Cells and Tissues Cells and Tissues l Carry

Cells and Tissues

Cells and Tissues l Carry out all chemical activities needed to sustain life l Cells are the building blocks of all living things l Tissues are groups of cells that are similar in structure and function For Example: muscle tissue

Anatomy of the Cell l Cells are not all the same l All cells share general structures l All cells have three main regions l Nucleus l Cytosol (cytoplasm) l Plasma membrane

The Nucleus l Control center of the cell l Contains l Three genetic material (DNA) regions l Nuclear envelope (membrane) l Nucleolus (plural nucleoli) l Chromatin (DNA coiled around protein – protein acts as support for fragile DNA)

The Nucleus

The Nucleus continued… l Nuclear envelope ( or nuclear membrane) l Barrier of the nucleus; separates in from out l Consists of a double membrane l Contains nuclear pores that allow for exchange of material with the rest of the cell

The Nucleus continued…. l Nucleoli l l l Nucleus contains one or more nucleoli Sites of ribosome production Ribosomes move into the cytoplasm through nuclear pores Nucleolus

The Nucleus continued…. l Chromatin l Composed of DNA and protein l Present when the cell is not dividing l Scattered throughout the nucleus l Coils and shortens to form chromosomes when the cell divides (protects fragile DNA during cell separation)

Plasma Membrane l Barrier for cell contents l Controls what exits and enters the cell through osmosis and diffusion l Also contains proteins, cholesterol, and glycoproteins (proteins with sugar attached)

Plasma Membrane PLAY Membrane Structure

Plasma Membrane Specializations l Microvilli l l Finger-like projections that increase surface area for absorption Microvilli are present in our intestines; helps absorp nutrients and water we consume by eating

Cytoplasm or Cytosol l Cytoplasm is the material outside the nucleus and inside the plasma membrane l It’s the fluid that all organelles are suspended in

Cytoplasm l Contains three major elements l Cytosol l Fluid that suspends other elements (jello) l Organelles l l machinery of the cell “Little organs” that perform functions for the cell l Inclusions l Chemical substances such as stored nutrients or cell products like waste

Cytoplasmic Organelles

Cytoplasmic Organelles l Mitochondria l l “Powerhouses” of the cell Change shape continuously Carry out reactions where oxygen is used to break down food Provides energy for cell

Cytoplasmic Organelles l Ribosomes l Made of protein and RNA l Sites of protein production l Found at two locations l l Free in the cytoplasm On Rough ER

Cytoplasmic Organelles l Endoplasmic reticulum (ER) l Fluid-filled tubes for carrying substances l Two types of ER l Rough endoplasmic reticulum l l l Covered with ribosomes Makes proteins Smooth endoplasmic reticulum l Functions in lipid and steroid production and also detoxifies drugs and pesticides that invade the cell

Rough Endoplasmic Reticulum Ribosome m. RNA Rough ER As the protein is synthesized on the ribosome, it migrates into the rough ER cistern. In the cistern, the protein folds into its functional shape. Short sugar chains may be attached to the protein (forming a glycoprotein). Protein The protein is packaged in a tiny membranous sac called a transport vesicle. Transport vesicle buds off Protein inside transport vesicle The transport vesicle buds from the rough ER and travels to the Golgi apparatus for further processing or goes directly to the plasma membrane where its contents are secreted.

Cytoplasmic Organelles l Golgi l l apparatus Modifies and packages proteins Produces different types of packages l l l Secretory vesicles Cell membrane components Lysosomes

Proteins in cisterna Rough ER Cisterna Membrane Lysosome fuses with ingested substances Transport vesicle Golgi vesicle containing digestive enzymes becomes a lysosome Pathway 3 Golgi apparatus Pathway 1 Golgi vesicle containing proteins to be secreted becomes a secretory vesicle Pathway 2 Secretory vesicles Proteins Secretion by exocytosis Golgi vesicle containing membrane components fuses with the plasma membrane Plasma membrane Extracellular fluid

Lysosomes l Contain enzymes that digest worn-out or nonusable materials within the cell

Cytoplasmic Organelles l Peroxisomes l Membranous sacs of oxidase enzymes l Detoxify harmful substances such as alcohol, hydrogen peroxide and formaldehyde l Break down free radicals (highly reactive chemicals)

Cytoskeleton l Network of protein structures that extend throughout the cytoplasm l Provides the cell with an internal framework which keeps the cell 3 -Dimensional

Cellular Projections l Not found in all cells l Used for movement l Cilia move materials across the cell surface l l Located in the respiratory system to move mucus Flagella propel the cell l The only flagellated cell in the human body is sperm