The Chromosome Basis of Genetic Variation Flashcards
Chromatin makeup
- DNA
- DNA- metabolising enzymes
- Histones (structural proteins)
DNA content of cells notation
C represents amount of DNA in cell
Organisation of human genome
30% coding
70% non-coding
Prophase
- Spindle fibres appear
- Chromosomes condense
- Breakdown of nuclear membrane
Prometaphase
- Spindle fibres attach to chromosomes
- Chromosomes condense
Metaphase
-Chromosomes align
Anaphase
- Centromeres divide
- Sister chromatids move to opposite poles
Telophase
- Nuclear membrane reforms
- Chromosomes decondense
- Spindle fibres disappear
Cytokinesis
- Cytoplasm divides
- Parent cell becomes 2 daughter cells with identical genetic information
Prophase I
- Chromosomes begin to condense
- Homologous chromosomes pair
- Crossing over occurs
- Recombinant chromosomes form
Metaphase I
- Spindle fibres attach to chromosomes
- Chromosomes line up in middle of cell
Anaphase I
Chromosomes start to move to opposite ends of cell as spindles shorten
Telophase I
- Chromosomes reach opposite ends
- Nuclear membrane forms
Prophase II
- Chromosomes begin to condense
- Nuclear membrane dissolves
- Spindle fibres form
Metaphase II
- Spindle fibres attach to chromosomes
- Chromosomes line up in centre of cell
Anaphase II
Centromeres divide and sister chromatids move to opposite ends of cell as spindle fibres shorten
Telophase II
- Chromosomes reach opposite ends
- Nuclear membrane forms
Difference between male and female meiosis
one male meiosis cycle results in four different sperm cells whereas one female meiosis cycle results in one mature egg cell and 3 polar bodies
Recombination
Production of new combinations of genes different from those of each parent
