Chapter 10 Cell Division Prokaryotic Division Chromosomes colored

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Chapter 10 Cell Division

Chapter 10 Cell Division

Prokaryotic Division Chromosomes (colored bodies) l Prokaryotes have a single, circular chromosome l •

Prokaryotic Division Chromosomes (colored bodies) l Prokaryotes have a single, circular chromosome l •

Prokaryotics l Cell Division l Prokaryotes (bacteria) reproduce through cell division l Binary fission

Prokaryotics l Cell Division l Prokaryotes (bacteria) reproduce through cell division l Binary fission l Circular chromosome (DNA) is replicated l Replicated chromosomes are attached to the cell membrane at nearby sites l As membrane expands, the copies separate l New cell wall forms between copies, cell splits

What about eukaryotic division? l l Mitosis l Eukaryotes use cell division to create

What about eukaryotic division? l l Mitosis l Eukaryotes use cell division to create new cells l MITOSIS: division of the nucleus l Growth, Maintenance and Repair Asexual cell division l Reproduction l MEIOSIS: a special, two-stage type of mitosis that results in daughter cells with half as many chromosomes as the parent cells

Humans l l 46 chromosomes Diploid state (2 n = 46) l 2 sets

Humans l l 46 chromosomes Diploid state (2 n = 46) l 2 sets of 23 chromosomes (diploid) l n = number of chromosomes in a set l Fundamental number, haploid number In humans 23 l l n = contribution from each parent l #23 = 1 sex chromosome, #1 -22 autosomes

Chromosomes l Maternal Paternal Sex: X or X X or Y Autosomes #: 1

Chromosomes l Maternal Paternal Sex: X or X X or Y Autosomes #: 1 1 2 2 ä ä 22 22 (homologous pairs)

The Cell Cycle l The Cell Cycle shows the stages of life of a

The Cell Cycle l The Cell Cycle shows the stages of life of a cell

Cellular Division l Cell division is how a cell makes a copy itself l

Cellular Division l Cell division is how a cell makes a copy itself l A cell spends most of its life in interphase l 1 st stage = G 1, a growth phase; the number of organelles and the amount of cytoplasm double l 2 nd stage = S phase; DNA replicates (the chromatins turn into chromosomes) l chromatins – loose uncoiled strands of DNA l chromosomes – DNA wrapped around proteins l How does DNA replicate? DNA Replication l 3 rd stage = G 2, another growth phase; the cell will continue to grow

The Cell Cycle

The Cell Cycle

Cellular Division l After interphase, the cell goes through mitosis l l Mitosis is

Cellular Division l After interphase, the cell goes through mitosis l l Mitosis is the next 4 phases of cellular division Mitosis occurs in all eukaryotic cells l Only in your somatic cells Eukaryotic cells are cells that have a nuclei and membrane bound organelle l Somatic cells are all body cells except for egg cells and sperm cells l

Mitosis Overview

Mitosis Overview

Phases of Mitosis First Phase – Prophase l What happens during prophase? l l

Phases of Mitosis First Phase – Prophase l What happens during prophase? l l l 1. Chromosomes condensed - become thicker 2. The nucleolus and nuclear membrane break down and disappear 3. Centrioles move to opposite sides of the cell 4. Spindle Fibers appear and radiate from the centrioles l Spindle fibers are protein tubes

What does prophase look like?

What does prophase look like?

Phases of Mitosis l Second Phase – Metaphase l What happens during metaphase? 1.

Phases of Mitosis l Second Phase – Metaphase l What happens during metaphase? 1. Chromosomes move to the middle of the cell l 2. Spindle fibers are attached to the chromosomes controlling their movement l

What does metaphase look like?

What does metaphase look like?

Phases of Mitosis l Third Phase – Anaphase l What happens during anaphase? l

Phases of Mitosis l Third Phase – Anaphase l What happens during anaphase? l 1. The centromere breaks down l l The centomere holds the chromosomes together 2. The spindle fibers pull apart the chromosome l Separating the sister chromatids

What does metaphase look like?

What does metaphase look like?

Phases of Mitosis Fourth Phase – Telophase l What happens in telophase? l 1.

Phases of Mitosis Fourth Phase – Telophase l What happens in telophase? l 1. Nuclear membrane forms around chromatids l l This Forms a nucleus with a nucleolus 2. Chromatids turn into chromatins l 3. The cell membrane starts to pinch inward to separate into 2 new cells l 4. Centrioles and spindle fibers disappear l

What does telophase look like?

What does telophase look like?

Phases of Mitosis l Cytokinesis is the last stage of cell division During cytokinesis

Phases of Mitosis l Cytokinesis is the last stage of cell division During cytokinesis the 2 cells actual split apart from each other l In a plant cells, a cell plate grows between to the two new cell l The cell plate develops into the cell wall l

What does cytokinesis look like?

What does cytokinesis look like?