Chapter 5: Cell structure

Function of nucleus

• Contain hereditary material (DNA)

• Control cell activities by regulating protein synthesis

• Contain enzymes for DNA replication, transcription and RNA processing

Function of nucleolus

• Synthesise rRNA

• Site of assembly of rRNA and proteins to form large and small ribosomal subunits

Function of rough endoplasmic reticulum

• Synthesise polypeptides at ribosomes which are transported to Golgi apparatus by transport vesicles

• Allow polypeptides to fold into native 3D conformation in cisternal space

• Glycosylate proteins into glycoproteins

Function of smooth endoplasmic reticulum

• Synthesise lipids and carbohydrates

• Detoxify drugs and poisons

Function of Golgi apparatus

• Glycosylate proteins and lipids into glycoproteins and glycolipids

• Modify existing glycoproteins and glycolipids by modifying sugar chains

• Sorts and package proteins into vesicles, target vesicles to other parts of the cell or for secretion out of cell

• Form lysosomes

• Synthesise polysaccharides eg. Pectin

Function of lysosomes

• contain hydrolysis enzymes which digest material taken in by the cell via endocytosis

• Digest unwanted or worn-out organelles (autophagy)

Function of mitochondria

• Site of certain parts of aerobic respiration to generate energy in the form of ATP

• Inner mitochondrial membrane is highly folded, increase surface area for oxidative phosphorylation

• Mitochondrial matrix is the site of link reaction and Kreb’s cycle

Function of chloroplasts

• Contain chlorophyll which convert light energy to chemical energy by photosynthesis

• Light-dependent reactions occur in membrane of thylakoid

• Light independent reactions occur in stroma