Chapter 2: Mitosis and Meosis Flashcards

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1
Q

The Nucleus is

A

-Found in eukaryotes
-Membrane-bound
-Houses genetic material (DNA)

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2
Q

Nucleolus

A

-Where ribosomal RNA (rRNA) is synthesized

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3
Q

-Nucleolus organizer region (NOR)

A

DNA that encodes rRNA

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4
Q

Nucleoid

A

-Found in prokaryotes
-NOT membrane bound

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5
Q

Cytoplasm includes:

A

-Nuclear cellular organelles are contained here

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6
Q

Cytosol

A

Colloidal material surrounding organelles

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7
Q

Cytoskeleton

A

Made of extensive system of tubules and filaments. Includes:
-Microtubules
-Microfilaments

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8
Q

Microtubules:

A

Made up of the protein tubulin

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9
Q

Microfilaments

A

Derived from the protein actin

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10
Q

Endoplasmic Reticulum

A

An organelle that:
-compartmentalizes cytoplasm
-increases the surface area for biochemical synthesis

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11
Q

Smooth Endoplasmic Reticulum

A

Site of fatty acid and phospholipid synthesis

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12
Q

Rough Endoplasmic Reticulum

A

Rough is studded with ribosomes
-Site of protein synthesis

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13
Q

Mitochondria

A

Within plant and animal cells
-Site of OXIDATIVE phases of cellular respiration, which generate ATP

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14
Q

Chloroplasts

A

Contained in plants, algae, protozoans
-Site of photosynthesis

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15
Q

Centrioles (ONE OF THE TWO LITTLE CUTE THINGS IN THE CENTROSOME)

A

-Found in the centrosome (the region, or the the cute little paired thingies involved in mitosis)
-Organize spindle fibers for movement of chromosomes during meiosis and mitosis
-Made of MICROTUBULES
-(inside of every cell) come to ends of cells and microtubules pulls the cells apart

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16
Q

Chromosomes exist as ___________ ______ in diploid organisms

A

HOMOLOGOUS PAIRS

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17
Q

Homologous chromosomes

A

-Similar, but not identical (different versions of the same gene)
- Carry genes for the same inherited characteristics
-May carry different versions of the same gene

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18
Q

Alleles

A

Different versions of the same gene

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19
Q

Centromere

A

-Constricted regions on chromosomes
-Location of centromere established appearance of chromosome

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20
Q

Different locations of the centromere, establishing the appearance of the chromosome:

A

-Metacentric: centromere is positioned in the middle
-Submetacentric: Slightly above the middle
-Acrocentric: Above the middle line
-Telocentric: Centromere is literally located on the top, forming an upside-down “c” shape

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21
Q

Sister chromatids

A

Draw a line vertically down the middle of homologous chromosomes, and you get the sister chromatids

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22
Q

Long arm on sister chromatid

A

q Arm

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23
Q

Short arm on sister chromatid

A

p arm

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24
Q

Somatic Cells

A

the regular body cells that have homologous pairs of chromosomes

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25
Q

Humans have ___ chromosomes, meaning they have ___ homologous pairs

A

46
23
Represents the diploid number, 2n

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26
Q

Karyotype

A

Illustrates the physical a[[earance of the differnet pairs of homolougous chromosomes
Remember the matching up activity in bio lab?!

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27
Q

Meiosis converts the diploid numner (2n) of chromosomes to the ________

A

haploid number (n)

Note: n is the number of chromosomes

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28
Q

Genome

A

genetic information in the haploid set

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29
Q

Locus

A

Homologous chromosomes contain identical gene sites along their lengths
Each site is called a locus

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30
Q

Biparental inheritance

A

inheritance from two parents
(diploid organisms contain two copies of each gene)

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31
Q

Alleles

A

alternative forms of the same gene

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32
Q

Sex-determining chromosomes

A

NOT homologous
Behave as homologs in meiosis
Ex. X and Y

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33
Q

Zygote

A

single-celled fertilized egg of multicellular organisms

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34
Q

Karyokinesis

A

genetic material partitioned to daughter cells during nuclear division

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35
Q

Cytokinesis

A

Cytoplasmic division

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36
Q

Cell cycle

A

composed of interphase and mitosis

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37
Q

Interphase (brief summary)

A

S phase: DNA is synthesized
Two gap phases: (G1 and G2)

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38
Q

Seperate phase that is part of interphase

A

G0 phase: point within G1 phase where cells are nondividing, but at a metabolically active state

Cancer cells do NOT have a G0 phase

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39
Q

Interphase

A

characterized by the absence of visible chromosomes
-Chromosomes are generally extended and uncoiled, forming chromatin

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40
Q

Mitosis has 5 discrete stages:

A

-Prophase
-Prometaphase
-Metaphase
-Anaphase
-Telophase

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41
Q

Prophase

A

Centrioles divide, move, and establish poles
Nuclear envelope breaks down
Chromosomes condense and become visible

42
Q

Sister chromatids in the Prophase

A

Sister chromatids: the two parts of each chromosome
Connected at the centromere
Held together by a multi-subunit protein complex called coheSIN

43
Q

Prometaphase

A

Period of chromosome movement to equatorial plane of the cell
Centrioles reached the poles
Spindle fiber forms

44
Q

Equatorial plane

A

METAPHASE PLATE

45
Q

Metaphase

A

Chromosome configuration following migration
Centromeres align on the metphase plate

46
Q

Kinetochore

A

Proteins associated with centromere
Spindle fibers bind to kinetochore; chromosomes migrate

47
Q

Kinetechore microtubules

A

Have one end near the centrosome region (the two little paired thingies) and the other anchored to the kinetochore

48
Q

Cohesin

A

Protein complex that holds sister chromatids together

49
Q

Separase

A

Enzyme that degrades cohesin

50
Q

Shugoshin

A

Protein that protects cohesin from being degraded by separase

51
Q

Anaphase

A

AKA disjunction
Sister chromatids seperate and are now called DAUGHTER CHROMOSOMES
-Migrate to opposite poles by shortening the spindle fibers
-Motor proteins or molecular motors use ATP

52
Q

Telophase

A

-Cytokinesis takes place
-Uncoiling of the chromosomes takes place
-reformation of the nuclear envelope
-Spindle fibers disappear
-Nuclear envelope reforms

53
Q

Cytokinesis

A

Two new cells are produced

54
Q

Cytokinesis in Plant cells

A

-a CELL PLATE is synthesized and laid down across the metaphase plate
-Becomes the MIDDLE LAMELLA

55
Q

Middle Lamella

A

a layer that cements together the primary cell walls of two adjoining plant cells.

56
Q

Cytokinesis in animal cells

A

a constriction of the cytoplasm or cell furrow

57
Q

Mitosis (brief summary)

A

Partitions chromosomes into dividing cells
Produces daughter cells with a FULL diploid complement of chromosomes

58
Q

CELL CYCLE REGULATION AND CHECKPOINTS

A

Mutations are known to exert an effect on the cell cycle

59
Q

Cell division cycle mutations (cdc) mutaions

A

related to enzymes called kinases

60
Q

Kinases

A

Can add phosphates to other proteins to regulate the cell cycle
-an enzyme that catalyses the transfer of a phosphate group from ATP to a specified molecule.
-Known as the MASTER CONTROL molecules functioning in conjunction with cyclin proteins

61
Q

Cell cycle checkpoints

A

monitor mitosis for errors

62
Q

Meiosis: reduction of genetic content and chromosomes

A

Reduces genetic material by half
-Produces haploid gametes or spores, each containing one member of a homologous pair of chromosomes

63
Q

Crossing over

A

A meiotic event in which there is a genetic exchange between members of homologous pairs of of chromosomes

64
Q

Over view of Meiosis

A

Meiosis I: Reductional division
Meiosis II: Equatorial division
DNA synthesis (during interphase): before the beginning of meiosis I
Does not occur again before Meiosis II

65
Q

Meiosis I and II

A

each have a prophase, metaphase, anaphase, and telophase

66
Q

Disjunction

A

Cause of genetic disease…
Occurs during meiosis I or II
sister chromatids aren’t seperated from each other, even through they should be

67
Q

Meiosis I: Prophase I

A

FIVE substages, each with specific events:
-Leptonema
-Zygonema
-pachynema
-Diplonema
-diakinesis

ENd of prophase I: centromeres are present on the equatorial plate

68
Q

Chromomeres

A

Kinda compact DNA

69
Q

Bivalent

A

homologous chromosomes

70
Q

Tetrad

A

total of 4 homologous chromosomes

71
Q

Chiasma

A

a point in which the two homologous chromosomes are in contact with each other

Afterwards is terminalization

72
Q

Substages of Prophase I: Leptonema

A

Chromosomes appear as long, single threads, unassociated with each other

73
Q

Substages of Prophase I: Zygonema

A

-Synapsis: pairing of two chromosomes
-Each pair of homologous chromosomes is known as bivalent (four chromatids)
-Tetrad: number of chromatids (four chromatids)

74
Q

Synapsis

A

pairing of two chromosomes (four chromatids)

75
Q

Substages of Prophase I: Pachynnema

A

Each bivalent becomes shorter, thicker, and splits into two sister chromatids called tetrads
-Crossing over occurs here: the exchange of genetic material between nonsister chromatids

76
Q

Terminalization

A

A process that occurs after corssing over in meisis.
-The chaismata move towards the ends of chromosomes
This helsps the homologous chromosomes seperate during cell division

77
Q

Which phase does crossing over occur in?

A

Prophase I, Pachynnema

78
Q

Terminalization doesnt occur in a specific stage of meiosis

A
79
Q

Substages of Prophase I: Diplonema

A

Within tetrads, sister chromatids seperate
Chiasma: Wherae chromatids are still intertwined (think of crossing over)

80
Q

Substages of Prophase I: Diakinesis

A

Nuclues and nuclear envelope break down
Centromeres attach to spindle fibers

81
Q

Meiosis I: Metaphase I

A

Chromosomes are at maximum shortness

82
Q

Meiosis I: Metaphase I (TERMINAL CHIASMATA)

A

These hold nonsister chromatids together
Binding to spindle fibers moves chromatids to metaphase plate

83
Q

Chiasma

A

the point of contact between two chromatids belonging to two homologous chromosomes

84
Q

Meiosis I: Anaphase I

A

Cohesion is degreaded between sister chromatids
Homologous chromosomes seperate
Nondisjunction may occur (failure of sister chromatids to separate)

85
Q

Meiosis I: Telophase I

A

Cytokinesis takes place
Two haploid cells result
Nuclear membrane forms
Nuclei enter interphase

86
Q

How many cells and what type of cells form after meiosis I?

A

Two haploid cells

87
Q

SUMMARY OF METAPHASE I, ANAPHASE I, AND TELOPHASE I

A

-homologous chromosomes seperate and move toward the poles
-Sister chromatids remain attached at centromeres
-Duplicated chromosomes reach the poles. each pole has a haploid set of chromosomes
-cytokinesis: two haploid daughter cells are formed
-nuclear envelope forms around the chromosomes in some species

88
Q

Sister chromatids are c shaped

A

like??? wow.

89
Q

Crossing Over produces genetic variation

A

Meiosis significatnly increases the level of genetic variation due to crossing over

90
Q

Does duplication occur in both Meiosis I and II?

A

No, it only occurs in Meiosis I

91
Q

Prophase II

A

each dyad is composed of one pair of sister chromatids attached by the centromeric region

92
Q

Dyad

A

a Pair of sister chromatids

93
Q

Metaphase II

A

The centromeres are positioned on the equatorial plate

94
Q

Anaphase II

A

sister chromatids are sperated to opposite poles
-Each haploid daughter cell from meiosis II has one member of each pair of homologous chromosomes

95
Q

Telophase II

A

one member of each pair of homologous chromosomes present at each pole
-Each chromosome is now a MONAD

96
Q

Cytokinesis in Meiosis

A

Results in 4 haploid cells

97
Q

Development of gametes differs between spermatogeneisis and oogenesis

A

Male gametes: produces by spermatogenesis in the testes
Female gametes: produced by oogenesis in the ovary

98
Q

Oogenesis

A

Formation of ova in the ovaries
Four daughter cells do not revcieve equal cytoplasm
Only one daughter cell recieves cytoplasm (PRIMARY POLAR BODY)
Develops into ovum

99
Q

Meiosis is critcal for successful sexual reproduction

Plant and fungi life cycles

A

Fungi: haploid vegetative cells arise via meiosis– proliferate via mitotic cell division
Plants: life cycle alternates between diploid sporophyte stage and haploid gametophyte stage

100
Q

Electron Microscopy

A

Chromosomes are only visible only during mitosis and meiosis
Chromatin fibers that make up chromosomes coil and condense
Folded-fiber model:

101
Q
A