CELL DIVISION + GENETIC DIVERSITY

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What is the expected percentage of difference between homologous chromosomes from different individuals?

0.1% (correct)

0.01%

1%

10%

During which phase of the cell cycle does DNA replication occur?

G2 phase

M phase

G1 phase

S phase (correct)

What is the ploidy level of human cells throughout most of the cell cycle?

Triploid (3n)

Haploid (n)

Tetraploid (4n)

Diploid (2n) (correct)

What happens to sister chromatids during mitosis?

They are pulled apart and considered individual chromosomes. Signup and view all the answers

What is uniquely true about sister chromatids?

They are identical unless a mutation occurs. Signup and view all the answers

What is the state of cells in G2 phase regarding DNA content?

2n and 4c Signup and view all the answers

Which of the following best describes homologous chromosomes?

Nearly identical, one from each parent, but not identical. Signup and view all the answers

Which cell types in humans are haploid?

Gametes Signup and view all the answers

What is the result of Meiosis II?

Four haploid gametes Signup and view all the answers

Which statement accurately describes the cells produced at the end of Meiosis?

Each cell has a haploid set of chromosomes Signup and view all the answers

What is the primary purpose of meiosis in animals?

To produce spermatozoa and ova Signup and view all the answers

During which phase does crossing-over occur in meiosis?

Meiosis I only Signup and view all the answers

What characterizes the process of spermatogenesis compared to oogenesis?

Spermatogenesis is a continuous process after puberty Signup and view all the answers

During which phase of the cell cycle does the DNA content double from 2 to 4?

G2 Phase Signup and view all the answers

What is the number of gametes produced through oogenesis after meiosis?

1 ovum and 3 polar bodies Signup and view all the answers

What is the primary reason males produce more spermatozoa than females produce ova?

More rounds of mitosis before meiosis Signup and view all the answers

What is the ploidy level (n) after Meiosis I?

1 Signup and view all the answers

What is the duration of spermatogenesis in males?

60 days Signup and view all the answers

How many mitoses occur before meiosis in males?

20-30 Signup and view all the answers

Which statement is true about the genetic mutations from parents?

Fathers pass on more mutations due to more mitotic divisions Signup and view all the answers

After Meiosis II, what is the DNA content (c) of the gametes?

1 Signup and view all the answers

What is the DNA content for a cell in the G1 phase of the cell cycle?

2c Signup and view all the answers

What occurs during hypertrophy?

Increase in cell size Signup and view all the answers

What happens to the DNA content during the S phase of the cell cycle?

It doubles from 2c to 4c. Signup and view all the answers

How is hyperplasia identified in a tissue sample?

Increased number of cells with normal morphology Signup and view all the answers

What is the ploidy number (n) of a typical somatic cell throughout the cell cycle?

2n Signup and view all the answers

What distinguishes homologous chromosomes from sister chromatids?

Homologous chromosomes are nearly identical but not identical. Signup and view all the answers

Which phase is NOT part of interphase?

M phase Signup and view all the answers

During which phase of the cell cycle does the DNA content reach 4c?

G2 phase Signup and view all the answers

What characterizes dysplasia in tissue?

Increase in nuclear size and abnormal morphology Signup and view all the answers

Which is the final step in cell division?

Cytokinesis Signup and view all the answers

What is the correct relationship between sister chromatids and their DNA content?

Sister chromatids have identical DNA sequences. Signup and view all the answers

What is a consequence of loss of control in the cell cycle?

Atrophy Signup and view all the answers

What is the main cause of differences between sister chromatids?

Differences are due to mutations during replication. Signup and view all the answers

What is true about a cell during the M phase of the cell cycle?

The cell's DNA content is halved. Signup and view all the answers

What defines the M phase of the cell cycle?

Both mitosis and cytokinesis Signup and view all the answers

Which is true regarding the cell cycle phases?

G2 phase prepares the cell for mitosis Signup and view all the answers

What happens to the DNA content during the transition from G1 phase to S phase?

It doubles from 2c to 4c. Signup and view all the answers

Which statement best explains the composition of chromosomes at the end of G2 phase?

Each chromosome consists of two identical sister chromatids. Signup and view all the answers

What is the significance of homologous chromosomes in terms of genetic variation?

They consist of one chromosome from each parent, allowing for genetic diversity. Signup and view all the answers

What defines the chromosome structure at the moment sister chromatids separate during mitosis?

They are considered individual chromosomes from that moment. Signup and view all the answers

How can we characterize the DNA content of human somatic cells throughout the cell cycle?

They are typically 2n throughout the cycle, except during S phase. Signup and view all the answers

What is true about the genetic composition of daughter cells after mitosis?

They maintain the same genetic composition as the parent cell. Signup and view all the answers

At which point during the cell cycle is the DNA content at its highest level?

During G2 phase. Signup and view all the answers

Which correctly describes the state of homologous chromosomes in a diploid organism such as humans?

They consist of one maternal and one paternal chromosome. Signup and view all the answers

What occurs to the sister chromatids during anaphase of mitosis?

They are pulled apart to opposite sides of the cell. Signup and view all the answers

Which phase of the cell cycle immediately follows the separation of sister chromatids?

Cytokinesis Signup and view all the answers

What is the significance of homologous chromosomes behaving independently during cell division?

They ensure genetic diversity through independent assortment. Signup and view all the answers

What role does condensin play during prophase of mitosis?

It facilitates the compaction of chromosomes. Signup and view all the answers

During which stage does the nuclear envelope break down?

Prophase Signup and view all the answers

What is the function of kinetochores during prometaphase?

They attach sister chromatids to the spindle microtubules. Signup and view all the answers

How do kinetochores differ between yeast and animal cells?

Animal kinetochores can bind more than 20 microtubules. Signup and view all the answers

What happens at the end of prometaphase?

All chromosomes are properly attached to spindle microtubules. Signup and view all the answers

What indicates a loss of condensin during prophase?

Partial compaction of chromosomes. Signup and view all the answers

Why is the attachment orientation of sister chromatids important?

It ensures even distribution of genetic material to daughter cells. Signup and view all the answers

What are motor proteins associated with kinetochores responsible for?

Moving chromosomes along the microtubules. Signup and view all the answers

What is a polar microtubule?

They interact with microtubules from the other pole Signup and view all the answers

What are astral microtubules?

Extend to the cell peripherally Signup and view all the answers

How do kinetechores attach?

only correct attachment creates tension to recruit more microtubules. initial attachment to kinetechores by microtubules is random so incorrect attachments can form. Incorrect attachments do not generate tension, and so they are destabalized by aurora protein kinase... the kinetechore then releases the microtubule and waits for another random attachment, this way only correct attachments persist. If something fails in the distribution of kinetechores then there will not be even distribution of genetic material. Signup and view all the answers

What is chromosome missegregation?

Incorrect microtubule and kinetochore attachments Signup and view all the answers

What is the role of Aurora kinase in cell division?

Incorrect microtubule-kinetochore attachments are destabilized by Aurora kinase. If Aurora kinase is missing or inactive, missegregation occurs. Signup and view all the answers

What are multipolar spindles?

Seen in cancer cells where they can't separate properly (multipolar, monopolar). Signup and view all the answers

What do unattached kinetechores activate?

unattached kinetechore active the spindle checkpoint. This activiation causes proteins to bind and inhibit Cdc20 which inactivates APC(Cdc20). As long as there are unattached kinetechores the cell cannot enter anaphase.. A faulty spindle checkpoint is cause of cancer -- cancer cells often have aneuploidy (incorrect number of chromosomes) as a result of missegregation. Signup and view all the answers

What happens to cells stuck in M-phase?

They eventually die due to the spindle checkpoint, and this method is commonly used in cancer drugs. Signup and view all the answers

What is senescence?

How cells die naturally over time Signup and view all the answers

Which of the following is considered normal: metaplasia or dysplasia?

Metaplasia is normal and so is hyperplasia Signup and view all the answers

Where does Vinca Alkaloid work as a cancer drug?

Between G2 and M phases of the cell cycle Signup and view all the answers

Where does Taxol work as a cancer drug?

During the M phase Signup and view all the answers

What is cytokinesis?

It is the final step of mitosis where a new cell membrane is formed between daughter nuclei. Signup and view all the answers

When does female oogenesis begin and end?

Begins during embryonic development and arrests in prophase I until the female begins ovulation at puberty Signup and view all the answers

Differences in mitosis and meoisis?

Meiosis I is long and complex, can take years to complete. Mitosis is short (30 mins in humans). Recombination does not happen in mitosis but happens in meiosis. There is no pairing of homologs in mitosis but there is in meiosis 1 Signup and view all the answers

Selection is _ and _ for each chromosome pair.

random and independent Signup and view all the answers

What are the main differences between spermatogenesis and oogenesis?

<ul> <li>Oogenesis begins during early embryonic development, while spermatogenesis starts at puberty.</li> <li>The duration of oogenesis can be 10-50 years, compared to 60 days for spermatogenesis.</li> <li>Oogenesis undergoes fewer mitotic divisions (20-30) than spermatogenesis (200-300).</li> <li>Oogenesis results in 1 ovum and 3 polar bodies, whereas spermatogenesis produces 4 spermatozoa.</li> </ul> Signup and view all the answers

When does crossing over occur during meiosis?

Prophase I of meiosis Signup and view all the answers

Is there genetic and biological basis for race?

False Signup and view all the answers

More genetic diversity occurs within [blank] and little across [blank].

racial groups, different races Signup and view all the answers

How does chromatin become chromosomes?

Chromatin becomes chromosomes through a series of coiling and folding processes that condense the DNA into a compact, organized structure, ready for cell division. Signup and view all the answers

What is chromatin?

Chromatin is the form that DNA takes when the cell is not dividing. It is a complex of DNA wrapped around proteins called histones, resembling a loosely coiled thread. This structure allows the DNA to be accessible for processes like transcription and replication. Signup and view all the answers

Polymorphism is found in more than what percentage of the population, while rare variants are found in less than what percentage?

1% and 1% Signup and view all the answers

What is polymorphism?

A DNA sequence variation that is common in the population (typically present in at least 1% of individuals). Single nucleotide polymorphisms (SNPs) are a common type of polymorphism. Signup and view all the answers