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Anatomy > L2 CELL DIVISION > Flashcards

L2 CELL DIVISION Flashcards

1
Q

What are the products of Mitosis?

A

Results in two daughter cells which contain

same number of chromosomes as in parent cell

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2
Q

What are the 4 stages of Mitosis?

A

Prophase
Metaphase
Anaphase
Telophase

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3
Q

What happens during interphase? (5)

A

1.Growing in size
2.Obtaining nutrients
3.Duplicating cell organelles, cytoplasmic components
4. By copying (replication) its DNA (each chromosome
contains 2 sister chromatids with single centromere)
5.Duplication of centrioles

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4
Q

How long do cells remain in interphase?

A

Most of its life cycle approx. 23hours.

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5
Q

What are the three phases of interphase and what happens during each?

A

G1
G2
S

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6
Q

What happens during prophase of mitosis?

A

Chromosomes begin to coil, become thick and short
-Each chromosome contains 2 chromatids (sister chromatids) joined at the centromere

Centrioles separate and move to the opposite poles of the cell

Parallel running microtubules (spindle fibres) formed and extend between 2 centrioles – spindle formation

Nucleolus disappears
Nuclear envelop disappears and chromosomes are released to cytoplasm

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7
Q

What happens during metaphase of mitosis?

A

As the nuclear membrane disappears the spindle
occupies the central region of cell

Chromosomes move toward the equator of the spindle and arrange themselves in a line- metaphase plate

Microtubules (spindle fibres) attached to centromeres of chromosomes

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8
Q

What happens during anaphase of mitosis?

A

Centromeres divide and sister chromatids separate
into individual chromosomes

Spindle fibers contract, the chromosomes are pulled to
opposite poles of the cell

Cleavage furrow is formed at the equator of the cell by in folding of the cell membrane

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9
Q

What happens during teleophase mitosis?

A

Chromosomes gather at opposite ends of the cell
and nuclear membrane is reformed around them

The spindle disintegrates

Cleavage furrow becomes deep and divides the cell
into two (cytokinesis)
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10
Q

What is meiosis?

A

Special type of cell division which occurs in testes and ovary during the production of sperms and ovum

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11
Q

What does meiosis result in?

A

Four daughter cells produced at the end of 2 divisions.

Each daughter cell contains half the number (haploid) of parent cell chromosomes

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12
Q

What are the stages of meiosis?

A

Two divisions occur in quick succession (meiosis I and meiosis II)

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13
Q

What happens during interphase of Meiosis?

A

Replication (duplication) of DNA takes place

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14
Q

How many phases does Meiosis I have?

A
  1. Prophase I
  2. Metaphase I
  3. Anaphase I
  4. Telophase I
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15
Q

How many phases does Prophase I of Meiosis have?

A
  1. Leptotene
  2. Zygotene
  3. Pachytene
  4. Diplotene
  5. Diakinesis
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16
Q

What happens during Leptotene phase of Prophase I?

A

Chromosomes appear as individual threads

Attached at one end to the nuclear envelope

Chromosomes show beads (chromomeres) throughout their length

17
Q

What happens during Zygotene phase of Prophase I?

A

Homologous chromosomes come together

Homologous chromosomes pair point to point and called bivalents

These are held together by a fibrillar band called synaptonemal complex

One end connected to nuclear membrane

18
Q

What happens during Pachytene phase of Prophase I?

A

Shortening and thickening of chromosomes continue

Two chromatids of a chromosome become visible

Chromatids from 2 chromosomes coil around each other

Exchange of DNA occurs by breaking and rejoining of chromatids – crossing over

19
Q

What happens during Diplotene phase of Prophase I?

A

Chromosomes become short and thick

Begin to separate except where the crossing
over has occurred

As the chromosomes become short, the
crossing points become visible

20
Q

What happens during Diakinesis phase of Prophase I?

A

Chromosomes become short, thick and get
separated, but homologous chromosomes lie
together

21
Q

What happens during Prophase I of meiosis?

A

The centrioles move to the opposite poles of
the cell
– Spindle formation take place between centrioles
– Nuclear envelope disappears and homologous
chromosomes are released to cytoplasm

22
Q

What happens during metaphase I of mitosis?

A 
As the nuclear membrane
disappears the spindle
occupies the central region
of cell
• Paired homologous
chromosomes move toward
the equator of the spindle
and arrange themselves in
a line
– metaphase plate
• Microtubules attached to
centromeres of paired
chromosomes
23
Q

What happens during anaphase I of mitosis?

A 
Spindle fibers
contract, the paired,
homologous
chromosomes are
pulled to opposite
poles of the cell
• Cleavage furrow is
formed at the equator
of the cell by in
folding of the cell
membrane
24
Q

What happens during telophase I of mitosis?

A

Chromosomes gather at opposite ends of the cell
and nuclear membrane is reformed around them
• The spindle disintegrates
• Cleavage furrow becomes deep and divides the
cell into two
• Each cell has 23 chromosomes
• Each chromosome is with 2 sister chromatids
• Each cell has haploid number of chromosomes but
with diploid amount of DNA
Nuclear membrane reforms

25
Q

What are the 4 stages of Meiosis II?

A
  1. Prophase II
  2. Metaphase II
  3. Anaphase II
  4. Telophase II
26
Q

What happens during prophase II of meiosis II?

A

Centrioles move to opposite poles

Spindle formation takes place

Nuclear envelope disappears and 23 chromosomes
(each with 2 sister chromatids) released to
cytoplasm

27
Q

What happens during metaphase II of meiosis II?

A

All 23 chromosomes arrange in a line at the equator

Microtubules (spindle fibres) attached to
centromeres of chromosomes

28
Q

What happens during anaphase II of meiosis II?

A

Centromeres split, sister chromatids are pulled to the opposite poles by the spindle fibres

Cleavage furrow is formed at the equator of the cell by infoldings of the cell membrane

29
Q

What happens during telophase II of meiosis II?

A

23 chromosomes gather at opposite ends of
the cell and nuclear membrane is reformed
around them

Spindle disintegrates

Cleavage furrow becomes deep and divides the
cell into two

30
Q

What are the four chromosomal abnormalities that can occur?

A

Down syndrome (trisomy 21)

Klinefelter syndrome

Turner syndrome (Monosomy X)

31
Q

What is Down syndrome?

A 
Down syndrome (trisomy 21) is a condition in which a
person has an extra chromosome
32
Q

What is Klinefelter syndrome?

A

Genetic condition that results when a boy is born with an extra copy of the X chromosome

33
Q

What is Turner syndrome?

(Monosomy X)

A

A condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing

Anatomy (9 decks)

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