CELL STRUCTURE AND CYCLE

The cell theory

• all organisms are made of cells

• the cell is the basic unit of life in all living things

• all cells come from existing cells

prokaryotic and eukaryotic cells

2 types of cells

Prokaryotic cells

• have no membrane covered nucleus

• have no membrane covered organelles

• have circular DNA

• Are bacteria

Eukaryotic Cells

• Have a nucleus

• Have a membrane covered organelles

• have linear DNA

• Are all other cells

Nucleus

• The control center of the cell

• governing power of cell

Nucleolus

• spherical body within the nucleus of most eukaryotic cells, involved in the

• synthesis of ribosomal RNA (rRNA) and formation of ribosomes

Cell Membrane

• outer layer of cells

• allow nutrients into the cell and waste outside of the cell

• gate into the city

• regulates the entry and exit of substances

Cytoplasm

• A jelly like fluid contained in the cell that holds the organelles

Mitochondria

• Power center of the cell

• Provides the energy the cell needs to move, divide, etc.

• produces energy through cellular respiration

Ribosomes

• Site where proteins are made

• Cell parts are made of proteins

• synthesizes proteins

Endoplasmic Reticulum

• Transportation system of cell

• transports proteins > rough er > synthesize lipids in smooth er

• it’s like a car

Rough ER

• transport and made proteins

• has ribosomes

• also modifies and folds proteins

Smooth ER

• no ribosomes

• synthesizes lipids

Golgi apparatus

• Packaging house of the cell

• packages, processes, and ships out the stuff the cell makes

• modifies, sorts, and packages proteins

Lysosomes

• Digests food particles and cell parts

• Garbage men

• Protects cells by digesting foreign invaders

• Police men

• breaks down waste materials

Vacuole

• Stores water, food, and wastes

• largest organelle in plant

Cell wall

• found only in plant cells

• protects and supports the cell

Chloroplasts

• found only in plant cells

• contains chlorophyll ( makes plants green )

• where photosynthesis takes place

Centrioles

• paired barrel shaped organelles

• located in the cytoplasm of animals near the nuclear envelope

Cell cycle

• a series of growth and development steps a cell undergoes between its “birth” - formation by the division of a mother cell - and reproduction = division to make 2 new daughter cells

interphase and mitotic phase

2 major phases of cell cycle

interphase

• cells grows and makes a copy of its DNA

mitotic phase

• cell separates its DNA into 2 sets

• divides its cytoplasm, forming 2 new cells

G1 phase

• also called first gap phase

• cell grows physically larger

• copies organelles

• makes to molecular building blocks it will need in the later steps

S phase

• the cell synthesizes a complete copy of the DNA i its nucleus

• duplicates a microtubule - organizing structure called CENTROSOME

G2 phase

• cell grows more

• makes proteins and organelles

• begins to reorganize its contents in preparation for mitosis

• end when mitosis begins

mitotic phase

• cell divides its copied DNA and cytoplasm to make 2 new cells

• involves 2 distinct division related processes: mitosis and cytokinesis

mitosis

• divided into 4 parts

cytokinesis

• cytoplasm of the cell split into 2, making 2 new cells

• begins just as mitosis is ending

• takes differently for animal and plant cells

Prophase

• chromosomes condense, and the nuclear membrane breaks down

Metaphase

• chromosomes align in the center of the cell

Anaphase

• chromatids are pulled apart to opposite poles

Telophase

• new nuclear membranes form around each set of chromosomes

cytokinesis

• the cell splits into 2 identical daughter cells