Meiosis Flashcards
____ is preceded by a process of DNA replication that converts each chromosome into two sister chromatids.
Meiosis
____ is the form of eukaryotic cell division that produces haploid sex cells or gametes from diploid cells.
Meiosis
Meiosis is the form of eukaryotic cell division that produces ____ from diploid cells.
haploid sex cells or gametes
____ contains a single copy of each chromosome.
Haploid Sex Cells or Gametes
____ contain two copies of each chromosome.
Diploid cells
Meiosis takes the form of ____ followed by ____.
- One DNA replication
- Two successive nuclear and cellular divisions
____ takes the form of one DNA replication, followed by two successive nuclear and cellular divisions.
Meiosis
The reproductive cycle of ____ ends when a sperm and egg fuse to form a diploid zygote.
Meiosis
Meiosis involves two sequential cycles of nuclear and cell division called ____.
Meiosis I and Meiosis II
Meiosis involves how many cycle of DNA replication?
1
____ is initiated after the parental chromosomes have replicated to produce identical sister chromatids at the S phase.
Meiosis I
Meiosis involves ____ and ____ between them.
pairing of homologous chromosomes; recombination
____ are formed at the end of meiosis II.
Four haploid cells
There are ____ rounds of chromosome segregation in Meiosis.
2
There are two rounds of ____ in Meiosis.
chromosome segregation
Two Rounds of Chromosome Segragation
____ segregates homologs.
Meiosis I
____ are pair of chromosomes that pair up with each other.
Homologs
The duplicated paternal and maternal homologs pair up alongside each other and become physically linked by the process of ____.
genetic recombination
In the ____, duplicated homologs are pulled apart and segragated into the two daughter cells.
first meiotic anaphase
Two Rounds of Chromosome Segragation
In ____, sister chromatids are pulled apart and segregated to produce haploid daughter cells.
Meiosis II
TRUE OR FALSE.
Each of the haploid nuclei contain both the maternal and paternal copy of each chromosome.
False
Either the maternal or paternal, but NEVER both.
____ is also known as the reductional division.
Meiosis I
Meiosis I is also known as the ____.
reductional division
Stages of Meiosis
The number of centromeres are equal to the number of chromosomes, and reduced by 1/2 at the end of this stage.
Meiosis I
In meiosis I, the number of ____ are equal to the number of ____, and are reduced by 1/2.
centromeres; chromosomes
____ is subdivided into 5 phases based on chromosomal behavior.
Prophase I
Five Phases of Prophase I
- Leptotene (Leptonema)
- Zygotene (Zygonema)
- Pachytene (Pachynema)
- Diplotene (Diplonema)
- Diakinesis
In early prophase I, homologs begin to associate along their length in a process called ____.
pairing
As prophase progresses, the homologs become more closely ____.
juxtaposed
Juxtaposed homologs form a four-chromatid structure called ____.
bivalent
____ are formed at several locations in each sister chromatid, resulting in large numbers of DNA recombination events between the homologs.
DNA double-strand breaks
DNA double-strand breaks are formed at several locations in each sister chromatid, resulting in large numbers of ____ events between the homologs.
DNA recombination
Prophase I leads to reciprocal DNA exchanges called ____.
crossovers
Phases of Prophase I
The homologs condense and pair
Leptotene (Leptonema)
Phases of Prophase I
Homology search starts to happen
Leptotene (Leptonema)
Phases of Prophase I
____ is known as the thin-threated stage.
Leptotene (Leptonema)
Leptotene is also known as the ____.
thin-threated stage
Phases of Prophase I
The synaptonemal complex begins to assemble at sites where the homologs are closely associated and recombination events are occurring.
Zygotene (Zygonema)
The ____ begins to assemble at sites where the homologs are closely associated and recombination events are occurring.
synaptonemal complex
Phases of Prophase I
Chromosomes undergo initial alignment, and will have rough pairing at the end of this phase.
Zygotene (Zygonema)
Phases of Prophase I
The complex formed by a pair of synapsed homologus chromosomes is called bivalent or a tetrad.
Zygotene (Zygonema)
The complex formed by a pair of synapsed homologus chromosomes is called ____.
bivalent or a tetrad
Phases of Prophase I
Continuous condensing of homologs
Zygotene (Zygonema)
Phases of Prophase I
Homologs become shorter and thicker
Zygotene (Zygonema)
Phases of Prophase I
Where the pairing starts
Zygotene (Zygonema)
Phases of Prophase I
____ is known as the yoked-threated stage.
Zygotene (Zygonema)
Zygotene is known as the ____.
yoked-threated stage
Phases of Prophase I
The assembly process is complete, and the homologs are synapsed along their entire lengths.
Pachytene (Pachynema)
Phases of Prophase I
During this stage, bivalent chromosomes now clearly appear as tetrads.
Pachytene (Pachynema)
Phases of Prophase I
Development of synaptonemal complex
Pachytene (Pachynema)
During the pachytene phase, ____ starts to develop.
synaptonemal complex
Homologs in the pachytene phase are separated with a distance of ____.
100 nm
Phases of Prophase I
More intimate arrangement and pairing
Pachytene (Pachynema)
Phases of Prophase I
Genetic transfer happens
Pachytene (Pachynema)
Phases of Prophase I
____ is known as the thick-threated stage.
Pachytene (Pachynema)
Pachytene is known as the ____.
thick-threated stage
Phases of Prophase I
Disassembly of synaptonemal complexes
Diplotene (Diplonema)
Phases of Prophase I
Concomitant condensation and shortening of the chromosomes
Diplotene (Diplonema)
Phases of Prophase I
Crossover events between non-sister chromatids can be seen
Diplotene (Diplonema)
During the diplotene phase, crossover events between non-sister chromatids can be seen as inter-homolog connections called ____.
Chiasmata
____ is the exchange of genetic material between two homologous chromosomes.
Crossing over
Crossing over process is mediated by the enzyme ____.
recombinase
Phases of Prophase I
Recombination is completed by the end of this stage
Pachytene (Pachynema)
Phases of Prophase I
____ is known as the double-threated stage.
Diplotene (Diplonema)
Diplotene is known as the ____.
double-threated stage
Phases of Prophase I
The final stage of meiotic prophase I
Diakinesis
Phases of Prophase I
Marked by terminalization of chiasmata
Diakinesis
Phases of Prophase I
The chromosomes are fully condensed, and the meiotic spindle is assembled.
Diakinesis
Phases of Prophase I
By the end of this stage, the nucleolus disappears, and the nuclear envelop breaks down.
Diakinesis
Phases of Meiosis I
The bivalent chromosomes align on the equatorial plate.
Metaphase I
Phases of Meiosis I
The microtubules from the opposite poles of the spindle attach to the pair of homologous chromosomes.
Metaphase I
Phases of Meiosis I
The homologous chromosomes separate, while sister chromatids remain associated at their centromeres.
Anaphase I
Phases of Meiosis I
Cohesin degradation happens
Anaphase I
Phases of Meiosis I
The nuclear membrane and nucleolus reappear, and cytokinesis follows.
Telophase I
The re-appearance of nuclear membrane and nucleolus, and the occurence of cytokinesis are collectively called as ____.
diad of cells
The stage between two meiotic divisions is called ____ and is generally short-lived.
interkinesis
Interkinesis is followed by ____.
Prophase II
____ is also known as the equational division.
Meiosis II
Stages of Meiosis
The number of centromeres and chromosomes remain equal by the end of this stage.
Meiosis II
In meiosis II, the number of ____ and ____ remain equal by the end.
centromeres; chromosomes
In meiosis II, the number of centromeres and chromosomes remain ____ by the end.
equal
The product of Meiosis II are ____.
4 haploid cells
____ is completed only at ovulation.
Meiosis I
Meiosis I is completed only at ____.
ovulation
____ is completed only after the egg is fertilized.
Meiosis II
Meiosis II is completed only after the egg is ____.
fertilized
____ is the phenomenon when homologs fail to separate properly.
Nondisjunction
What is the result of nondisjunction?
- Some gametes lack a chromosome.
- Some gametes have more than one copy of the chromosome.
____ increase greatly with advancing maternal age.
Segregation errors
Mitosis vs. Meiosis
One division
Mitosis
Mitosis vs. Meiosis
Two divisions
Meiosis
Mitosis vs. Meiosis
Two daughter cells per cycle
Mitosis
Mitosis vs. Meiosis
Four daughter cells per cycle
Meiosis
Mitosis vs. Meiosis
Daughter cells genetically identical
Mitosis
Mitosis vs. Meiosis
Daughter cells genetically different
Meiosis
Mitosis vs. Meiosis
Chromosome number of daughter cell same as that of the parent cell
Mitosis
Mitosis vs. Meiosis
Chromosome number of daughter cell half that of the parent cell
Meiosis
Mitosis vs. Meiosis
Occurs in somatic cells
Mitosis
Mitosis vs. Meiosis
Occurs in germline cells
Meiosis
Mitosis vs. Meiosis
Occurs throughout life cycle
Mitosis
Mitosis vs. Meiosis
Completes after sexual maturity
Meiosis
Mitosis vs. Meiosis
Used for growth, repair, and asexual reproduction
Mitosis
Mitosis vs. Meiosis
Used for sexual reproduction, producing new gene combinations
Meiosis
____ is a protein that provides structural support for a chromosome.
Histone
Histone is wrapped by ____.
DNA
A histone wrapped by a DNA is collectively called ____.
Nucleosome
____ is the constriction of chromosome.
Centromere
____ are fluorescent structures at the end of each chromosome.
Telomeres
Functions of Telomere
- Protection from nucleolitic degradation
- Protection from unnecessary recombination
- Chromosome repair
____ serve as protection from nucleolitic degradation.
Telomeres
____ serve as protection from unnecessary recombination.
Telomeres
____ functions in chromosome repair.
Telomere
____ pairs of chromosomes are autosomes.
22
22 pairs of chromosomes are ____.
autosomes
The ____ pair of chromosomes are sex chromosomes.
23rd
The 23rd pair of chromosomes are ____.
sex chromosomes
The homologous (XX) pair of chromosomes are for ____.
females
The non-homologous (XY) pair of chromosomes are for ____.
males
The DNA may be composed of ____ nucleotides in a chain.
100,000 to 10,000,000,000
____ have large linear chromosomes.
Eukaryotic cells
____ have smaller circular chromosomes.
Prokaryotic cells
____ has been developed by the Standing Committee on Human Cytogenetic Nomenclature.
International System for Human Cytogenetic Nomenclature (ISCN)
____ is the central reference for the description for karyotyping.
International System for Human Cytogenetic Nomenclature (ISCN)
Other functions of International System for Human Cytogenetic Nomenclature (ISCN)
- Fluorescence in situ hybridization (FISH)
- Provides rules for cytogenetic findings in laboratory reports
Chromosome short arms are called ____.
p (petit)
Chromosome longs arms are called ____.
q (queue)
Four Types of Chromosomes Based on the Position of Centromere
- Metacentric
- Submetacentric
- Acrocentric
- Telocentric
Four Types of Chromosomes Based on the Position of Centromere
The centromere occurs in the center and all the four chromatids are of equal length.
Metacentric
Four Types of Chromosomes Based on the Position of Centromere
The centromere is a little away from the center and therefore chromatids of one side are slightly longer than the other side.
Submetacentric
Four Types of Chromosomes Based on the Position of Centromere
The centromere is located closer to one end of chromatid therefore the chromatids on opposite side are very long.
Acrocentric
____ is a small, round structure, attached by a very thin thread.
Satellite
____ is the connection of satellite to the chromatid.
Stalk
Four Types of Chromosomes Based on the Position of Centromere
The centromere is placed at one end of the chromatid and hence only one arm.
Telocentric
____ are long regions of repetitive non-coding DNA that cap chromosomes to stop replication.
Telomeres
____ undergo partial degradation each time a cell undergoes division.
Telomeres
____ is a laboratory test where you can see the individual’s complete set of chromosomes.
Karyotype
Which phase of reproduction is optimal for karyotype viewing?
Metaphase