Anatomy of a cell

• What is a cell?


  Basic unit of life

  Smallest part of organism that retains characteristics of entire organism
• What is the cellular level of an organism?


  Where metabolic processes occur that keep organism alive
• What are prokaryotes?


  Simplest forms of cells (archaea & bacteria)

  Usually live as single cells gathered into masses or colonies

  DNA free floating in cytoplasm

  Each cell contains everything needed to function independently
• What are eukaryotes?


  More complex (animals & plants)

  DNA bound inside nucleus

  Cytoplasm contains organelles

  Often a multicellular unit
• Components of animal cells:

  • Plasma membrane forming outer boundary of cell
  • Nucleus
  • Cytoplasm (gel-like liquid & cellular material between membrane & nucleus)
• What is the cytoplasm composed of?


  Cytosol & organelles
• What are organelles?


  Specialised structures within the cell that perform specific functions
• What is cytosol?


  Fluid part of cytoplasm containing:

  Proteins & dissolved substances e.g, ions

  cytoskeleton

  cytoplasmic inclusions e.g, lipid droplets or pigments (e.g, melanin)
• Cytoskeleton function:

  Supports cell & holds nucleus & other organelles in place.

  Consists of 3 groups of proteins: microtubules, microfilament & intermediate filament
• Mitochondria function:

  Provides energy for cell (ATP)

  cellular respiration
• Mitochondria structure:


  Bounded by 2 membranes (smooth outer & an inner which is thrown into folds called Cristae to increase S.A)

  Inside mitochondrion is matrix (includes enzymes & DNA)

  
• How are mitochondria semi-autonomous?


  Can move within cell, divide & fuse (without using normal cell division)
• What does the plasma membrane do?

  • Cover cell surface & separates it from its environment
  • Controls passage of substances in & out cell
  • Has cell adhesion molecules (CAMs) to attach cells to eachother
• What do carbohydrates on the plasma membrane do?

  Help cell recognition (cell recognises if it's in contact with another cell of same type)
• What is the cytoplasm?


  Fluid filling interior of cell

  Provides support & organelles & solutes

  e.g, glucose, proteins, ions
• What is the Golgi apparatus?


  • Stack of flattened sacs in cytoplasm (contain cisternae)
  • Modifies proteins & lipids (adds carb component) from ER & packages them into vesicles which are distributed to locations
  • Plays part in lysosome formation
• What is the endoplasmic reticulum?


  Network of membrane-lined interconnected sacs, tubules & cavities in cell cytoplasm

  broad & flattened (interior= cisterns)

  2 types: Rough & smooth
• Rough endoplasmic reticulum:


  • Ribosomes on surface
  • Transports proteins that have been synthesised by ribosomes
• Smooth endoplasmic reticulum:


  • No ribosomes on surface
  • Synthesis & transport of lipids & steroids