multicellular organisms Flashcards
Give the way cells organise into organisms.
Groups of the same specialised cell are organised into tissues, different tissues working together to perform a function are organised into organs, different organs working together to perform a function are organised into organ systems. All the organ systems together are an organism.
Explain why multicellular organisms need specialised cells.
Large, multicellular organisms have a small surface area:volume ratio, and internal cells have no contact with the external environment. Therefore cells need to be specialised to gather nutrients and excrete waste products.
. Describe and explain the organelles involved in the release of a protein from a cell.
The nucleus contains the DNA that is transcribed into mRNA. The mRNA travels out of a nuclear pore and is translated by a ribosome attached to endoplasmic reticulum, producing a protein. The protein is ‘pinched off’ the rER inside a vesicle, that travels to and fuses with the Golgi apparatus. The Golgi apparatus process and packages the protein into a vesicle, again this is ‘pinched off’ from the Golgi apparatus. The vesicle fuses with the cell surface membrane and the protein is released outside the cell.
Explain why a cell involved in secreting proteins would have large amounts of mitochondria and Golgi vesicles.
Many mitochondria release energy in the form of ATP for protein synthesis and the movement of vesicles. The many Golgi vesicles contain the protein to be released from the cell, and will travel to the cell membrane where they fuse with it to be released by exocytosis.
Glycoproteins are produced by cells. One is a polypeptide with lactose attached. Describe how lactose is formed and where it would be attached to the polypeptide to form a glycoprotein.
Glucose and galactose would undergo a condensation reaction to form a glycosidic bond joining the monosaccharides into lactose. Lactose would be added to the polypeptide at the Golgi apparatus.
