5 Written questions
5 Matching questions
- Meiosis II
- Diploid dominant species
- Anaphase I
- Purpose for division
- a 1)Pairs of sister chromatids align themselves along a plane called the metaphase plate
2) Each pair of chromatids is attached to both poles by kinetochore microtubules
3)Arrange in a single row on the equatorial, metaphase plate
Arrangement of maternal and paternal chromosomes doesn't matter
Make sure each pair is connected to either pole
- b One purpose of cell division is asexual reproduction
A second important reason for cell division is multicellularity
Plants, animals and certain fungi are derived from a single cell that has undergone repeated cell divisions
Humans start out as a single fertilized egg
End up as an adult with several trillion cells
- c b/c all of our somatic cells are diploid mitosis dominates
Each type of chromosome has 2 copies, 1 maternal homologue and 1 paternal homologue
- d For a diploid organism with 6 chromosomes, mitosis begins with 12 chromatids joined as 6 pairs of suster chromatids
Meiosis 2 begins w/ 6 chromatids joined as 3 pairs of sister chromatids
THERE IS NO S PHASE
Already in the form of sister chromatids
PROMETAPHSE- each pair of S chromatid is connected to either pole.
Then we have metaphase - a single row of very differenlt looking s. chromatids.
Anaphase - each pair of s. chromatids becomes a chromosome
Telophase 2, cytokensis
Results in 4 cells as 2 rounds of meiodid
In the book it says 4 daughter cells, but cells from meiosis are NOT DAUGHTER CELLS BECAUSE THEY ARE NOT GENETICALLY IDENTICAL. They are gametes.
- e ANAPHASE
The two pairs of sister chromatids separarate from each other. However the connection that holds sister chromatids together does not break
Polar MT - polymerize
Kinetochore MT - depolarize
Each pair for sister chromatids move towards the poles.
You get a reduction in the number of chromosomes
Sister chromatids reach their respective poles and decondense. The nuclear envelope reforms to produce 2 separate nuclei.
Only 1 copy of each type of chromosome on either pole
1 copy of each type of
Chromosome complement looks different from the original cell.
5 Multiple choice questions
- Prophase I most important division: chromosomes that align along themselves.
Most common changes: compaction and condensation of chromosomes
1) LEPTOTENE -
Tetrads = 2 centromeres = bivalent stage
Non sister chromatids = association is between maternal and paternal homologues that crossing over creates variation.
- compaction of chromosome, homologous partner seek for one another (this occurs towards the end of leptotene). The first major change is compaction.
- A long flagellum
The head contains a haploid nucleus
Capped by the acrosome
- In actively dividing cells, G1, S and G2 are collectively known as interphase
A cell may remain for long periods of time in the G0 phase
A cell in this phase has
Either postponed making a
decision to divide
Or made the decision to never
Terminally differentiated cells
(e.g. nerve cells)
- Interphase I
Early Prophase I
Late Prophase I
5 True/False questions
binary fission → prokaryotes reproduce via binary fission: Prior to division, the bacterial cell replicates its DNA
Then the cell divides into two daughter cells by a process termed binary fission
1)Cell increases in density
2)Gets a signal for DNA to divide
3)n prokaryotic organisms, dna is naked DNA, it is not enclosed in a membrane bound nucleus
4)Once the cell reaches maximum density, it divides into 2 clusters of circular DNA
5)Then there is septum formation
6)This requires FTSZ protein - filamenting temperature sensitive mutant z
First identified in a mutant form where the circular form is elongated and did not form the septum well
This protein is the first one deposited in the form of the ring in the middle of the bacterial cell (a ring) acts as a motor to recruit 9 other proteins to form septum
Then it divides into 2 daughter cells.
Conjugation + plasma transfer = genetic recombination in prokaryotes
Relationship between genetic trait and inheritance of a sex chromosome → X linked influence of characters and genes
Embryogenesis and changes over time
Lamarck - theory of acquired inheritance
If you don't use something it is vestigial
Morgan thought if he would but the flies in a dark room, their eyes will atrophy.
This was not true
He exposed them to radiation
1 male white eyed fly was found
This is an example of discovery based research
Now he must conduct hypothesis based research
The white eyed fly was mated with true breeding red eyed females
All of the f1 were red eyed
F1 mated - you will not get a white eyed female
4.4 red : 1 white
Gene has effect one some of the population but not all semi lethal gene
White eyed condition is known as semi lethality
There is an influence pattern and he thoughtit was on the x chromosome
He took a white eyed male and crossed with with a female
ZYGOTENE → they have found their partners and come close together. Then, proteins are deposited which create the synaptonemal complex. This is in the form of lateral elements between the chromosomes and a center element that acts as a zipper and fuses them together. There are certain conditions where the synaptonemal complex but physical exchange of chromosomal sections occurs (crossing over)
there are 2 pairs of sister chromatids at the zygotene phase.
mitosis vs meiosis → Mitosis - produces 2 diploid daughter cells
Meiosis produces 4 haploid d. cells
Mitosis produces daughter cells that are genetically identical
Meiosis produces gametes (resulting cells) that are not genetically identical - gametes
The cells contain only 1 homologous chromosome from each pair.
Aster microtubulues → polymerize toward chromosomes. Push centrosomes away from each other, positioning spindle apparatus