Cells

what is the structure of the nucleus

• surrounded by a double membrane (nuclear membrane) which is perforated by nuclear pores

• inside membrane is nucleolus and chromatin

what is chromatin

DNA and histone proteins

what happens to chromatin during cell division

chromatin condenses to form chromosomes

what is the function of the nucleus (4)

• site of ribosome production- in nucleolus

• holds genetic information for production of polypeptides

• site of DNA replication

• site of transcription

which 2 parts make up the mitochondria

matrix and cristae

what is the structure of a mitochondria

• double membrane bound

  • outer membrane- controls movement of substances in and out of mitochondria

  • inner membrane is folded into cristae, increases inner SA and has enzymes involved in aerobic respiration attached to surface

  • in inner membrane is liquid matrix containing DNA & ribosomes- synthesise own proteins

what is the function of a mitochondria

site of aerobic respiration and ATP production

what is ATP

source of energy for metabolic reactions

define eukaryotic cell

• contains a nucleus

• contains membrane bound organelles

what is the role of an epithelial cell and how is it adapted to its function

1. absorption and secretion in digestive system

   • cell membrane is folded into microvilli to increase SA for absorption

what does ATP consist of

• nitrogenous organic base

• three phosphate groups

• ribose sugar

what is the structure of endoplasmic reticulum

• a system of membranes found throughout the cell forming a cytoplasmic skeleton

• continuous with the nuclear membrane, membrane system forms a series of encloses flattened sacs called cisternae

what does the ER provide

a pathway for the transport of materials throughout the cell

what is the structure of rough endoplasmic reticulum

1. flattened membrane sacs called cisternae with ribosomes attached

what is the function of rough endoplasmic reticulum

1. ribosomes synthesis proteins

2. cisternae transport proteins throughout cell

why would a cell have lots of RER

if it makes a lot of protein i.e. secrete enzymes or antibodies

what is the structure of smooth endoplasmic reticulum

• flattened membrane sacs called cisternae

• no ribosomes

what is the function of smooth endoplasmic reticulum

produce lipids and transport them through the cell

what is the structure of ribosomes

• small structure found in all cells

• made of 2 sub units

• no membrane

• 2 types- 80s in eukaryotes and 70s in prokaryotes

what is the function of ribosomes

• site of protein synthesis

what us the structure of Golgi apparatus

• stacks of flattened sacs of membrane (cisternae) with transport vesicles that pinch off from the edges

• only one Golgi body in each cell

what is the function of the Golgi body

• receives and modifies proteins from the RER to make them functional

• e.g. add carb chain to make glycoproteins

• then packages them into vesicles fro transport

• transports functional protein to where its needed

what might Golgi vesicles form

lysosomes- which contain digestive enzymes

what is the structure of lysosomes

• bound by a single membrane

• no internal structure

• contain large number of enzymes- lysozymes in an acid solution, which must be kept separate from the rest of the cell contents to avoid damage

what is the function of lysosomes

used to breakdown (hydrolyse) unwanted structures within cell

give an example of a cell which contains many lysosomes

phagocytes- hydrolyse invading pathogens

what is the function of a cell membrane

• controls the passage of molecules into and out of the cell

what is the structure of the cell membrane

• made up of phospholipids, proteins and carbohydrates arranged into a fluid mosaic

what is the structure of microvilli

• finger like projections of a folded cell membrane

what is the function