2.4 - Eukaryotic Cell Structure Flashcards Preview

OCR A Biology A Level - Chapter 2 > 2.4 - Eukaryotic Cell Structure > Flashcards

Flashcards in 2.4 - Eukaryotic Cell Structure Deck (16)
Loading flashcards...

What are the functions and features of the nucleus?

  • Contains DNA which directs protein synthesis
  • Controls cell activites such as metabolism 
  • Largest organelle


What are the features & functions of the nuclear envelope?

  • Separates genetic material from cytoplasm - protecting from damage
  • Has nuclear pores allowing mRNA from nucleus to ribosomes


What are the features and functions of the nucleolus?

  • Situated inside the nucleus
  • Produces ribosomes 
    • Has proteins and RNA


Give the structure & function of mitochondria

  • Outer mitochondrial space: separates mitochondria contents from rest of cell, compartmentalising for aerobic respiration
  • Matrix: Contains enzymes for Krebs cycle and link reaction – also has mtDNA
  • Intermembrane space: Proteins pumped into this space by ETC. Conc. of the proteins builds up quickly due to its size
  • Inner mitochondrial membrane: Has ETC and ATP synthase
  • Cristae: Projections of inner membrane – increase the SA for oxidative phosphorylation


What are vesicles?

What are lysosomes?


Membranous sacs that store and transport substances inside a cell


Specialised vesicles with hydrolytic enzymes to break down pathogens and dead cell contents (old organelles)


What are the components of the cytoskeleton and what is the role of the cytoskeleton?

  • Role in giving mechanical/structural support, enables organelle and whole cell movement
  • Comprised of microfilaments, microtubules intermediate fibres


Describe the role and structure of microfilaments, microtubules & intermediate fibres

Micorfilaments: Has actin (contracticle protein) which is responsible for cell movement and cell contraction in cytokinesis (making 2 daughter cells)

Microtubules: Globular tubuiln polymerises to give a scaffold-like structure to create cell shape

  • Have role in moving organelles, vesicles and spindle fibres

Intermediate Fibres: Give mechanical strength



What is the role and structure of centrioles?

  • Composed of microtubules
  • 2 centromeres is a centrosome
    • Involved in spindle fibre organisation
  • Have role in positioning cilia & flagella


What is the role of flagella?

  • Whip-like extension from cells
  • Longer than cilia but flagella are fewer in number
  • Enables cells motility (ability for a cell to independantly move)
  • Sensory organ - detecs chemical changes in cell


Give the structure and function of cilia.

  • Stationary cilia act as sensory organelles in sensory organs (e.g. nose)
  • Mobile cilia beat to cause fluids or objects adjacent to the cell to move
    • E.g. mucus in trachea
    • E.g. egg cell in falopian tube, from ovary to uterus


Describe the structure of cilia.

  • Has 2 central microtubules
  • 9 pairs of surrounding microtubules arranged in a wheel
    • Known as 9+2 arrangement
      • Pairs of microtubules slide over one another to cause cilia movement


What are the protein synthesis organelles?

ER (rough and smooth)


Golgi apparatus



What are the 2 types of ER and their functions?

What is the structure of endoplasmic reticulum?

Smooth ER: Lipid and CHO synthesis and storage

Rough ER: Ribosomes bound to surface for synthesis and transport of proteins

  • Network of flattened sacs called cisternae - connected to outer surface of nucleus


What are the features of ribosomes?

  • Site of protein synthesis
  • Can be free-floating or attached to ER (making it rough ER)
  • Made of RNA from the nucleolus


What are the features of the Golgi Apparatus?

  • Formed of cisternae 
  • Role in modifying proteins made in ribosomes - often adds CHO group
  • Repackages proteins into vesicles to leave or stay in cell


Describe the transport and production of proteins.

  1. mRNA leaves nucleus via nuclear pores
  2. Used by ribosomes on ER to produce proteins
  3. Proteins travel in a vesicle to the GA via the cytoskeleton by travelling along the microtubules
  4. GA modifies and repackages the protein
  5. Vesicle fuses with plasma membrane to be secreted