Term
| Describe the structure of a DNA molecule. |
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Definition
Double stranded/ double helix.
Made of sub-unit called nucleotides.
Each nucleotide consists of:
- phosphate
- desoxyribose sugar
- a base (adenine, thymine, guanine or cytosine).
Bases on each strand form complementary pairs. |
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Term
| What holds a DNA strand together? |
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Definition
| A bond between the sugar of one nucleotide and the phosphate of the adjacent nucleotide. |
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Term
| What type of bond holds the two strands together o form the double helix? |
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Definition
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Term
| What is determined by the base sequence? |
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Definition
| The genetic code. In proteins, the base sequence determines amino acid sequence. |
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Term
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Definition
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Term
| What are the chemical elements found in proteins? |
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Definition
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Term
| Structure of proteins is determined by… |
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Definition
| DNA sequence which itself determines the order of amino acids. |
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Term
| Name of the type of bond between amino acids |
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Definition
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Term
| Give 5 examples functions of proteins |
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Definition
Enzymes: speed up chemical reactions.
Hormones: carry chemical messages around the body (e.g. insulin)
Antibodies: recognize molecules of invading organisms to defend the body against disease.
Structural: connect and support tissues (e.g. collagen).
Receptors: participate in cell signaling. |
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Term
| Where does protein synthesis take place? |
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Definition
| In ribosomes in the cytoplasm. |
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Term
| What carries the sequence information from where it is stored (i.e. in the nucleus) to where it is needed (ribosome) |
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Definition
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Term
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Definition
- Single stranded
- sugar is ribose
- Uracil (U) is found in place of thymine (T). |
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Term
| Describe a chemical reaction in general terms |
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Definition
| A substrate is chemically altered into a product |
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Term
| Explain the meaning of the term “catalyst”. |
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Definition
| A catalyst is a substance which speeds up the rate (i.e. the speed) of a chemical reaction without being changed or used up.(i.e. a catalyst is neither a substrate nor a product as it is unaffected by chemical reactions). |
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Term
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Definition
| An enzyme is a biological catalyst made up by all living cells. It speeds up reactions and is left unchanged. |
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Term
| Which part of the enzyme binds to the substrate? |
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Definition
| The active site. The shape of the active site is complementary to that of its specific substrate. |
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Term
| Explain the word “specific” as applied to enzymes and their substrate |
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Definition
| Each enzyme only works on one substrate because the shape of the active site is only complementary to that of its specific substrate. E.g. Amylase only breaks down starch. Enzymes and substrates have matching shapes like a “lock and key”. |
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Term
| Explain why enzymes are required for the functioning of living cells. |
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Definition
| The cell processes necessary for life would happen too slowly without enzymes. |
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Term
| Give an example of an enzyme involved in a breakdown reaction. |
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Definition
C-L-A-P
- Catalase: breaks down hydrogen peroxide into water and oxygen
- Lipase: breaks down fats into fatty acids and glycerol
- Amylase: It breaks down starch into maltose.
- Pepsin: breaks down proteins into polypeptides and amino acids. |
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Term
| Give an example of an enzyme involved in synthesis (building up) |
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Definition
| Potato phosphorylase: in potatoes, joins molecules of Glucose-1-phosphate to form starch. |
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Term
| State what type of molecule enzymes are. |
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Definition
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Term
| Describe the effect of temperature on enzyme activity |
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Definition
| At low temperatures, enzymes do not work effectively (molecules move too slowly). Enzymes work best at a temperature called the optimum. Beyond that temperature, the shape of the enzyme and its active site change which slows down reaction rate. Above a certain temperature, an enzyme becomes denaturated, i.e. it is irreversibly damaged. |
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Term
| Describe the effect of a range of pH on the activity of an enzyme |
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Definition
| Each enzyme has an optimum pH, i.e. a pH at which it works most effectively (faster rate of reaction). Enzyme may work at other pH but the rate of the chemical reaction that they control is usually not as fast. |
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Term
| Explain the term “optimum” as applied to the activity of enzymes |
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Definition
| The conditions at which enzymes works best are called optimum conditions: optimum pH and optimum temperature. |
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Term
| Explain what a control is. |
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Definition
| A repeat of an experiment to show that the effect observed is only due to the factor being investigated (e.g. activity of an enzyme). |
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