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Spindle
________ fibres attach to centromeres only on exposed sides.
original number of chromosomes
When an ovum is fertilized by a sperm, the ________ (46= 2n) is restored, forming a zygote.
G2
________ (second cell growth stage): rebuilds energy reserves and prepares for mitosis.
Humans
________ have 23 pairs of chromosomes (46 chromosomes total)
Growth Differentiation
________: Mitosis enables organisms to grow from a single- celled zygote into a mature organism that might contain hundreds of trillions of specialized cells.
DNA strands
________ shorten and thicken, causing chromatin to condense into visible chromosomes.
Homologous pairs
________ move to centre → centromeres on either side of equator.
Chromosomes
________ do not uncoil to form chromatin.
DNA Molecule
________: two sugar- phosphate backbones with nitrogen base "rungs.
Chromatids
________ move to opposite poles of cell (same number of single- copy chromosomes should be at each pole)
Gametes
________ (sperm or eggs) are haploid cells.
somatic cells
All ________ contain homologous pairs of chromosomes.
Centrioles
________ separate and move to opposite poles of cell.
life cycle
The ________ of all sexually reproducing organisms alternates between haploid and diploid cells.
Histones
________: DNA molecule wraps around ________, forming a bead- like structure.
Maintenance
________: new cells produced to replace worn out /dead cells.
formation of ova
The ________ and sperm follow the process of meiosis, specializations dependent on their function.
Repair
________: They can regenerate damaged tissues (finger cut → new skin)
Interphase
________: growth stage consists of G1, S & G2.
Chromatin
________ Strands: The bead- like structure is packed tightly, producing ________ strands.
Genetic differences
________ rarely occur, but are the result of a mutation.
Sperm
________ are designed for movement (little cytoplasm), lots of cell division, produce 4 small sperm.
Chromatin Fibres
________: Stands from loops which are attached to a supporting protein scaffold.
Meiosis II
________ is completed if /when the oocyte is fertilized.
Spindle
________ fibres attach to the centromeres.
Chromosomes
________: Protein scaffold folds further to condense the genetic material into ________ (duplicate during replication)
Chromatids
________ move to opposite poles.
Spindle
________ fibres attach to centromeres.
Growth/Differentiation
Mitosis enables organisms to grow from a single-celled zygote into a mature organism that might contain hundreds of trillions of specialized cells
Maintenance
new cells produced to replace worn out/dead cells
Repair
They can regenerate damaged tissues (finger cut → new skin)
DNA Molecule
two sugar-phosphate backbones with nitrogen base "rungs"
Histones
DNA molecule wraps around histones, forming a bead-like structure
Chromatin Strands
The bead-like structure is packed tightly, producing chromatin strands
Chromatin Fibres
Stands from loops which are attached to a supporting protein scaffold
Chromosomes
Protein scaffold folds further to condense the genetic material into chromosomes (duplicate during replication)
Interphase
growth stage consists of G1, S & G2
G1 (first cell growth stage)
organelle replication
S (synthesis phase)
DNA is replicated
G2 (second cell growth stage)
rebuilds energy reserves and prepares for mitosis
Cell Division (Mitosis)
division of genetic material & nucleus
Meiosis I
separates homologous chromosomes (first division)
Meiosis II
separates sister chromatids (second division)
Note
Meiosis II is very similar to Mitosis
Eggs are designed to nourish the zygote
only one ovum is produced per oocyte → the other 3 polar bodies sacrifice their cytoplasm to produce one large egg
Note
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