What unique configurations do chromosomes assume in Diakinesis?
Due to the repulsion of chromatid pairs.
What is meiosis?
A type of cell division that reduces the chromosome number by half, resulting in four haploid cells.
Where are chromosomes located in animals during Leptotene?
Near the nuclear membrane close to the centriole.
What happens to chromosomes during Telophase I?
Chromosomes regroup and their coiled structures begin to relax.
What is the significance of the precise synapsis during Zygotene?
It ensures homologues pair accurately.
What is separated during Anaphase I?
Homologous chromosomes (HCs).
p.21
Differences Between Mitosis and Meiosis
How does cytokinesis differ from karyokinesis?
Cytokinesis is the division of the cell cytoplasm, while karyokinesis is the division of the nucleus during mitosis.
What happens to chromosomes during Leptotene?
Chromosomes appear as single individual structures.
What is meant by 'equational meiosis'?
Each haploid daughter cell produces 2 daughter cells that are also haploid.
Where can the lesson be accessed?
https://passel2.unl.edu/view/lesson/f57a1a8ce6f5/16.
What are the two phases of Zygotene in meiotic prophase I?
Early Zygotene and Late Zygotene.
What is meiosis?
A process where one single cell divides twice to produce four cells containing half the original amount of genetic information.
p.12
Crossing Over and Genetic Recombination
Why is the synaptonemal complex essential?
It is essential for crossing-over.
How does Metaphase II differ from Metaphase in Mitosis?
At Metaphase II, only single chromosomes with 2 sister chromatids line up at the metaphase plate.
p.21
Differences Between Mitosis and Meiosis
What is cytokinesis?
The division of the cell cytoplasm.
What is the role of the synaptonemal complex (SC) during Zygotene?
It facilitates molecular pairing of homologous chromosomes (gene-by-gene matching).
What is synizesis in the context of Leptotene?
In some plants, chromosomes clump on one side of the nucleus.
p.26
Consequences of Meiosis
What is the chromosome number of rice cells before and after Meiosis I?
Before: 2n = 24; After: n = 12.
p.35
Importance of Meiosis in Genetic Diversity
What is the main purpose of meiosis in terms of genetic integrity?
To enable the maintenance of genetic integrity per species and conservation of chromosome number.
Where do bivalents or homologous chromosomes move during Metaphase I?
To the metaphase plate (center).
p.3
Importance of Meiosis in Genetic Diversity
What is the role of meiosis in genetic integrity?
It enables the maintenance of genetic integrity per species and conserves chromosome number.
What happens in other species regarding cytokinesis after Meiosis II?
Two walls develop simultaneously after Meiosis II.
What happens at telophase I regarding paternal and maternal chromosomes?
Each has an equal probability of being located in one or the other daughter nucleus.
p.4
Differences Between Mitosis and Meiosis
What is the purpose of mitosis?
To enable growth and repair by producing identical cells.
What happens during Anaphase I of meiosis?
Chromosomes move from the metaphase plate to the poles.
What phase of meiosis does Anaphase I account for?
The reductional phase of Meiosis I.
p.26
Consequences of Meiosis
How do the daughter cells differ after Meiosis I?
They may differ in the allelic composition of the genes.
p.35
Consequences of Meiosis
What types of cells are produced during meiosis?
Gametes, including egg cells, sperm cells, pollen, and spores.
What is not yet known about homologous chromosomes during Zygotene?
How specific pairing of homologues happens.
What occurs to the cytoplasm during Telophase I?
The cytoplasm is divided.
What may form in some species during Telophase I?
The nuclear membrane may be formed.
p.34
Consequences of Meiosis
What can each ascospore in the ascus of Neurospora crassa do?
Germinate to form new colonies of bread mold (n).
How does cytokinesis occur in some species after Meiosis I?
A cross wall develops at the Metaphase I plate, followed by a second wall at a right angle after Meiosis II.
p.30
Life Cycles of Eukaryotes
What characterizes the diploid (2n) phase in eukaryotic life cycles?
A series of mitosis for growth.
What is the composition of each anaphase group after Anaphase I?
Each group is composed of a haploid number of chromosomes.
p.29
Crossing Over and Genetic Recombination
What is crossing-over?
A mechanism by which genes may be shuffled and exchanged between non-sister chromatids.
p.29
Consequences of Meiosis
What is the effect of non-sister chromatid exchanges on gametes?
They result in virtually infinite different kinds of gametes with genetic combinations and recombination.
What process do the haploid daughter cells undergo after Meiosis I?
They undergo 'PMAT' (Prophase, Metaphase, Anaphase, Telophase).
How many sister chromatids are present in bivalents during Pachytene?
A total of 4 sister chromatids.
What can happen to chromatids during Pachytene?
Chromatids could break and then be repaired.
p.34
Types of Meiosis in Different Organisms
Which organism is an example of Initial Meiosis?
Neurospora crassa (bread mold, fungus).
Where are the chromatid ends positioned during Metaphase I?
Directly on the metaphase plate.
p.31
Types of Meiosis in Different Organisms
What is terminal or gametic meiosis?
A type of life cycle where meiosis occurs at the gamete stage.
p.27
Consequences of Meiosis
What is the probability of a gamete containing only chromosomes from one parent?
(1/2^n), where n is the number of chromosomes.
p.29
Importance of Meiosis in Genetic Diversity
What is the primary role of meiosis?
It provides the physical basis for the segregation of paired genes.
How do chromosomes appear in Leptotene?
They look slender and long with beads and knobs.
What is the main focus of the provided link?
Stages of Prophase in Meiosis.
p.29
Importance of Meiosis in Genetic Diversity
Why is genetic variability essential?
It is essential for evolution.
p.5
Importance of Meiosis in Genetic Diversity
What is the main purpose of meiosis?
To produce gametes for sexual reproduction.
p.34
Types of Meiosis in Different Organisms
What is Initial or Zygotic Meiosis?
Meiosis that occurs immediately after fertilization in some algae, fungi, and diatoms.
How are centromeres positioned during Metaphase I?
On both sides of the metaphase plate.
How many haploid daughter cells are produced at the end of Meiosis II?
4 haploid daughter cells.
p.4
Differences Between Mitosis and Meiosis
How many daughter cells are produced in mitosis?
Two identical daughter cells.
p.6
Differences Between Mitosis and Meiosis
What is another key difference?
Mitosis results in two identical daughter cells, while meiosis results in four genetically diverse cells.
p.30
Life Cycles of Eukaryotes
What follows the formation of haploid cells in eukaryotic life cycles?
A series of mitotic divisions.
p.27
Consequences of Meiosis
For corn (Zea mays, 2n=20), what is the probability of a pollen grain containing only maternal chromosomes?
1/1024, calculated as (1/2)^10.
p.6
Differences Between Mitosis and Meiosis
What is a sixth key difference?
Mitosis does not involve crossing over, while meiosis does.
What are the distinct substages of Prophase I in Meiosis I?
Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis.
What happens to chromosomes during Diakinesis?
Chromosomes become more contracted.
What mnemonic is used to remember the substages of Prophase I?
LZPDD (Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis).
p.32
Consequences of Meiosis
What is the result of meiosis in terms of ovum formation?
Only 1 ovum is formed per completed meiosis of 1 primary oocyte.
What occurs during the Diplotene stage of meiosis?
Bivalents or homologous chromosomes longitudinally separate, initiating diplonema.
How many stages are there in meiosis?
Two main stages: Meiosis I and Meiosis II.
p.26
Consequences of Meiosis
What process contributes to genetic variation during Meiosis?
Recombination from exchanges of chromatid segments during chiasmata formation.
p.14
Differences Between Mitosis and Meiosis
How do homologous chromosomes and bivalents differ?
Homologous chromosomes are individual chromosomes, while bivalents are pairs of homologous chromosomes that align during meiosis.
p.6
Differences Between Mitosis and Meiosis
What is one key difference between two concepts?
Differences can include aspects such as structure, function, or process.
p.30
Life Cycles of Eukaryotes
What is the purpose of meiosis in eukaryotic life cycles?
For gamete (n) formation.
p.6
Differences Between Mitosis and Meiosis
What is a fifth key difference?
Mitosis maintains the chromosome number, while meiosis halves it.
p.6
Differences Between Mitosis and Meiosis
What is a fourth key similarity?
Both processes are regulated by similar cellular mechanisms.
What occurs during the Zygotene stage of meiosis?
Pairing (or synapsis) of homologous chromosomes.
Where is the College of Agriculture located?
Central Mindanao University, Musuan, Bukidnon.
What happens to chromosomes during Pachytene?
Chromosomes are thickened due to coiling.
What happens to the synaptonemal complex during Diplotene?
It is no longer functional.
How do homologous chromosomes separate during Diplotene?
Starting at the centromere and moving to both ends, except at the chiasmata.
p.13
Crossing Over and Genetic Recombination
What process occurs during the repair of broken chromatids?
Crossing-over between homologues and the formation of chiasma.
p.3
Consequences of Meiosis
How does meiosis affect chromosome number during reproduction?
It reduces the chromosome number so that upon fertilization, the chromosome number is restored and remains the same.
p.27
Crossing Over and Genetic Recombination
How are maternal and paternal chromosomes combined in gametes?
They may be combined in each gamete, leading to genetic variation.
p.7
Differences Between Mitosis and Meiosis
What type of cells undergo mitosis?
Body cells or somatic cells.
p.7
Differences Between Mitosis and Meiosis
What is the chromosome number of daughter cells in mitosis compared to the parent cell?
Same chromosome number as the parent cell.
p.7
Differences Between Mitosis and Meiosis
What type of cell division is meiosis referred to as?
Reductional cell division.
What is the main focus of Lecture 3 in the BIO 31 course?
The Chromosomal Basis of Heredity (Meiosis & more).
What department is Joy M. Jamago associated with?
Department of Agronomy & Plant Breeding.
p.26
Consequences of Meiosis
What is produced after Meiosis I?
2 daughter cells with halved chromosome numbers.
What are the two phases of Pachytene in meiotic prophase I?
Early Pachytene and Late Pachytene.
p.14
Differences Between Mitosis and Meiosis
What is a homologous chromosome?
A chromosome that is similar in shape, size, and genetic content to another chromosome from the same organism.
p.14
Differences Between Mitosis and Meiosis
What is a bivalent in meiosis?
A structure formed during prophase I of meiosis where two homologous chromosomes pair up.
What is Interkinesis?
A brief transitional period that occurs before the cell proceeds to the next stage.
What are the haploid daughter cells produced at the end of Meiosis II called?
Gametes (either egg cells, sperm cells, or pollen).
p.4
Differences Between Mitosis and Meiosis
How many daughter cells are produced in meiosis?
Four genetically diverse gametes.
p.6
Differences Between Mitosis and Meiosis
What is a third key difference?
Mitosis occurs in somatic cells, whereas meiosis occurs in germ cells.
What are the two main stages of meiosis?
Meiosis I and Meiosis II.
p.33
Types of Meiosis in Different Organisms
What type of meiosis occurs in flowering plants?
Intermediary or Sporic Meiosis.
What is the composition of the synaptonemal complex?
It is composed of 2 lateral elements and a central element lying between them.
How do homologous chromosomes pair during synapsis?
Side by side, chromomere by chromomere, in a zipper-like fashion.
p.35
Consequences of Meiosis
How does meiosis affect the chromosome number of a species?
It reduces the chromosome number so that upon fertilization, the chromosome number is restored and remains the same.
p.5
Crossing Over and Genetic Recombination
What happens during crossing over in meiosis?
Homologous chromosomes exchange genetic material, increasing genetic diversity.
What is terminalization in the context of Diplotene?
The process where chiasmata appear to move toward the ends of the chromosomes.
p.30
Life Cycles of Eukaryotes
What is the common pattern in the life cycles of eukaryotes?
Diploid phase, meiosis for gamete formation, mitotic divisions of haploid cells, and fertilization.
p.6
Differences Between Mitosis and Meiosis
What is a second key similarity?
Both processes are essential for the life cycle of organisms.
p.32
Types of Meiosis in Different Organisms
What type of meiosis occurs immediately before the formation of gametes in animals?
Terminal or Gametic Meiosis.
p.32
Types of Meiosis in Different Organisms
In which organisms does terminal meiosis occur?
In animals, including humans, and some lower plants.
p.33
Types of Meiosis in Different Organisms
What are the two types of spores produced in flowering plants?
Megaspores (female) and microspores (male).
p.26
Consequences of Meiosis
Why can daughter cells have different genetic compositions?
Each daughter received a homologue with potentially different genetic composition from paternal and maternal chromosomes.
What happens during Anaphase II?
Sister chromatids per chromosome separate.
What is meiosis?
A process where one single cell divides twice to produce four cells containing half the original amount of genetic information.
p.27
Consequences of Meiosis
What is the formula for the number of possible combinations of chromosomes in gametes?
2^n, where n is the number of chromosomes in the genome.
p.6
Differences Between Mitosis and Meiosis
What is a fourth key difference?
Mitosis involves one division, while meiosis involves two divisions.
p.6
Differences Between Mitosis and Meiosis
What is a third key similarity?
Both processes involve the replication of DNA.
p.5
Differences Between Mitosis and Meiosis
What is a key difference between meiosis and mitosis?
Meiosis results in four genetically diverse haploid cells, while mitosis produces two identical diploid cells.
p.3
Consequences of Meiosis
What types of cells are produced during meiosis?
Gametes, including egg cells, sperm cells, pollen, and spores.
p.4
Differences Between Mitosis and Meiosis
What is the primary difference between mitosis and meiosis?
Mitosis results in two identical daughter cells, while meiosis results in four genetically diverse gametes.
p.4
Differences Between Mitosis and Meiosis
What type of cells are produced by meiosis?
Gametes (sperm and eggs).
p.31
Types of Meiosis in Different Organisms
What is intermediate or sporic meiosis?
A type of life cycle where meiosis occurs at the sporophyte stage.
p.6
Differences Between Mitosis and Meiosis
What is a fifth key similarity?
Both processes result in the distribution of genetic material to daughter cells.
What is cytokinesis after Meiosis I?
The process of cytoplasmic division that varies among species.
p.27
Importance of Meiosis in Genetic Diversity
What is the role of haploid gametes in sexual reproduction?
They restore the original chromosome number of the species.
p.31
Types of Meiosis in Different Organisms
What is initial or zygotic meiosis?
A type of life cycle where meiosis occurs immediately after fertilization.
p.30
Life Cycles of Eukaryotes
What occurs during fertilization in eukaryotic life cycles?
Fusion of two gametes or haploid nuclei, resulting in the 2n phase of the organism.
What does PMAT stand for in the context of mitosis?
Prophase, Metaphase, Anaphase, and Telophase.
p.7
Differences Between Mitosis and Meiosis
What is the chromosome number of daughter cells in meiosis compared to the parent cell?
Half the chromosome number of the parent cell.
p.4
Differences Between Mitosis and Meiosis
What is the purpose of meiosis?
To produce gametes for sexual reproduction.
p.6
Differences Between Mitosis and Meiosis
What is a seventh key difference?
Mitosis is used for growth and repair, while meiosis is used for reproduction.
p.6
Differences Between Mitosis and Meiosis
What is an eighth key difference?
Mitosis produces diploid cells, while meiosis produces haploid cells.
p.7
Differences Between Mitosis and Meiosis
What type of cell division is mitosis referred to as?
Equational cell division.
p.7
Differences Between Mitosis and Meiosis
In what type of cells does meiosis occur?
Sex cells (special cells in ovaries and testes of animals, ovaries and anthers of plants).
p.6
Differences Between Mitosis and Meiosis
What is one key similarity between two concepts?
Both processes involve cell division.
