Is a written representation of something.
It keeps changing its shape because amoeba move around with pseudopodia (false feet) for taking food and to adapt to their environment.
Answer: The statement is true
Explanation:
Gene activation is one of the ways hormones exert their functions. And this require a second messenger system.
Usually, the hormone:
- binds to a specific receptor protein on the target cell
- the bound-complex causes the formation of second messengers such as cAMP (a cyclic nucleotide) that diffuses into the nucleus and binds directly with DNA, ACTIVATING GENE and switching "on" or "off" protein synthesis.
Answer:
Following are two characteristics of mitochondria and chloroplast that are similar to prokaryotic cells:
- Unlike other organelles, both chloroplasts and mitochondria have their own characteristic circular DNA
- Both mitochondria and chloroplasts possess their own ribosomes that have 50S and 30S sub-units like a prokaryote instead of 40 and 60S ribosomes found in eukaryotes.
Explanation:
Endosymbiotic Theory:
The endosymbiotic theory helps explain the origins of multi-cellular organisms. An endosymbiont is defined as an organism that lives inside another organism in a state of "endosynmbiosis." The theory states that some of cellular organelles were originally separate prokaryotic organisms engulfed by an amoeba like organism. These engulfed prokaryotes sustained inside the amoeba and evolved into present day mitochondria and chloroplasts.
- Mitochondria were formed by engulfing bacteria capable of aerobic respiration.
- Chloroplasts were formed when cyanobacteria or photosynthesizing bacteria were engulfed.
Apart from the aforementioned similarities, mitochondria and chloroplasts are roughly the same size as a prokaryotic cell and can self replicate by binary fission.