Understanding Biological and Cell Life Cycles

Classified in Biology

Written on January 21, 2025 in English with a size of 3.82 KB

Biological Life Cycle: Different Stages in a Living Being

Any biological life cycle can be divided into three parts:

Early Stage: In most organisms, this begins with a single-cell stage.
Development: This is the stage at which changes in size occur, as well as the differentiation of internal structures. Development ends when the new body has reached the characteristics of an adult.
Reproduction: This is the phase in which organisms produce "breeding units" that will give rise to new individuals with the characteristics of the parent.

A set of phenomena of variable duration that occurs in the period that begins after cell division:

Interphase: The period between two consecutive divisions.
Division Phase: In which cell multiplication occurs, lasting between 5 and 10% of the cell cycle.

The offspring are genetically identical copies of their single parent.

The descendants have a new combination of characteristics that makes them unique genetically.

Somatic Line: Non-specialized cells in reproduction in multicellular organisms.
Germ Line: Specialized cells in reproduction. There are two types of germ cells:
- Gametes: In most cases, they need to join another gamete to form the egg cell or zygote.
- Spores: Develop directly and, without joining with others, originate a new individual.

Prophase: The nuclear envelope disassembles, and chromatin condenses, including the formation of the spindle by centrioles.
Metaphase: Chromatin condensation reaches its maximum; the chromosomes become visible and are replicated in two chromatids.
Anaphase: Microtubules shorten and pull each of the two chromatids in opposite directions.
Telophase: The chromatids, now considered chromosomes, are located at the poles and are enveloped by a nuclear membrane, and begin to decondense.

In Animals: A ring of contractile filaments forms that tapers to break into the center spindle.
In Plants: A phragmoplast is formed, which is a wall of vesicles derived from the Golgi apparatus.

Bipartition: Occurs in unicellular organisms (monerans and protoctists) in which the reproductive unit is the whole cell.
Budding: Can be considered a form of bipartition in unicellular organisms where the two daughter cells differ in size. In multicellular organisms, cells are separated from the parent body as a bud and occur in sponges and coelenterates.
Fragmentation: Spontaneous breakage of the parent body into two or more fragments, each of which gives rise to a complete individual.
Regeneration: The process by which some multicellular organisms are able to rejoin parts, such as starfish and crabs.
Sporulation: Subsequent divisions of the mother cell nucleus; each daughter nucleus is surrounded by a small quantity of cytoplasm and is isolated by a diaphragm on the inside of the stem cell.

Isogamy: The two types of gametes are morphologically similar but have different behaviors; occurs in protoctists.
Anisogamy: Consists of a female gamete (normally immobile) and a male gamete (mobile).
Gonads: Specialized organs for gamete production in animals.

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