cell biology

• the cytoplasm contains organelles, ribosomes and enzymes
• the nucleus is the control centre of the cell
• the nucleus is the control centre of the cell, it contains DNA which controls all activities within the cell.
• mitochondria produce energy through respiration
• chloroplasts contain chlorophyll to absorb light energy during photosynthesis
• mitochondria is the powerhouse of the cell as it produces energy from glucose through respiration
• chloroplasts contain chlorophyll which absorbs light to make food (glucose) during photosynthesis
• nucleus contains genetic material that controls activities of the cell
• Cytoplasm is a gel like substance, where most of the chemical reactions happen. It contains enzymes that control these chemical reactions.
• Cell membrane holds the cell together and controls what goes in and out
• Mitochondria is where most of the reactions for aerobic respiration happen, respiration transfers energy that the cell needs to work
• Ribosomes are where proteins are made in the cell
• Cell wall made of cellulose, supports the cell wall and strengthens it
• The permanent vacuole contains cell, sap, a weak solution of sugar and salt
• Chloroplast where photosynthesis occurs, which makes food for the plant they contain, agreed substance called chlorophyll, which absorbs the light needed for photosynthesis
• Plant and animal cells are eukaryotes
• Bacteria are prokaryotes
• Bacteria, don’t have chloroplasts or mitochondria
• bacteria cells don’t have a nucleus. Instead, they have a single circular strand of DNA that floats freely in the cytoplasm.
• Bacteria may also contain one or more small rings of DNA called plasmids
• Light microscopes use light and lenses to form an image of a specimen and magnify it. They let us see individual cells and large sub cellular structures like nuclei.
• Electron microscope is electrons, instead of light form an image they were much higher magnification than light microscopes
• Electron microscopes have a higher resolution than light microscopes
• Resolution is the ability to distinguish between two points, so a higher resolution gives a sharp image
• Electron microscopes, let us see smaller things in more detail, like the internal structure of mitochondria and chloroplasts. They even let us see tiny things like ribosomes and plasmids.
• Magnification image formula is magnification = image size/ real size
• To convert micro meters to millimetres, you need to divide by 1000
• what is a light microscope


  they use light and lenses to from an image of a specimen and magnify it. they let us see individual cells and large subcellular structures
• what is an electron microscope


  they use electrons and have a higher magnification and resolution that light microscopes
• what is resolution


  the ability to distinguish between two points (e.g. higher resolution + sharper image)
• what is differentiation


  the process by which a cell changes to become specialised for a specific function.
• what are specialised cells


  cells designed to carry out a particular role/specific function in the body
• how are sperm cells specialised


  for reproduction:

  -long tail and streamlined head = help swim to egg

  -lots of mitochondria = provides energy needed

  -carries enzymes in head = to digest through egg cell membrane
• how are nerve cells specialised


  for rapid signalling:

  -function = to carry electrical signals from one part of body to another

  -long length = to cover more distance

  -branched connections at ends = to connect to other nerve cells and form a network throughout the body
• how are muscle cells specialised


  for contraction:

  -function = to contract quickly

  -long length = for space to contract

  -lots of mitochondria = generate energy needed for contraction
• how are root hair cells specialised


  for absorbing water and minerals:

  -they are cells on surface of plant roots that stick into soil

  -big surface area fro absorbing water and mineral ions from the soil
• how are phloem and xylem specialised


  for transporting substances:

  -from phloem and xylem tubes = transport substances (food + water) around plants

  -cells are long and joined end to end = to form the tubes

  -xylem cells are hollow = stuff can flow through

  -phloem cells have very few subcellular structures = stuff can flow through
• what are chromosomes


  -coiled up lengths of DNA molecules

  -carries a large number of genes (control characteristics)

  -46 chromosomes (23 from mum, 23 from dad)