organelles

• What is the nucleus?

  Sight of dna replication and transcription (making mrna) contains genetic code for each cell
• What is the nuclear envelope?

  Double membrane
• what is the nucleolus?

  smaller sphere inside nucleus. site of rRNA production and makes ribosomes
• what are nuclear pores?

  entry/exit points dotted around the nucleus.
• what is a mitochondria?

  description:usually oval shaped and have a double membrane. the inner one is folded to form cristae. inside is the matrix which contains enzymes used in respiration

  function:site of aerobic respiration that produces ATP ( common energy source in the cell) they are found in large numbers in cells. it has DNA to code for enzymes needed in respiration.
• what are ribosomes?

  description:small organelles that float freely in the cytoplasm or is connected to the rough endoplasmic reticulum. it is made up of 2 subunits: RNA 80s (found in eukaryotic cells (25nm)) and 70s (found in prokaryotic cells, mitochondria and chloroplasts) and proteins. it is not surrounded by membrane.

  function:site of protein synthesis
• what is the Golgi apparatus?

  description:a group of fluid filled membrane bound flattened sacs. vesicles are found at the edges

  function:processes and packages new lipids and proteins. it also makes lysosomes.
• what are the Golgi vesicles?

  description:small fluid filled sac in the cytoplasm surrounded by membrane and produces by the Golgi apparatus.

  function:stores products made by the apparatus and transports them out of the cell.
• what is the rough endoplasmic reticulum?

  description:a system of membranes enclosing a fluid filled space with ribosomes on the surface. it has folded membranes called cristae.

  function:folds and processes proteins that have been made at the ribosomes.
• what is the smooth endoplasmic reticulum?

  description:similar the RER but has no ribosomes

  function:synthesises and processes lipids
• what is a chloroplast?

  description:surrounded by a double membrane. they contain thylakoids(folded membranes embedded with pigments)it has a fluid filled stroma which contains enzymes for photosynthesis in plants

  function:site of photosynthesis
• what is a cell wall?

  description:in plants and algae it is made of cellulose but in fungi it is made of chitin.

  function:provides rigity and stability to the cell
• what is a vacuole?

  description:filled with fluid surrounded by a single membrane called tonoplast.

  function:temporary store of sugar and amino acids. makes cells turgid and provide support. contain chloroplast and so they may become coloured due to the pigments to attract pollinators
• what are lysosomes?

  description:bags of digestive enzymes

  function:hydrolyse phagocytic cells. completely breaks down dead cells. exocytosis-release enzymes to outside of cell to destroy material. digest worn out organelles to reuse materials