Lab Exercise nos. 3, 4, and 5 (Continuation)

Question 1

Mitosis

Answer 1

-happens in somatic cells/body
  cells only;
- parent cell divides and results to
  2 identical diploid daughter cells
 -stages (Prophase, Metaphase,
  Anaphase, and Telophase);
  each stage shows nucleus
  particularly the chromosomes’
  structural changes

Question 2

Interphase (Mitosis)

Answer 2

includes G1, S, and G2

Question 3

S phase (Mitosis)

Answer 3

-where DNA replication together
with chromosome duplication
happens

Question 4

Apoptosis

Answer 4

• [programmed] cell death that is part of

development

Question 5

Meiosis

Answer 5

-happens in germ
  cells/gametes/sex cells only;
  give rise to haploid cells
-leads to trait combinations
  Example:
  1 gamete (green eyes and
  freckles);
  1 gamete (brown eyes and no
  freckles)
-brought about an individual
  that differs genetically from
  its siblings and parents,
  this exhibits genetic diversity
-stages: Meiosis I (reductional
  division) and Meiosis II
  (equational division)

Question 6

Germ Cells/Gametes/Sex Cells

Answer 6

haploid; with 23 chromosomes (in humans); 4 chromosomes (in fruit fly - Drosophila melanogaster)

Question 7

Homologous chromosomes/Homologues

Answer 7

-pair of chromosomes;
contain the same genes in the
same order, but these genes can
also be alleles

Question 8

What is the highlight of mitosis?

Answer 8

Each stage shows nucleus, particularly the chromosomes’ structural changes

Question 9

Is there a change between the parent and daughter cells for mitosis?

Answer 9

None. They’re still both diploid.

Question 10

What is not a stage of Mitosis?

Answer 10

Interphase.

Question 11

When does Interphase occur?

Answer 11

Happens before mitosis.

Question 12

Why do cells need to undergo apoptosis?

Answer 12

It needs certain cells to die to achieve a form or structure for the certain parts of the organism. (e.g. foot)

Question 13

What are germ cells/gametes/sex cells referring to?

Answer 13

Sperm cell and egg cell

Question 14

What is the number of chromosomes in germ cells/gametes/sex cells.

Answer 14

It’s the haploid number = 23 chromosomes.

Question 15

Scientific name of fruit fly.

Answer 15

Drosophila melanogaster

Question 16

Counterpart of haploid

Answer 16

Diploid

Question 17

What does it mean when “genes can also be alleles”?

Answer 17

Although they are the same genes, these genes can be variants as well – not totally the same.

Question 18

Chromosomes are pairs on the aspect of _____.

Answer 18

Chromosomes are pairs on the aspect of SAME GENES IN THE SAME ORDER.

Question 19

Chromosome number for mitosis.

Answer 19

Diploid. 46 chromosomes.

Question 20

Chromosome number of meiosis.

Answer 20

Haploid. 23 chromosomes.

Question 21

Prophase I substages

Answer 21

1. Leptonema
2. Zygonema
3. Pachynema
4. Diplonema
5. Diakinesis

Question 22

What corresponds to the 5 stages of Prophase I or characterizes the stages?

Answer 22

The changes of chromosome structures during prophase I.

Question 23

Leptonema/Leptotene

Answer 23

Chromosomes
- extended and visible and along each chromosome are chromomeres (localized condensations)

Homology search
- needed for initial pairing of homologs

Question 24

How can the chromosomes in the Leptotene stage be visualized as?

Answer 24

It can be visualized as beads on a string.

Question 25

Zygonema/Zygotene

Answer 25

• chromosomes continue to shorten and thicken

Homology Search
- rough pairing; initial alignment of homologous chromosomes/have a certain position for homologous chromosomes

• Lateral elements are noticeable between paired homologs towards the end of Zygonema; Eventually, the synaptonemal complex form between the homologs

Question 26

Bivalent

Answer 26

paired homologs

Question 27

How is homology search depicted?

Answer 27

Through the distinct colors of red and blue.

Question 28

Pachynema/Pachytene

Answer 28

• chromosomes continue to coil and thicken and synaptonemal complex further develops
• each homolog is seen as a double structure
• tetrad - four-membrane structure; 2 pairs of sister chromatids

Question 29

Diplonema/Diplotene

Answer 29

• each tetrad can be clearly seen; with in each tetrad, each pair of sister chromatids start to separate
• chiasma, where non-sister chromatids are intertwined and carry out crossing over (genetic exchange)
• Crossing over - results to new combinations of genetic material

Question 30

Plural of chiasma

Answer 30

Chiasmata

Question 31

Diakinesis

Answer 31

• chromosomes pull farther apart, but non-sister chromatids remain loosely associated at the chiasmata

Question 32

Metaphase I

Answer 32

• chromosomes shortened and thickened fully
• each tetrad’s terminal chiasmata is present
• each tetrad interacts with spindle fibers, this allows its movement to the metaphase plate

Question 33

Anaphase I

Answer 33

• Disjunction - separation of homologous chromosomes

Question 34

Telophase I

Answer 34

• nuclear membrane firns

- nuclear proceeds to a short interphase (chromosomes do not replicate here)

Question 35

Metaphase II

Answer 35

• centromeres are aligned at the metaphase plate

- centromeres separate due to shugoshin complex’s disintegration

Question 36

1/2 of tetrad

Answer 36

Dyad

Question 37

Anaphase II

Answer 37

• sister chromatids of each dyad are directed to opposite poles

Question 38

Telophase II

Answer 38

• Monad - one number of each pair of homologous chromosomes