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BIO 105 > LEC 15 > Flashcards

LEC 15 Flashcards

Mitosis & Meiosis

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1
Q

Parts of Mitotic Phase (2)

A
  1. “mitosis” (process of nuclear division)
  2. “cytokinesis” (cytoplasm division)
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2
Q

Mitotic Phase end result

A

2 new daughter cells

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3
Q

Mitosis Phases (4)

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

Mitosis time frame

A

60 min

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5
Q

Mitosis def

A

process by which a single parent cell divides to make two new daughter cells in 4 phases

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6
Q

What happens to centrioles during prophase?

A

centrioles move to opposite poles of cell

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7
Q

What happens to nuclear membrane during prophase?

A

disappears

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8
Q

What happens to centromeres during prophase?

A

Centromeres on the sister chromatids develop into two separate structures – one for each duplicated DNA molecule

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9
Q

What happens to the microtubule portion of cytoskeleton during prophase? (2)

A

comes apart and reforms a mitotic spindle which lengthens between centrioles

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10
Q

What happens to the mitotic spindle during prophase? (2)

A

reforms and lengthens between centrioles

crosses through the middle of the cell after nuclear membrane disappears

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11
Q

Prophase in order (5)

A
  1. Centrioles move to opposite poles of cell
  2. Microtubule portion of cytoskeleton comes apart
  3. Reforms a mitotic spindle which lengthens between centrioles
  4. The nuclear membrane disappears
  5. Mitotic spindle now crosses through the middle of the cell
  6. Centromeres on the sister chromatids develop into two separate structures – one for each duplicated DNA molecule
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12
Q

Metaphase is called the:

A

position-changing phase

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13
Q

Metaphase time frame (2)

A

20 minutes and cell appears to rest

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14
Q

Metaphase in order (2)

A
  1. Duplicated chromosomes align across the centre of the cell (“metaphasic plate”)
  2. Mitotic spindle attaches to the two portions of the centromeres
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15
Q

Anaphase is called the:

A

apart phase

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15
Q

metaphasic plate

A

Centre of the cell where the duplicated chromosomes align

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16
Q

Anaphase time frame

A

1 minute

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17
Q

Anaphase end result

A

two complete & separate sets of identical chromosomes at opposite sides of the cell

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18
Q

Anaphase in order (2)

A
  1. Centromeres split, detaching the sister chromatids from each other
  2. Sister chromatids (now called daughter chromosomes) move to opposite poles as the mitotic spindle contracts and pulls
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19
Q

Anaphase needs _____ in the form of _____ and contractile proteins that act as “_____”

A
  1. energy
  2. ATP
  3. motors
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20
Q

Telophase is called the:

A

end phase

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21
Q

Telophase begins when:

A

the two sets of chromosomes arrive at poles of cell

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22
Q

Telophase is the _______ of prophase.

A

reverse

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23
Q

Telophase in order (3)

A
  1. The mitotic spindle comes apart
  2. Nuclear membranes form around chromosomes
  3. Chromosomes uncoil and revert back to non-visible form (chromatin)
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24
Q

Cytokinesis steps (4)

A
  1. Cytoplasm divides
  2. Contractile ring of protein filaments (remainders of the cytoskeleton) forms just inside the plasma membrane
  3. The contractile ring tightens and forms a cleavage furrow
  4. Cell gets “pinched” into two
    “daughter cells”
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25
Q

“daughter cells” def

A

Are identical to each other and their parent cell

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26
Q

Daughter cells produced through mitosis are ________

A

DIPLOID

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27
Q

46 chromosomes = ______ pairs of chromosomes

A

23

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28
Q

All human cells (except sperm and egg) have:

A

46 chromosomes

29
Q

“diploid” literal meaning

A

“diploos” meaning “two fold”

30
Q

23 chromosomes have: (2)

A

22 pairs of autosomes (chromosomes other than sex chromosomes)

1 pair of sex chromosomes (X & Y)

31
Q

why does mitosis & cytokinesis happen? (2)

A

happens constantly in some areas of the body for growth and repair of tissues

32
Q

where does mitosis & cytokinesis happen? (3)

A
  1. Epithelial cells
    Dead cells constantly worn away, need to be replaced
  2. Stomach lining
    Gastric juices are harsh, constantly wear away the lining
  3. Red bone marrow
    RBC have lifespan of 120 days
    Rate of 2 million new RBC are produced per second
33
Q

Abnormal cell division def

A

Malignant cancer cells
- Uncontrolled cell division
- Keep dividing and tend to spread

34
Q

Abnormal cell division causes

A

Mutations caused by carcinogens or viruses

35
Q

What can mutations lead to?

A

change in cell function

36
Q

Abnormal cell division treatment (2)

A

Removal of the malignant cells – radiation
Stop cell division - chemotherapy

37
Q

Meiosis is aka

A

Reduction-Division

38
Q

daughter cells of meiosis (2)

A
  1. gametes or mature sex cells
  2. haploid
39
Q

Meiosis def (2)

A
  1. two successive nuclear & cell divisions
  2. reduces the number of chromosomes by half in each daughter cell)
40
Q

What does meiosis create in males?

A

Sperm
Occurs in the testicles – men
Process of spermatogenesis

41
Q

Where does meiosis happen in males?

A

testicles

42
Q

What is the process of meiosis called in males?

A

spermatogenesis

43
Q

What does meiosis create in females?

A

ova (egg)

44
Q

Where does meiosis happen in females?

A

ovaries

45
Q

What is the process of meiosis called in females?

A

oogenesis

46
Q

Ova & sperm have a __________ number of chromosomes

A

haploid

47
Q

After _______ (when the two gametes join), the new individual () will have the number of chromosomes

A
  1. fertilization
  2. zygote
  3. diploid
48
Q

Prior to meiosis starting, cell goes through the ___________

A

normal S-phase

49
Q

What happens in the S-phase? (2)

A
  1. DNA replicates
  2. Sister chromatids held together by centromere
50
Q

Stages of Meiosis: (2)

A
  1. Meiosis I (Prophase I, Metaphase I, Anaphase I,
    Telophase I)
  2. Meiosis II (Prophase II, Metaphase II, Anaphase II,
    Telophase II)
51
Q

Meiosis I – Prophase I VS Mitosis Prophase

A

Same except crossing over occurs in meiosis

52
Q

Meiosis I – Prophase I crossing over (3)

A
  1. Duplicated homologous chromosomes pair up and form a tetrad
  2. The duplicated homologous chromosomes of each tetrad then “swap” sections of DNA (this is the “crossing over”)
  3. The result is a “re-shuffled genes” to give the homologous chromosomes a “recombination” of the parental genes
53
Q

Meiosis I – Metaphase I

A

Each tetrad (homologous pairs) line up along the equator of the cell, independent of the other tetrads

54
Q

Meiosis I – Anaphase I

A

Homologous pairs separate and move to opposite poles as the spindle fibres contract
The result is a random combination of maternal and paternal chromosomes

55
Q

Meiosis I – Telophase I

A

Cytokinesis occur
Cell cleaves and splits into two

56
Q

Meiosis I – End Result

A
  1. Two NON - IDENTICAL daughter cells
  2. Cells IMMEDIATELY enter into Meiosis II (DNA is NOT replicated before starting Meiosis II)
57
Q

Meiosis I – End Result Daughter cells

A

Each one has haploid number (23) of chromosomes, each consisting of two sister chromatids

58
Q

Is DNA is replicated after Meiosis 1 and before starting Meiosis II?

A

No

59
Q

Meiosis II

A
  1. Proceeds just like mitosis
  2. Sister chromatids separate
60
Q

End of result of MEIOSIS II

A

4 non-identical daughter cells

61
Q

Meiosis II – End Result Daughter cells (2)

A
  1. Each cell has haploid number (23 total) of chromosomes
  2. Daughter cells are NOT genetically identical to the original parent cells
62
Q

Differentiation

A

Cell becomes different from its parent or sister cell

63
Q

Differentiation why?

A

Due to certain genes being expressed

64
Q

Differentiation where and when?

A

At any point during the lifespan of the cell/organism

65
Q

Genes are __________ by ____________ factors around the cell

A
  1. influenced
  2. environmental
66
Q

zygote

A

slide 34

67
Q

compactation stage

A

slide 34

68
Q

morula

A

slide 34

69
Q

blastocyst

A

slide 34

70
Q

Factors affecting fetal development

A

Embryo may not survive or may have abnormalities if affected at the right time in the right concentration by external sources

71
Q

Factors affecting fetal development - External Sources: (7)

A
  1. Cigarettes – Increased cancer risk in offspring
  2. Alcohol – Fetal alcohol syndrome
  3. Legal Drugs – Thalidomide, marijuana etc.
  4. Illegal Drugs – Heroin, cocaine, etc.
  5. Chemical exposures – DDT, formaldehyde, PCB’s, lead, etc.
  6. Radiation – Ionizing and non-ionizing
  7. Intrauterine infections – HIV, syphilis, rubella (German measles)

BIO 105 (18 decks)

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