Cell Cycle and Mitosis Video 1 Video 1

Asexual Reproduction Asexual reproduction is reproduction that involves a single parent producing an offspring. Asexual reproduction is reproduction that involves a single parent producing an offspring. The offspring produced are, in most cases, genetically identical to the single cell that produced them.

Asexual Reproduction In single-celled organisms, cell division is a way to create new individuals. Asexual reproduction is a simple, quick, and effective way for an organism to produce a large number of offspring. Asexual reproduction is a simple, quick, and effective way for an organism to produce a large number of offspring.

Asexual Reproduction Both prokaryotic and eukaryotic single-celled organisms and many multicellular organisms can reproduce asexually. Both prokaryotic and eukaryotic single-celled organisms and many multicellular organisms can reproduce asexually.

Asexual Bacteria reproduce using binary fission. Bacteria reproduce using binary fission.

Asexual Kalanchoe plants form plantlets.

Asexual Hydra reproduce by budding. Hydra reproduce by budding.

Sexual Reproduction In sexual reproduction, offspring are produced by the fusion of two sex cells – one from each of two parents. These fuse into a single cell before the offspring can grow.

Sexual Reproduction The offspring produced inherit some genetic information from both parents. The offspring produced inherit some genetic information from both parents. Most animals and plants, and many single-celled organisms, reproduce sexually. Most animals and plants, and many single-celled organisms, reproduce sexually.

Sexual Reproduction Main advantage: Main advantage: creating genetic diversity in a population -gives the population a better chance of surviving in a changing environment.

Sexual vs. Asexual

An advantage of sexual reproduction over asexual reproduction is that sexual reproduction A) takes less time B) requires more time C) provides genetic diversity D) produces identical offspring

Cell Division The process by which a cell divides into two new “daughter” cells. The process by which a cell divides into two new “daughter” cells. Daughter cells are the NEW cells  the product of cell division. Daughter cells are the NEW cells  the product of cell division.

Cell Division Before cell division occurs, the cell replicates (copies) all of its DNA. Before cell division occurs, the cell replicates (copies) all of its DNA. Each cell gets one complete copy of genetic information Each cell gets one complete copy of genetic information

Chromosomes and the Cell Cycle Chromosome Chromosome Threadlike structure within the nucleus that contains genetic information Threadlike structure within the nucleus that contains genetic information

Chromosomes and the Cell Cycle Bundle of DNA Bundle of DNA Replicated at the beginning of the cell cycle Replicated at the beginning of the cell cycle Passed on from parent cell to daughter cell Passed on from parent cell to daughter cell

Chromosomes Organisms contain various numbers of chromosomes. Organisms contain various numbers of chromosomes. Humans have 46 chromosomes per cell. Humans have 46 chromosomes per cell. Fruit flies have 8 chromosomes per cell. Fruit flies have 8 chromosomes per cell. Adders-tongue fern =1,440 chromosomes! Adders-tongue fern =1,440 chromosomes! Adders-tongue fern Adders-tongue fern

Chromosomes Chromosomes coil up to make it possible to separate DNA precisely during cell division. Chromosomes coil up to make it possible to separate DNA precisely during cell division. Chromosomes form a close association with histones (type of protein). Chromosomes form a close association with histones (type of protein).

Chromatin Vid 2 Vid 3 Vid 2 Vid 3 Vid 2 Vid 3 Vid 2 Vid 3 This complex of unwound DNA and proteins is known as chromatin. This complex of unwound DNA and proteins is known as chromatin.

What is the product of cell division? a) Two genetically identical “son” cells b) Two genetically different “son” cells c) Two genetically identical “daughter” cells d) Two genetically different “daughter” cells

Chromosomes contain: a) Wisdom b) Genetic information c) The nucleus d) RNA and proteins

Cell Cycle During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells. During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells.

Cell Cycle Consists of 4 phases Consists of 4 phases G1 phase G1 phase S phase S phase G2 phase G2 phase M phase M phase

Interphase Period of cell cycle between cell divisions. Period of cell cycle between cell divisions. Divided into 3 phases: Divided into 3 phases: G1 phase G1 phase S phase S phase G2 phase G2 phase

G1 Phase G1= Growth; increase in size G1= Growth; increase in size Cells synthesize some proteins and organelles during this phase. Cells synthesize some proteins and organelles during this phase.

S Phase S stands for synthesis (to make). S stands for synthesis (to make). During this phase, new DNA is synthesized when the chromosomes are replicated (doubled). During this phase, new DNA is synthesized when the chromosomes are replicated (doubled). DNA makes a new copy of itself- each chromosome is doubled DNA makes a new copy of itself- each chromosome is doubled They immediately attach themselves to their new copy They immediately attach themselves to their new copy

S Phase The cell at the end of this phase contains twice as much DNA as it did at the beginning. The cell at the end of this phase contains twice as much DNA as it did at the beginning.

G2 Phase organelles and molecules required for cell division are produced. organelles and molecules required for cell division are produced. The replicated DNA is checked for errors, and repaired if needed. The replicated DNA is checked for errors, and repaired if needed.

Curse of the ‘C’ words! Chromatid Chromatid – one of two identical “sister” parts of a duplicated chromosome Chromatid – one of two identical “sister” parts of a duplicated chromosome

Curse of the ‘C’ words! Centromere Centromere – region of a chromosome where the two sister chromatids attach Centromere – region of a chromosome where the two sister chromatids attach

Curse of the ‘C’ words! Centriole Centriole – structure in an animal cell that helps to organize cell division Centriole – structure in an animal cell that helps to organize cell division Curse of the ‘C’ words! …chromosome, chromatin, cytokinesis… Curse of the ‘C’ words! …chromosome, chromatin, cytokinesis…

Which pair includes a phase of the cell cycle and a cellular process that occurs during that phase? a.G 1 phase, DNA replication b.G 2 phase, preparation for mitosis c.S phase, cell division d.M phase, cell growth

When during the cell cycle is a cell’s DNA replicated? a.G 1 phase b.G 2 phase c.S phase d.M phase

The structures labeled B in Figure 10–5 are called A) centromeres. B) centrioles. C) sister chromatids. D) spindles.

M Phase Two new daughter cells are produced during this phase. Two new daughter cells are produced during this phase. M comes from the word mitosis. M comes from the word mitosis.

M Phase This phase has two stages – This phase has two stages – Mitosis Mitosis Cytokinesis Cytokinesis In many cells, this process may overlap. In many cells, this process may overlap.

Mitosis Video 3 Video 3 Video 3 Video 3 Consists of 4 stages Consists of 4 stages Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase

Prophase Chromatin inside the nucleus condenses and the duplicated chromosomes become visible. Chromatin inside the nucleus condenses and the duplicated chromosomes become visible.

Prophase Outside the nucleus, the centrioles begin to move to opposite sides of the cell Outside the nucleus, the centrioles begin to move to opposite sides of the cell Centriole starts to form a spindle. Centriole starts to form a spindle. Spindles –system of microtubules that will help to separate the duplicated chromosomes. Spindles –system of microtubules that will help to separate the duplicated chromosomes.

Prophase Nucleolus disappears Nucleolus disappears Nuclear envelope (membrane) breaks down Nuclear envelope (membrane) breaks down

Prophase

Metaphase Sister chromatids line up in middle of cell Sister chromatids line up in middle of cell Spindle fibers connect the centromere of each chromatid to opposite poles Spindle fibers connect the centromere of each chromatid to opposite poles

Anaphase During anaphase, the chromosomes separate by contracting spindle fibers During anaphase, the chromosomes separate by contracting spindle fibers Once anaphase begins, each sister chromatid is now considered an individual chromosome. Once anaphase begins, each sister chromatid is now considered an individual chromosome.

Anaphase Anaphase comes to an end when this movement stops and the chromosomes are completely separated into two groups. Anaphase comes to an end when this movement stops and the chromosomes are completely separated into two groups.

Telophase Chromosomes begin to unwind into chromatin Chromosomes begin to unwind into chromatin A nuclear envelope reforms around each cluster of chromosomes A nuclear envelope reforms around each cluster of chromosomes Spindle breaks down Spindle breaks down

Telophase

Cytokinesis Cytokinesis is the division of the cytoplasm Cytokinesis is the division of the cytoplasm This process is different in animal cells and in plant cells. This process is different in animal cells and in plant cells.

Cytokinesis in animal cells The cell membrane is drawn inward until the cytoplasm is pinched into two nearly equal parts. The cell membrane is drawn inward until the cytoplasm is pinched into two nearly equal parts.

Cytokinesis in plant cells The cell membrane is not flexible enough to pinch because of the rigid cell wall. The cell membrane is not flexible enough to pinch because of the rigid cell wall. A structure known as the cell plate forms halfway between the divided nuclei. A structure known as the cell plate forms halfway between the divided nuclei. The cell plate gradually develops into cell membranes and a cell wall The cell plate gradually develops into cell membranes and a cell wall

During which phase(s) of mitosis are structures like the one shown visible? A) anaphase only B) prophase, metaphase, and anaphase anaphase C) metaphase only D) anaphase and interphase

Which of the following represents the phases of mitosis in their proper sequence? A) prophase, metaphase, anaphase, telophase B) interphase, prophase, metaphase, anaphase, telophase C) interphase, prophase, metaphase, telophase D) prophase, anaphase, metaphase, telophase

During normal mitotic cell division, a parent cell that has four chromosomes will produce two daughter cells, each containing A) two chromosomes. B) four chromosomes. C) eight chromosomes. D) sixteen chromosomes.

1. Nature Reviews Molecular Cell Biology 11, (February 2010) | doi: /nrm2832