Bio

• what does MRSGREN stand for?

  Movement

  Respiration: energy production

  Sensitivity/ Stimulus: detecting and responding to changes

  Growth: the ability to make more cells

  Reproduction: the ability to pass on genetic info

  Excretion: remove of wastes

  Nutrition: take in and use appropriate nutrients
• Prokaryotic and Eukaryotic Common Features

  cell membrane, nucleic acids (DNA), proteins, ribosomes
• What doesn't a prokaryotic cell have?

  membrane-bound organelles, nucleus
• Prokaryotic vs Eukaryotic

  
• How many cells does a prokaryotic cell have?

  One (uni-cellular)
• What is the shape of chromosomes in a prokaryotic cell?

  A single large loop - circular chromosome (DNA found in a central region called nucleoid.)
• Prokaryotic cell features


  Ribosomes: in the cytoplasm

  Cell wall: rigid (made from peptidoglycan) - helps to provide an extra layer of protection to maintain shape and prevent dehydration

  Capsule: sticky, outermost layer of carbohydrates that help the cell to attach to surfaces in its environment

  Pili: hair like covering important for adhesion

  Flagellum: tail-like structure involved in sensitivity and movement

  Size: 0.1-5.0 micrometers
• Eukaryotic cell features


  - Nucleus

  - Liner DNA packaged into chromosomes (multiple chromosomes)

  - Membrane-bound organelles

  - Respiration occurs in cytoplasm and mitochondria

  - Photosynthesis occurs in chloroplast (plant cells)

  Plant cell = cell wall for structural support
• What is cell compartmentalization

  The way different parts of the cell are separated which helps to limit where certain processes can happen and what enters and leaves an area
• Nucleus


  - controls cell activity: determines which proteins are to be made via protein synthesis, and therefore determine the structure and function (enzymes) of the cells

  - stores genetic material (chromosomes)

  - double membrane

  channels called nuclear pores that help control what enters/exits the nucleus

  
• Nucleolous


  - region within the nucleus that is responsible for producing and assembling ribosomes

  
• Lysosome


  - Contain digestive enzymes to break down waster materials (catalase) which breaks down toxic hydrogen peroxide into water and oxygen.
• chloroplast


  *Type of plastid only found in plants and algae

  - Involved in synthesis and storage of food - carrying out photosynthesis (where photosynthesis takes place)

  
  

  - Double membrane organelle

  - a stack of membrane bound compartments called thylakoids - they provide a large surface area for chlorophyll to maximise the opportunity for the cell to capture light energy

  
• Mitochondria


  - Carries out the latest stages of respiration (plants and animals)

  
  

  - Double membrane

  - Inner membrane is folded into structures called cristae which provide a large surface area, allowing for an efficient synthesis of ATP (energy)

  
• Golgi Body


  - Involved in the process of packaging and secretion of proteins and lipid molecules

  - Substances secreted out of the cell are firstly packaged into vesicles, which then buds off from the Golgi body, then the vesicle moves to the cell membrane and fuses with it and then releases its contents into the extracellular environment - called exocytosis

  
• Ribosome


  - the site for protein synthesis

  
  

  - made of RNA and protein

  - reads the sequence of the messenger RNA (mRNA) and, using the genetic code, translates the sequence of RNA bases into a sequence of amino acids.

  
• Vaculoe


  - fluid filled spaces that are used in the control of water and salt balance

  
  

  Plant: large permanent vacuole - help maintain water balance and cell shape

  Animal: small temporary vacuole - help sequester waste products
• Endoplasmic Reticulum (ER)


  - A system of tubules that run from the nuclear envelope (part of the nucleus) to the the cell membrane

  - It carries out the transport of materials from one part of the cell to another

  Rough ER: has ribosomes to the outer surface and is adjacent to the nucleus - involved in the synthesis proteins and membrane.

  Smooth ER: involved in the synthesis of lipids and carbohydrates

  
• Centriole


  - barrel-shaped organelle that lives within the centrosome

  - centrosome: area of the cytoplasm next to the nucleus

  - centrioles are made of microtubes which are crucial for cell division

  
• Cytoskeleton


  - Helps maintain cell shape and internal organization

  - Provides mechanical support that enables cells to carry out essential functions (such as division and movement)

  
  

  - Made of proteins

  
• How thick is the cell membrane?

  Extremely thin to allow for movement in and out of the cell - 0.008 mircmetres
• Why does the cell membrane need to be semi-permeable?

  Allows some molecules to pass through, while large molecules or charged molecules cannot pass through
• What is a lipid?


  A fat
• What lipids are in the cell membrane?

  - phospholipids (50-60%)

  - Cholesterol

  - Glycolipids
• What are phospholipids made of?

  - Phosphate head: hydrophilic (attracts water)

  - Fatty acid tail: hydrophobic (repels water)

  
  

  *Since water is found outside of the cell, the phospholipids arrange themselves into a lipid bilayer

  
• Where is cholesterol found?

  Sandwiched in-between the phospholipids in the cell membrane.

  
• What does cholesterol do?

  Restrict sideways movement of phospholipids and proteins in the lipid bilayer.

  
  

  Prevents the membrane from becoming too solid at lower temperatures and too fluid at higher temperatures

  
• What are glycolipids made from?

  Carbohydrate molecules combine with lipid, forming glycolipids

  
• What do glycolipids do?

  The carbohydrate component of a glycolipid projects from the exterior surface of cells forming a marker that allows cells to recognize one another.
• Why is cell recognition important?

  It allows the immune system to differentiate between normal body cells and foreign cells.

  
  

  foreign cells are targeted for removal by the cells of the immune system.
• Cell membrane proteins


  - proteins are a majority of the cell membrane
• What are the types of cell membrane proteins?

  Integral protein and Peripheral protein
• What are integral proteins?

  - They penetrate partway or all the way through the hydrophobic interior of the cell membrane

  - They connect the membrane to the cytoskeletal, providing structure to the cell

  
• What are peripheral proteins?


  They are loosely connected to the lipid bilayer or integral proteins at the boundary of the cell

  
• What are transport proteins function?

  To transport substances across the membrane which may not be able to move through the lipid layer.
• What are receptor proteins function?

  To relay signals (messages) between the cell and the extracellular space, instructing cells as to 'jobs' it needs to undertake
• What are enzyme proteins function?

  To speed up chemical reactions that occur at the boundary or within the membrane of the cell
• What are cell recognition proteins function

  To serve as makers that are recognized by membrane proteins on other cells.
• How does temperature influence cell membrane fluidity?

  Low temp: phospholipids pack tightly forming a regular arrangement that is more solid and less permeable to solutes.

  
  

  High temp: phospholipid molecules move apart and the membrane becomes more fluid and permeable to solutes.
• How does cholesterol influence cell membrane fluidity?

  The cholesterol holds the phospholipids so they do not separate too far, letting unwanted substances in, or compact too tightly, restricting movement across the membrane.