Cells

• What is the structure of the plasma membrane and what is it composed of?

  Phospholipid bilayer -hydrophilic phosphate heads point outwards and hydrophobic lipid tails point inwards
• Structure and function of nucleus

  Double membrane perforated by nuclear pores - mRNA leaves

  Chromatin wounds around histones

  Site of transcription to produce polypeptides
• What is the name of the double membrane that surrounds the nucleus?

  The nuclear envelope
• Why is the nuclear envelope perforated with nuclear pores?

  To allow substances like rRNA to exit into the cytoplasm
• How is DNA arranged in the nucleus of eukaryotic cells?

  Linear, wrapped around histone proteins, arranged in chromosomes
• Where is rRNA located in the nucleus?

  The nucleolus
• What is the inner most part of the mitochondria called?

  The matrix
• What are the folds of the inner membrane in the mitochondria called?

  The cristae
• What are grana composed of?

  Thylakoids stacked on top of each other
• What is the fluid in chloroplasts called?

  Stroma
• What pigment do thylakoids contain?

  Chlorophyll-a and other photosynthetic pigment
• What is the Golgi apparatus composed of?

  Cisternae, fluid-filled membranes
• What is the function of the Golgi apparatus?

  -Modifies and packages molecules such as lipids and proteins

  -Secondary function = lysosome production
• How do substances enter and exit the Golgi apparatus?

  Via Golgi vesicles
• What are lysosomes?


  Vesicles that contain lysozymes/ hydrolytic enzymes
• What is the difference between the RER and the SER?

  RER - Covered in ribosomes whereas SER isn't
• What are the RER and SER made of?


  Fluid-filled membranes called cisternae
• What is the role of the RER and SER?

  RER - Synthesis of proteins

  SER - Synthesis of lipids
• Why do complex multicellular organisms require specialised cells?

  Most of their cells aren't in direct contact with the environment
• What is the membrane of a vacuole called?

  The tonoplast
• What does the vacuole contain?

  Cell sap
• What are the functions of the vacuole?

  Maintains cell rigidity and sequesters cellular waste
• What is the cell wall made from in plants?

  Cellulose
• What is the cell wall made of in fungi?

  Chitin
• What type of DNA do prokaryotes have?

  Circular DNA that floats freely in the cytoplasm
• What are cell walls made from in prokaryotes?

  Murein
• What surrounds prokaryotic cells?

  A waxy capsule
• How do prokaryotic cells replicate?

  Binary fission
• What is a tissue?

  A group of cells that act together to perform a specific function
• What is an organ?

  A group of different tissues that work together to perform a specific function
• What is an organ system?

  A number of organs working together to carry out an overall function
• What are the three different tissue arrangements?

  Single, stratified, psuedostratified
• What is a viral genome?

  The viruses DNA or RNA
• What is the name of the protein coat around a virus?

  A capsid
• Why are viruses acellular?


  Because they aren't considered to be alive
• What is the name of a virus free in its environment?

  A virion
• What is the equation for magnification?

  magnification = image size/actual size
• how to calibrate an eyepiece graticule?

  use a stage micrometer and align it with the eyepiece graticule.

  then, calculate the length of each subdivision as being 1 nanometer
• Name the three stages of cell fractionation

  Homogenisation, filtration, ultracentrifugation
• Explain how a specific organelle type can be extracted via cell fractionation

  - Put sample in a blender (homogenisation) to break open the plasma membrane and release the organelles

  - Pass through gauze to filter

  - Add ice cold, isotonic, buffered solution to the sample

  - Spin in a centrifuge to form a pellet, formed from the heaviest organelles present, and a supernatant

  - Pour off supernatant and spin at a higher speed