Mitosis & Meiosis Flashcards

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0
Q

Types of cell division in prokaryotic organisms

A

Prokaryotic fission

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1
Q

Types of cell division in eukaryotic organisms

A

mitosis; meiosis

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2
Q

What are the functions of mitosis, in both multicellular organisms and in some protists, fungi, plants and animals?

A

Multicellular organisms:
Growth, cell replacement
Some protists, fungi, plants, animals:
Asexual reproduction

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3
Q

List the steps of interphase

A

G1, S, G2

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4
Q

List the steps of mitosis

A

prophase, metaphase, anaphase, telophase

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5
Q

G1 interphase

A

The time of normal self functioning and growth

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6
Q

S interphase

A

DNA replication

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7
Q

G2 interphase

A

Time when proteins are made for cellular division

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8
Q

What keeps cellular division in check?

A

Inbuilt molecular break in the G1 phase; once S phase begins, cycle generally runs through G2 and then meiosis. Cancer involves the malfunction of this G1 molecular break, cousin a runaway in the cycle.

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9
Q

What occurs during early, then late prophase?

A

Early prophase: duplicated chromosomes begin to condense.
Late prophase: new microtubules are assembled, one centriole pair is moved towards opposite pole, nuclear envelope starts to break up.

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10
Q

When does the spindle form?

A

During the transition to metaphase.

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11
Q

Where do the spindle microtubules attach to the chromatids?

A

The kinetochore, one on the side of each of the two sister chromatids of each chromosome.

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12
Q

During what phase of mitosis are chromosomes maximally condensed?

A

metaphase

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13
Q

During what phase do spindle microtubules become attached to the kinetochores?

A

Transition to metaphase

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14
Q

During which phase are all chromosomes lind up at the spindle equator?

A

metaphase

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15
Q

What are separated chromatids called?

A

chromosomes

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16
Q

Doing which phase are sister chromatids of each chromosome pulled apart?

A

anaphase

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17
Q

What occurs during telophase?

A

Chromosomes de-condense; two nuclear membranes form: one around each set of under duplicated chromosomes

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18
Q

What are the results of mitosis?

A

Two daughter nuclei, each with the same chromosome number as the parent cell, in unduplicated form.

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19
Q

When does cytoplasmic division occur?

A

Generally between late anaphase and the end of telophase.

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20
Q

What is the mechanism for cytoplasmic division in plants?

A

cell plate formation

21
Q

What is the mechanism for cytoplasmic division in animals?

A

cleavage: A contracting ring of actin and myosin microfilaments create a cleavage furrow as they pinch off the phospholipid bilayer.

22
Q

Homologous pairs

A

Pairs of chromosomes that have the same genes but can possess different alleles

23
Q

karyotype

A

(Greek karyon = kernel, seed or nucleus) The number and appearance of chromosomes in the nucleus of a eukaryotic cell, under a light microscope

24
Q

chromatin

A

DNA fibres in a loose state, composed of roughly equal amounts of DNA and protein molecules.

25
Q

Interphase

A

Period of cell growth, when new organelles and molecules are synthesised. By late interphase, much of the DNA has been duplicated, but cannot be seen individually because it is still loosely packed as chromatin.

26
Q

Prophase

A

Miotic spindle begins to form, discreet chromosomes form, appearing no duplicated forms as two sister chromatids connected at the centromere.

27
Q

Prometaphase

A

Nuclear envelope disappears, microtubules attach to the new kinetochore on each side of the centromere from each end of the miotic spindle.

28
Q

Metaphase

A

Miotic spindle fully formed, chromosomes converge equidistantly from the poles of the spindle, known as the metaphase plate. Kinetochores of each chromatid face the poles.

29
Q

Anaphase

A

Begins when the two centromeres of each chromosome comes apart, separating the chromatids. Each separated chromatid are now labeled daughter chromosomes. Cell elongates as poles move further away from each other.

30
Q

Telophase

A

Cell elongation begun in anaphase continues, dual daughter nuclei appear at either pole of the cell. Mitosis complete as chromatin unravels and the miotic spindle disappears.

31
Q

Cytokinesis

A

Division of cytoplasm, usually occurs along with telophase with the separation of the two new cells.

32
Q

Metaphase plate

A

An imaginary plane equidistant the two poles of the miotic spindle, where chromosomes align during metaphase.

33
Q

Binary fission

A

(Dividing in half), mode of reproduction for prokaryotes.

34
Q

Cell plate

A

During telophase of mitosis in plants, vesicles containing cell wall material collect at the middle of the parent cell, forming the cell plate, which extends out towards the existing walls to cull off a new cell.

35
Q

Somatic cell

A

Typical body cell, diploid, contains a homologous pair of chromosomes.

36
Q

Sex chromosomes

A

X and Y in humans, which one inherited determines sex of an individual. (XX female, XY male)

37
Q

diploid

A

A cell containing a homologous pair of chromosomes.

38
Q

gametes

A

Haploid cells created for sexual reproduction, containing a single set of chromosomes, only one of each of the parent cell’s original homologous pair.

39
Q

haploid

A

A cell with a single set of chromosomes.

40
Q

zygote

A

Fertilised egg containing two sets of homologous chromosomes.

41
Q

Fertilisation

A

A haploid sperm cell fuses with a haploid egg cell.

42
Q

Synapsis

A

A process in which homologous chromosomes, each composed of two sister chromatids, come together as pairs. The resulting structure is known as a tetrad.

43
Q

Tetrad

A

Structure consisting of four chromatids, two pairs of homologous chromosomes, during prophase I

44
Q

What is the difference between mitosis and meiosis II?

A

Miosis II starts with a haploid cell, while mitosis starts with a diploid cell.

45
Q

When does crossing over occur?

A

During prophase I.

46
Q

Crossing over

A

The exchange of corresponding segments between non-sister chromatids of homologous chromosomes.

47
Q

chiasma

A

The sites of crossing over, appearing as X-shaped regions under a microscope.

48
Q

Genetic recombination

A

The production of gene combinations different from those carried by the original parental chromosomes, achieved through crossing over.

49
Q

What is the average rate of crossover per chromosome pair in humans?

A

2-3 chiasma per chromosome pair.

50
Q

Nondisjunction

A

An error during meiosis where members of a chromosome pair fail to separate; can occur either during meiosis I or II

51
Q

Polyploid

A

A species that has more than two sets of homologous chromosomes in each somatic cell.