Skip to main content
Ch. 2 - Mitosis and Meiosis
Klug - Essentials of Genetics 10th Edition
Klug10th EditionEssentials of GeneticsISBN: 9780135588789Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoKlug 10th EditionCh. 2 - Mitosis and MeiosisProblema 29
Capitolo 2, Problema 29

Consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., Am and Ap). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. Be sure to indicate when chromatids are paired as a result of replication and/or synapsis.
Assume that during meiosis I none of the C chromosomes disjoin at metaphase, but they separate into dyads (instead of monads) during meiosis II. How would this change the alignments that you constructed during the anaphase stages in meiosis I and II? Draw them.

Guida verificata passo dopo passo
1
Step 1: Begin by representing the original diploid cell with three pairs of chromosomes: AA, BB, and CC. Each pair consists of a maternal (e.g., A^{m}) and a paternal (e.g., A^{p}) chromosome. Before replication, each chromosome is a single chromatid.
Step 2: Illustrate chromosome replication during the S phase, where each chromosome duplicates to form two sister chromatids joined at the centromere. Now, each pair (e.g., A^{m}) consists of two identical sister chromatids (A^{m} and A^{m}), and similarly for A^{p}, B^{m}, B^{p}, C^{m}, and C^{p}. This results in pairs of sister chromatids for each chromosome.
Step 3: For meiosis I, show synapsis where homologous chromosomes pair up (e.g., A^{m} pairs with A^{p}), forming tetrads (four chromatids). This pairing occurs for all three chromosome pairs (AA, BB, CC). Indicate that crossing over may occur at this stage, but focus on the pairing structure.
Step 4: At anaphase I of meiosis, normally homologous chromosomes separate and move to opposite poles. However, the problem states that the C chromosomes do not disjoin at metaphase I, meaning both homologous C chromosomes move together to the same pole as dyads (pairs of sister chromatids still joined). Illustrate that AA and BB pairs separate normally, but CC pairs remain together as dyads.
Step 5: At anaphase II, sister chromatids usually separate into monads. However, the problem specifies that C chromosomes separate into dyads instead of monads. This means sister chromatids of C chromosomes do not separate and move together to the poles. Show that for AA and BB, sister chromatids separate normally, but for CC, sister chromatids remain paired as dyads during anaphase II.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
2m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Chromosome Structure and Replication

Chromosomes consist of two sister chromatids joined at a centromere after DNA replication. In a diploid cell, each chromosome pair has one maternal and one paternal homolog. Replication duplicates each chromatid, resulting in paired sister chromatids that are identical until separated during cell division.
Video consigliato:
Percorso guidato
07:10
Chromosome Structure

Mitosis and Meiosis Stages

Mitosis produces two identical diploid daughter cells by separating sister chromatids during anaphase. Meiosis involves two divisions: meiosis I separates homologous chromosomes (dyads), and meiosis II separates sister chromatids (monads). Synapsis and crossing over occur in prophase I, pairing homologs tightly.
Video consigliato:
Percorso guidato
09:06
Meiosis Steps

Chromosome Disjunction and Non-disjunction

Disjunction is the normal separation of chromosomes or chromatids during anaphase. Non-disjunction occurs when chromosomes fail to separate properly, leading to abnormal chromosome numbers. In the question, C chromosomes fail to disjoin in meiosis I but separate as dyads in meiosis II, altering the expected alignment and segregation patterns.
Video consigliato:
Percorso guidato
07:10
Chromosome Structure
Pratica correlata
Domanda del libro di testo

Consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., Am and Ap). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. Be sure to indicate when chromatids are paired as a result of replication and/or synapsis.

Are there any possible combinations present during prophase of meiosis II other than those that you drew in Problem 26? If so, draw them.

584
views
Domanda del libro di testo

Consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., Am and Ap). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. Be sure to indicate when chromatids are paired as a result of replication and/or synapsis.

During meiosis I, assuming no crossing over, what chromatid combination(s) will be present at the completion of prophase I? Draw all possible alignments of chromatids as migration begins during early anaphase.

590
views
Domanda del libro di testo

Consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., Am and Ap). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. Be sure to indicate when chromatids are paired as a result of replication and/or synapsis.

Draw all possible combinations of chromatids during the early phases of anaphase in meiosis II.

507
views
Domanda del libro di testo

Consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., Am and Ap). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. Be sure to indicate when chromatids are paired as a result of replication and/or synapsis.

Assume that each gamete resulting from Problem 29 fuses, in fertilization, with a normal haploid gamete. What combinations will result? What percentage of zygotes will be diploid, containing one paternal and one maternal member of each chromosome pair?

903
views