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Bio 204 > Miosis > Flashcards

Miosis Flashcards

(80 cards)

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1
Q

Sexual reproduction

A

Producing offspring via gametes
Depends on miosis, DNA recombination
Consists of n cells

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2
Q

Fertilization

A

The nuclei of an egg and a sperm meet producing a zygote, further mixing DNA

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3
Q

Fertilization cycle

A

Fertilization (2n)– miosis(2n)–spore(n)–mitosis–gametes

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4
Q

Spores

A

Divide using mitosis

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5
Q

Animals

A

2n phase dominates miosis directly followed by gamete formation

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6
Q

Males miosis

A

Each miotic cell turns into a functional sperm

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7
Q

Females miosis

A

1/4 nuclei turn into a functional egg cell

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8
Q

Most plants, some fungi

A

Alternate n and 2n generations. Fertilization produces 2n sporophytes. Miosis occurs and n spores are produced

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9
Q

Spores in plants

A

Become n gametophytes which can mature into gametes. Identical because miosis does not occur

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10
Q

Most fungi

A

2n phase is limited to only the zygote

Immediatly after fertilization miosis produces n, where mitosis can occur

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11
Q

Fungi fertilization

A

2, n gametes (+)/(-) meet. 4, n cells produced from 1 2n cell

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12
Q

Miosis

A

Produces 2 different cells. Occurs in specialized tissues producing gametes and spores

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13
Q

Homologous chromosomes have

A

The same genes in the same order in the DNA, but might have different alleles

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14
Q

Homologous chromosomes are made of

A

1 paternal chromosome and 1 maternal chromosome

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15
Q

Roles of miosis

A

Increase variability and half the chromosome number

Each n cell carries half the genes for a homologous chromosome

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16
Q

Genetic recombination purpose

A

Have maternal and paternal genes passed on

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17
Q

Meiocytes

A

Cells that divide by miosis. S phase occurs, creating 2 daughter cell SNA for G2 phase

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18
Q

Miosis I

A

Synapsis occurs. Chromosomes pair lengthwise gene for gene and recombination occurs. 2 daughter cells with n (double) chromosomes are produced

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19
Q

Miosis II

A

Sister chromatids are separated. 4 cells with n chromosomes are created

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20
Q

Internkinesis

A

Interphase that seperates the 2 miotic cycles. No DNA replication occurs

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21
Q

Prophase I

A

Duplicated chromosomes fold and condense
pairing and synapsis occurs
recombination between homologous pairs
Spindle fibers form

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22
Q

Synapsis

A

Homologous pairs line up side by side forming tetrads

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23
Q

Tetrads

A

A make up of 4 chromatids

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24
Q

Prometaphase I

A

Nuclear membrane breaks
Spindle fibres connect
Kinetochore microtubules connect to 1 sister chromatid

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25
Metaphase I
Spindles line chromosomes on the metaphase plate
26
Anaphase I
Double structured sister chromosomes are divided to the poles
27
Telophase I
Brief, nuclear membrane may reform
28
Interkinesis
Spindle fibers disassemble and become 2 spindle fibers for miosis II
29
Prophase II
Chromosomes condense
30
Prometaphase II
Nuclear membrane breaks down, spindle fibers enter and attach
31
Metaphase II
Spindle movement brins chromosomes to the metaphase plate
32
Anaphase II
Sister chromatids separate and move to the poles (now are single chromosomes)
33
Telophase II
Chromatids decondense, spindles disintegrate and the nuclear envelope forms
34
Failure in chromosome separation miosis I
A whole tetrad moves to 1 pole in anaphase. Results in 2, 24 chromosome cells and 2, 22 chromosome cells
35
Failure in chromosome separation miosis II
A chromatid doesn't separate in anaphase. Results in 1 24 chromosome cell, 1 22 chromosome cell, and 2 23 chromosome cell
36
Down syndrome
2 copies of chromosome 21 end up in 1 cell
37
Sex chromosomes
Different in males and females for the same species
38
XX
Homologous chromosomes in females
39
XY
Males, the y is smaller, homologous throughout the shot region. Act as homologous chromosomes in division
40
Miosis purpose
Create repaired chromosomes to allow organisms to grow
41
Repairing chromosomes
Make a good chromosome if both of the parents ones are damaged
42
Genetic variability comes from
1. Genetic recombination of homologous chromosomes 2. Differing maternal and paternal genes segregated during anaphase I, II) 3. Different combos of chromatids after anaphase II 4. Which male and female gametes mix
43
Genetic recombination is miosis
Homologous chromosomes are similar enough to pai, but different. DNA segments are switched using enzymes
44
Synaptonemal complex
Holds homologous chromosomes tightly together during synapsis Disassembles at the end of prophase I
45
Products of miosis
Unchanged parental chromatid and recombinant chromatids. 2x per division
46
Cross over (chiasmata)
When non sister chromatids cross each other. 2/4 chromatids are altered Pair on top of each other not side by side
47
Cross over location
Can occur on any part, for any length of chromatid
48
Random srgregation
In prometaphase spindles attach randomly therefore some maternal and some paternal chromatids end up in each cell
49
Random segregation formula
2^n
50
Alternative combinations at miosis II
A recombinant and a non recombinant in every cell
51
Random fertilization
Egg and sperm combine fully by chance. The only exception is identical twins, triplets...
52
Mobil elements (jumping genes)
DNA that can move and does not require homology | Move around within a genome of a given cell
53
Transport elements (TEs)
Mechanisms of movement involving non homolgous recombination call transposition
54
Types of transposition
Cut and past, copy and paste
55
Cut and past transposition
TE leaves its original position and transposes to a new location
56
Copy and paste transposition
A copy of the TE is transposed to a new location, the original stays
57
TE transportation
DNA contact is always maintained. Starts with contact between TE and the target site
58
Roles of TEs
Gene mutation causing and increase or decrease in gene expression, alter the function or increase genetic variability
59
Bacterial TEs
Move between bacterial chromosomes, bacterial chromosomes and plasmids, and plasmids
60
Bacterial TEs can
Transpose anywhere, others have hot spots for insertion
61
Types of TEs
Insertion sequences and transposon
62
Insertion sequences (IS)
Small, simple and contain genes for transposition and transposase Have an inverted repeat sequence
63
Transposase
An enzyme that catalyzed recombination reactions for TE
64
Inverted repeat sequences
Occur on each end of the IS. Same DNA sequence running in opposite directions
65
Inverted repeat sequences purpose
Allow transposase to identify the ends of the TE | Create the homology needed for Hfr
66
Transposon
Inverted repeat sequence with 1 or more genes in between
67
Transposon in bacteria
Inverted repeat sequence is the IS
68
Additional genes in transposon
Often Often code for antibody resistance. Can be form bacterial chromosomes or plastids
69
Antibiotic resistance
Occurs because of resistance genes. Conjugation passed this along to many cells
70
TE discovery
Leaf and Kenal mutations of corn rapidly went away under some conditions. Allele mapping showed alleles could move in corn chromosomes
71
1970 TE
They were accepted for eukaryotes and prokaryotes
72
Types of eukaryotic TE
Transposons and retrotransposons
73
Retrotransposons
Copy and paste. Transposition happens via an intermediate RNA cop of the TE
74
3 steps to retrotransposon
1. The retrotransposons part of the DNA is transcribed 2. Reverse transcriptase 3. The DNA copy is inserted into its new location. DNA backbones are broken and rejoined
75
Reverse transcriptase
An enzyme coded by retrotransposon gene that uses RNA as a template
76
Retrotransposon in gametes
Can be inherited and therefore exists in many generations
77
TE mutations
Happen until the DNA is a nonmobile, residual sequence. Eukaryotes have many of these
78
Retroviruses
Eukaryotic viruses that act the same as retrotransposon by releasing RNA into the host cells DNA after it is copied
79
Proviruses
Similar to the prophage of bacteria
80
Retroviruses can...
Cause DNA rearrangement (deletion or translocation) Pick up host genes and move them to recipients Lead to abnormal activity (often resulting in cancer

Bio 204 (23 decks)

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