Animal cells

• EUKARYOTIC cells make up multicellular organisms such as plants and animals. They are complex cells with a nucleus and membrane-bound organelles.
• Nucleus

  • double membrane called the nuclear envelope
  • Nuclear envelope has holes called nuclear pores, which allows the passage of molecules such as mRNA, in and out of the nucleus. mRNA is needed to make proteins
  • Within the dense nucleolus, RNA and ribosomes are made
  • also contains chromatin which is made of DNA coiled around proteins called histones.
• Mitochondrion

  • site of ATP production by aerobic respiration
  • ATP releases energy for cellular and metabolic reactions
  • have double membrane, inner is highly folded to form cristae to increase surface area for the attachment enzymes such as ATP synthase
  • mixtrix - chemical reactions take place in the fluid filled space
• three parent baby

  • mother - nucleus
  • donor - mitochondria
  • father - nucleus/sperm
• rough endoplasmic reticulum

  • 80S Ribosomes site of protein (polypeptide) synthesis
  • Proteins for secretion outside the cell are transported inside the cisternae (flattened sacs)
  • RER synthesises AND transports proteins throughout the cell.
  • In the RER proteins are packaged into vesicles ready for transport
• smooth endoplasmic reticulum

  • Responsible for the synthesis and transport of lipids
  • no ribosomes
• 80s ribosomes

  • Tiny organelles attached to the RER or free floating in the cell.
  • They are the site of protein synthesis (linking together amino acids)
  • Made up of 2 rRNA proteins subunits (made in the nucleolus).
• Golgi apparatus

  • The Golgi apparatus sorts and modifies proteins (and lipids), then packages these into vesicles to be transported.
  • Golgi vesicles are also used to form lysosomes
• Lysosomes

  • Small spherical membrane bound sacs containing hydrolytic enzymes.
  • These enzymes digest pathogens (e.g., bacteria) AND breakdown waste materials including worn out organelles
• Secretion of proteins by exocytosis

  • DNA in nucleus contains genetic code to make proteins
  • New protein is synthesised on ribosomes
  • Protein is transported through rough ER
  • Vesicles pinched off from the rough ER (with polypeptide chains inside) are transported to the Golgi apparatus
  • Vesicle fuses with Golgi membrane and contents are shed into Golgi sacs
  • Proteins are built into more complex molecules such as enzymes or glycoproteins
  • Vesicles containing modified proteins (for secretion or cell membrane) bud off at the other end of the Golgi
  • Vesicles fuse with cell membrane
• Secretion of proteins by exocytosis pt2

  • protein released by exocytosis
  • Lysosomes (contain digestive enzymes
• Centrioles

  • These fibres pull the chromosomes apart during cell division (known as mitosis).
  • These organelles are not found in plant cells.
• Plasma membrane

  • Composed of a phosholipid bilayer, with proteins and other biological molecules embedded in the layer.
  • The membrane is selectively permeable and therefore regulates which molecules can be transported in and out of the cell.
  • Separates cell contents from the outside environment.
• Cytoplasm

  • where metabolic reactions occur