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Julia's Biology Final > Mitosis, Meiosis, and Gamete Formation > Flashcards

Mitosis, Meiosis, and Gamete Formation Flashcards

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1
Q

What are the two major stages of the cell cycle? Which one does the cell spend most of its time in?

A 
M phase (Mitosis and Cytokinesis) and Interphase
The cell spends most of its time in interphase. 
If the cell stops growing, it goes into G0 - not in the cell cycle.
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2
Q

What are the three stages of interphase? What happens in each of them?

A

G1 - cell grows, organelles are copied
S - DNA is copied. S=synthesis -> building and doubling the DNA
G2 - more cell growth, check for DNA errors

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3
Q

What are the four stages of mitosis? Which is the longest?

A

Prophase - longest phase
Metaphase
Anaphase
Telophase

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4
Q

What happens during PROPHASE of mitosis?

A
  1. Chromatin condenses - “packing the boxes”
  2. Centrioles move to opposite sides of the cell and form spindle fibers
  3. Nuclear membrane breaks down
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5
Q

What do the spindle fibers do?

A

Pull apart the chromosomes

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6
Q

What happens in METAPHASE of mitosis?

A
  1. Chromosomes line up down the middle of the cell

2. Spindle fibers attach to centromeres (the belt holding the two sister chromatids together) of each chromosome

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7
Q

What happens during ANAPHASE of mitosis?

A
  1. Centromeres separate, separating the sister chromatids into individual chromosomes
  2. Chromosomes move to opposite sides of the cell
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8
Q

What happens during TELOPHASE of mitosis?

A
  1. Chromosomes become CHROMATIN (un-condense back into a hot mess)
  2. Nuclear membrane reforms around each of the two clusters of chromosomes/chromatin
  3. Spindle fibers break apart
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9
Q

What happens during CYTOKINESIS?

A

Division of the rest of the cell

- Mitosis leaves us with one cell that has two nuclei; now the cytoplasm needs to split

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10
Q

How do animal cells do cytokinesis?

A

Cell membrane pinches in the middle - cleavage

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11
Q

How do plant cells do cytokinesis?

A

A CELL PLATE forms between the two halves, forming a cell membrane and a cell wall

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12
Q

What is BINARY FISSION?

A

The way that prokaryotic cells divide

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13
Q

How do prokaryotic cells divide?

A

Their DNA is circular. It’s copied, and then the cell membrane pushes inward between the two DNA copies and pinches off into two individual cells

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14
Q

How is prokaryotic DNA different than eukaryotic DNA?

A

Prokaryotic DNA is circular, eukaryotic DNA is linear

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15
Q

How does a cell know when it’s time to divide?

A

CYCLINS - special proteins that are present in various amounts throughout the cell cycle. These proteins help signal when the cells should should proceed to the next stage.

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16
Q

What is cancer?

A

When cells lose the ability to control growth.

They form masses of cells called tumors.

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17
Q

What are the two major stages of Meiosis?

A

Meiosis I and Meiosis II

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18
Q

Right before Meiosis I, all the chromosomes…

A

…duplicate

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19
Q

What happens in PROPHASE I of meiosis?

A
  1. Nuclear membrane breaks down and spindle fibers start to form (like in prophase of mitosis)
  2. Instead of each replicated chromosome lining up individually, each replicated pair joins with it pair to form a group of four sister chromatids, aka a TETRAD. Pairing process is called SYNAPSIS
  3. When in tetrad formation, homologous chromosomes may twist around each other and exchange segments of chromosomes, called CROSSING OVER
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20
Q

What is SYNAPSIS?

A

When each replicated chromosome lines up with its homologous pair in Prophase I

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21
Q

What is a TETRAD?

A

A group of four sister chromatids

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22
Q

What is CROSSING OVER? When does it happen?

A

When segments of chromosomes are exchanged while in tetrad formation in Prophase I

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23
Q

What happens in METAPHASE I of meiosis?

A
  1. Chromosomes line up in the center of the cell in TETRAD FORMATION
  2. The spindle fibers attach to the tetrads at their centromeres
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24
Q

What happens in ANAPHASE I?

A
  1. The homologous pairs separate from each other and move to opposite sides of the cell - this is called DISJUNCTION
  2. The two cells that will result are HAPLOID, however, each chromosome is still double stranded
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25
Q

What happens in TELOPHASE I of meiosis?

A

Cell divides into two new haploid cells that still has double stranded chromosomes

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26
Q

Is there any chromosome duplication for Meiosis II?

A

Nope - just gonna separate the sister chromatids.

JUST LIKE MITOSIS!

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27
Q

What happens in PROPHASE II of meiosis?

A
  1. Each daughter cell forms spindle fibers

2. The chromosomes (still in their replicated, double stranded form) move to the middle of the cell

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28
Q

What happens in METAPHASE II of meiosis?

A
  1. In each of the new cells formed from Meiosis I, chromosomes line up in the center of the cell, one by one
  2. The spindle fibers attach to the centromeres
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29
Q

What happens in ANAPHASE II?

A
  1. The two chromatids separate, each becoming a SINGLE STRANDED chromosome
  2. The chromosomes move to the opposite sides of the cell
30
Q

What happens in TELOPHASE II?

A
  1. Both daughter cells divide, forming 4 haploid cells
  2. Chromosomes return to chromatin
  3. Nuclear membrane reforms
31
Q

By the end of mitosis, are we left with a haploid or diploid cell?

A

Diploid (2n)

32
Q

By the end of meiosis, are we left with a haploid or diploid cell?

A

Haploid (n)

33
Q

At the end of mitosis, do the daughter cells have the same number or a different number of chromosomes as the parent cell? Explain.

A

The same number - the cell is exactly the same as its parent cell.

34
Q

At the end of meiosis, do the daughter cells have the same number or a different number of chromosomes as the parent cell? Explain.

A

Different number - it has half the amount. It has one chromosome from each homologous pair, and each chromosome is different, due to crossing over

35
Q

What are the cells produced from mitosis used for?

A

In multicellular organisms, they’re used as additional body cells for growth.
In unicellular organisms, they’re used as asexual reproduction

36
Q

What are the cells produced from meiosis used for?

A

Gametes, cells used in sexual reproduction

37
Q

What are the female gonads called, and what do they produce?

A

Ovaries; produce egg cells

38
Q

What are the male gonads called, and what do they produce?

A

Testes; sperm

39
Q

What is gametogenesis?

A

The process by which gametes develop in the gonad via meiosis

40
Q

What is oogenesis?

A

Process of ovum formation that happens in the ovaries

Produces ONE usable egg cell and TWO POLAR BODIES

41
Q

What are oogonia?

A

The diploid cell before meiosis that will eventually become an egg. They develop into primary oocytes before birth.

42
Q

By the time a girl is born, what stage of meiosis are her eggs frozen in?

A

Prophase of Meiosis I - they then enter a resting phase.

43
Q

What is a polar body?

A

A small, nonfunctional cell. It dies.

44
Q

What is a secondary oocyte?

A

Large cell that receives most of the cytoplasm at the end of Meiosis I

45
Q

When does Meiosis II happen?

A

At fertilization

46
Q

What does the secondary oocyte divide into?

A

An ootid and a polar body

47
Q

What’s does an ootid develop I Told?

A

A mature egg

48
Q

What is spermatogenesis?

A

Process of sperm formation, which occurs in the testes

49
Q

What are spermatogonia? What can they develop into?

A

Diploid cells
They undergo mitosis throughout the entire life of a male to produce more spermatogonia
Some enlarge and become primary spermatocytes

50
Q

What do primary spermatocytes become after Meiosis I?

A

Haploid cells called SECONDARY SPERMATOCYTES

51
Q

What do secondary spermatocytes become after Meiosis II?

A

Four equal sized cells called SPERMATIDS

52
Q

What do spermatids develop into?

A

They grow tails and become sperm cells

53
Q

What is fertilization?

A

Union of a haploid sperm cell and a haploid egg. Forms a diploid ZYGOTE

54
Q

What are the two types of fertilization?

A
  1. External fertilization - outside the body

2. Internal fertilization - inside the body

55
Q

How does external fertilization occur? How many eggs/zygotes?

A

Gametes join together outside the female.
Many eggs.
A large number of zygotes are produced because they are more likely to get damaged outside.

56
Q

How does internal fertilization occur? How many eggs/zygotes?

A

Gametes join together inside the female.
Few eggs.
Few zygotes are produced because if the moist internal environment inside the female

57
Q

What is a chromosomal mutation?

A

Variations in the number of individual chromosomes

58
Q

What is TRISOMY?

A

Three copies of a single chromosome

2n+1

59
Q

What does Down Syndrome result from? What is its frequency? What are some characteristics?

A

Results from a trisomy of 21 –> have 47 chromosomes
Found in 3 out of every 1,000, and frequency increases with mother’s age
Shorter stature with small round heads, mentally delayed, shorter life expectancy, more likely to have respiratory diseases and heart conditions

60
Q

What is Kleinfelter Syndrome?

A

Males with male genitalia but underdeveloped testes that cannot produce sperm
Some female sexual development occurs, such as enlargement of breasts
Karyotype determines that these individuals have a trisomy of the sex chromosomes - have an extra X chromosome

61
Q

What is a MONOSOMY?

A

Only have one chromosome - 2n-1

62
Q

What is Turner Syndrome?

A

Have only one X chromosome

Female secondary sexual characteristics don’t fully develop

63
Q

What is parthenogenesis? Give an example where this happens.

A

Development of an egg cell into a mature organism without being fertilized by a sperm cell
Ex male bees

64
Q

What are the 5 steps of normal embryo formation?

A
  1. Fertilization
  2. Cleavage
  3. Gastrulation
  4. Differentiation
  5. Growth of size and number of cells
65
Q

What is cleavage in embryo formation?

A

The zygote divides many times by mitosis, forming a hollow ball with a single layer of cells called a BLASTULA

66
Q

What happens during gastrulation? What are the three layers of the gastrula called?

A

One side of the blastula becomes indented, forming a GASTRULA
Outer layer - ectoderm
Inner layer - endoderm
Middle layer - mesoderm

67
Q

What happens during differentiation of the gastrula?

A

Cells of the three layers differentiate into various tissues and organs

68
Q

Prenatal Testing test the cells of a fetus for…

A

…genetic diseases

69
Q

What does fetal karyotyping allow parents and doctors to see?

A

The chromosomes of the fetus - the doctor can then check them for abnormalities

70
Q

Amniocentesis

A

A needle and syringe are used to remove a small amount of amniotic fluid. The fluid contains fetal cells, which are grown in a lab for 1-4 weeks to get a good sample size to get enough DNA to analyze

71
Q

Chorionic Villi Sampling (CVS)

A

A tissue sample is taken from a part of the placenta (hitch provides nourishment for the baby) called the chorionic villi. Doctors can then obtain a karyotype from these cells and test the DNA

Julia's Biology Final (7 decks)

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