BIOL 1208 CH. 12

telomeres
located at the ends of chromosomes and give stability
genome
All the genetic information in an organism; all of an organism’s chromosomes.
centrioles
a tube of tubulin protein responsible for formation of the mitotic spindle
microtubles
protein complexes responsible for moving chromosome during cell division
chiasmata
Point where two chromatids are intertwined, or where a crossover occurs
contain homologous chromosome pairs, majority of cells (except sex cells), complete set of chromosomes, diploid #: 2n
Characteristics of diploid cells
contain 1 chromosome of each type, sex cells, 1/2 set of chromosomes until fertilization, haploid #: 1n
Characteristics of haploid cells
interphase, prophase, metaphase, anaphase, telophase
Phases in order of the Cell cycle
Interphase G1
most important state of interphase. period before replication where the cell grows and receives signals to decided if it should divide (if positive->go to S phase/ if negative-> will not divide)
S Phase
Second phase of interphase where the DNA replicates and the chromosomes duplicate themselves producing sister chromatids
G2
3rd phasse of interphase. after the DNA replicates, cell continues to grow
prophase, metaphase, telophase, cytokinesis
What events happen in mitosis?
Prophase I, Metaphase I, Anaphase I, Telophase/citokinesis I, prophase II, Metaphase II, Anaphase II, telophase/Cytokinesis II
What events occur in meiosis?
2 daughter cells that are identical to each other and the parent
what does mitosis produce?
after interphase
when does mitosis occur?
cytokinesis
The division of the nucleus is usually followed by what?
early prophase
part of prophase that the chromosomes condense and become visible (cytoskeleton) and the centrioles move towards the poles of cell
late prophase
part of prophase where the nucleolus and nuclear envelope disappear and the centrioles are at opposite poles. polar microtubules elongate cell
metaphase
phase where the microtubles lengthen and shorten and the chromosomes line up on equator (mid plate)of the cell PERFECTLY. the sister chromatids face towards opposite poles
anaphase
segregation of homologous chromosomes to opposite poles
telophase
phase where spindle microtubules breakdown and the nuclear envelope forms around chromosomes at each pole. chromatins uncoil
cytokinesis, telophase
what two phases occur at the same time?
G1 to S phase
checkpoint that determines if DNA is intact and suitable for replication
G2 to M phase
Checkpoint that determines if NDNA was accurately replicated with no errors
Metaphase to Ana phase
determines if chromosomes are attached to spindle microtubles and aligned properly along cell equator
mitosis
What stops if one check point determines a problem?
prophase 1
where pairing and crossing over between homologous chromosomes
synapsis
the state where paired homologs become physically connected to each other along their lengths by a zipper-like protein structure
crossing over
a genetic rearrangement between non sister chromatids involving the exchange of DNA molecules, begins during pairing and is completed during synapsis
no variation
if synapsis wouldn’t occur what would happen??
metaphase 1
What phase do the centronomes move to the poles of the cell and the spindle attaches to the centromeres
Anaphase 1
The chromosomes are pulled apart to the opposite poles
telophase 1
When the nuclei are reformed on each side
cytokinesis
Separation of the cell after telophase 1
Prophase 2
The two spindle apparatus form and move toward the metaphase 2 plate
Metaphase 2
chromosomes are going to line up and meet in the middle (______ plate), they are not genetically identical
Anaphase 2
the two chromosomes are pulled to either side
Telophase 2
nuclei form and the chromosomes begin decondensing causing cytokinesis to form, Separates into 4 cells
4 genetically distinct chromosomes with only 1/2 of chromosomes
What is produced after meiosis 1 and 2?
sister chromatids
what separates in both meiosis 1 and 2?
in plant cells vesicles first line up to form a new cell wall whereas in animal cells the cell membrane pinches and divides
how does cytokinesis differ in plants and animals?
Mitosis: conserve chromosome # (no change), one nuclear division, identical cells, somatic cells Meiosis: Reduces chromosome # by 1/2, 2 nuclear division, variation, sex cells (gametes)
Difference between mitosis and meiosis
G1-> S, G2->M, Meta->Anaphase
What are the 3 check points?
G1-> S
Checkpoint that determines if DNA is intact and suitable for replication
G2->M phase
Checkpoint that determines if DNA was accurately replicated w/ no errors
Metaphase->anaphase
determines if chromosomes are attached to spindle microtubles and aligned properly along cell equator (M phase)
interphase
What phase do the first 2 checkpoints occur in?
1/2
During meiosis, a cell in anaphase 3 will have how many chromatids compared to when it was in anaphase I?
equal amount
During meiosis, a cell in anaphase 2 will have how many chromosomes compared to when it was in metaphase 1?
G1->S->G2->M
What are the steps in correct order of the cell cycle?
3 during meta, 0 during prophase 2, and 0 during anaphase 2
If a parent cell has 6 chromosomes in the G1 stage, how many homologous pairs of chromosomes will each daughter cell have during meta 1, pro 2, and anaphase 2?
half;half
Upon the completion of meiosis 1, each daughter cell will have __ number of chromosome compared to the parent cell in prophase 1. upon the completion of meiosis 2, each daughter cell will have ___ number of chromosome compared to the parent cell of pro 1.
prophase 1
crossing over between homologous chromosomes occurs at which of the stages of meiosis?
G1
during which stages of the cell cycle would a chromosome consist of only a single chromatid?
four chromatids
A tetrad is composed of ____.
are attached to the same centromere during G2 phase of the cell cycle
Which of the following is not a characteristic of homologous chromosomes?
tetraploid
A cell with 4 sets of chromosomes
46
How many chromosomes are found in a human somatic cell nucleus during G2 (duplicated)?
23
How many pairs of chromosomes are found in a human somatic (body_ cell nucleus during G2?
92
How many sister chromatids are found in a human somatic cell nucleus during G2?
meiosis
What process is sued to make mature germ-like cells or gametes?
M phase
What is the short segment of the cell cycle during which cells divide?
Shorter G1 stage so it can divide quicker
If a cell begins to divide rapidly (as often seen in wound repair) what would you expect to happen to the G1 stage?
cytokinesis
The process in which the cytoplasmic contents are separate to produce two daughter cells is called___.
stem
Type of cell that can be divided multiple times and differentiate into different types of cells.
poles
During anaphase of mitosis, where are the chromosomes located?
G1
At what point in the cell cycle does a cell decide whether to undergo cell division?
cell plate
What structure is formed during cytokinesis in plant cells?
homologous chromosomes
In meiosis 1, the diploid number (2n) of chromosomes is reduced to the haploid number (n) because of the separation of what?
4 haploid gamete cells
In meiosis 2, the non-sister chromatids separate and produce what?
the chromosomes must be duplicated (interphase)
What must happen before a cell can begin mitosis?
diploid
The ____ varies among species and is identified nonspecifically as 2n .
Haploid
The _____ number, or n, is the number of chromosomes contained in the nuclei of gametes, the non somatic cells.
interphase
In meiosis, interphase is followed by 2 successive rounds of cell division, meiosis 1 and 2. Meiosis results in 4 haploid daughter cells because there is no ____ between these 2 meiotic cell divisions.
F; S
T/F: Chromosomes first become duplicated in the G2 phase of the cell cycle?
F; homologous chromosomes
Meiosis 1 result in the separation of the sister chromatids.
T
A tetrad is composed of a pair of homologous chromosomes with each chromosome containing two sister chromatids
T
The site of crossing over is known as chiasmata.
F; chromatid
During anaphase 2 of meiosis, the homologous chromosomes separate
F; location
Loci are different version of a gene.
separation of sister chromatids, formation of mitotic spindle
What two things happen during M phase of cell division?
DNA replication, duplication of chromosomes
What two things happen during interphase?
kinetochore
Assembles of proteins that function in attaching the chromosomes to spindle microtubules.
zygote
When gametes fuse during fertilization, a ____ is produce.