BIO200: Genetics - Chapter 2

How many ova, plural for ovum, can be produced from two primary oocytes through meiosis?

2

Suppose a scientist measures the amount of DNA per cell of a particular diploid species at various stages of meiosis. She finds that the meiotic cells contain 3.7 pg, 7.3 pg pg, or 14.6 pg of DNA. Match each stage of the cell cycle to the corresponding amount of DNA contained within a cell at that stage.

3.7 pg: - after cytokinesis of meiosis II 7.3 pg: - metaphase II - G1 14.6 pg: - prophase I - telophase I before cytokinesis - G2

Assume that a cell has six chromosomes while it is in the G1 stage of the cell cycle. How many chromosomes and how many DNA molecules will it have in the G2 stage?

6 chromosomes and 12 DNA molecules

Which statement is characteristic of the bacteria and makes them different from both the archaea and the eukaryotes?

Bacteria have no histones associated with their chromosomes and the other two groups do.

Match the checkpoint to its function. What are checkpoints?

G1/S checkpoint: - maintains cell until necessary enzymes for replication are synthesized G2/M checkpoint - detection of DNA damage after replication Spindle‑assembly checkpoint - ensures that each chromosome is attached to spindle fibers from opposite poles transition points during the cell cycle that ensure all cellular components are functioning properly

Classify each cell as haploid or diploid.

Haploid: - microspore - first polar body - spermatid - megaspore - ovum - secondary oocyte Diploid: - primary spermatocyte - microsporocyte - oogonium - spermatogonium

A biologist examines a series of cells and counts 160 cells in interphase, 20 cells in prophase, 6 cells in prometaphase, 2 cells in metaphase, 7 cells in anaphase, and 5 cells in telophase. The complete cell cycle requires 24 hours. Match the average duration to the appropriate cell cycle stage in these cells.

M phase: - 4.8 hours Prophase: - 2.4 hours Metaphase: - 14.4 minutes Telophase: - 36 minutes

A section of Elodea leaf is stained and examined under a microscope. The total number of cells in each stage of the cell cycle is recorded and presented in the table. If the complete cell cycle in an Elodea leaf requires 24 hours, what is the average duration of metaphase in the cycle? Assume no cells are in Go.

Metaphase: 0.75

Cells are categorized as either prokaryotic or eukaryotic. Classify the characteristics as being unique to prokaryotic cells, common to both cell types, or unique to eukaryotic cells. Move each description into the correct category.

Prokaryotic cells; - relatively small, typically less than 10 𝜇min size - lack a true cytoskeleton Both cell types; - contain DNA - use ribosomes to synthesize proteins Eukaryotic cells; - nuclear membrane surrounds DNA

In which stage of the cell cycle does the cell duplicate its DNA?

S

Which of the statements is not a difference between mitosis and meiosis?

Sister chromatids separate during mitosis but not during meiosis.

A cell has a circular chromosome and histone proteins associated with its DNA, but lacks a nuclear membrane. Choose the domain of the cell with the best justification.

The cell belongs to Archaea because it has histone proteins, which are present in Archaea and Eukaryota but absent in Eubacteria.

Which stage of mitosis involves sister chromatids separating and moving toward opposite poles?

anaphase

In which stage of meiosis does the separation of homologous chromosomes occur?

anaphase I

The products of mitosis normally

are genetically identical to the parent cell.

What is the constricted region of the chromosome where the kinetochore forms?

centromere

Which molecule holds sister chromatids together during mitosis and meiosis?

cohesin

Meiosis results in genetic variation among its product cells. One source of this genetic variation is the random distribution of maternal and paternal chromosomes, and the other source of genetic variation is

crossing over occurring at prophase I.

In flowering plants, meiosis in the male portion of the flower produces

four microspores that will divide mitotically to form male gametophytes.

In order to pass the G2/M checkpoint the cell must

have its DNA completely replicated and undamaged.

Eukaryotic cells that contain more than two sets of genetic information are referred to as

polyploid.

What is the function of the telomere?

to protect the end of a DNA molecule