Mitosis and Meiosis Flashcards
In which phase of the cell cycle does genetic information get duplicated?
S-phase
What occurs in the G1 and G2 phase?
G1- checks conditions, G2- checks for dna damage
Describe the process of mitosis
Prophase- Spindle fibres appear and chromosomes condense. Nuclear membrane breaks down
Prometaphase- Spindle fibres attach to to chromosomes at the centromere
Metaphase- Chromosomes align on centre of cell
Anaphase- Centromeres divide, sister chromatids pulled to opposite sides of cell
Telophase- Nuclear membrane reforms, chromosomes decondense and spindle fibres disappear
Cytokinesis- Cytoplasm divides
Describe the process of meiosis
Interphase- At this point the the chromosome number is 92 (replicated chromosomes)
Prophase 1- Homologous chromosomes pair and exchange DNA to form recombinant DNA
Metaphase 1- Chromosomes align in centre of cell. Independent assortment of alleles
Anaphase 1- Chromosomes pulled to opposite poles of the cell
Telophase 1- 2 cells, 23 PAIRS in each cell
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2 to give for haploid daughter cells
What is a gene?
unit of heredity that codes for a protein
What is an allele?
An alternative form of a gene.
Describe different inheritance patterns
Autosomal dominant (one in each generation), Autosomal recessive (two heterozygotes= 25% chance of condition in child), sex linked (X or Y chromosome)
Describe the process of co-inheritance. In what circumstances would linked genes not be co-inherited?
2 genes on same chromosome that are close are said to be linked, they co-segregate. Crossing over could result in linked genes being seperated
What is genetic mapping?
The arrangement and distance between genes on a chromosome deduced from studies of recombination. Frequency of recombination can give information of how close two loci are.
What is non-disjunction?
the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division (anaphase). Usually resulting in abnormal distribution of chromosomes in daughter nuclei.
What is the danger with mitotic non disjunction?
aneuploidy is associated with cancer
Why does mitotic non disjunction in the first post zygotic cell division not lead to a mosaic karyotype and what is the exception?
the monosomy cell lin dies unless it is X
What are the consequences of non disjunction in meiosis 1 vs meiosis 2?
In Meiosis 1, non disjunction will affect every gamete, in Meiosis 2 it will only affect half
