3.4 - Eukaryotic cell structure

• what are the 3 functions of the nucleus ?

  make rRNA and ribosomes, retains DNA and chromosomes, produce mRNA and tRNA for protein synthesis
• what's the nuclear envelope and its function ?

  a double membrane surrounding the nucleus, controls entry and exit of materials and contains reactions occurring in the nucleus
• what does the nuclear envelope have to control exit and entry ?

  nuclear pores which control substance exit and entry
• what makes up the bulk of the nucleus and what's its function ?

  nucleoplasm, contains chromatins wound around a group of proteins called histomes
• what do chromosomes consist of ?

  protein-bound, linear DNA
• what's the function of a nucleolus ?


  manufactures rRNA and assembles ribosomes
• true or false - there can only be 1 nucleolus in a nucleus ?

  false, there can be many nucleoli in a nucleus
• why can't DNA leave the nucleus ?

  the molecule is too large to fit through the nuclear pores
• why is it an advantage that DNA can't leave the nucleus ?

  it would be at risk to damage or mutation, would also be inefficient to have the whole molecule leave every time protein synthesis occurred
• the function of mitochondria ?

  produce ATP therefore releasing energy via aerobic respiration
• what's the folded inner membrane of a mitochondrion called ?

  cristae
• what kind of membrane do mitochondria have ?

  a double membrane
• what's the function of the cristae ?

  they provide a large surface area for the attachment of enzymes/proteins involved in respiration
• what makes up the remainder of a mitochondrion ?

  the matrix
• what does the matrix contain and why ?

  lipids, proteins, ribosomes and DNA, meaning the mitochondrion can produce some of its own proteins/enzymes
• what is the chloroplast envelope ?


  a double membrane that's highly selective
• what is the name and function of the disks in a chloroplast ?

  thylakoids, they contain the photosynthetic pigment chlorophyll
• what is a stack of thylakoids known as ?

  a granum (plural is grana)
• what are grana connected by ?

  lamella
• what occurs in the grana ?


  the first stage of photosynthesis (light absorption)
• what's the jelly like substance in a chloroplast called and what's its function ?

  the stroma, the second stage of photosynthesis occurs here
• what other structure can be found in the stroma of a chloroplast ?

  starch grains
• 3 advantageous adaptations of chloroplasts ?

  granal membranes provide a large SA for the attachment of chlorophyll, electron carriers and enzymes, the stroma possesses enzymes needed to make sugars in the 2nd stage, chloroplasts contain DNA and ribosomes so they can make proteins for photosynthesis
• what is the ER continuous with ?

  it's continuous with the outer nuclear membrane
• what are the 2 types of ER ?


  smooth and rough
• what's the RER made of ?

  flattened sacs called cisternae
• what's the SER made of ?

  it consists of tubules
• what is the RER covered in ?

  ribosomes
• what's the 2 functions of the RER ?

  provide a large SA for protein synthesis and provides a pathway for the transport of materials throughout the cell
• what's the function of the SER ?

  the synthesis and transport of lipids and carbohydrates
• what are the disks called that make up a golgi apparatus ?

  cisternae
• what containers does the golgi apparatus make and contain ?

  vesicles
• how does the golgi modify proteins ?

  adds carbohydrates to them to form glycoprotein
• what 2 things do golgi apparatus make ?

  secretory enzymes and carbohydrates
• what does the golgi apparatus transport, modify and store ?

  lipids and proteins
• where are lysosomes produced ?

  the golgi apparatus
• what are lysosomes ?

  when vesicles made by the golgi apparatus contain protease and lipase enzymes
• what do lysozymes do and where can they be found ?

  they are found in lysosomes and they're enzymes that hydrolyse bacteria
• what are the 2 ways in which lysosomes can release their enzymes ?

  to the outside of the cell (exocytosis) or into a phagocytic vesicle in the cell
• what are the 4 functions of lysosomes ?


  digesting worn out organelles, breaking down dead cells (autolysis), destroy material around the cell (exocytosis), hydrolyse material ingested by phagocytic cells