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level: Level 3 - Consolidate

Questions and Answers List

level questions: Level 3 - Consolidate

QuestionAnswer
What is a genome?The entire DNA of an organism
What is a gene? (1)A section of a molecules of DNA which codes for a protein
Where are chromosomes located? (1)In the cell nucleus
Where are genes located? (1)On chromosomes, in the cell nucleus
Describe the structure of DNA (3)DNA is a double helix Contains bases A,T, C,G Sugar-phosphate backbone Double stranded
What is the base pairing rule?A + T, C +G Apple in the Tree Car in the Garage
How is the structure of RNA different to that of DNA? (2)RNA is single stranded RNA contains Uracil (U) instead of Thymine (T).
What are the two main stages of protein synthesis called?Transcription & Translation
What is the role of mRNA in protein synthesis?The gene in the DNA is transcribed to form mRNA, which can leave the nucleus and deliver the base-sequence to the ribosome for translation
What is the role of the ribosome in protein synthesis?The ribosome is where translation of the gene from mRNA to a chain of amino acid occurs, with the sequence of the mRNA being read in codons, coding for one amino acid.
What is the role of tRNA in protein synthesis?tRNA contains an anti-codon to the mRNA codon which are complementary. The tRNA delivers the correct Amino Acid to the chain of Amino acids forming in translation.
What are the roles of codons and anticodons in protein synthesis?The mRNA contains codons, the tRNA anticodons which are complementary. This ensures that only the correct amino acid for coded in the sequence is added tot he resulting polypeptide.
How do we end up with differences in inherited characteristics?There are different forms of any given gene called alleles. We inherit one allele from each parent, resulting in two copies of every gene.
Describe the stages of mitosis (5)P - Prophase - preparation, chromosomes condense M - Metaphase - middle, chromosomes line up across the middle of the cell A - Anaphase - away, the sister chromatids are pulled away to opposite poles by their centromeres T - Telophase - two, two nuclei are formed C - Cytokinesis - the cytoplasm pinches and separates forming two separate cells
Which type of cell division results in two identical daughter cells?Mitosis
List the reasons why a cell may divide by mitosis. (4)Growth Repair Cloning Asexual Reproduction
Which type of cell division results in four non-identical daughter cells?Meiosis
Why would a cell a cell divide my meiosis and where in the body would this happen?To produce gametes in the testes or ovary
Why does random fertilisation produce variation in offspring?Every gamete is different so every combination will result in genetically different offspring
What is the haploid number of chromosomes in humans?23
What is the diploid number of chromosomes in humans?46
Are gametes diploid or haploid?Haploid
Are body cells haploid or diploid?Diploid
What are the two types of variation?Genetic and Environmental
Mutations in which cell type will mean that it will be passed onto the next generation?Gametes
How can a mutation affect the phenotype of an organism?The sequence of amino acids is changed in a protein
How can a mutation result in a non-functioning enzyme?The sequence of amino acids in the protein is changes, so does the 3D shape, resulting in an active site that can no longer fit the substrate.
Do most mutations have a significant effect?No - most are silent mutations and do not affect the resulting protein. (because the code is degenerate, multiple codons code for the same Amino Acid)
List as many mutagens as you can:Ionising Radiation such as: Gamma-rays X-Rays Ultraviolet Rays (sun exposure) Chemical mutagens such as: Cigarettes Processed food