Meiosis (Q1) Flashcards
How much of the chromosomes of the parent cell does meiosis produce?
Half of the chromosomes
Meiosis occurs in ________. (somatic cells or gametes)
Mitosis occurs in gametes/sex cells.
Meiosis is produced from a ________ (haploid or diploid) parent cell to produce ________ (haploid or diploid) cells.
Meiosis is produced from a diploid parent cell to produce haploid cells.
Meiosis produces ________ (two or four) ________ (unique or identical) daughter cells.
Meiosis produces four unique daughter cells.
When do gametes fuse to form a diploid offspring?
During fertilization
What differentiates homologous chromosomes from non-homologous chromosomes?
Homologous chromosomes have different alleles but they must have the same genes, chromosomal arm length, and centromere position.
In the human body, the 22 autosomes are ________ while the X and Y chromosomes are ________.
Homologous, non-homologous
What differentiates sister chromatids from non-sister chromatids?
Sister chromatids should have the same gene, allele, and centrosome.
True or False: Homologous chromosomes are non-sister chromatids.
True, sister chromatids share the same gene and allele. Homologous chromosomes only share the same gene.
What are the two divisions of meiosis?
Meiosis I and Meiosis II
What happens in Meiosis I?
Division results in reducing the number of chromosomes
What happens in Meiosis II?
Similar to mitotic division but the number of chromosomes is reduced to half
Stages of Meiosis I
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I and Cytokinesis
Disappearance of nuclei
Prophase I
Nuclear membrane breaks down
Prophase I
Formation of spindle fiber and movement of centrosomes
Prophase I
What are the stages of Prophase I?
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis
Chromosomes start to condense. What stage of Prophase I is this?
Leptotene
Synaptonemal complex forms. What stage of Prophase I is this?
Zygotene
DNA exchanged by non-sister chromatids. What stage of Prophase I is this?
Pachytene
Synapsis ends and chiasma is visible. What stage of Prophase I is this?
Diplotene
Nuclear membrane disintegrates and prophase ends. What stage of Prophase I is this?
Diakinesis
What is the difference between synapsis and crossing over?
Synapsis is the alignment and pairing of homologous chromosomes with their counterpart. Crossing over is the sharing of genetic material between non-sister chromatids in a homologous pair.
Point of contact or region of crossing over between a homologous pair
Chiasma (sing.) or chiasmata (plural)
Protein structure formed during Prophase I that connects paired homologous chromosomes
Synaptonemal complex
Homologous chromosomes align at the metaphase plate and follow independent assortment
Metaphase I
What is independent assortment?
Because of the random orientation of homologous chromosomes, different alleles are indepedently inherited.
Recombination occurs
Metaphase I
Both chromatids of one homolog are attached to kinetochore microtubules.
Metaphase I
Breakdown of cohesin allows homologous pair to separate
Anaphase I
Synaptonemal complex breaks down
Anaphase I
Sister chromatid cohesion persists at centromere
Anaphase I
Homologs move toward opposite poles
Anaphase I
Cells are now haploid
Telophase I/Cytokinesis
Each chromosome is composed of two sister chromatids with regions of non sister chromatids
Telophase I/Cytokinesis
Spindle apparatus forms
Prophase II
Chromosomes composed of two sister chromatids are moved towards metaphase plate
Late Prophase II
Chromosomes position at the metaphase plate
Metaphase II
Sister chromatids are not genetically identical
Metaphase II
Sister chromatid separates and cohesin breaks down
Anaphase II
Nuclei form and chromosome decondense
Telophase II/Cytokinesis
This phase produces four genetically distinct daughter cells
Telophase II/Cytokinesis
Meiosis is involved with ________ reproduction. (asexual or sexual)
Sexual
