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Gentics > Lecture 3: Mitosis and Meiosis > Flashcards

Lecture 3: Mitosis and Meiosis Flashcards

1
Q

Mitosis and meiosis allow for

A

Mitosis and Meiosis allow for observation of chromosomes
Distinguish size, shape and number

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2
Q

What does the cell do in preparation for meiosis and mitosis

A

In preparation for mitosis and meiosis, each chromosome is a double structure
Composed of a pair of chromatids
Sister chromatids
Held together at the centromere

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3
Q

Dividing cell in mitosis in meiosis

A

Each new cell requires a copy
Prior to division each chromosome makes an exact copy of itself
Results in 2 chromatids
Sister chromatids
In early division stages the sister chromatids remain attached at the centromere
Once in separate nuclei they are again referred to as single chromosomes

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4
Q

Karyotype is

A

A display of a cell’s chromosomes ordered according to size
Enables detailed analysis
Cells arrested in mid-mitosis
Autosomes
Sex chromosomes

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5
Q

Chromosome numbers are

A

can vary between species

Chromosome number is constant for ‘all’ cells of a given species
#can very between species

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6
Q

Homologous pairs are

A

Chromosomes can be arranged in matching pairs
Homologous pairs
Homologous pairs have same size, shape, and functions – same genes (but perhaps different alleles)
They look the exact same

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7
Q

Locus is

A

chromosomal location of a specific gene
Gene address

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8
Q

Diploid is

A

Cell with 2 sets of chromosomes
maternal set + paternal set
2 copies of every gene
2n (n = # of chromosomes in 1 set)

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9
Q

Haploid is

A

Cell with 1 set of chromosomes
1 copy of every gene
Gametes are 1n

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10
Q

Mitosis is

A

Each cell receives the same number and type of chromosomes as were present in the parental cell

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11
Q

Meiosis is

A

Division resulting in cells with half the chromosome number of the parental cell
Sexual reproduction
Gametes are haploid (1n)
If not, the chromosome # would double every generation

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12
Q

Cell cycle is

A

Cell cycle is a series of phases that lead to cell division
The order and regulation of these phases is vital for the process of cell division

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13
Q

Phases of the cell cycle

A

G1
S
G2
M
Collectively the first 3 phrases are called interphase

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14
Q

G1 step of the cell cycle is

A

the first gap phase
Cell growth

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15
Q

S of the cell cycle is

A

synthesis phase
DNA replicated (single to duplicated chromosomes)

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16
Q

G2 part of the cell cycle is

A

the second gap phase
Protein synthesis for division

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17
Q

M in the cycle cycle is

A

mitosis and cytokinesis

18
Q

Mitotic cell division is

A

Cell divides to produce 2 new cells that are genetically identical to the original cell
Involves mitosis and cytokinesis
Mitosis – division of the nucleus into 2 nuclei
Cytokinesis – division of the cytoplasm to produce 2 daughter cells

19
Q

Biological significance of mitosis

A

Enables the growth of an organism
From unicellular zygote to multicellular organism
Repair of damaged tissues
Normal cellular replacement (skin, gut lining)
Asexual reproduction reproduction
New organism produced from one parent

20
Q

Stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

21
Q

Prophase of mitosis

A

Duplicated chromosomes condense
Nuclear membrane dissociates
Mitotic spindle begins to form

22
Q

Metaphase of mitosis

A

Duplicated chromosomes are aligned along the metaphase plate (equator) in a single row
Metaphase plate is halfway between the 2 poles
Spindle microtubules attach to the centromeres of the duplicated chromosomes

23
Q

Anaphase of mitosis

A

Sorting process occurs
Connection between sister chromatids is broken
Single chromosomes separate

24
Q

Telophase in mitosis

A

Single chromosomes have reached poles
Nuclear membranes reform to produce 2 separate nuclei
Chromosomes decondense

25
Q

Cytokinesis in mitosis is

A

Division of cytoplasm to produce distinct daughter cells
Involves cleavage area
Constricts like a drawstring to separate cells
At end of cytokinesis the daughter cells are in interphase

26
Q

Meiosis is the proccess in and results in

A

Process by which haploid cells are produced from a cell that was originally diploid
A type of nuclear division involved in gamete production
Involves one round of chromosome replication and two successive rounds of nuclear division
Results in 4 haploid daughter cells

27
Q

Biological significance of meiosis

A

Ensures consistent chromosome number from generation to generation
Ensures variability among offspring due to new combinations of alleles
independent of chromosomes at metaphase I
Swapping of pieces of homologous chromosomes
New combinations of alleles on the same chromosome
Random fertilization of gametes

28
Q

Cell cycle differentiats of meisosis is

A

Meiosis begins after a cell has progressed through G1, S and G2
Two rounds of division are called meiosis I and meiosis II
In meiosis I homologous chromosomes are separated – halves the number of chromosomes
In meiosis II sister chromatids are separated

29
Q

Synapses and crossing over in meiosis

A

Synapsis and crossing over are 2 key events that occur in meiosis but not mitosis
Synapsis is the process of forming a bivalent
Bivalent is formed when homologous chromosomes become very closely associated

30
Q

Crossing over is

A

Involves a physical, reciprocal exchange of DNA between homologous non-sister chromatids
Allows for increased variation in genetic information
Chiasma = connection at a crossover site of 2 chromosomes

31
Q

Stages of meiosis

A

Prophase I
Metaphase I
Anaphase I
Telophase I

32
Q

Prophase I in meiosis is

A

Chromosomes condense
Meiotic spindle begins to form
Nuclear membrane dissociates
Homologous chromosomes synapse and form bivalents
Crossing over occurs

33
Q

Metaphase I in meiosis

A

Bivalents attach to microtubules of spindle apparatus
Bivalents align at Metaphase I plate

34
Q

Anaphase I in meiosis

A

Homologous chromosomes separate and move to opposite poles
Sister chromatids are still attached at centromere

35
Q

Telophase I in meiosis

A

Duplicated chromosomes arrive at the poles
Nuclear membranes form
Chromosomes begin to decondense
Cytokinesis I occurs
2 cells are produced, each with the haploid number of duplicated chromosomes

36
Q

Meiosis II is

A

Meiosis II is similar to mitosis
However, there is no “S” phase before meiosis II begins
The chromatids of each chromosome may no longer be identical because of crossing over

37
Q

Steps in meiosis II

A

Prophase II
Metaphase II
Anaphase II
Telophase II

38
Q

Difference between meiosis and mitosis chromosome behaviour

A

Mitosis: Homologous chromosomes independent
Meiosis: Homologous chromosomes pair (synapse) forming bivalents until anaphase I

39
Q

Difference between meiosis and mitosis chromosome numbers

A

Mitosis- identical daughter cells
Meiosis- daughter cells haploid

40
Q

Difference between meiosis and mitosis genetic identity of progeny

A

Mitosis: identical daughter cells
Meiosis: daughter cells have new assortment of parental chromosomes
Meiosis: chromatids are not identical
Crossing over

Gentics (8 decks)

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