Genetic diversity and gene mutations Flashcards
What is Meiosis?
Meiosis is a specialised type of cell division that produces gametes, which require a haploid genome in order to participate in sexual reproduction.
What divisions occur during Meiosis?
The first meiotic division: separates the chromosomes in each homologous pair
The second meiotic division: separates the two chromatids made by DNA replication before meiosis started.
What is a homologous pair?
A pair of chromosomes containing a maternal and paternal chromatid. They have the exact same gene.
What is crossing over?
It is the process by which the two chromosomes of a homologous pair exchange equal segments of each other. It occurs in the first division of mitosis
What is a Chromosome mutation ?
A change in the number of chromosomes
What is non-disjunction ?
When chromosomes fail to separate properly during meiosis, then a gamete may end up with 2 copies of a chromosome.
What is a gene mutation?
A change in the DNA base sequence of a gene, forming a new version of the gene. It usually happens when DNA is replicated.
What is a neutral mutation ?
A gene mutation which has no effect on the function of that protein
What is base deletion?
It is when a base is lost from the base sequence. As a result of this, the whole base sequence following the deleted base moves back on place. This has a big effect of encoded protein as it can alter the sequence of codons.
Base substitution ?
When the wrong base is included in the base sequence it results in a different amino acid being included in the polypeptide chain.
What is a mutagenic agent?
They are environmental factors which lead to the increase in the rate of mutation. They include: toxic chemicals, ionising radiation and high-energy radiation.
