biology paper 1

• Gene


  a segment of DNA that determines characteristics of your body
• How many chromosomes do humans have?

  46 (23 pairs)
• How many chromosomes do gametes (sex cells) have?

  23
• Mitosis


  The process of cell division, resulting in two identical cells
• The cell cycle


  The cycle of your body's cells dividing in a series of stages
• How long does the cell cycle take?

  Anywhere from 24 hours to years (depending on the organisms stage of life)
• Cell division in organisms

  Pre-born baby- quick and constant

  Child afterbirth- Fairly rapid

  End of Puberty and Adulthood- slows drastically
• Stage 1- Cell Cycle

  -Longest stage

  -Grows bigger

  -Increased mass

  -Duplicate their DNA

  -Increase number of ribosomes, mitochondria, etc. for cell divide
• Stage 2- Cell Cycle


  -Mitosis occurs

  -Organelles get pulled apart and nucleus splits
• Stage 3- Cell Cycle

  -Cytoplasm and Cell membrane split

  -Two identical daughter cells
• Cloning


  Producing identical offspring
• Zygote


  A fused egg and sperm cell
• embroyonic stem cells


  Inner cells of the embryo
• Embryo


  One half of the zygote
• adult stem cells


  An undifferentiated cell of any organism that can rise to many more cells of the same type
• Problems with embryonic stem cells

  -Human rights debate

  -Slow, expensive, unpredictable

  -Possibly cause cancer

  -Potentially infected with viruses
• Therapeutic cloning


  research using cells from an adult to produce a cloned embryo of themselves
• Stem call research could possibly treat:

  -Spinal cord injuries

  -Diabetes

  -Eyesight

  -Heart damage

  -Damaged bone and cartilage
• Tissue


  A group of similar cells that perform the same function.
• Organs


  Groups of tissues that work together to perform a specific function or related functions
• Organ system


  group of organs that work together to perform a specific function
• Organ Systems in our body

  Digestive system, respiratory system, and the circulatory system
• Levels of organization (small to large)

  cell, tissue, organ, organ system, organism
• Digestive system


  body system the breaks down food and absorbs nutrients (digestion occurs)
• Enzymes


  break down large molecules for digestion to occur
• Small intestine


  absorption of molecules into your blood
• Function of muscular walls of the small intestine

  Squeeze undigested food into your large intestine
• Liver


  produces bile
• Stomach


  breaks down and digests food into order to extract nutrients
• Large intestine


  absorbs water and leaves waste to be stored and passed out as faeces
• Main compounds of a cell

  Carbohydrates, lipids and proteins
• Carbohydrates Function


  main source of energy
• Simple carbhydrates


  composed of only one or two units of sugars e.g Sucrose
• Complex carbohydrates


  composed of long chains of simple sugar units bonded
• Lipids


  -fats and oils

  -insoluble in water

  -made of carbon, hydrogen, oxygen

  -Made up of three fatty acids joined to glycerol
• Proteins function


  build, maintain and repair tissue and cells in body
• How much of your body mass is protein?

  15-16%
• What are proteins made of?

  carbon, oxygen, nitrogen, hydrogen
• What composes a protein molecule?


  long chains of amino acids (amino acids are the building blocks of protein)
• Denatured


  loss of an enzyme's normal shape so that it no longer functions