eukaryotic/prokaryotic cells

• What are the components of the nucleus?

  • Nuclear envelope
  • Nucleoplasm
  • Nucleolus
  • Nuclear pores
• What is the nuclear envelope?

  • A double membrane that surrounds the nucleus.
  • Its outer membrane is continuous with the endoplasmic reticulum.
  • Controls entry and exit of materials in and out of the nucleus and contains the reactions taking place in it.
• What is the nucleoplasm?

  The granular, jelly-like material that makes up the bulk of the nucleus
• What is the nucleolus?

  • a small, dense spherical region within the nucleoplasm.
  • Manufactures ribosomal RNA and assembles the ribosomes.
• What is the function of the nucleus?

  • acts as the control center of the cell through the production of tRNA and mRNA 
  • retains the genetic material of the cell in the form of DNA and chromosomes
  • contains the nucleolus which manufactures ribosomal RNA and ribosomes needed for protein synthesis
• What is the structure of the mitochondria?

  • Has a double membrane around the organelle that controls the entry and exit of material. The inner of the two membranes is folded to form the cristae
  • Cristae are extensions of the inner membrane, increases surface area for respiration and enzymes
  • The matrix contains enzymes involved in respiration
• What is the function of the mitochondria?

  • Site of aerobic respiration
  • Provides energy
  • Produces ATP
  • They are found in large numbers in cells that are very active and require a lot of energy.
• What is the structure of the chloroplast?

  • Contains chlorophyll 
  • It is surrounded by a double membrane, and has flattened sacs inside called thylakoids. They can be stacked to form grana.
  • Grana increases surface area for light absorption. Grana are linked together by lamellae.
  • Stroma is thick fluid found in chloroplasts and contains enzymes involved in photosynthesis
  • Contains starch granules as food storage
• What is the function of the chloroplast?

  • Absorbs light
  • Performs photosynthesis
  • Stores starch
  • Produces carbohydrates/lipids/proteins/sugars
• What is the structure of the endoplasmic reticulums?

  A system of membranes enclosing a fluid-filled space. The surface is either smooth or covered with ribosomes.
• What is the structure and functions of the RER (rough endoplasmic reticulum)?

  • Rough ER has ribosomes present on the outer surface of the membrane.
  • Folds and processes proteins that have been made at the ribosomes.
  • Does the transport of proteins around cell
  • Provides a large surface area for protein synthesis
• What are the functions of the RER?

  • Rough ER has ribosomes present on the outer surface of the membrane.
  • Provides a large surface area for protein synthesis
  • Folds and processes proteins that have been made at the ribosomes.
  • Transports proteins to golgi apparatus
• What are the functions of the SER?

  • Smooth ER has no ribosomes on its surface and is more tubular in appearance
  • Its functions are to synthesise and process lipids and carbohydrates
• What is the structure of the Golgi apparatus?

  The Golgi apparatus consists of flattened, membrane-bound sacs called cisternae.
• What are the functions of the Golgi apparatus?

  • Transport vesicles form at the ER and fuse with the Golgi apparatus.
  • The transport vesicles empty proteins and lipids into the lumen of the Golgi apparatus.
  • Golgi apparatus processes and packages lipids and proteins for transport.
  • It also makes lysosomes.
• What are Golgi vesicles?

  • A small fluid-filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus.
  • Seen in a high density near the edges of the sacs.
  • Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell (via the cell-surface membrane).  
• What are lysosymes?

  • Lysosomes are a special type of Golgi vesicle. They are sacs surrounded by membranes
  • They contain digestive enzymes called lysozymes.

   

  • Lysosomes store digestive enzymes to break down waste materials/break down old organelles/break down pathogens
• What are the structures and functions of the ribosome?

  Two types of ribosome:

  • 80S found in eukaryotic cells, 25 nanometers in diameter
  • 70S found in prokaryotic cells, mitochondria and chloroplasts
  • Ribosomes have two subunits one large and one small
  • Floats free in cytoplasm or attached to RER

  Functions of the ribosome:

  • Contains ribosomal RNA and protein
  • Site of protein synthesis 
• What are the structure and functions of vacuole?

  A membrane-bound organelle found in the cytoplasm. It contains cell sap. The surrounding membrane is called the tonoplast.

  
  

  Functions of the vacuole:

  Tonoplast helps to maintain pressure inside the cell and keep the cell rigid. This stops plants wilting.

  It's also involved in the isolation of unwanted chemicals inside the cell.

  The vacuole serves as a storage site for various substances, including water, ions, sugars, amino which acts as temporary food storage
• What are the structure and functions of the cell wall?

  • Consists of microfibrils of cellulose
  • Supports cell and prevents it from changing shape
• What are the structure and functions of the cell membrane?

  • Controls the exchange of substances between the internal cell environment and the external environment
  • The membrane is ‘partially permeable’
  • The cell membrane is formed from a phospholipid bilayer of phospholipids 
• What is the capsule/cell wall in a prokaryotic cell?

  • Cell wall, supports the cell and prevents it from changing shape. It’s made of a polymer called murein (a glycoprotein) so differs from cellulose plant cell wall.
  • Protects themselves with a layer of mucilaginous slime called a capsule protects the bacteria from drying out and from host immune system
• What is the plasmid/nucleoid in the prokaryotic cell?

  • The genetic material in bacteria is in the form of a circular strand of DNA(nucleiod). 
  • Plasmids are small circular pieces of DNA that can reproduce themselves independently and contain genes for things like antibiotic resistance, and can be passed between prokaryotes.
  • Plasmids are not always present in prokaryotic cells. Some prokaryotic cells have several.
• What are the flagellum/pili in prokarytoic cells?

  • Has one or more flagella which allows movement
  • Pili - used by cell to attach itself to surfaces