4958818
Description
Flashcards by Laura Perry, updated more than 1 year ago
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Created by Laura Perry
about 8 years ago
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| Question | Answer |
| What do genes code for? | Polypeptides (such as proteins) and enzymes |
| Genetic Code (definition) | The sequence of bases on a gene which codes for instructions for the construction of proteins |
| What is the triplet code? | Three bases that code for one amino acid |
| What is the first stage in protein synthesis? | Transcription |
| Describe the stages of the first part of protein synthesis | -The DNA unwinds and unzips by DNA helicase, causing hydrogen bonds to break. -RNA nucleotides match up with the bases (template strand) forming hydrogen bonds. -This creates a copy of the coding strand. -mRNA leaves the DNA and passes through a nuclear pore out of the nucleus. |
| What is the second stage of protein synthesis? | Translation |
| What occurs in the second stage of protein synthesis? | -mRNA binds to a ribosome -the tRNA brings the correct amino acid - the next three bases are read and the same thing happens, with a peptide bond forming between the amino acids - this happens until the stop codon is reached and the polypeptide chain is complete |
| What is a mutation? | A random change in the amount of, or arrangement of the genetic material in a cell |
| What is a DNA mutation? | Changes to genes due to changes in nucleotide base sequences. |
| What is the effect of mutations in mitosis? | These are somatic mutations and are not passed onto their offspring. May cause ageing or cancer. |
| What is the effect of mutations in meiosis? | These mutations can be inherited by offspring |
| What is a point mutation? | A point mutation is a substitution mutation. It involves one of the bases being swapped or replaced for another. |
| What is an insertion/deletion mutation? | A mutation where one or more nucleotide bases are inserted or deleted (added or taken away) from a length of DNA, causing frameshift. |
| What is a silent mutation? | A silent mutation is one where the mutation has no effect on the amino acid, and therefore no effect on the polypeptide chain created. |
| What is a mis-sense mutation? | A mutation where the base changing causes a different amino acid to form and therefore the whole polypeptide chain changes. This may then affect a whole protein |
| What is a non-sense mutation? | A mutation where the base change causes a stop codon to be produced, shortening the polypeptide chain, causing the protein to perform differently |
| How can a mutation be beneficial? | A mutation may change the amino acids produced, therefore changing the polypeptide. Overall this may alter the phenotype of an organism, giving them an advantage. |
| How can a mutation be neutral? | The mutation may occur in a non-coding area of the DNA, so the mutation may not be noticed. The mutation may also be silent so it does not effect the organism. |
| How can a mutation be harmful? | Changing the amino acids produced may alter the phenotype of the organism, resulting in a harmful characteristic. |
| What is the function of cAMP in protein synthesis? | Cyclic AMP can activate the protein so that way it can change its 3D shape to better complement certain molecules. |
| What is the structure of the lac operon and what is the function of each part? | |
| What happens in the lac operon when lactose is not present? | - the repressor protein binds to the operator region, blocking the active site of the promoter region. -the mRNA then cannot bind. -the structural genes are not transcripted into mRNA and the genes are not produced. |
| What happens in the lac operon when lactose is present? | -lactose binds to the repressor protein and the molecule changes shape so it cannot bind to the operator region. -RNA polymerase binds to the promoter region. - genes Z and Y are produced. |
| What are homeobox genes? | Homeobox genes control the development of the body plan of an organism, including the polarity and position of organs. |
| How do homeobox genes work? | The homeobox sequence codes for a gene product which binds to DNA and initiates transcription. They switch genes for body development on and off. |
| Apoptosis (definition) | Programmed orderly cell death that occurs in multi-cellular organisms. |
| How is apoptosis controlled? | It is controlled by cell signals such as hormones, ligands, growth factors and cytokines. |
| What are the events of apoptosis? | -the cell cytoskeleton breaks down -the cytoplasm becomes dense -the cell surface membrane changes -chromatin condenses -nuclear envelope breaks down -DNA fragments -cell breaks into vesicles taken up by phagocytosis |
| What is cell necrosis? | Untidy and damaging cell death that occurs after trauma and releases hydrolytic enzymes. |
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