Binary fission, mitosis, and meiosis

Binary fission

passing on genetic information for bacteria, mitochondria, and chloroplasts

Mitosis

passing on genetic information for eukaryotes, somatic cells, and some single-cell organisms

Meiosis

passing on genetic information for eukaryotes, sexual reproduction; single-cell or multicellular

During replication, chromosomes assort to ________ ______ of cell

opposite sides

Chromosomes associate with _______ that anchor them to poles

proteins

Steps of binary fission (prokaryotes)

1. as chromosome replicates, each origin of replication segregates to opposite sides

2. proteins anchor chromosomes to poles

3. cell divides in middle, partitioning chromosomes

4. plasmids are distributed equally

Somatic eukaryotic cells reproduce by

mitosis and cytokinesis

daughter cells are essentially ______ in asexual reproduction

clones

mitosis

nuclear division

cytokinesis

cytoplasmic division

temporary cytoskeletal machine for mitosis

mitotic spindles with microtubules

temporary cytoskeletal machine for cytokinesis

contractile ring with myosin filaments

when does mitosis happen?

prophase → telophase

interphase

nuclear membrane is present and chromosomes are relaxed

prophase

chromosomes condense (each possess 2 chromatids) and mitotic spindle forms

prometaphase

nuclear membrane disintegrates and spindle microtubules attach to chromatids

metaphase

chromosomes line up on metaphase plate

anaphase

sister chromatids separate and move toward opposite poles

telophase

chromosomes get to spindle poles, nuclear membrane re-forms, and chromosomes relax

phases of mitosis (in order)

1. interphase

2. prophase

3. prometaphase

4. metaphase

5. anaphase

6. telophase

meiosis consists of __ divisions

2

2 divisions of meiosis

1. reduction division

2. equational division

reduction division

reduce chromosome number by half (2n → n) and separate homologous chromosomes

equational division

separate sister chromatids

meiosis produces

4 haploid gametes

first step of sexual reproduction

meiosis

second step of sexual reproduction 

fertilization

meiosis increases

genetic variation

how does meiosis increase genetic variation

crossing over and/or random separation of chromosomes

__________ occurs prior to Meiosis I

replication

middle prophase I

chromosomes begin to condense and the spindle forms

late prophase I

homologous chromosomes pair, crossing over occurs, and nuclear membrane breaks down

metaphase I

homologous pairs of chromosomes line up along metaphase plate

when are sister chromatids no longer identical during meiosis?

prophase I (allele shuffling)

anaphase I

homologous chromosomes separate and move to opposite poles

telophase I

chromosomes arrive at spindle poles and cytoplasm divides

steps of meiosis I in order

1. middle prophase I

2. late prophase I

3. metaphase I

4. anaphase I

5. telophase I

prophase II

chromosomes recondense

metaphase II

individual chromosomes line up on the equatorial plate

anaphase II

sister chromatids separate and move to opposite poles

telophase II

chromosomes arrive at the spindle poles and the cytoplasm divides

steps of meiosis II in order

1. prophase II

2. metaphase II

3. anaphase II

4. telophase II

products of meiosis II

four haploid gametes carrying a unique combination of alleles