Cell Reproduction  Prokaryotes Bacteria  Eukaryotes Plants & animals

Prokaryotes  Lack a nucleus  Have a single chromosome  Reproduce by binary fission  Include bacteria

Steps in Binary Fission  Used by bacteria  Cells increase their cell mass slightly  DNA & cell components are replicated  Each cell divides into 2 daughter cells

Binary Fission of Bacterial Cell

E. Coli Dividing by Binary Fission

Eukaryotes  Contain a nucleus & membrane bound organelles  Asexually reproduce cells by mitosis

7 All eukaryotic cells store genetic information in chromosomes All eukaryotic cells store genetic information in chromosomes Most eukaryotes have between 10 and 50 chromosomes in their body cells Most eukaryotes have between 10 and 50 chromosomes in their body cells Human body cells have 46 chromosomes or 23 identical pairs Human body cells have 46 chromosomes or 23 identical pairs

Human Chromosomes

9 Each chromosome is composed of a single, tightly coiled DNA molecule Each chromosome is composed of a single, tightly coiled DNA molecule Chromosomes can’t be seen when cells aren’t dividing and are called chromatin Chromosomes can’t be seen when cells aren’t dividing and are called chromatin

Cell Cycle  Stages in growth & division  G1 Phase  S Phase  G2 Phase  M Phase  Cytokinesis

G1 Phase  First growth stage  Cell increases in size  Cell prepares to copy its DNA

Synthesis Phase  Copying of all of DNA’s instructions  Chromosomes duplicated

G2 Phase  Time between DNA synthesis & mitosis  Cell continues growing  Needed proteins produced

M Phase  Cell growth & protein production stop  Cell’s energy used to make 2 daughter cells  Called mitosis or karyokinesis (nuclear division)

Life Cycle of a Cell Mitosis is a cycle with no beginning or end.

Interphase – Resting Stage  Cells carrying on normal activities  Chromosomes aren’t visible  Cell metabolism is occurring  Occurs before mitosis

Interphase

18 Chromosomes in Dividing Cells Duplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids

19 Mitosis Division of the nucleus Division of the nucleus Also called karyokinesis Also called karyokinesis Only occurs in eukaryotes Only occurs in eukaryotes Has four stages Has four stages Doesn’t occur in some cells such as brain cells Doesn’t occur in some cells such as brain cells

Stages of Mitosis  Prophase  Metaphase  Anaphase  Telophase

Cells Undergoing Mitosis

Steps in Prophase  DNA coils tightly & becomes visible as chromosomes  Nuclear membrane disappears  Nuceolus disappears  Centrioles migrate to poles  Spindle begins to form

Prophase

Eukaryotic Chromosome

Steps in Metaphase  Spindle fibers from centrioles attach to each chromosome  Cell preparing to separate its chromosomes  Cell aligns its chromosomes in the middle of the cell

Metaphase

Steps in Anaphase  Cell chromosomes are separated  Spindle fibers shorten so chromosomes pulled to ends of cell

Mitotic Spindle

Anaphase

Steps in Telophase  Separation of chromosomes completed  Cell Plate forms (plants)  Cleavage furrow forms(animals)  Nucleus & nucleolus reform  Chromosomes uncoil

Telophase Plant Animal

Cytokinesis  Occurs after chromosomes separate  Forms two, identical daughter cells

Cytokinesis Cell Plate Forming in Plant Cells

34 Mitotic Stages

35 Mitosis Animation Name each stage as you see it occur?

36 Eukaryotic Cell Division Used for growth and repair Used for growth and repair Produce two new cells identical to the original cell Produce two new cells identical to the original cell Cells are diploid (2n) Cells are diploid (2n) Chromosomes during Metaphase of mitosis ProphaseMetaphase Anaphase Telophase Cytokinesis

37 Locate the Four Mitotic Stages in Plants Metaphase Prophase Anaphase Telophase

38 Uncontrolled Mitosis If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors Oncogenes are special proteins increase the chance that a normal cell develops into a tumor cell Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell Cancer cells