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LF104: Molecules, Cells And Organisms > Lecture 45. Meiosis - Shuffling The Genetic Deck > Flashcards

Lecture 45. Meiosis - Shuffling The Genetic Deck Flashcards

1
Q

What move chromosomes?

A

Microtubules

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2
Q

How long is the DNA in a human cell?

A

Two metres

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3
Q

When can chromosomes be studied?

A

When they are condensed

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4
Q

What is a karyotype?

A

A catalogue of all the chromosomes in an organism

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5
Q

Do plants have sex chromosomes?

A

Some do

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6
Q

What are telomeres?

A

Found at the ends of the chromosome, they maintain length and have a repeated structure

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7
Q

What is the centromere?

A

Where the spindles attach to the chromosome, satellite DNA

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8
Q

What do euchromatin and heterochromatin do in the chromosome?

A

Package DNA, RNA & protein

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9
Q

What are the four structures a chromosome can have?

A

Telocentric
Acrocentric
Submetacentric
Metacentric

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10
Q

What is the short arm of a submetacentric chromosome called?

A

p

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11
Q

What is the long arm of a submetacentric chromosome called?

A

q

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12
Q

What can the visible bands in chromosomes tell you?

A

High resolution physical map position

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13
Q

What are the two types of cell division?

A

Mitosis and meiosis

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14
Q

What are the stages of mitosis?

A

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

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15
Q

What happens during interphase?

A

Chromosomes & organelles replicate

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16
Q

What happens during prophase?

A

Spindle begins extending from poles, and attaches to centromeres (kinetochore)

17
Q

What happens during metaphase?

A

Centromeres align at the equator (metaphase plate) - bipolar attachment

18
Q

What happens during anaphase?

A

Chromosomes migrate to opposite poles - sister chromatids are now chromosomes

19
Q

What happens during telophase?

A

Chromosomes at poles, spindle disassembles, nuclear membrane reforms

20
Q

What happens during cytokinesis?

A

Chromosomes decondense and cells divide

21
Q

What breaks down the cohesin protein between metaphase and anaphase?

A

Separase

22
Q

What does meiosis result in?

A

Four genetically distinct cells

23
Q

What occurs in prophase I during meiosis?

A

Centrosome splits & move to poles DNA condensing begins
Homologous chromosomes align & synaptonemal complex forms
Doublestrand breaks arise & chiasmata form
Nuclear membrane breaks down
Spindle begins to form DNA fully condensed, synaptonemal complex breakdowns, & monopolar kinetochores attach chromosomes to spindle

24
Q

What occurs in metaphase I during meiosis?

A

Kinetochores have aligned at the equator (metaphase plate)

25
Q

What occurs in anaphase I during meiosis?

A

Monopolar attachment pulls homologous chromosomes to opposite poles

26
Q

What occurs in telophase I and anaphase I during meiosis?

A

Haploid cells have formed
‘Shuffling the deck’ has occurred by independent assortment of parental chromosomes and crossing-over of chromosome arms

27
Q

What are the five stages of prophase I?

A

Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis

28
Q

What occurs in leptotene?

A

Leptotene - ‘thin thread’ stage
Chromosomes start to condense & become visible
Homolog pairing begins
Double-strand DNA breaks are introduced (potential sites for crossing-over)

29
Q

What occurs in zygotene?

A

Zygotene - ‘paired threads’ stage
A synaptonemal complex begins to form between homologous pairs (Synapsis)
Paired homologs now referred to as bivalents

30
Q

What occurs in pachytene?

A

Pachytene - ‘thick thread’ stage
Condensing of chromosomes continues
Synaptonemal complex is complete
Bivalents now have four sister chromatids (tetrads)
Crossing-over is completed

31
Q

What occurs in diplotene?

A

Diplotene - ‘two thread’ stage
Synaptonemal complex disassembles
Each pair of sister chromatids begins to separate
Chiasmata are visible regions of cross-over between non-sister chromatids

32
Q

What occurs in Diakinesis?

A

Diakinesis - ‘moving apart’ stage
Chromosomes repel each other
Non-sister chromatids remain loosely associated via chiasmata
Nuclear membrane and nucleolus disappear
Monopolar attachment of chromosomes to spindle fibers

33
Q

What are the functions of the synaptonemal complex?

A

Facilitates late stages of recombination
Prevents different homolog pairs from getting entangled

LF104: Molecules, Cells And Organisms (33 decks)

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