2.4 eukaryotic cell structure Flashcards
What is metabolism?
Involved both the synthesis and the breaking down of molecules.
What do chemical reactions in cells require?
Enzymes and specific reaction conditions
What does the nucleus do?
Contains coded genetic information in the form of DNA molecules. DNA directs the synthesis of all proteins required by the cell. So the DNA controls the metabolic activities of the cell, as many of these proteins are the enzymes necessary for metabolism to take place.
Size of nucleus
Often the biggest single organelle in the cell
Structure of the nucleus
DNA is contained within a double membrane called the nuclear envelope to protect it from damage in the cytoplasm. The nuclear envelope contains nuclear pores that allow molecules to move into and out of the nucleus (e.g. smaller RNA molecules).
What is chromatin?
DNA associates with proteins called histones to form a complex called chromatin. Chromatin coils and condenses to form structures known as chromosomes. These only become visible when cells are preparing to divide.
What is the nucleolus?
An area within the nucleus + is responsible for producing ribosomes. Composed of proteins and RNA. RNA is used to produce ribosomal RNA (rRNA) which is then combined with proteins to form the ribosomes necessary for protein synthesis.
What are mitochondria?
The site of the final stages of cellular respiration, where the energy stored in the bonds complex, organic molecules is made available for the cell to use by the production of ATP.
Correlation between mitochondria and energy
The more numbers of mitochondria in a cell, the more energy it is likely to use so is more active.
Structure of mitochondria
Mitochondria have a double membrane. Inner membrane is highly folded to form structures called cristae + the fluid interior is called the matrix. The membrane forming the cristae contains enzymes used in aerobic respiration.
What else do mitochondria contain?
A small amount of DNA called mitochondrial (mt) DNA. Mitochondria can produce their own enzymes and reproduce themselves.
What are vesicles?
Membranous sacs that have storage and transparent roles. They consist simply of a single membrane with fluid inside. Vesicles are used to transport materials inside the cell.
What are lysosomes?
Specialised forms of vesicles that contain hydrologic enzymes.
What is the role of lysosomes?
Responsible for breaking down waste material in cells, including old organelles. Important to the immune system as they break down pathogens ingested by phagocytic cells. Also play a role in programmed cell death or apoptosis.
What is the cytoskeleton?
A network of fibres necessary for the shape and stability of a cell. Organelles are held in place by the cytoskeleton + it controls cell movement + the movement of organelles within cells.
