Topic 4 - Genetic Diversity: Mutations And Meisosis Flashcards
What is a genetic mutation?
Mutation refers to any change in the base sequence or quantity of DNA mutations can arise spontaneously during RNA replication.
What are the effects of mutations?
- can alter the sequence of amino acid in a protein potentially affecting its function.
- Some mutations may not impact the proteins due to the genetic code being degenerate.
- Some can result in a non-functional protein or have harmful effects.
What is a substitution mutation?
When a nucleotide in the DNA sequence is replaced by another.
What is a deletion mutation?
When a nucleotide is removed from the DNA sequence.
What is the effect of a substitution mutation?
It may have no effect due to the code being degenerate. It could lead to a different amino acid being incorporated which may alter the protein structure or function. The protein become truncated or non-functional.
What are the potential effects of a deletion mutation?
Causes a frameshift mutation altering the way colones are read from the point of deletion onwards this usually result in a completely different amino acid sequence leading to an non-functional protein.
What is meant by polyploidy?
Polyploidy occurs when there is a change in the whole set of chromosomes resulting in an organism having three or more sets of chromosomes of the usual two.
What is chromosome non-disjunction?
Nondisjunction occurs when homologous chromosomes or sister chromatids failed to separate properly during cell division.
What are the effects of non-disjunction?
This result in gametes having either one extra or one missing chromosome.
What is meiosis?
Form of cell division that produces for genetically unique daughter cells with half the number of chromosomes of the parent cell.
How does meiosis introduce genetic variation?
Through independent assortment of chromosomes and crossing over.
What is independent assortment of chromosomes and crossing over?
Independent assortment of chromosomes: homologous chromosomes are randomly distributed into daughter cells.
Crossing over: exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase 1.
Explain in detail independent assortment of chromosomes.
- during meiosis 1 homologous chromosomes lineup in pairs along the equator of the cell.
- The orientation of each pair is random meaning that the maternal or paternal chromosomes can go to either daughter cells.
- This creates different combinations of chromosomes in the gametes
Explain crossing over in detail
- crossing over occurs during prophase 1 of meiosis when homologous chromosomes form pairs called bivalents
- the chromatids of homologous chromosomes intertwine and sections of DNA are exchanged between them at points called chiasm at a.
- this leads to a new combination of alleles on each chromosomes, increasing genetic diversity
What is mitosis?
- produces two genetically indentical diploid daughter cells
- essential for growth, repair and asexual reproduction
