Chromosomes Flashcards
Chromosomes form during the _____ of mitosis in the cell cycle.
metaphase (M phase)
During _____ phase of the cell cycle, one complete set of DNA moves into one of the two new cells made during _____, and the second complete set moves into the other new cell.
- M
2. mitosis
The correct movement of the DNA into the two new cells requires that the _____ separate chunks of DNA twist very _____, forming dense _____, which can be seen (when stained) using a standard microscope.
- 46
- tightly
- chromosomes
Chromosomes, as _____ structures, have the important job of the precise delivery of DNA to the two new cells.
temporary
After DNA _____ has occurred, the visible chromosome now contains _____ the DNA and will split in _____ during _____, allowing one new cell to reeve the left half of the chromosome and the other new cell to receive the right half.
- replication
- twice
- half
- mitosis
_____ formation begins with the chunk of DNA (after _____) corresponding to the _____ supercoiling itself and becoming a shorter but much _____ structure.
- Chromosome
- chromosome
- denser
When DNA _____, it is done in multiple organized steps rather than just as a random tangle.
supercoils
As the dsDNA starts to coil more tightly, the tighter structure begins to wind around a set of globular protein balls known as _____, forming a “bead” on the DNA strand.
histones
_____ allow the tightly wrapped DNA coil to compact itself without creating tangles or damaging its basic structure.
Histones
The thicker beaded groups continue to coil neatly and form the basic structure of the _____.
chromosome
During _____ phase of mitosis, each chromosome forms and moves to the center of the cell that is about to divide.
M (metaphase)
Just before the cell splits into two cells (_____), each chromosome is pulled apart (_____) so that half of each chromosome goes into one new cell, and the other half goes into the other new cell.
- cytokinesis
2. nucleokinesis
_____ is the actual number of chromosomes present in a single-cell nucleus at mitosis.
Ploidy
Humans have _____ chromosomes divided into _____ pairs.
- 46
2. 23
A complete set of one of each chromosome is the _____ chromosome number (_____) representing 23 individual chromosomes.
- haploid
2. 1N
When the nucleus contains both pairs all chromosomes, the number present is the _____ chromosome number (_____).
- diploid
2. 2N
When additional whole sets of extra chromosomes are present, the condition is termed _____.
polyploidy
Polyploidy examples:
69 chromosomes is _____ or _____.
92 chromosomes is _____ or _____.
- triploidy
- 3N
- tetraploidy
- 4N
Normal human _____ cells are body cells that are not reproductive cells and have a nucleus with a _____ number of chromosomes, _____ pairs.
- somatic
- diploid
- 23
Mature human germ line cells are reproductive cells: ova (eggs) and spermatocytes (sperm) each have the _____ number of chromosomes, 23, _____ of each pair.
- haploid
2. half
When a cell’s nucleus contains the normal diploid number of chromosomes for the species, the cell is termed _____.
euploid
When a cell contains more or fewer chromosomes than the normal diploid number for the species, it is termed _____.
aneuploid
_____ act as a chromosome cap that holds the DNA strands together similarly to the way a small plastic tube keeps the ends of a shoestring from raveling.
Telomeres
The pinched-in area of the chromosome connecting the two sides is the _____.
centromere
The _____ also connects the chromosome segments above it and below it.
centromere
Each longitudinal left and right half of the chromosome is a _____.
chromatid