Cell structure

• What is the function of the cell membrane?

  Hold the cell together, separating the inside of the cell from the environment outside, controlling what can and cannot enter or leave the cell
• What's the function of the cytoplasm?

  A jelly-like substance where many chemical reactions inside the cell happen, surrounds sub-cellular structures
• What is the function of the DNA?

  The genetic material that controls the activities of the cell
• What's the function of ribosomes?

  The site of protein synthesis in the cell
• What are the 2 types of cells?

  • Eukaryotic - plant and animal cells
  • Prokaryotic - bacteria
• Eukaryotic cells

  • Plant and animal cells are both eukaryotic
  • a defining feature of eukaryotic cells is that their genetic material(DNA) is enclosed within a nucleus
  • they vary in size between 10 and 100um μm
• Differences between an animal and plant cell?

  Label them

  A) A

  B) B

  C) C

  D) D

  
• Prokaryotic cells - structure

  • bacterial cells are a type of prokaryotic cell
  • genetic material is not enclosed within a nucleus, it is found as a single loop of DNA within the cytoplasm
  • additional smaller, circular pieces of DNA called plasmids may also be present
  • cell membranes are surrounded by a cell wall
  • much smaller than eukaryotic cell 1μm
• Image of prokaryotic cell 


  prokaryotic cell

  
• Components of Eukaryotic and Prokaryotic cells

  • cell membrane - both
  • cytoplasm - both
  • genetic material - Eukaryotic in a nucleus, Prokaryotic in cytoplasm
  • Nucleus- eukaryotic yes and prokaryotic no
  • cell wall -eukaryotic no and eukaryotic yes
• What unit do scientists use to measure the size of cells?

  micrometers (μm) 0.001 micrometers = 1x10^-3 mm or 0.000001 metres
• How to convert?

  • 1m = 1000mm
  • 1mm = 1000μm
  • 1μm = 1000nm
• Size of cells and components

  • HIV VIRUS - 100nm
  • MITOCHRONDRIA AND CHLOROPLAST - 1.5μm
  • CHOLERA BACTERIUM - 1.5μm
  • CHEEK CELL(animal) - 65μm
  • PALISADE MESOPHYLL(plant) - 70μm
• Animal cells

  • eukaryotic cells have subcellular structures, each carrying out a specific function
  • organelles are subcellular 'compartments' where specific processes take place within the cell
• What are the main subcellular structures in an animal cell?

  • Nucleus
  • Cell membranes
  • Mitochondria
  • Ribosomes
  • Cytoplasm
• Which organisms are visible under a light microscope in a animal cell?

  • Nucleus
  • Cell membrane
  • Cytoplasm
• Which organisms are visible under an electron microscope in an animal cell?

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Ribosomes
  • Mitochondria
• What's the function of the nucleus?

  • contains the genetic material (DNA) which controls the activities of the cell
• What's the function of the cytoplasm?

  • a gel-like substance composed of water and dissolved solutes
  • supports internal cell structures
  • site of many chemical reactions
  • site of aerobic respiration
• What's the function of cell membrane?

  • holds the cell together, separating the inside of the cell from the outside
  • controls which substance can enter and leave the cell
• What's the function of ribosomes?

  • found in cytoplasm
  • site of protein synthesis
• What's the function of mitochondria?

  • site of most of the reactions involved in aerobic respiration, where energy is released to fuel cellular processes
  • cells with high rates of metabolism(carrying out many different cell reactions) have significantly higher numbers of mitochondira than cells with fewer reactions taking place
• In plant cells what other subcellular parts are found?

  • a cell wall made of cellulose
  • a permanent vacuole filled with cell sap
  • plant cells found in a leaf and stem may also contain chloroplast
• Which organisms are visible under an electron microscope in a plant cell?

  • Ribosomes
  • Mitochondria
  • Cell membrane
  • Cell wall
  • Permanent vacuole
  • Cytoplasm
  • Chloroplast
• Which organisms are visible under a light microscope in a plant cell?

  • Cell wall
  • Cell membrane
  • Permanent vacuole
  • Cytoplasm
  • Chloroplast
• What's the function of the cell wall?

  • made of cellulose(a polymer of glucose)
  • gives the cell extra support, defining its shape
• What's the function of chloroplasts?

  • contains green chlorophyll pigments(to absorb light energy) and the enzymes needed for photosynthesis
• What's the function of a permanent vacuole?

  • contains cell sap; a solution of sugars and salts dissolved in water
  • used for storage of certain materials
  • also helps support the shape of the cell
• Specialised cells

  • A specialised cell is a cell that has a structure that aids its specific function
  • This could relate to cell shape, or the combination of cellular structures present within the cell
  • Cells specialise by undergoing a process called differentation
• Nerve cells

  Nerve

  
• What’s the function of nerve cells?

  Conduction of electrical impulses
• What are special features of nerve cells which aid function?

  • Nerve cells are long, meaning they can conduct nerve impulses between different areas of the body
  • Extension of cytoplasm known as dendrites allowing nerve cells to communicate with other cells, muscles and glands
  • The axon is covered with fatty sheath which speeds up nerve impulse transmission
• What does a muscle cell look like?

  Muscle cell - contain layers of fibre which allow them to contract

  
• What’s the function of a muscle cell?

  Contraction of movement
• What are special features of muscle cells that aid function?

  • Muscle cells have many mitochondria to release energy for contraction
  • All muscle cells contain protein filaments that can slide over each other to allow muscle contraction
• What does a sperm cell look like?

  Sperm cell - they are mobile and their tail helps to propel them forward in search of an egg cell

  
• What’s the function of a sperm cell?

  Transfer of genetic material to an egg cell for fertilisation
• What are special features in a sperm cell which aid function?

  • The mid-piece is packed with mitochondria to release energy(via respiration) for the tail
  • The tail rotates, propelling the sperm cell forwards and allowing it to move
  • The acrosome in the head contains digestive enzymes that can break down the outer layer of an egg cell so that the haploid nucleus can enter to fuse with the eggs nucleus
  • The head contains a nucleus with half the normal number of chromosomes, allowing the sperm cell to fuse with an egg cell to restore the normal chromosome number
• What’s the function of a root hair cell?

  Absorption of water and mineral ions from soil
• What are special features of a root hair cell which aid function?

  • Root hairs increase surface area so the rate of water uptake by osmosis is greater
  • Thinner walls than other plant cells so that water can move through easily due to shorter diffusion distance
  • Mitochondria release energy for active transport of mineral ions