← genetics chapter 3 Test
5 Written Questions
5 Matching Questions
- Anaphase I
- Polar micro tubulues
- G1 phase
- Sex Determination
- How are homologues identified
- a In many animal species, chromosomes play a role in sex determinationThe sex chromosomes are designated Z and W
Males contain two Z chromosomes
Females have one X and one Y chromosome
Males are known as the drones
They are haploid
Females include the worker bees and queen bees
They are diploid
Xx and Xy in humans
Xx and Xo in insects (ratio of chromosomes to autosomes, ratio of 1 = female, .5 = male)
ZZ (male) ZW female (fish)
Fertilization vs. parthenogenesis (ants, bees, wasps) - males are always haploid, females are diploid.
Environmental factors that influence sex alligators
At a 33 degrees it is males
Below 33 it creates females
- b a cell prepares to divide
The cell reaches a restriction point and is committed on a pathway to cell division
- c polymerize toward chromosomes. Push centrosomes away from each other, positioning spindle apparatus
- d Size, position of centromere, and banding patterns
They are not identical to each other
Although we have the same genes, we have different alleles.
- 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
- 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.
- bound to the centromere of each individual chromosome
- propagate towards palama membrane, hold the 2 centrosomes in position
- A long flagellum
The head contains a haploid nucleus
Capped by the acrosome
5 True/False Questions
telophase and cytokinesis → daughter 2n cells.
Gamete Formation in Plants → The life cycles of plant species alternate between two generations
Haploid, which is termed the gametophyte
Diploid, which is termed the sporophyte
Meiosis produces haploid cells called spores
Spores divide by mitosis to produce the gametophyte
Alternate between gametophyte and sporeophyte
Alternation of generation plant have huge sporophyte and tiny gametophytes
Angiosperm - plant that produces flowers and seeds
- spermatogenesis takes place in the anther
- they hold the pollen grains
Creates 4 microspores
They undergo mitosis
You end up with 8 cells.
There is a tube cell and a generative cell (which will under go mitosis and create 2 sperm cells after the pollen grain falls on the stigma nuclei)
The tube and generative cell have a thick cell wall that creates the pollen grain
Megasporocyte undergoes meiosis creates 4 megaspores but 3 degenerate
The megaspore will undergo 3 rounds of mitotic division with asymmetrical cytokenisis this leads to 7 cells instead of the expected 8
Only 7 rounds of cytokenesis
1 central cell with 2 haploid nuclei, then you have 3 antipodal cells and 2 synergid cells. This all results from the 3 mitotic divisions.
1 cell does not undergo cytokenesis you have 2 haploid nuclei in 1 central cell. This is called the endosperm (provides nutrition)
Once the pollen grain falls on the stigma, the tube cell crates the pollen tube, the sperm will fertilize the egg and one will fertilize the central cell. This creates a zygote and an ensodsperm. The first fertilization is btw the egg and sperm
Ovary = seed
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.
interphase → 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)
Cytogenetics → The field of genetics that involves the microscopic examination of chromosomes
A cytogeneticist typically examines the chromosomal composition of a particular cell or organism