Biology Unit 1

• The nucleus contains the genetic material (DNA) that controls all cellular activities.
• The cell theory states that all organisms are composed of cells, they all come from pre-existing cells, as well as the fact that the cell is the smallest living organisational unit.
• Ribosomes - site of protein synthesis
• Cell membrane - regulates what enters/leaves the cell
• MRS GREND describes attributes shared by all living things
• Movement = all organisms have some level of self powered movement
• Respiration = conversion of carbohydrates into ATP through cellular respiration
• SENSITIVITY TO STIMULI = An organisms response to its environment
• GROWTH = An irreversible change in mass
• REPRODUCTION=Production of an offspring - passing attributes to the next generation
• EXCRETION OF WASTES = production of wastes that need to be removed, eg dead cells, urine
• NUTRITION = Intake of food or nutrients
• DNA=the molecule the codes for the production of proteins
• The 4 properties of all cells include having either DNA or genetic material, having a plasma/ cell membrane, having ribosomes
• the properties of a prokaryote include the capsule, cell wall, plasma membrane, non-membrane bound organelles, Ribosomes, Plasmids(smaller pieces of DNA), Cytosol
• Characteristics shared by Bacteria include the fact that they are unicellular, live in moist, low light, low salt, moderate temperature, have little oxygen requirements, break down substances, they are either gram pos or gram neg
• Archaea are unicellular, can live in extreme environments( low pH, high salt, high temperature), their membrane is made of lipids which makes it easier to live in extreme environments
• differences between Archaea and Bacteria include archaea releasing methane in their digestive process, archaea's ability to live in extreme conditions, their plasma membranes are made differently
• Facts about Mitochondria and Chloroplasts

  - Both have their own DNA

  - Both have ribosomes

  - Both reproduce through binary fission

  - both have sizes that fall between the bacterial range
• What is the endosymbiotic theory?

  A special case of symbiosis in which one of the organisms lives inside the other

  
  

  example, single-celled algae living inside the cells of coral
• Cilia and Flagella

  Hair-like extensions on the exterior of the cell's surface
• Centrioles

  A pair of cylindrical structures made of microtubules

  
  

  Mostly found in animal cells

  
  

  Involved in cell division + and formation of

  cilia and flagella
• Cytoskeleton

  Supports the cell's structure - allows the cell to move to assist in the transport of organelles and vesicles within the cell
• Plastid

  - Involved in the storage and synthesis of different chemical compounds

  - It contains double-stranded DNA molecules and a double-membrane

  
  

  
  

  Different types include:

  - Chloroplasts - contain chlorophyll

  - Amyloplasts - stores starch

  - Chromoplast - contains carotenoids(colour pigment)
• Vacuole

  Stores water and nutrients, acts as a support for the cell

  
  

  Can account for 90% of cell volume
• Describe the Cell wall

  - Only present in plant cells

  - Composed of cellulose - complex carb

  - Acts as structural support
• Define the role of Chlorophyll

  Chlorophyll( pigment) absorbs sunlight

  Chloroplasts(organelle) trap light energy - which is used to split water molecules into hydrogen and water - hydrogen binds to CO2 to create glucose, oxygen in released as a waste product
• Describe the membrane system

  Composed of a system with 3 membranes - outer inner and thylakoid system

  
  

  ( thylakoids are disc-shaped sacs)

  
  

  this system of membranes forms compartments within the compartments with different enzymes inside
• Describe Chloroplast

  Specialised subunits:

  Site of photosynthesis
• Cytosol

  highly organised liquid inside the cell - contains dissolved cubstances
• Cytoplasm

  Where cellular activity occurs in the cell
• Lysosomes

  membrane-bound vesicle

  contains a high concentration of enzymes

  break apart unwanted material/ damaged organelle

  reuse anything possible
• Mitochondria

  Contain their own genetic information

  its outer membrane is smooth and permeable

  its inner membrane has folds(Criatae)

  There are 2 compartments:

  intermembrane space and mitochondrial matrix(has its own DNA, converts nutrients into ATP= cellular respiration)
• Golgi Apparatus/ Body

  Entry point - Cis face

  Exit point - Trans face

  linked to the ER

  modifies protein packages and materials for secretion

  secretory cells have well developed GA but in other cells they are smaller
• Describe the Rough Endoplasmic Reticulum

  covered in ribosomes

  ribosomes create proteins

  collected by vesicles who transport them outside the cell
• Describe the Smooth Endoplasmic Reticulum

  attached to the outside RER

  creates lipids and carbohydrates

  used by the cell or excreted
• Describe Ribosomes

  Attached to the RER to create proteins

  Composed of prothesis and ribosomal DNA/rRNA

  
  

  Used in 2 subunits: attached to the RER to be excreted outside the cell, or used to sloat inside the cell
• Describe the Nucleolus

  Contains DNA, RNA, as well as where ribosomes are assembled

  
  

  created some proteins
• Describe the Nucleus

  contains DNA

  
  

  double layered membrane - which is permeable made of fatty tissue

  
  

  DNA inside the nucleus is transcribed into RNA

  
  

  RNA(transcription of DNA) is sent out of the nucleus to bind to ribosomes - they are then sent outside of the cell
• How do some cells compensate for decrease in SA:V ratio

  On the outside of cells, microvilli are able to absorb extra nutrients