F215.1.1- Cellular Control Biology Revision Cards

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Revision questions on F215.1 Cellular Control
Laura Perry
Flashcards by Laura Perry, updated more than 1 year ago
Laura Perry
Created by Laura Perry over 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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