biology

• what are proteins?


  proteins are organic molecules made up of hydrogen, oxygen, nitrogen (and sometimes sulfur)
• proteins are present in

  all cells
• protein molecules are the ___ and most ___ of all food substances and are mainly found in ___

  largest; complicated; the meat of animals
• amino acids are the __


  basic building blocks of protein
• ____ link up ____ to form___

  polypeptides
• polypeptides are linked up to form an even longer chain of ___

  amino acids
• one or more ___ fold to form a ___ called protein


  polypeptides; 3-d complex molecule
• denaturation of proteins


  the 3D molecules of proteins are held by weak bonds. the coils held in place by the weak bonds are easily broken up by heat or chemicals. when protein is denatured, they lose their function
• when protein is ___,

  they lose their function
• function no. 1


  synthesize new protoplasm for the growth and repair of worn out body cells
• function no. 2


  synthesize enzymes and some hormones
• function no. 3


  involved in the formation of antibodies to combat diseases
• how are they tested?

  biuret test
• biuret test


  a blue solution made up of sodium hydroxide and copper (ii) sulfate
• how to carry out the biuret test?

  1. add 1cm3 of sodium hydroxide solution into 2cm3 of food sample in a test tube, mix well

  2. add 1% of copper (II) sulfate, dropwise, shaking after each drop

  3. protein (present); solution turns from blue to violet

  protein (absent): solution remains blue

  short chain polypeptides: purplish pink
• Mitochondria (plural)


  - site of aerobic respiration.

  - they break down food molecules into small substances to provide energy for the cell to carry out its cellular activities
• Ribosomes


  synthesis protein
• cell membrane


  control substances moving in and out of the cell
• cell wall


  - gives the cell a fixed shape

  - protects the cell from injury
• rough endosplasmic reticulum


  - transports proteins made by the ribosomes to the golgi body
• Smooth Endoplasmic Reticulum


  - involved in detoxification

  - synthesises fats and steriods
• nucleus


  - controls all activities in a cell

  - contains dna
• chromosomes


  made of proteins and dna
• DNA (deoxyribonucleic acid)


  - contains hereditary information

  - contains information used for the cell to carry out its cellular activities
• chloroplasts


  site of photosynthesis in plant cells
• cytoplasm


  Site of chemical reactions (most cellular activities occur here)
• golgi body


  - stores and modifies substances made by the ER for secretion

  - secretes substances made by the ER out of the cell
• nuclear membrane


  separates the contents from the nucleus from the rest of the cytoplasm