Unit 2: cell division mitosis and meiosis

What is a prokaryotic cell?

A cell without a nucleus; its DNA is located in a nucleoid region.

Where is DNA located in a prokaryotic cell?

In the nucleoid region of the cytoplasm.

Do prokaryotic cells have membrane-bound organelles?

No.

What are examples of prokaryotes?

Bacteria and archaea.

What is a eukaryotic cell?

A cell with a nucleus and membrane-bound organelles.

Where is DNA located in a eukaryotic cell?

Primarily in the nucleus, organized into linear chromosomes.

What are examples of eukaryotes?

Animals, plants, fungi, and protists.

What are mitochondria?

Organelles involved in producing ATP through cellular respiration.

What is the cell cycle?

The series of events through which a cell grows, copies its DNA, and divides.

What are the main stages of the prokaryotic cell cycle described in the notes?

DNA replication, cell elongation, septum formation, and separation.

What happens during DNA replication in prokaryotes?

The cell copies its DNA.

What happens during cell elongation in prokaryotes?

The cell grows and becomes longer.

What happens during septum formation?

A dividing structure forms as the cell prepares to separate.

What happens during the final stage of prokaryotic cell division?

The daughter cells separate, each receiving genetic material.

Do prokaryotes undergo mitosis or meiosis?

No. Prokaryotes typically divide through binary fission.

What are the stages of the eukaryotic cell cycle?

G1, S, G2, and M.

What happens during G1 phase?

The cell grows and carries out normal cellular functions.

What happens during S phase?

The cell replicates its DNA.

What happens during G2 phase?

The cell continues growing and prepares for division.

What happens during M phase?

The cell undergoes mitosis, followed by cytokinesis.

What is cytokinesis?

The division of the cytoplasm to form separate daughter cells.

What is mitosis?

Nuclear division that produces two genetically similar daughter nuclei.

What is the purpose of mitosis?

To support growth, tissue repair, and cell replacement.

How many daughter cells typically result from mitosis and cytokinesis?

Two.

What are the stages of mitosis in order?

Prophase, metaphase, anaphase, and telophase.

What happens during prophase?

Chromosomes condense, and spindle fibers form.

What happens during metaphase?

Chromosomes line up at the middle of the cell.

What happens during anaphase?

Sister chromatids separate and move toward opposite poles.

What happens during telophase?

Nuclear envelopes reform around the separated chromosome sets.

What is a sister chromatid?

One of two copies of a chromosome produced during DNA replication.

When do sister chromatids separate during mitosis?

Anaphase.

What is the spindle apparatus?

A structure made of microtubules that helps move and separate chromosomes.

What is meiosis?

A specialized type of cell division that produces haploid cells for sexual reproduction.

What is the purpose of meiosis?

To reduce chromosome number by half and contribute to genetic variation.

How many divisions occur during meiosis?

Two: meiosis I and meiosis II.

How many cells are typically produced by meiosis?

Four haploid cells.

What is the main difference between meiosis I and meiosis II?

Meiosis I separates homologous chromosomes; meiosis II separates sister chromatids.

What happens during prophase I?

Homologous chromosomes pair, and crossing over can occur.

What are homologous chromosomes?

Chromosomes that carry the same types of genes at corresponding locations, one inherited from each parent.

What is crossing over?

The exchange of corresponding DNA segments between nonsister chromatids of homologous chromosomes.

Why is crossing over important?

It creates new combinations of alleles and increases genetic variation.

What happens during metaphase I?

Homologous chromosome pairs line up at the cell's middle.

What is independent assortment?

The random orientation of homologous chromosome pairs during metaphase I, producing different combinations of maternal and paternal chromosomes.

What happens during anaphase I?

Homologous chromosomes separate toward opposite poles.

Do sister chromatids separate during anaphase I?

No. Sister chromatids generally remain joined.

What happens during telophase I and cytokinesis?

The cell divides into two cells, each with one chromosome from each homologous pair.

What happens during prophase II?

Chromosomes condense, and a new spindle forms in each cell.

What happens during metaphase II?

Chromosomes line up individually at the cell's middle.

What happens during anaphase II?

Sister chromatids separate and move toward opposite poles.

What happens during telophase II and cytokinesis?

Nuclei reform and the cells divide, typically producing four haploid cells.

What is the difference between homologous chromosomes and sister chromatids?

Homologous chromosomes are a matching pair inherited from different parents; sister chromatids are duplicated copies of one chromosome.

What are the two major sources of genetic variation during meiosis?

Crossing over and independent assortment.

What is genetic recombination?

The formation of new combinations of genetic material.

How does crossing over affect linked genes?

It can separate alleles on the same chromosome, creating recombinant combinations.

What are parental-type combinations?

Allele combinations that match those present on the original parental chromosomes.

What are recombinant combinations?

New allele combinations created through recombination.

How does the distance between two genes affect crossing-over frequency?

Genes farther apart on a chromosome generally have a higher probability of a crossover occurring between them.

What does a high recombination frequency suggest about two genes?

They are generally farther apart on the same chromosome, or may be on different chromosomes.

What does a low recombination frequency suggest about two genes?

They may be relatively close together on the same chromosome.

How does meiosis differ from mitosis in its products?

Mitosis typically produces two similar cells; meiosis typically produces four genetically varied haploid cells.