Why do cells divide? -to allow materials to flow in and out more efficiently (get food, eliminate waste easier)

How are chromosomes, DNA and chromatin material the same? How are they different? SAME: All genetic material All in the nucleus All made of DNA DIFFERENT: State or shape

2. What is meant by the term haploid? -a cell with one set of chromosomes or genes 3. What is meant by the term diploid? -a cell with two sets of chromosomes or genes 4. Give an example of a cell that is haploid. -an egg or sperm cell 5. Give an example of a cell that is diploid. -a body tissue cell

N -abbreviation for type or shape of a chromosome In Humans: 2N = 46 Two of Each type total # chromosomes How many different types? 23

Mitosis Meiosis Produces somatic cells (body cells) Purpose: growth & repair Daughter cells genetically identical to parent 2N → 2N Asexual reproduction (runners, budding – essentially clones) Produces gametes (sex cells- egg or sperm) Purpose: reproduction Genetic variation in daughter cells 2N → N Sexual reproduction Egg + Sperm→ zygote N + N → 2N

Cell Cycle:

Interphase: -where cell spends most of life -actively living, feeding, doing job -includes: G st Growth Phase S – Synthesis (DNA replicated) G 2 – 2 nd Growth Phase M – Mitosis (dividing stages) Cytokinesis – cytoplasm divides into new cells

Interphase – “resting stage” -nucleus & nucleolus present -replication occurs (DNA is completely copied) -chromosomes not visible

Prophase: -chromosomes visible -chromosomes in diad form -major cell changes -nuclear membrane dissolves, spindle fibers formed

Metaphase: -chromosomes line up at equator

Anaphase: -chromatids separate and move to poles -each chromatid is now considered a separate chromosome

Telophase: -cytokinesis occurs -2 new cells formed -cell becomes reorganized (nucleus reforms)

1.Is the following cell diploid or haploid? diploid 2. How do you know? 2 of each shape present 3. What do the colors represent? maternal / paternal chromosomes Ordominant / recessive traits

Circle a pair of homologous chromosomes. Homologous chromosomes: have the same size & shape & carry the same trait (or alternate forms of the trait)

Regulating the Cell Cycle Generation time –The time it takes a cell to complete the cell cycle. –Varies widely Cell Cycle Regulators –Cyclin – proteins that regulate the timing of the cell cycle. Internal external