Term
| With what and where does protein synthesis begin? |
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Definition
| Transcription, in the nucleus. |
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Term
| In transcription, how is messenger RNA formed? |
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Definition
| A section of DNA that codes for a specific polypeptide separates, revealing exposed bases on one side of the DNA, on which RNA nucleotides base pair to form a strand of mRNA. |
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Term
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Definition
| A section of DNA that codes for a specific polypeptide or protein. |
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Term
| When and where does translation occur? |
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Definition
| During protein synthesis, after transcription, at a ribosome, in the cytoplasm. |
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Term
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Definition
| each 3 base group on the mRNA, which codes for a specific amino acid or a start/stop code. |
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Term
| Describe transfer RNA and its role in translation. |
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Definition
| Transfer RNA molecules have one end attahed to 3 exposed bases called an anticodon, which base pair with the mRNA strand. The other end is attached to a specific amino acid which attaches to the last amino acid on the chain. The tRNA then separates leaving the amino acid as part of the polypeptide. |
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Term
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Definition
| Inorganic substances such as zinc and iron (cofactors) and vitamins(coenzymes) which attach to the active site of an enzyme altering its structure so that it compliments the shape of the substrate. |
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Term
| What are the two types of enzyme inhibitors? |
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Definition
| Competitive and non-competitive |
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Term
| Define competitive inhibitors |
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Definition
| chemicals that resemble an enzyme's normal substrate and compete with it for the active site eg. penicillin, sulpha drugs. |
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Term
| Define non-competitive inhibitors |
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Definition
| chemicals which do not enter the active site, but bind to another part of the enzyme altering its shape, which in turn alters the active site eg. cyanide, lead and mercury. |
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Term
| Why is it important that enzymes act in series, each enzyme catalysing a different reaction in a pathway? |
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Definition
| It enables processes to occur in small controlled stepsa that require or release small amounts of energy at each step and prevents heat damaging the cells. |
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Term
| What environmental conditions affect enzyme activity? |
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Definition
Extreme temperature- too high may denature(unravel) the enzyme
pH should be 6-8 |
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Term
| What are some extra limiting factors on enzyme activity? |
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Definition
Substrate concentration
Enzyme concentration
surface area of substrate (more is better- chewed food is digested more quickly) |
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Term
| What specifically do enzymes do to speed up a reaction? |
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Definition
| Lower the activation energy required for a reaction. |
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Term
| Describe the 'induced fit model' |
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Definition
| A change in the shape of an enzyme's active site to ensure a better fit with the substrate. This puts stress on the substrate(s) helping to either cause a synthesis or breakdown reaction. |
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Term
| What are end product inhibitors? |
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Definition
| Provide negative feedback to ensure too much of a product is not produced. The end product attaches to the first enzyme in a pathway, this prevents over production. |
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Term
| What does semi-conservative mean? |
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Definition
| In DNA replication, each molecule formed has one original strand and one new, or copied strand. |
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Term
| Basic steps of DNA replication? |
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Definition
| Enzymes 'unzip' the DNA leaving exposed bases, free DNA nucleotides base pair with the exposed DNA bases. |
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Term
| What enzyme joins DNA nucleotides together? |
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Definition
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Term
| When does DNA replication occur? |
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Definition
| During the 's' phase of interphase, prior to either mitosis or meiosis. |
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Term
| What process, other than DNA sequencing, is used to compare the similarity from two different species? |
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Definition
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Term
| Describe the process of DNA hybridisation. |
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Definition
| DNA from two different sources are heated to separate the strands. Then they are mixed together and allowed to cool. On cooling DNA from the two sources can combine together, the more similar the DNA the more bonds that form and the harder they are to separate when heated again. |
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Term
| How does DNA change over time in an evolutionary sense? |
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Definition
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Term
| What circumstances can make mutations more likely to occur? |
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Definition
| Heat, Radiation, Mutagenic chemicals |
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Term
| What are the three types of mutations? |
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Definition
| Substitution, Addition, Deletion |
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Term
| Explain substitution (mutations) |
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Definition
| one base incorrectly replaces another in the sequence of DNA. This results in a point mutation and leads to the wrong amino acid being inserted into the structure of the protein. |
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Term
| Explain Addition (mutations) |
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Definition
| Extra bases may be added or sections of other chromosomes spliced in. This affects all of the amino acids that will be synthesized from this point onward. |
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Term
| Explain Addition (mutations) |
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Definition
| A base or more may be left out. affects the entire structure of the protein that could be formed from this code. |
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