Honors Biology Chapter 12 - Cell Division

mitosis

the division of the nucleus

mitosis is a _____ process; once it begins it takes about…

continuous; thirty minutes

draw and label the overall diagram of mitosis

3 phases of the cell cycle

interphase, mitosis, cytokinesis

interphase

a period of growth and development

cytokinesis

the division of the cytoplasm to form two cells

which phase of the cell cycle does the cell spend most of it’s life

interphase

3 phases of interphase

G1 phase, S phase, G2 phase

G1 phase

the cell doubles in size and enzymes and organelles roughly double in number

S phase

DNA replicates

G2 phase

the cell undergoes rapid growth and prepares for cell division (mitosis)

cells that stop growing and dividing…

exit in the G1 phase and enter the G0 phase

what cells do not divide once they are made

muscle and nerve cells

what else happens during interphase

the nucleus is building up nucleic acids; the cytoplasm is building up proteins

draw and label interphase

4 phases of mitosis

prophase, metaphase, anaphase, telophase

5 steps of prophase

the cell gets ready for the separation of it's nuclear material; chromatin begins to thicken and by the end of prophase, distinct chromosomes are visible; asters appear; spindle fibers appear; the nucleolus and nuclear membrane disappear

asters

short fibers extending from the centrioles; function: to move the centrioles

spindle fibers

long fibers extending from one centriole to another and they move chromosomes

draw and label early prophase

draw and label late prophase

2 steps of metaphase

chromosomes line up in the middle of the cell; spindle fibers become attached to the centromeres of the chromosomes

draw and label metaphase

which phase of mitosis is the shortest

anaphase

3 steps of anaphase

chromosomes separate and move to opposite ends of the cell; the spindle fibers move the chromosomes; in anaphase, a nondisjunction may occur

nondisjunction

the failure of chromosomes to separate during cell division

draw and label anaphase

5 steps of telophase

chromosomes return to chromatin; spindle fibers and asters disappear; the nuclear membrane and nucleolus reappear; in animal cells only, a furrow forms; the centrioles replicate

furrow

the pinching in of the cytoplasm

draw and label telophase

Mitosis is completed when…

the daughter cells are formed and enter interphase

draw and label the daughter cells

differences between plant and animal cells

plant cells do not have centrioles, asters, or a furrow; plants have spindle fibers that form a cell plate that eventually becomes the cell wall

meiosis

cell division in the gamete cells

draw and label meiosis

stages of meiosis

prophase 1, metaphase 1, anaphase 1, telophase 1, interkinesis, prophase 2, metaphase 2, anaphase 2, telophase 2

reasons why meiosis is known as “reduction division”

the parent cell contains the diploid number; DNA replicates once; the cell divides twice; daughter cells have the haploid number

which stage of meiosis is the longest

prophase 1

prophase 1

at the beginning of prophase 1, each chromosome has already replicated; synapsis: chromosomes line up with their homologous chromosomes and become attached at their centromere; chromosome pairs consisting of four chromatids are called tetrads; crossing-over occurs

synapsis

chromosomes line up with their homologous chromosomes and become attached at their centromeres

tetrads

chromosome pairs consisting of four chromatids

crossing-over

the exchange of genetic material between the homologous chromosomes

why crossing-over is not dangerous

homologous chromosomes control the same traits

draw and label early prophase 1

draw and label late prophase 1

metaphase 1

homologous chromosomes line up in the middle of the cell

draw and label metaphase 1

anaphase 1

homologous chromosomes separate and move to opposite ends of the cell; nondisjunctions may occur

draw and label anaphase 1

telophase 1

the cytoplasm divides, forming two cells

draw and label telophase 1

interkinesis

similar to interphase, but DNA does not replicate

draw and label interkinesis

draw and label prophase 2

metaphase 2

chromosomes line up in the middle of the cell

draw and label metaphase 2

anaphase 2

chromosomes separate and move to opposite ends of the cell; nondisjunctions may occur

draw and label anaphase 2

telophase 2

cytoplasm divides and four haploid daughter cells are made

draw and label telophase 2

4 similarities between mitosis and meiosis

same stages and structures; DNA is replicated once; they are both cell division; the parent cell contains the diploid number

7 differences between mitosis and meiosis

mitosis occurs in somatic cells while meiosis occurs in gametes; mitosis divides once while meiosis divides twice; daughter cells can divide again in mitosis while daughter cells cannot divide again in meiosis; mitosis has 2 daughter cells with a diploid number while meiosis has 4 daughter cells with a haploid number; mitosis has chromosomes while meiosis has homologous chromosomes; mitosis is involved in asexual reproduction while meiosis is involved in sexual reproduction; mitosis has no interkinesis while meiosis has interkinesis