DNA structures
Proteins are chains of amino acids, polymers, long chains of repeating units:
Nitrogen forms peptide bonds:
a compound consisting of two or more amino acids linked in a chain, the carboxyl group of each acid being joined to the amino group of the next by a bond of the type -OC-NH-.
And these peptide bonds form chain of amino acids:
Nucleic Bases are in DNA and RNA:
DNA is organized into a double helix:
DNA is bundled up into chromosomes:
RNA is half of the DNA strand:
RNA has Uracil instead of Thymine
RNA is read by ribosomes in DNA Translation to make proteins by linking amino acids to make chains of amino acids, polymers, also called polypeptides.
Genetic sequences in chromosomes are called genes
plural noun: genes
(in informal use) a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
"proteins coded directly by genes"
(in technical use) a distinct sequence of nucleotides forming part of a chromosome, the order of which determines the order of monomers in a polypeptide or nucleic acid molecule which a cell (or virus) may synthesize.
Chromosomes go through changes to create a variety of gametes
Crossing over occurs between prophase I and metaphase I of meiosis, some genes are swapped to create unique gametes.
A gamete is a mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
Gamete production is meiosis:
Life forms have gone from tiny archaea, to single celled prokaryotes, to complex multi-cellular organisms that have tissues that form organs.
Speciation is the forming of a whole new species.
Adaptation comes from changes in genetics that help the species survive.
New species may result from adaptation and niche filling.
To reduce competition creatures might engage in different behaviors, or eat different, things and eventually become a different species.
Animals that are able to survive are able to pass on their genes and their offspring are better able to survive.
Genes can affect color, shape, behavior, scent, and texture.
In evolutionary biology, adaptive radiation is the process of quick adaptation and change as members of a species find different niches and become separate species, this may happen when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.
Author: Jazmin Gannon
A place to grow