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Activities

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: 9
SCIENCE 8: QUARTER 4 a

CELLULAR
REPRODUCTION

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2. } a Gow
», Do you remember getting bruises

M {after you have fallen from your

7 bicycle? Or after you stumbled down
while playing hide and seek with
your friends? '
Have you ever wondered how a very
small and cute baby becomes as big
or tall as you are right now?

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There is an answer to all of that, it is
because our cells reproduce! A cell VA
reproduce by means of cell division.
EMP 2
is the process in which
one cell, called the parent cell, divides
‚to form new cell, referred to as
daughter cells.

+

4. The Chromosome

acid (DNA)
Tg

(Parts of the Chromosome

> »

. - two identical halves of a

replicated chromosome after the Synthesis
phase of the S phase of the cell cycle.

2. - the attachment points of the two

chromatids of a chromosome.

3. - upper arms of the
chromosome which is usually shorter

4. - lower arms of the chromosome which is

usually longer.

-a region of repetitive DNA sequences
at the end of a chromosome -

Ep

A > Meal

is an organized structure of deoxyribonucleic
and protein found in the nucleus of the cell.

|

——— Telomere

———+ Centromere

‘Chromosome

=, Short arm

Longer arm

Sister chromatid

5. 'd Rn :

For the cell to reproduce, it
must undergo a sequence of
phases called cell cycle.
The cell cycle has two main
stages; the Interphase
which is divided into three
sub stages - Gap 1 Phase
(G,),Synthesis stage
(S phase) and Gap 2 Phase
(G2) and the Mitotic Phase
or M Phase with sub stages -

Prophase, Metaphase,
Anaphase and Telophase

6. Interphase is the interval between two
cell divisions. During this stage, the cell
is not dividing; it obtains nutrients and
metabolizes, grows, replicates its DNA

in pteparation for mitosis.

7. a

. First gap period or Gy where ) 8
Cell grows initially
Synthesis of protein and 4a
ribonucleic acid or RNA occurs -
Mitochondria increase in number 3. Second gap period or Gz where

+ Cell grows rapidly

* Cell prepares for the actual cell
. Synthesis stage or S phase where [2 _ division
DNA are synthesized thus j
replicating the chromosomes in
preparation for the next cell
division

Sot.
at,

ı y.

10. ¡Mitosis is a cellular process wherein two nuclei and two cells are”
ptoduced due to the division of the original nucleus, each of
which contains the same chromosome number sa parent cell.
itosis is divided into four stages namely: Prophase, Metaphase:
Anaphase and Telophase (PMAT)

11. >

"LET'S LOOK AT® >»
THE STACES ,

OF MITOSIS |,
r > 4 Ea Bi

12. The repeated coiling of chromosomes occurs
resulted to its thicker and shorter structure. These

are made up of two sister chromatids that are
identical to each because of the replication of
DNA during S phase

The two chromatids are still attached at the
centromere

The nuclear membrane breaks down.

13. Chromosomes align at the equatorial
plate
* Each spindle fiber from both

centrosomes connects to each À

chromosome through its kinetochore Py

14. ES

Spindle fibers begin to contract and become

shorter. Continued contraction causes the
separation of the genetically identical sister
chromatids.

Centromeres divide.

The single chromatids move towards the opposite

poles

15. The chromosomes ate now at the opposing poles
of the spindle.
The microtubules disappear.

Two sets of chromosomes are surrounded by new

nuclear membranes, completing the nuclear Wy

division process known as karyokinesis. J J

16. a Dd NE / 2"

Cytoplasmic division called
CYTOKINESIS occurs
concurrently, splitting the
cell into two

19. E
Directions: Complete the graphic organizer below of the Cell Cycle and Its Stages. Follow the
correct sequence of each substages. Copy and answer the graphic organizer in your notebook.

j > mE =

Main stages

20. : ACTIVITY —~—

Directions: Match the following statement from column I to column II. Write

the letter of your answer in your notebook.
P= nn. =

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1. Chromosomes are align at the equatorial plane. A. f LA E.

2. The cytoplasm of a cell divides to create
two new daughter cells.

3. The single chromatids move towards
the opposite poles.

4. Two sets of chromosomes are surrounded
by new nuclear membranes.

23. A type of cell division where a single cell divides twice

and produces four daughter cells with half the amount

of genetic material (sex cells).

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24. >

"LET'S LOOK AT® >»
THE STACES ,

OF MEIOSIS |,
r > 4 Ea Bi

26. SM

Meiosis starts with this stage and

includes the following substages:

leptotene, zygotene, pachytene,
diplotene, and diakinesis.

27. Each chromosome is made up of two

long threads of sister chromatids as a

result of replication during the S phase

of the cell cycle.

28. Substage 2:

The homologous chromosomes Prophase

start to pair off through the

process known as synapsis. Pairs
of chromosomes that are similar Zygotene
in size and shape are called si
homologous chromosomes or A
Synaptonemal complex

tetrads.

29. Crossing over takes place during this stage where

a segment of a sister chromatid of one

of the sister chromatid of the homologous

chromosome through the formation of a cross-

linkage of the segments called a chiasma.

DT ) wma A

30. a A/A

Substage 4: Diplotene

Prophase |
FE The two homologous chromosomes
forming a tetrad begin to repel one
another and move apart. They ate Z| Delta:

held only by the chiasma.

Chiasma

31. This is the last stage of meiosis

Prophase |

prophase 1. Diakinesis stage is

characterized by chiasmata | oiatiness

terminalization. After diakinesis, the y

dividing cell enters metaphase

32. Spindle fibers from the centrosomes

of each pole connect to bivalents or

tetrads through the kinetochores.
Homologous chromosomes line up
at the equatorial plane. There is
double alignment of the

chromosomes.

33. Spindle fibers begin to contract and

separate the bivalent or tetrads.

= ES
Homologous chromosomes separate

and migrate to each pole of the cell.

34. en

Chromosomes decondense.

Nuclear membranes reform.
Cytokinesis or the cytoplasmic
division occurs and two haploid (N)
daughter cells with chromosomes

with two sister chromatids are

formed.

36. Chromosomes (chromatids) condense

to form metaphase chromosomes

+ Nuclear membrane dissolves and
nucleolus disappears
+ Centrosomes move towards each pole
of the cell.

37. Spindle fibers attach to chromatids
at the kinetochores.
¢ Chromosomes line up at the

equatorial plane.

(Single alignment of chromosomes)

38. Spindle fibers shortened and

separated the sister
chromatids.

Chromatids that are now called
chromosomes move towatds
each pole of the cell.

39. Single-stranded chromosomes decondense
=» + Nuclear membrane and nucleolus reforms
= ay
+ Cytoplasm divides (cytokinesis)
» Four haploid (n) daughter cells are
formed

a

40. PROPHASE

THE WHOLE PROCESS

ae y
DS /

hs
0

SECOND PHASE

a

41. DIFFERENCES IN CHARACTERISTICS
MITOSIS AND MEIOSIS

RER ——

BETWEEN |

CHARACTERISTICS

MITOSIS

MEIOSIS

Location

Somatic cells

Reproductive cells

Steps required to complete the cell
division phase

Prophase, Metaphase, Anaphase,
and Telophase

Chromosome number of parent cell Diploid (2n) or haploid (n) Diploid (2n)
Chromosome number of daughter Diploid (2n) or haploid (n) Haploid (n)
cell
Number of daughter cells produced Two Four
Number of nuclear divisions One Two

Prophase I, Metaphase I, Anaphase
I, Telophase I, Prophase II,
Metaphase II, Anaphase II, and
Telophase II

with

Occurrence of synapsis None Yes
Occurrence of crossing over None Yes
Presence of chiasma Absent Present
Kind of reproduction associated Asexual Sexual

42. en
L
Directions: Match the cellular activities with their appropriate phases in meiosis. The stages
can be used more than once or not at all. Write the letter of your answer in your notebook.
O eae |
A.Prophase I D. Telophase I G. Anaphase II
B.Metaphase II E. Prophase II H. Telophase II
C.Anaphase I F. Metaphase II I. Interphase
1.Synapsis occurs.
2.Crossing over occurs.
3.DNA replication occurs.
4.Homologous pairs separate.
5.Two daughter cells are created.
6.Chromatids align along equator.
7.Chromatids move to opposite poles.
8.Daughter cells divide forming four haploids cells.
9.Homologous chromosomes or tetrads align at the equator.
10.Spindle fibers attach to tetrads through their kinetochores.

43. ; ACTIVITY2 —

Directions: Put a check (/) in the appropriate column to tell whether the characteristics and
roles describe mitosis or meiosis or both. Copy and answer the table in your notebook.

= rom me
CHARACTERISTICS AND ROLES MITOSIS | MEIOSIS | BOTH 3
|

. Produces body cells.

. Ensures genetic stability.

. Divides the parent cell once.

. Divides the parent cell twice.

. Produces four daughter cells.
. Gives way to genetic diversity.

. Produces gametes or sex cells.

. Produces daughter cells with the same number of
chromosomes like the mother cell.

9. Aids in the repair of genetic defects.

10. Associated with sexual reproduction.
11. Associated with asexual reproduction.
12. Produces diploid or haploid daughter cells

© N Ou 5 &© Dm

44. .