Topic 1: Cell biology

• Animal cells have:

  • cell membrane
  • cytoplasm
  • nucleus
• Bacteria cells have

  • cell wall
  • cell membrane
  • cytoplasm
  • plasmids
• centi = x0.01

  milli =x 0.001

  micro= x 0.000001
• sperm cells carry DNA to egg cell for reproduction

  • long tail to swim
  • mitochondria for respiration
• nerve cells transmit electric impulses from one place to another

  • mitochondria to supply energy to make transmitter chemicals
• muscle cells contract quickly to move bones to cause movement

  • proteins slide over each other
  • mitochondria for respiration
  • can store glycogen
• root hair cells: large surface area, large surface area for absorbing water and minerals, large surface area for absorbing minerals
• xylem cells: hollow tubes that transport water and mineral ions to the roots and shoots
• differentiation: the process by which a cell becomes specialised for its function
• electron microscopes have a higher resolution than light microscopes

  • electron microscopes can see ribosomes
• magnification of eye piece x magnification of objective lens= magnification of microscope
• size of object= size of image/ magnification
• sterilise petri dish before use to not contaminate with harmful bacteria
• inoculating loops are used to kill unwanted microorganisms
• The lid of the petri dish should be partly sealed to stop airborne culture from contaminating the microorganisms
• petri dish should be stored upside down to stop condensation and affecting the growth
• should be incubated at 25 degrees since 37 degrees is harmful to humans at body temperature
• In animals, all cells go under differentiation and make more of the same cell by undergoing mitosis which divides a cell to produce 2 identical cells.
• Red blood cells cannot undergo mitosis and are therefore are replaced with adult stem cells
• electrons have a much small wave length than the light microscope
• Microscopy is often measured in standard form
• The culture medium contains carbohydrates for energy, minerals, vitamins, and amino acids
• Microorganism culture can be used to on:

  • an agar jelly plate
  • nutrient broth solution
• The agar jelly plate is used to test for the presence of bacteria.

  • Agar acts as the culture medium, bacteria grown to form colonies.
• Petri dishes should be sterilised before use to stop:

  • contamination of other microorganisms
  • mutation of a harmful bacteria taking place
• Bacteria can split through binary fission which is the splitting of the cell into two identical cells. This is a type of asexual reproduction.
• Bacteria can be used to test the different affects on antibiotics.
• Antibiotic practical

  • soak paper disc in different antibiotics and place on agar plate
  • if the bacteria is resistant they will not die

  leave the plates for 2 days in 25 degrees

  • the bigger the zone of inhibition, the more bacteria killed
• the nucleus contains genetic information
• genes are found in chromosomes which contains coils of DNA
• A gene is a short section of DNA which codes for a particular protein.
• there are 23 chromosome pairs meaning that there is 46 chromosomes in the human body.
• Gametes (sex cells) are haploid, meaning they have half the number of chromosomes of a normal cell which is 23
• The cell cycle is a series of steps a cell has to undergo in order to divide
• Mitosis steps

  • inter-phase: the cells grow, organelles increase and grow in number, synthesis of proteins occur. DNA is replicated
  • Mitosis: chromosome line up at the equator of the cell and the cell fibres pull each chromosome to the side
  • cytokinesis: two identical daughter cells from when the cytoplasm and cell membrane divide
• cell division by mitosis is important in their growth and development when replacing damaged cells.
• Mitosis is a vital part of asexual reproduction which is the process of producing genetically identical offspring
• A stem cell is a cell that can differentiate into any type of cell with different functions.
• embryonic stem cell

  • forms when an egg and sperm cell fuse to form a zygote
  • differentiate into an cell in the body
• Adult stem cells they are found in bone marrow and can differentiate into many different types of cells