Mitosis

What is the most important part of a cell when it wants to divide? What important “stuff” is inside the nucleus? NUCLEUS!!! DNA!!

What role does DNA play in our cells? It tells your cell how to act and what to become

What is DNA made up of? What does DNA look Like? Nucleic Acid What does DNA look Like? DNA looks like spaghetti in the cell In this form it is called chromatin DNA can wind up on itself to form chromosomes 46 chromosomes in human cells

Human Karyotype

Human Karyotype Shows many chromosomes are present Shows chromosomes with their pair One from mom and one from dad Also can identify gender Y Chromosomes are much smaller XX = female (two long chromosomes) XY = male (1 short and 1 long chromosome) Can use karyotypes to identify chromosomal abnormalities (trisomy 21)

Chromosome Parts Sister chromatids (identical copies) Single stranded chromosome Double stranded chromosome – It has gone through DNA replication Sister chromatids (identical copies)

Why Do Cells Reproduce? To make new cells in order to grow and repair itself

Cell Cycle A repeating process of cell growth and division

CELL CYCLE Interphase A cell spends 90% of it’s life in interphase.

3 Phases of Interphase G1- First growth phase S phase- DNA copied G2- Second growth phase

Mitosis (M) Phase The nucleus and DNA divide Mitosis is divided into phases: Prophase Metaphase Anaphase Telophase

What Cell Parts Are Involved? Nuclear Membrane Cytoplasm Nucleus Chromosomes (DNA) Cell Membrane Centrioles

Prophase Nuclear Membrane Centriole Chromosomes Spindle Fibers

Prophase Chromosomes thicken Nuclear membrane begins to disappear Spindle fibers start to form between the centrioles

Metaphase Centriole Chromosomes Spindle Fibers

Metaphase Chromosomes line up across middle Spindle fibers are attached to each chromosome (at the centromere)

Anaphase Centriole Chromosomes Spindle Fibers

Anaphase Centromeres divide Sister chromatids are pulled toward opposite ends of the cell

Telophase Nuclear Membrane Centriole Chromosomes Furrowing

Telophase Nuclear membrane begins to re-form Chromosomes uncoil (becoming less visible) Furrowing occurs

Cytokinesis Cytoplasm divides and two separate daughter cells are produced

Mitosis Each cell now has 46 chromosomes (same it started with) Each new cell grows until it is ready to divide

Mitosis All body cells in humans are made through mitosis Sex cells (egg & sperm) are NOT made through mitosis

Put It All Together!!! Animal Cell Mitosis

All Cells are Different!! All cells live for different lengths of time Cells carry out mitosis at different speeds to replace cells that are worn out Brain cells 30-50 yrs Red Blood Cells 120 days Platelets 10 days Stomach Lining 2 days Cells Liver Cells 200 days Intestine Lining 3 days Skin cells 20 days

Mitosis In which body organs do cells carry out mitosis the most often? Stomach, Intestine, Skin In which body organs do cells carry out mitosis the least often? Brain

Plant vs. Animal Cell Mitosis Plant cells do not have centrioles There is no furrowing in telophase. A cell wall forms instead.

Put It All Together!!! Plant Cell Mitosis

Flaws in Mitosis When cells are dividing out of control, tumors are produced Cancer is one type of tumor that can result from out of control mitosis

Mutations Mutations = random mistakes in DNA copied during Interphase Can result from UV radiation, genetics, smoking, etc.