Genetics Report: Cell Cycle Stages, Mitotic Index, and Growth Effects

This report is a comprehensive analysis of genetics, focusing on chromatin structure, the process of mitosis, and the cell cycle. It begins by explaining the structure of chromatin in eukaryotic chromosomes and its role in DNA packaging and cell division. The report then delves into the transformations of chromatin during mitosis, the mechanism of chromosome separation, and the stages of interphase. The core of the report involves an experiment on onion root growth under different conditions (control, dark cellar, sunlight with babybio plant feed, and sunlight in a space station), calculating the mitotic index for each condition. The findings are presented in tables and graphs, followed by a statistical analysis using the Fisher's exact test to determine the significance of the results, including P-value interpretations for each growth condition. The report concludes by discussing the effects of each growth condition on onion root growth, linking mitotic index and P-values to the observed outcomes and includes a list of relevant research references.

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Number of words: 1500
Genetics report (questions and answers)
1. Chromatins are found in Eukaryotic chromosomes. Explain what chromatins are and their
structure as found in eukaryotic chromosomes
Chromatins are a complex of nucleic acids either RNA or DNA that condenses to a chromosome
during cell multiplication. In eurokaryotic (organisms with membrane bound nucleus) cells the
chromatin is found within the nucleus where it helps in packaging of DNA into smaller volumes
so as to fit in a cell. It also strengthens the DNA to allow for the process of meiosis and mitosis
Chromatin structure of eukaryotic chromosomes
The chromosomes contain long DNA strands that carry genetic information. The eukaryotic cells
have large genomes than prokaryotes that has multiple and linear chromosomes. However, the
length plus linear nature of the chromosomes increases the ability of keeping the genetic material
organized as well as of passing the correct amount of DNA to every daughter cell during the
process of mitosis.
2. What are the transformations in chromatin structure that exist during the process of mitosis?

During the initial phase, interphase chromatin remains in condensed form as well as appears
loosely distributed in the entire nucleus. Condensation of the chromatin starts during the
prophase stage where the chromosomes become visible and remains condensed in the rest of the
phases of mitosis up to the final stage telophase.
3. The mechanism of chromosomes mitotic separation.
Before the commencement of anaphase, a replicated chromosomes reoffered to as sister
chromatids are aligned at the centre of the cell. The sister chromatids are joined at the
centromere where during this stage each chromosome pair is separated into two chromosomes
that are identical and independent. The chromosomes are then separated by the mitotic spindle
which is made up of microtubules that are attached to the chromosome at one pole as well as to
the end of a cell at the other pole. However, the sister chromatids are divided concurrently at the
centromere where the separate chromosomes are pulled by a spindle to the other sides of the
cell.
4. What is interphase and what happens during this stage of the cell cycle?
Interphase is a stage of the cell cycle where a cell spends most of its life. During this stage, the
cell duplicates their DNA as it prepares for mitosis. Interphase can be defined as the metabolic
stage of a cell where it get’s nutrients as well as metabolizes them , reads the DNA and performs
other functions of the cell. A vast number of eukaryotic cells spend most of their time in this
phase where a cell gets ready for meiosis or mitosis. Diploid cells or somatic cells of the body go
through mitosis so as to reproduce themselves via cell multiplication whilst diploid germ cells go
through meiosis to form gametes for reproduction.
5. What the percentage cell in each stage of the cell cycle denotes
The distribution of cells continues to decline as a cell undergoes meiosis or mitosis from the
initial stage, interphase to telophase.
6. Calculating the mitotic index value for onion root samples

Mitotic index for the control group = (30/350) × 100
= 8.57%
Mitotic index for the dark cellar on earth = (12/312) × 100
= 3.85%
Mitotic index for the sunlight on earth in babybio plant feed = (72/480) ×100
= 15%
Mitotic index value for sunlight in space station = (60/480) ×100
= 12.5%
7. A table showing the number of m-phase cells, interphase cells plus the mitotic index for the
datasets
.
Growth condition Interphase metaphase Mitotic index
Control group (in
sunlight on earth)
320 7 8.75%
In dark cellar on earth 300 2 3.85%
In sunlight on earth
with babybio plant
feed
408 19 15%
In sunlight in space
station
420 16 12.5%

8. A graph comparing mitotic index with growth condition
control group in dark cellar on
earth in sunlight on
earth in sunlight in
space station
0
2
4
6
8
10
12
14
16
Growth condition vs mitotic index
mitotic index (%)
9. Comparing then mitotic plus interphase cells for different growth conditions
Mitotic cells= (P+M+A+T)*100
Mitotic cells counted for dark cellar =7+2+2+1=12
Control sunlight dataset’s mitotic cells=11+7+8+4=30
Mitotic cells counted for baby bio=30+19+15+8=72
Mitotic cells counted for space=26+16+14+4=60
Dark cellar Control sunlight data
set
Marginal tow total
Interphase 300 320 620
Mitotic cells 12 30 42
Marginal column totals 312 350 662(grand total)

Using the fisher’s exact test, the statistical p value is 0.01586. The result is significant at p <
0.05
Babybio plant feed Control sunlight
dataset
Marginal row total
Interphase 408 320 728
Mitotic cells 72 30 102
Marginal column totals 480 350 830(grand total)
The fisher test statistical P –value is 0.00534 and the result is significant at P< 0.05
Space station Control sunlight
dataset
Marginal row total
Interphase 420 320 740
Mitotic cells 60 30 90
Marginal column totals 480 350 830 (grand total)
The fishers exact test statistical value is 0.089529. The result is not significant at P< 0 .05
A table of the resulting P values
Categories Resulting P-value
Dark cellar 0.01586
Babybio plant feed 0.00534
Space station 0.089529
10. What the P-value denotes in regard with the datasets being compared? Purpose of the p
value is to test the validility of the null hypothesis of the data
In the dark cellar category, the p value is 0.01586 which is significant at p < 0.05 while in the
babybio plant feed, the resulting P value is 0.00534 which is significant at P<0 .05. Lastly, in the
space station the P value is 0.089529 which is not significant at p<0.05

11. The effect of growing onion roots in a dark cellar condition
Growth condition Mitotic index p-value
In dark cellar 3.85% 0.01586
Sunlight with babybio plant
feed
15% 0.00534
In space station 12.5% 0.089529
The smaller the mitotic index the more significant the p value. From the dark cellar condition , it
can be deduced that the smaller the ratio between the number of cells undergoing mitosis versus
those not undergoing leads to an increase in the growth of onion roots where the calculated p
value is less than the critical value.
12. The effect of growing onion roots in sunlight with Babybio plant.
The larger the mitotic index, the smaller the p value becomes. From the sunlight with babybio
plant feed condition , it can be concluded that the larger the ratio between number of cells in a
population undergoing mitosis and those not undergoing will lead to a decreased p value which
is less significant to the critical value
13. The effect of growing onion roots in space has had.
In space station, the larger the mitotic index the larger the value of P which is not significant. this
is because the calculated p value is larger compared to the critical p value hence the faster
growth of onion roots due to rapid cell division.
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