2 - Cell structure + Microscopes

• What organelles are present in animal cells?

  • cell surface membrane
  • rough endoplasmic reticulum
  • smooth endoplasmic reticulum
  • ribosomes (70S)
  • nucleus (+nucleolus)
  • mitochondria
  • cytoplasm
  • golgi apparatus
  • lysosome
  • centrioles
  • cytoskeleton
• What is the structure + function of the nucleus?

  Large, surrounded by a nuclear envelope (double membrane containing nuclear pores), holds DNA in the form of chromatin (DNA associated w/ histones), contains a nucleolus which creates ribosomes.
• What is the structure and function of a lysosome?

  Structure: round + membrane-bound

  Function: contain hydrolytic / digestive enzymes for digesting pathogens
• Structure + function of a ribosome?

  Structure: small, may be attached to RER, made up of proteins + RNA - no membrane

  Function: protein synthesis (mRNA into polypeptides)
• What is the structure and function of the RER?

  Structure: fluid filled membranes w/ ribosomes

  Function: folds, processes + transports proteins made in ribosomes
• What is the structure + function of the SER?

  Structure: RER w/out ribosomes

  Function: synthesises + stores lipids + carbs
• Structure + function of a vesicle

  Structure: fluid-filled, membrane-bound sack

  Function: transport of substances in + out of cell - can be formed at ER or golgi, or cell surface
• Structure + function of golgi apparatus

  Structure: fluid-filled, membrane-bound, flattened sacs

  Function: package proteins + lipids into vesicles + make lysosomes
• Mitochondria structure + function

  Structure: double membrane (inner one folds, forming cristae), matrix (area inside membrane) contains enzymes for respiration

  Function: site of aerobic respiration (creates ATP)

  *there are lots in active cells to provide enough ATP
• Chloroplast structure + function

  Structure:

  • have a double membrane, which contains the fluid stroma
  • thylakoids stacked to form grana hold chloroplasts (high SA)
  • contain their own chloroplasts + ribosomes

  Function:

  • site of photosynthesis
• Centrioles structure + function

  Structure: hollow cylinders made of microtubules

  Function: produce spindle fibres for separation of chromosomes in cell division

  *found in all animal cells, but only some plant cells
• Cilia structure + function

  Structure:

  • hair-like
  • on the CSM of some animal cells
  • 9+2 formation of microtubules, to allow movement

  Function:

  • movement of substances around cell
• Flagellum structure + function

  Structure

  > longer that cilia

  > 9+2 formation of microtubules

  Function

  > move to propel cells (e.g. swimming sperm cell)
• What are the 3 different types of cytoskeleton + what do they do?

  > Microfilaments - contract, composed of actin (contract to divide cell in cytokinesis)

  > Microtubules - act as 'tracks' for subcellular structures to move along, scaffold-like (determines cell shape), create spindle

  > Intermediate fibres - give mechanical strength + maintain integrity
• What organelles are present in plant cells but NOT in animal cells?

  > chloroplasts

  > cellulose cell wall (containing plasmodesmata)

  > vacuole - contains cell sap + tonoplast pushes against cell wall to maintain turgor
• How are the organelles involved in protein synthesis + transport?

  1. ribosomes make proteins
  2. proteins are folded + processes in RER
  3. proteins then packaged into vesicles + go to golgi (enters through cis face)
  4. golgi structurally modifies proteins + packages them into vesicles + they leave through trans face
  5. secretory vesicles leave CSM through exocytosis
• What is the equation for maginification (+ define magnification)?

  $maginification=$$image size/real size$

  Magnification - how many times bigger the image of a specimen is compared to its real size