eukaryotic

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MITOSIS

G2 Interphase: The chromosomes have two chromatids each. The drawing shows two cells. Each cell has 8 chromosomes. Each chromosome has 2 chromatids for a total of 16 chromatids per cell.

G1 Interphase: The chromosomes have 1 chromatid. Two cells each cell has 8 chromosomes. Each chromosome has 1 chromatid for a total of 8 chromatids per cell.

Telophase: The cell divides into two. The chromosomes uncoil. The nucleus reforms. The spindle apparatus disassembles.

Anaphase: The chromatids separate, the number of chromosomes doubles. A cell with 16 chromosomes. Each chromosome has 1 chromatid total is 16 chromatids

Metaphase: The chromosomes become aligned.

Prophase: -The chromosomes coil. -The nuclear membrane disintegrates. -Spindle fibers (microtubules) form. A cell with 8 chromosomes. Each chromosome has 2 chromatids for a total 16 chromatids.

Interphase: Chromosomes not visible because they are uncoiled

STRUCTURES

Organelles

Functions: an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer.

Ribosomes

Functions: site of protein synthesis (translation). Found in all eukaryotic and prokaryotic cells.

Cytoplasm

Functions: A complex network of thread jelly-like and tube-like structures, which provides support, shape, and movement. -Microfilaments -Intermediate filaments -Microtubules

Cell membrane

Functions: Contain carbohydrates for cell recognition and serve as sites for bacterial attachment. Contain sterols which increase resistance to osmotic lysis.

Flagella and Cilia

Functions: for locomotion and movement substances along cell surface.

MEIOSIS

Phases in Meiosis II – SIMILAR TO MITOSIS The second meiotic division is like mitosis, the number of chromosomes does not get reduce (still 4 but single chromatid. As in mitosis, pairs of chromatids will form later)

PHASES

Telophase I: -The nuclear envelope reforms -Two cells formed -Each cell is N with 4 chromosomes -In the first meiotic division, the number of cells is doubled (one cell to two cells) and the number of chromosomes is reduced by half (8 to 4 with 8 chromatids)

Anaphase I: Separation of homologous chromosome

Metaphase I: -Bivalents (tetrads) aligned in the center of cell and attached to spindle fibers. -The chromosome alignment illustrated from a cell with a diploid chromosome number of 8.

Prophase I: -Events similar to prophase of mitosis. The chromosomes coil up, the nuclear membrane disintegrate, and centrosomes moving apart. -Synapsis (joining) of homologous chromosomes produce tetrads. -The two chromosomes may exchange fragments by a process called crossing over.

ORGANELLES

Others organelles

Centriole - Function: Help to organize the assembly of microtubules during cell division.

Chromoplast - Function: Synthesize and store pigments.

Peroxisomes - Functions: -Oxidation of organics substances -Decompose H2O2 (catalase) -Oxidize toxic substances

Mitochondria

Function: site of cellular respiration, produces ATP

Chloroplasts

Function: captures sunlight for photosynthesis.

Vacuoles

Functions: -Central vacuole: In plant cells. Store starch, water, pigments, poisons, and wastes. -Contractile vacuole: Regulate water balance, by removing excess water from cell. -Food or Digestion Vacuole: Engulf nutrients in many protozoa (protists).

Lysosomes

Functions: -Molecular garbage dump and recycler of macromolecules -Destruction of foreign material -Digestion of food particles taken in by cell.

Golgi Apparatus

Function: protein packaging factory.

Endoplasmic Reticulum (ER)

Smooth ER - Functions: -Lipid Synthesis -Breakdown of toxic compounds -Regulates sugar -Calcium storage

Rough ER - Functions: -Synthesis and modification of proteins. -Synthesis of cell and organelle membranes.

Nucleus

Function: Directs cell activity