Cell structure

• In complex multicellular organisms, eukaryotic cells become specialised for specific functions. Specialised cells are organised into tissues, tissues into organs and into systems
• The mitochondira are responsible for aerobic respiration. They have 4 components.

  Cristae - Provide a larger surface area for attachment of enzymes & other proteins in respiration.

  Matrix - Contains proteins, lipids, ribosomes & DNA that allow mitochondria to control production of some their own proteins.

  Inner & Outer membrane - Form double membrane which controls entry & exit of material.
• The golgi apparatus:

  • Adds carbohydrates to proteins to form glycoprotein
  • Produces secretory enzymes & carbohydrates
  • Transports, modify & stores lipids
  • Forms lysosomes
  • Transport out cell (exotysis)
• The chloroplasts are responsible for photosynthesis. They contain 4 things:

  Thylakoids - Stacks of up to 100 disc-like structures which contain chlorophyll.

  Stroma - Fluid-filled matrix where 2nd stage of photosynthesis takes place.

  Chloroplast envelope(inner&outer) - Double plasma membrane, highly selective about what enters & leaves the cell.
• Cytoplasm is a gel-like liquid called cytosol which helps support the cell.
• Lysosomes do the following things:

  • Hydroylse material ingested by phagocyte cells
  • Release enzymes to the outside of the cells, to destroy material
  • Digest worn out organelles so that useful chemicals can be re-used
  • Completely break down cells after death (autolysis)
• The cell wall does the following things:

  • Allows water to pass along it
  • Provides strength to prevent cell from bursting
  • Has a thin layer called middle lamella
• Ribosomes are the site of protein synthesis. There are 2 types:

  • 80s - Eukaryotic
  • 70s - Prokaryotic
• There are two types of endoplasmic reticulum:

  • Rough ER - Provides large SA for synthesis of proteins and glycoproteins.
  • Smooth ER - Synthesise, store and transport lipids and carbohydrates.
• The nucleus is made up of 5 parts:

  Nuclear envelope - Double membrane that surronds the nucleus. Controls entry and exit of materials in and out nucleus.

  Nucleolus - Manufactures rRNA & assembles the ribosomes, could be more than 1 in the nucleus.

  Nucleoplasm - Granular, jelly-like material that makes up most of the nucleus.

  Nuclear pores - Allow the passage of large molecules out of the nucleus.

  Chromatin - Material that makes up chromosomes.
• The vacuole does these things:

  • Support herbaceous plants, by making cells turgid
  • Sugar & amino acids act as food stores
  • Pigment may attract pollinating insects
• Centrioles help chromosomes separate during cell divison.