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Biology Chapter 11
Meiosis and Sexual Reproduction
| Question | Answer |
|---|---|
| How many phases are in meiosis? | Two phases called meiosis 1 and meiosis 2. |
| What is a zygote? | The union of two gametes (haploid cells usually egg and sperm cells). |
| What is a haploid cell? | A cell with only ONE copy of chromosomes. |
| What is a diploid cell? | A cell with TWO copies of chromosomes. |
| What is a somatic cell? | All the cells of a multicellular organism except for the gametes/reproductive cells (sperm and egg cells) |
| What is the end result of meiosis? | Four haploid cells that are genetically unique when compared to the parent cells. |
| What are homologous chromosomes? | These are matched pairs of chromosomes that contain the same genes in identical locations along their lengths. |
| What happens before meiosis? | Same as mitosis. Interphase containing G1, S, and G2 phase |
| What holds the sister chromatids together? | At the centromere, sister chromatids are held by cohesion proteins until anaphase 2. |
| What is a synapsis? | The tight pairing of the homologous chromosomes. This synapsis aligns the genes of two chromosomes precisely. |
| What is crossing over? | This is where chromosomes exchange segments of DNA with each other. |
| What encourages/supports crossing over? | The synaptonemal complex. |
| What is the synaptonemal complex? | A lattice of proteins between the homologous chromosomes. This covers the entire length of the chromosomes. |
| What is a recombination nodule? | Protein assembly formed on the synaptonemal complex that mark the points of crossover events and mediate the multistep process of crossing over. |
| What is chiasmata? | The structure that forms at the crossover points after genetic material is exchanged. |
| What is a tetrad? | The pair of two homologous chromosomes only held together at the chiasmata during prophase 1. |
| What happens in prophase 1? | Homologous chromosomes are attached to the nuclear envelope before being fully developed. Then, as the nuclear envelope disappears, the proteins holding the chromosomes attract them to their pair. |
| What happens in proMETAphase 1? | Attachment of spindle fibers to the kinetochores of chromosomes. This is when the nuclear envelope has broken down entirely. |
| What are kinetochore proteins? | These are proteins that link the spindle fiber microtubules to the centromeres of chromosomes. |
| What happens in metaphase 1? | The homologous chromosomes arrange at metaphase plate. The homologous chromosomes orient themselves randomly. |
| When do the two major diversity steps occur? | During Prophase 1 (crossovers) and Metaphase 1 (random alignment of chromosomes). |
| What happens in Anaphase 1? | The linked chromosomes are pulled apart. |
| What is interkinesis? | This is like another interphase, but it lacks an S phase where DNA is duplicated. |
| What is reductional division? | Nuclear division that makes haploid (having one-half as many chromosome sets as the parental nuclei) daughter nuclei. (Meiosis 1 is an example.) |
| What is a gametophyte? | A multicellular haploid life-cycle stage that makes gametes. (Usually in plants) |
| What is a sporophyte? | A multicellular diploid life-cycle stage that makes haploid spores by meiosis. |
| What is a spore? | A haploid cell that makes haploid multicellular organisms or can fuse with another spore to form diploid cells. |
Created by:
tali_Alley
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