BIOL 1308: DNA Replication, Cell Division, and Reproduction

Comprehensive practice flashcards covering DNA replication, binary fission, mitosis, sexual reproduction, meiosis, chromosomal alterations, and plant life cycles for BIOL 1308 Chapters 8 and 9.

What is the main purpose of cell division in a multicellular organism?

To support growth, maintenance, and repair by reproducing cells and replacing damaged or old tissues.

How does asexual reproduction compare to sexual reproduction in terms of genetic recombination and offspring?

Asexual reproduction occurs without genetic recombination and generally produces genetically identical offspring, whereas sexual reproduction involves genetic recombination and produces genetic variation.

What is apoptosis?

Programmed cell death, which is a coordinated cellular process that dismantles a cell.

Why must chromosomes be duplicated before cell division occurs?

So that each resulting daughter cell can receive a complete set of genetic information.

What does the semiconservative model of DNA replication describe?

Each newly formed DNA molecule contains one original parent strand and one newly synthesized strand.

Which enzyme separates and unwinds the two DNA strands at the origin of replication?

DNA helicase.

What structure forms as DNA is unwound at an origin of replication?

A replication bubble.

What is the role of DNA polymerase during replication?

It reads the parent template strand and builds a complementary strand by adding complementary nucleotides.

If DNA polymerase encounters an adenine (A) on the parent strand, which complementary base is added to the new strand?

Thymine (T), because A pairs with T and C pairs with G.

If a parent DNA strand has the sequence A-C-G-T, what is the sequence of the newly synthesized complementary strand?

T-G-C-A.

In which direction does DNA polymerase read the parent template DNA strand?

In the $3'$ to $5'$ direction.

When does DNA replication officially end?

When the products from adjacent replication bubbles merge.

Which organisms commonly reproduce through binary fission?

Prokaryotes, such as bacteria and archaea.

What happens during binary fission in prokaryotes?

A prokaryotic cell grows to nearly twice its size and divides into two similar daughter cells.

Where is the circular chromosome of a prokaryotic cell located?

In the nucleoid region.

What are plasmids?

Smaller circular pieces of DNA found in some prokaryotes.

What is eukaryotic chromatin made of?

DNA and associated proteins that maintain chromosome structure and regulate genes.

What happens to chromatin as a eukaryotic cell prepares to divide?

It becomes highly compact and visible as individual chromosomes.

What are sister chromatids?

Two identical copies of a duplicated chromosome joined together.

What is the function of the centromere?

It joins sister chromatids together and serves as the attachment region for spindle microtubules.

What is the correct sequence of the three subphases of interphase?

G1, S, and G2.

What is the primary event of the G1 phase?

Cell growth.

What critical process takes place during the S phase of interphase?

Chromosomes are duplicated through DNA replication.

What major event occurs during the G2 phase of interphase?

The cell prepares for division, which includes synthesizing structures such as spindle fibers.

What cellular structure does mitosis divide?

The cell nucleus (a process also called karyokinesis).

What events characterize prophase of mitosis?

Chromatin condenses into visible chromosomes, the nucleolus and nuclear membrane dissolve, and spindle fibers begin attaching to chromosomes.

What cellular event identifies metaphase of mitosis?

Duplicated chromosomes line up along the cell equator (middle of the cell).

What occurs during anaphase of mitosis?

Sister chromatids separate at their centromeres and move toward opposite cell poles.

What events take place during telophase of mitosis?

Nuclear envelopes reform around separated chromosome sets, and chromosomes decondense back into chromatin.

What is cytokinesis?

The division of the cytoplasm and other cellular contents to produce two distinct daughter cells.

How does cytokinesis differ between animal and plant cells?

In animal cells, a cleavage furrow forms and deepens to pinch the cell in two; in plant cells, a cell plate forms across the middle and develops into new cell membranes and cell walls.

What is the expected result of mitotic cell division?

Two genetically identical daughter cells.

What are growth factors?

Chemical signals that trigger a cascade of reactions to initiate cell division.

What is a tumor?

An abnormally growing mass of body cells.

How does a benign tumor differ from a malignant tumor?

A benign tumor remains localized at its original site, whereas a malignant tumor can invade neighboring tissues and spread.

What is metastasis?

The spread of malignant tumor cells to other locations in the body.

How do cancer cells behave with respect to the cell cycle?

They can lose control over cell division, fail to respond to standard regulatory signals, and divide indefinitely.

What cancer treatment relies on concentrated beams of high-energy radiation?

Radiation therapy.

What cancer treatment uses toxic chemicals to target rapidly dividing cells and is primarily used for metastatic tumors?

Chemotherapy.

What is targeted therapy in cancer treatment?

Using drugs that specifically target molecules unique to cancer cells.

What is immunotherapy in cancer treatment?

Stimulating or utilizing the body's immune system to attack cancer cells.

How many parents are involved in asexual reproduction versus sexual reproduction?

Asexual reproduction requires one parent; sexual reproduction requires two parents.

What does diploid ($2n$) mean?

A cell containing two homologous sets of chromosomes, one set inherited from each parent.

What are homologous chromosomes?

A matched pair of chromosomes possessing genes that control the same characteristics.

In humans, how many pairs of autosomes are there, and which pair is the sex chromosome pair?

Humans have $22$ pairs of autosomes, and pair $23$ is the sex chromosome pair.

What is the distinction between a characteristic and a trait?

A characteristic is a general feature (such as hair color), whereas a trait is a specific variation of that feature (such as blonde or black hair).

What is a gene locus?

The specific physical position or location of a gene on a chromosome.

What are alleles?

Different versions or variations of the same gene located at the same locus.

What defines a haploid ($n$) cell?

A cell that possesses only a single set of chromosomes.

Which human cells are considered gametes?

Sperm cells and egg cells.

What happens during fertilization?

A haploid sperm and a haploid egg unite to form a single diploid zygote.

Why is it necessary that gametes are haploid?

To prevent the chromosome number from doubling every generation after fertilization occurs.

Which specific cells undergo meiosis, and where are they located in animals?

Specialized germ cells undergo meiosis, and they are located in animal gonads (testes and ovaries).

What are somatic cells?

Body cells other than sperm, eggs, or the precursor cells that develop into them.

What are the two major outcomes of meiosis?

The production of haploid gametes (halving chromosome count) and the reshuffling of genetic information.

How many times does DNA replicate and how many nuclear divisions occur during meiosis?

DNA replicates once, followed by two successive nuclear divisions (Meiosis I and Meiosis II).

What is the typical final result of meiosis?

Four genetically unique haploid daughter cells.

What is synapsis and when does it take place?

The pairing of homologous chromosomes, which occurs during prophase I of meiosis.

What is a tetrad?

A paired group of homologous chromosomes consisting of four chromatids.

What is crossing over?

The reciprocal exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I.

What structures align at the cell equator during metaphase I?

Tetrads (homologous chromosome pairs).

What structures separate during anaphase I of meiosis?

Homologous chromosome pairs separate and move toward opposite poles, while sister chromatids remain joined.

Does chromosome replication occur between meiosis I and meiosis II?

No, meiosis II proceeds without an intervening round of chromosome duplication.

What aligns at the cell equator during metaphase II of meiosis?

Duplicated chromosomes line up individually at the equator in each of the two haploid cells.

What structures separate during anaphase II of meiosis?

Sister chromatids separate at their centromeres and move toward opposite poles.

What is independent assortment?

The random orientation of maternal and paternal homologous chromosome pairs along the cell equator during metaphase I.

Which three processes generate genetic diversity in sexually reproducing organisms?

Crossing over, independent assortment of chromosomes, and random fertilization.

How do the daughter cells produced by mitosis differ from those produced by meiosis?

Mitosis produces two genetically identical diploid cells, whereas meiosis produces four genetically unique haploid cells.

What is nondisjunction?

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis, yielding gametes with an abnormal chromosome count.

What is aneuploidy?

An abnormal or incorrect chromosome number for one particular chromosome pair.

What is the difference between monosomy and trisomy?

Monosomy means having only one chromosome where a homologous pair should be; trisomy means having three chromosomes where a pair should be.

What is polyploidy?

The condition of possessing more than two complete sets of chromosomes.

What sex chromosome pattern and total chromosome count are observed in Triple X syndrome?

$XXX$ with a total of $47$ chromosomes.

What sex chromosome configuration and total chromosome count characterize Klinefelter syndrome?

$XXY$ with a total of $47$ chromosomes.

What sex chromosome configuration and total chromosome count define Jacobs syndrome (Supermale)?

$XYY$ with a total of $47$ chromosomes.

What sex chromosome configuration and total chromosome count characterize Turner syndrome?

A single $X$ chromosome (one sex chromosome missing) with a total of $45$ chromosomes.

What type of chromosomal structural alteration occurs when a segment is lost?

A deletion.

What type of chromosomal structural alteration occurs when a segment is repeated?

A duplication.

What type of chromosomal change occurs when a fragment detaches, reverses direction, and reattaches to the same chromosome?

An inversion.

What type of chromosomal change occurs when a segment detaches and joins a different, non-homologous chromosome?

A translocation.

In plant alternation of generations, what is the sporophyte generation and what does it produce?

The sporophyte is the diploid ($2n$) generation that undergoes meiosis to produce haploid spores.

In plant alternation of generations, what is the gametophyte generation and how does it produce gametes?

The gametophyte is the haploid ($n$) generation that develops from spores and produces gametes through mitosis.

What is alternation of generations?

A plant life cycle that alternates between a multicellular diploid sporophyte and a multicellular haploid gametophyte.