cell biology

• the cell is a structural and functional unit of all the living organisms
• the term cell was first invented by robert hook in 1965
• 2/3 of the cell is made up of water and the rest is a mixture of molecules like protein,lipids, carbohydrates
• cells convert raw materials in the food into the molecules our body needs, using different metabolic reactions
• cell diversity:

  cell type diversity refers to the range of different cell types that comprise a tissue or an organism
• cellular diversity is important when building complex organisms like the human body
• variation allows the cell to be better adapted
• eukaryotic cell is made up of

  golgi body

  mitochondrion

  free ribosomes

  rer

  ser

  glyoxysome

  lysosome

  plasmalemma

  vacuole/vesicle

  centrioles

  nuclear membrane

  nucleolus

  chromatin in nucleus

  perioxisome

  chloroplast
• prokaryotic cells

  comprise of bacteria and archaea
• prokaryotic cells have a diameter of 0.1-5um
• prokaryotic cells dna is not contained within a nucleus and their dna is circular and can be found in a region called nucleoid which floats in the cytoplasm
• prokaryotes are organisms that consist of a single prokaryotic cell
• prokaryotic cells consists of

  outer rigid cell wall

  inner lipid cell membrane

  pili/flagella structures to allow movement

  embedded transport proteins in membrane that allow passage of material into and out of the cell

  interior cytoplasm material

  dna contained in a single closed circular loop

  free floating ribosomes

  free floating plasmid dna

  mesosome
• cell wall strengthening material is murein
• eukaryotic cells are found in plants fungi animals and protists
• eukaryotic cells range from 10-100um in diameter
• eukaryotic dna is contained within a membrane bound nucleus
• eukaryotes are organisms containing eukaryotic cells
• eukaryotic cells

  cytoplasm contains cytoskeleton to give structure

  highly organised

  contain sub cellular organelles with specific functions
• plants vs animal cells

  plants have chloroplast and cell walls but animal cells don’t

  animal cells have centrioles but plants don’t
• plants may have lytic vacuoles which act like lysosomes in animal cells
• plant cells also have microtubules and secretory vesicles
• cell membrane and plasma membrane are the same thing
• both plants and animal cells have mitochondria
• both animals and plant cells have vacuoles
• plant cells

  are specialised to make their own glucose using photosynthesis

  plant cells chloroplast are key to this process of using light to make food

  supported by a cytoskeleton and a plasma membrane

  plant cells have a supportive cell wall, not present in animal cells

  they have numerous small vesicles to contain waste, transport materials and perform many other functions
• animal cells

  use glucose from the animals good to carry out cellular respiration

  supported by a cytoskeleton and a plasma membrane

  use number plus small vesicles to contain waste, transport materials and perform many other functions
• similarities of prokaryotic and eukaryotic cells:

  1. composed of cells
  2. contain dna as a heritable genetic material
  3. have cytoplasm
  4. can reproduce
  5. transcribe dna into rna
  6. translate rna into proteins on ribosomes
  7. regulate transport across a cell membrane
  8. require chemical energy
• differences between prokaryotic and eukaryotic cells:

  cell size:

  prokaryotes: small cells <5um

  eukaryotes: large cells >10um
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: always unicellular

  eukaryotes: often multicellular
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: no nucleus or any membrane bound organelles like mitochondria

  eukaryotes: always have nucleus and other membrane bound organelles
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: dna is circular without proteins

  eukaryotes: dna is linear and associated with proteins to form chromatin
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: ribosomes are small 70s

  eukaryotes: ribosomes are large 80s
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: no cytoskeleton

  eukaryotes:always has a cytoskeleton
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: motility by rigid rotating flagellum made up of flagellin

  eukaryotes: motility by flexible waving cilia or flagellae made of tubulin
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: cell division by binary fission

  eukaryotes: cell division by mitosis or meiosis
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: asexual reproduction

  eukaryotes: sexual or asexual reproduction
• differences between prokaryotic and eukaryotic cells:

  prokaryotes: huge variety of metabolic pathways

  eukaryotes: common metabolic pathways
• atoms-molecules-cells-tissue-organs-organs systems-organisms
• all the reactions that takes place in cell is known as cell metabolism