Ch 2 Flashcards
Cell cycle
Division of one cell into another
G1 - active growth
S - DNA synthesis
G2 - preparation for devision
Mitosis - devision
Cytokinesis - final separation into two cells
Mitosis interphase
Chromosomes not visible
Centriole are visible
Chromatin becomes shorted and thicker
Mitosis prophase
Chromatin condenses more forming 2 chromatids held at a centromere
Spindle fibers form
Nucleolus disappears
Nuclear membrane breaks down
Mitosis metaphase
Spindle fibers move chromatids to metaphase plate
Mitosis anaphase
Spindle fibers pull chromatids apart (become chromosomes) at Centromere to opposing poles
Mitosis telophase
Chromosomes decondense and become less visible
New nuclear envelope forms
Nucleoli reforms
Spindle disassembles
Cytokinesis in animal cells
Division of cytoplasm after mitosis
Membrane pinches in the middle forming a cleavage furrow
Cytokinesis in plant cells
Division of cytoplasm after mitosis
Vesicles accumulate at cell plate and fuse which ceperates cytoplasm by creating a new cell wall
Binary fission
Reproduction of cells in prokaryotes
Produces 2 identical daughter cells
Allele
The alternative versions of the same gene
Eg blue eyes and brown eyes
Karyotype
The standard graphical image used to display and analyse chromosomes
What is synapsis
Pairing of homologous chromosomes during prophase
What’s a tetrad
4 sister chromatids consisting of 2 homologous pairs
l l l l
X X
What happens during crossing over
DNA which has gone through crossing over during prophase 1 where alleles swap in homologous chromosomes (when they have formed a tetrad)
Define binary fission
The process of asexual reproduction where prokaryotic cells divide into two identical daughter cells
What are the stages of mitosis
interphases
prophase
metaphase
anaphase
telophase
what’s a centromeres purpose in mitosis
the position on chromosomes where spindle fibres attach
what are the 4 ways to describe the position of a centromere on a chromosome
metacentric – in the middle
submetacentric – between the middle and the ends
acrocentric – closer to the ends
telocentric - at the end
What are the steps of meiosis
Meiosis I
- Prophase I
- Metaphase I
- Anophase I
- Telophase I
Cytokinisis
Metaphase II
- Prophase II
- Metaphase II
- Anophase II
- Telophase II
Cytokinesis
what does meiosis produce
4 daughter cells/gametes
Prophase II
spindle forms at right angles to the first one
Anaphase II
chromatids separate & move to poles
Metaphase II
chromosomes move to equator
Telophase II
spindle fibers disappear, chromosomes de-condense, nuclear envelope & nucleoli form
