CYTOGENETICS Flashcards
It is a special type of cell division necessary for sexual
reproduction in eukaryotes.
Meiosis
What are the cells produced in Meiosis?
Spores or Gametes
What is the name of gametes?
Sperm and Egg Cell
What is the the type of special division wherein gametes form from special cells?
Germline
Meiosis halves the amount of genetic material, so what happens when the sperm cell meets the egg cell?
The full amount of genetic material is restored.
In recombination:
This shuffles the genes between the two chromosomes in each pair (one received from each parent), producing chromosomes with new genetic combinations in every gamete generated.
Meiosis
In recombination:
This does not shuffle the genes, producing chromosomes pair identical to those in the parent cell.
Mitosis
In chromosome count:
It produces four genetically unique cells, each with half the number of chromosomes as in the parent.
Meiosis
In chromosome count:
It produces the two genetically identical cells, each with the same number of chromosomes as in the parent.
Mitosis
What contain 23 different chromosomes, constituting one copy of the genome?
Gametes/Sex Cells
What contain 23 pairs or 46 chromosomes?
One member of each pair comes from the person’s mother and one from the father.
Somatic Cells/Body Cells
What cells are diploid (2n)?
Somatic Cells/Body Cells
What cells are haploid (n)?
Gametes/Sex Cells
What cells have only one of each type of chromosome?
Gametes/Sex Cells
This is the term for genetically overloaded cell without meiosis.
Polypoid
The sperm cell and egg cell would each contain 46 chromosomes and the fertilized ovum would have twice the normal amount of number of chromosomes (92).
Polypoid
If this is the case, the fertilized ovum will not develop and do not develop to be born.
Polypoid
What cell division mixes up trait combination?
Meiosis
What is the mechanism of sexual production?
Genetic Diversity
This mechanism may allow a population to survive an environmental challenge.
Genetic Diversity
What are the two divisions of Meiosis?
Meiosis I and Meiosis II
Meiosis I is also called as what?
Reduction Division
Why is Meiosis I called as Reduction Division?
Because it reduces the number of chromosomes from 46 to 23
The reduction division produces ___?
Four haploid cells from a single diploid cell
In reduction division:
The parent cell contains ___?
Replicated chromosomes
In reduction division:
The four daughter cells contains ___?
Unreplicated chromosomes
Is Meiosis a life cycle/cycle?
Meiosis, itself, is not a cycle
In Meiosis, daughter cells are that is produced in reduction division is?
Not identical to the parent
In mitosis, daughter cells that is produced is?
Identical to the parent
What kind of division eukaryotes undergoes?
Both Mitosis and Meiosis
What kind of division prokaryotes undergoes?
Binary Fission
Meiosis II is also called as what?
Equational Division
Why is Meiosis II called as Equational Division?
Because it does not reduce the number of chromosomes
The Equational division produces ___?
Produces 4 cells from the two cells formed in the first division by “Splitting the replicated chromosomes”
Mitosis/Meiosis will occur after what phase of the cell?
Interphase
Define interphase.
Replication of DNA (Doubles the DNA)
In meiosis, one homolog will come from the ___ and the other homolog from the ___?
Mother; Father
PHASES OF MEIOSIS:
Begins as the replicated chromosomes condensed and become visible when stained.
Prophase I
PHASES OF MEIOSIS:
Spindle fibers form.
Prophase I
What even occurs toward the middle of Prophase I, the
homologs line up next to one another, gene by gene?
Synapsis
What holds (2) a chromosome pair together?
RNA and Protein
What is the term in Prophase I where the homologs exchange parts?
Cross-over
PHASES OF MEIOSIS:
All 4 chromatids that comprise each homologous chromosome pair are pressed together as exchange occur.
Prophase I
PHASES OF MEIOSIS:
After crossing over each homolog bear the genes from each parent.
Prophase I
PHASES OF MEIOSIS:
Prior to this; all of the genes on a homolog were derived from one parent.
Prophase I
PHASES OF MEIOSIS:
When the homologs align down the center of the cell.
Metaphase I
PHASES OF MEIOSIS:
Each member of a homolog pair attaches to a spindle fiber at opposite poles.
Metaphase I
PHASES OF MEIOSIS:
For each homolog pair, the pole the maternally or paternally
derived member genes go to is random.
Metaphase I
The alignment of chromosomes is important in Metaphase I because?
It is important in generating genetic diversity.
In metaphase I, 2 pairs of homologs can produce what?
4 (2) different metaphase alignments are possible.
In metaphase I, 3 pairs of homologs can produce what?
8 (2) different metaphase alignments are possible.
What law is the random alignment of chromosomes?
Law of Independent Assortment
What law is the fate of a gene on one chromosome is not
influenced by a gene on a different chromosome?
Law of Independent Assortment
This principle states that the alleles for a trait separate when gametes are formed. These allele pairs are then randomly united at fertilization.
Law of Independent Assortment
PHASES OF MEIOSIS:
Homologs separate in this phase and finish moving to opposite poles.
Anaphase I
PHASES OF MEIOSIS:
Movements establish a haploid set of still-replicated chromosomes at each end of the stretch out cell.
Anaphase I
PHASES OF MEIOSIS:
Centromeres of each homolog remains together unlike in mitosis.
Anaphase I
In this phase, chromosomes unfold into very thin threads.
Interphase II
Proteins are manufactured , but DNA is not replicated a second
time.
The single DNA replication, followed by the double division of
meiosis, halves the chromosome number.
Interphase II
PHASES OF MEIOSIS:
Marks the start of the second meiotic division.
Prophase II
PHASES OF MEIOSIS:
Chromosomes are again condensed and visible.
Prophase II
PHASES OF MEIOSIS:
The replicated chromosomes align down the center of the cell.
Metaphase II
PHASES OF MEIOSIS:
The centromeres part and the newly formed chromosomes, each now in the unreplicated form move to opposite poles.
Anaphase II
PHASES OF MEIOSIS:
Nuclear envelope form around the four nuclei w/c then separate into individual cells.
Telophase II
What is the result of Meiosis?
Four haploid cells carrying new assortment of genes and chromosomes that represent a new single copy of a genome.
When does a male begin manufacturing sperm?
During puberty and throughout lifetime
When does a female begin meiosis?
During Fetus
When is a meiosis completed in a female?
Only if a sperm fertilizes an egg cell of the female
What is the formation of sperm cells?
Spermatogenesis
What is the diploid stem cell of a sperm cell?
Spermatogonium
Does a sperm cell divide through meiosis or mitosis?
Mitosis
What happens to the two daughter cells of a sperm cell?
One continuous to become a specialize mature sperm.
The other will remain as a stem cell, to produce more sperm.
What happens when spermatogonia mature, and they accumulate their cytoplasm and replicate their DNA?
Primary Spermatocytes
What happens when each primary spermatocytes has undergone reduction division to form two equal sized haploid cells?
Secondary Spermatocytes
What happens when secondary spermatocytes undergo equational division?
Spermatids
What happens to spermatids when they mature?
Sperm Cells
What happens to secondary spermatocytes in Meiosis II?
They produce 2 equal spermatids each.
What specific feature does a spermatid develop during maturation?
Flagellum or Sperm Tail
How can a sperm cell propel itself in the female tract?
Due to the tail having ATP molecules
How long does a sperm cell need to travel to reach an egg cell?
18cm or 7in
What are the three parts of a sperm cell?
1) Head
2) Body or Midpiece
3) Tail
What is the membrane-covered area of the head of a sperm cell that contains an enzyme that help the sperm cell penetrate the protective layers of an egg cell?
Acrosome
Where is DNA found in sperm cells?
In the head
What is the status of the DNA in the head of the sperm cell?
Genetically inactive
What happens to spermatogonia that is exposed to toxins?
Damaged and never matures into a sperm
What is the formation of egg cells? It is also the meiosis for females.
Oogenesis (Egg Making)
What is the diploid stem cell of an egg cell?
Oogonium
Is the Oogonia attached to the egg cell?
No
What surrounds the egg cell?
Follicle Cells
What happens when an Oogonium grows, the cytoplasm accumulated, and the DNA has replicated?
Primary Oocyte
What happens in the ensuing meiotic division in oogenesis?
They produce cells of DIFFERENT SIZES
What consists of an oocyte surrounded by a single layer of squamous granulosa cells?
Primordial Follicle
What happens to the primordial follicle when granulosa cells become enlarged and cuboidal?
Primary Follicle
What is formed when the primary follicle enlarges and the granulosa cells form more than one layer?
Zona pellucida
What is the structure called when fluid-filled vesicles develop among the granulosa cells and a well-developed capsule or theca becomes apparent among the granulosa cells?
Secondary Follicle
It possesses the internal and external layers of an egg cell.
Theca
What is the structure called when the fluid-filled vesicles form an “Antrum”?
Matured Follicle
What is the surrounding granulosa cells of cumulus mass that surrounds the oocyte released from the follicle?
Corona radiata
Following ovulation, what is formed when granulosa cells divide rapidly and enlarge?
Yellow corpus luteum
What do you call a degenerated corpus luteum?
Corpus albicans
During Meiosis I, what is produced when the primary oocyte divides into two small cells with very small cytoplasm?
First polar body
During Meiosis I, what is produced when the primary oocyte divides into two small cells with very large cytoplasm?
Secondary Oocyte
What can happen in the first polar body during Meiosis II?
Either yield 2 polar bodies with the same unreplicated chromosomes or decompose
During Meiosis II, what is produced when the secondary oocytes divides into two small cells with very small cytoplasm?
Small polar body
During Meiosis II, what is produced when the secondary oocytes divides into two small cells with very large cytoplasm?
Mature Egg Cell or Ovum
What happens if a polar body is not absorbed by the body and is fertilized by a sperm cell?
Blighted Ovum, a type of miscarriage
Before birth a female’s million or so oocytes arrest in where?
Prophase I of Oogenesis
At what stage does Meiosis of females stop?
Metaphase II
What event is the response to specific hormonal cues each month one ovary releases a secondary oocyte?
Ovulation
When is meiosis completed in females?
When sperm has fertilized the secondary oocyte
What happens when the secondary oocyte is not fertilized?
Menstrual Flow
How much can a female produce oocytes between puberty and menopause?
400 Oocytes
