The Nucleus Asexual Reproduction: Mitosis & Cell Division

General Info: Nucleus: –the “brain” of the cell –controls the cells activities –responsible for cell division, protein synthesis

General Info Cont. Nucleus: –contains genetic material called DNA –DNA long chain (chromatin) of genetic information (eukaryotes) –In prokaryotes (bacteria) DNA is in the shape of a ring called a plasmid

Chromatin Nucleolus Nucleus

Chromosomes: –made of Deoxyribonucleic Acid  DNA wrapped around proteins –Chromosomes in eukaryotes are “rod shaped” structures made of DNA and proteins

Chromosomes: consist of 2 halves called chromatids “sister chromatids” are connected in the center by a centromere

Chromosome (Coiled chromatin)

Ck question Topic: DNA and Chromosomes Date: Genetic material of a cell is called … 2.The location of #1 3.The ring of DNA found in Bacteria is… 4.Chromosomes consist of 2 halves known as…

Chromosome Numbers: Each species has a characteristic number of chromosomes in each cell. ex. Fruit flies (drosophila) = 8 chromosomes horse has 64 chromosomes humans have 46 and chimpanzees have 48 chromosomes

From 7 characteristics of living things: All living things  Grow Growth occurs from the division of cells. Cell Division (cellular reproduction) allows cells to: 1.Grow in size 2.Grow in number 3.Replace worn out, injured or dying cells

2 Forms of Cellular Reproduction (cell division): 1.Asexual Reproduction  involves only one parent cell a.Occurs in Autosomes or somatic cells … body cells b.Plants/animals

2 Forms of Cellular Reproduction (cell division) Cont… c. protists (protozoan) = single celled organisms (binary fission) d. fungi e. bacteria = binary fission

2 Forms of Cellular Reproduction (cell division): 2.Sexual Reproduction involves 2 parents cells a. Gametes = sex cells b. Making gametes!!!

Sexual reproduction: Occurs in sperm cells and egg cells

The Cell Cycle Asexual Reproduction aka MITOSIS The Cell Cycle is responsible for: –birth and death of a cell –Cell division of nucleus, home of hereditary information…chromosomes –Cell division (Cell Cycle) consists in 3 processes

Cell Cycle consists in 3 processes 1. Interphase 2. Division of the nucleus= mitosis 3. Division of the cytoplasm = cytokinesis

Ck question Topic: Cell reproduction Date: How many chromosomes does a normal humans have? 2.Identify 3 reasons cells divide. 3.The 2 types of cellular reproduction are… 4.Define gametes. 5.Define autosome.

Before a cell divides…. Interphase (nucleus) Cell spends most time here

Interphase: Divided into 3 phases 1.G1 – cells grow to mature size 2.S – DNA is copied or duplicated called DNA replication 1.G2 – cell prepares to divide Some cells have a G0 phase, they do not replicate after maturity. Ex. Nervous System

Mitosis: One cell (PARENT CELL) divides into 2 identical cells (Daughters) –divisions: nucleus divides –a series of chronological steps: 1.prophase 2.metaphase 3.anaphase 4.telophase Division of the nucleus (DNA)!!

Mitosis

Prophase: Chromatin condenses, becomes visible strands of DNA called chromosomes 2 chromosomes are made of “sister chromatids” chromatids are connected by centromere centrioles in animal cells begin to separate (opposite ends or poles)

Prophase Cont. spindle fibers form (football shape) from the centrioles and connect to centromere of each chromatid nuclear membrane fades chromatids (chromosomes) begin moving to center

CentriolesSpindle fibers Chromosomes Centromere

Metaphase: (middle) chromosomes (chromatids) line up in the middle of the cell centromere divide chromosomes are pulled apart  separate chromosomes (???)

Chromosome Centromere Spindle fibers

Anaphase: (away) centromere divides chromatids separate move to opposite ends of cell complete set of chromatids go to each pole

chromatid

Telophase: final step of mitosis chromatids unwind, spindle fibers disappear nuclear membrane forms around each of chromatids

Cytokinesis: final step in the cell cycle cytoplasm (and organelles) divide equally in cells animals-pinching in of the cell membrane forming a cleavage furrow plants - cell plate forms across the middle growing outward

In animal cells (begins outside the cell)

In plate cells (begins inside the cell)

Results of Mitosis: division of the nucleus (Asex. Reprod.) products are 2 new cells with identical information to each other and to the parent cell most cells reproduce asexually  mitosis –ex. Of cells produced through mitosis include: in animals: blood cells, skin cells, cheek cells, in plants: root cells, stem cells, leaves

Parent Cell Identical Daughter Cells

Parent Cell Two identical daughter cells

mitosis