Eukaryotic cell structure and function (animals)

organelles and their function in animals

plasma membrane

• controls movement of molecules into and out of the cell

• cell signalling and adhesion

• phospholipid bilayer

• separates cell from external environment

mitochondria

• generates ATP (through oxidation of glucose/fatty acids)

• has own genome

• double membrane

  • outer mitochondrial membrane = very permeable

  • inner mitochondria membrane = highly specific, 80% protein, cristae, ETC

lysosymes (ONLY ANIMAL)

• group of enzymes that degrade material internalised by cell (e.g. old membranes)

• break down polymers into monomers that are reused

• examples: nucleases, protesases, phosphatases

• acidic conditions (lysosomal membrane pumps H+ into lumen)

nuclear envelope

• encloses content of nucleus

• inner membrane: defines nucleus

• outer membrane: continuous with RER

• nuclear pores

nucleolus

• subcompartment where rRNA is synthesised

nucleus

• contains DNA (organised as chromatins)

• site of mRNA and RNA synthesis

smooth endoplasmic reticulum (SER)

• contains enzymes that synthesise lipids

• Ca²⁺ storage

rough endoplasmic reticulum (RER)

• synthesis and processing of proteins

• cystolic side: ribosomes attached

• proteins to be secreted accumulate in lumen

• has cisternae to increase SA for ribosomes

golgi complex

• processes and sorts proteins

• proteins undergo series of enzyme-catalysed chemical modifications essential for protein function

• proteins transported out by vesicles

secretory vesicles

• store secreted proteins

• fuse with plasma membrane to release contents

peroxisomes

• enzymes that oxidise fatty acids into smaller molecules

• detoxify some molecules

• form hydrogen peroxide H₂O₂

  • catalase degrades H₂O₂ into water and oxygen

cytoskeleton

• fibres that form bundles and networks that support cellular structures and help in cell movement

• classes of fibres: microtubules, microfilaments, intermediate filaments

• important in cell division

microvilli

• increase surface area for absorption