biology ch 7

Which description below explains the G₂ checkpoint?

• Determines whether all conditions are favorable for cell division to proceed. this is the point at which the cell irreversibly commits to the cell division process. Checks for genomic DNA damage; a cell that does not meet requirements (such as adequate reserves and cell size) will not be allowed to progress into the S phase.

• Ensures that all of the chromosomes have been replicated and that the replicated DNA is not damaged. The cell cycle is halted if the checkpoint mechanisms detect problems with the DNA and will either complete DNA replication or repair the damaged DNA.

• Occurs near the end of the metaphase stage of karyokinesis. Known as the spindle checkpoint, it determines whether all sister chromatids are correctly attached to the spindle microtubules.

• Ensures that all of the chromosomes have been replicated and that the replicated DNA is not damaged. The cell cycle is halted if the checkpoint mechanisms detect problems with the DNA and will either complete DNA replication or repair the damaged DNA.

Scientists believe sexual reproduction is common in organisms because ________.

• it is energetically efficient

• it increases genetic variation

• organisms interact with each other so frequently

• it increases genetic variation

Human chromosomes are named based on ________.

• approximate centromere position

• approximate size order

• gene numbers

• approximate size order

During anaphase I, ________ are separated.

• Kinetochores

• sister chromatids

• homologous chromosomes

homologous chromosomes

The ________ microtubules contribute to cell elongation during mitosis.

polar

Chromatin is less complex than ________

chromosome

Identify mechanisms that help ensure genetic diversity.

Crossing over within a homologous pair during meiosis

Identify the human cells that would be diploid.

muscle

Mitosis is most similar to which part of meiosis?

meiosis II

Cells with ________ have a higher chance of increasing a person's risk of developing cancer

damaged DNA

Why is trisomy of the X chromosome less severe than many other trisomies?

X inactivation will inactivate 2 copies if 3 are present.

If we are examining an aneuploid individual, we know that they have _______

a change in the number of copies of an individual chromosome

What occurs during the S phase of the cell cycle?

chromosomes are duplicated

In animal cells, the beginning of cytokinesis and telophase occur _______

concurrently after anaphase

Mitosis

results in two identical sister cells genetically identical to the original parent cell

Meiosis

starts with diploid cells but results in haploid

Genetic variation is an important factor contributing to the ________.

long-term survival of a population