BELL RINGER 9/1: WHAT ARE THE 4 ELEMENTS THAT MAKE UP LIFE? (ONE IS CARBON) Cells part 1

OVERVIEW of Cellular Life Cells are made up of:  Mostly Carbon, nitrogen, hydrogen, oxygen  Mostly protein in the structure  Trace elements are also really important  Calcium- needed for blood clotting  Iron- needed in hemoglobin to carry oxygen  Iodine- needed to make thyroid hormone which controls metabolism Interstitial fluid: salt-water solution that surrounds all cells  Derived from blood and all exchanges between cells and blood are made through this fluid

OVERVIEW of Cellular Life Cells vary dramatically in length  2 micrometers ( 1/12,000 th of an inch) in smallest cell  Over a meter (3 feet) in the nerve cells that cause you to wiggle your toes Cells also differ in shape  Disk-shape (red blood cells)  Threadlike (nerve cells)  Toothpicks (smooth muscle cells)  Contain head and tail (Sperm)

General Anatomy of a Cell Even though cells are so diverse in structure and function, they DO share many similar structures Three main regions of a cell  Nucleus  Cytoplasm  Plasma membrane

General Anatomy: Nucleus “Headquarters” Contains all the genetic material  DNA- blueprint for building the body  More specifically- DNA has blueprints for building PROTEINS  Most often circular but the nucleus can conform to the shape of the cell (muscle cell nuclei are elongated)

General Anatomy: Nucleus “Headquarters” Three regions of the nucleus  Nuclear envelope  double membrane barrier that surrounds the cell. Aka Nuclear Membrane  Between the membranes is a nuclear moat filled with fluid that contain pores (nuclear pores) that aid in passing substances in and out of the cell.  Nucleoli (aka Nucleolus)  small dark bodies where ribosomes are assembled  Chromatin  when the cell isn't dividing, DNA is compacted into loose threads called chromatin. When the cell is dividing, these coil/condense to create chromosomes

Fragile, transparent barrier surrounding the cell  Sometimes also called a cell membrane HOWEVER all cell organelles have membranes so we will call the outer barrier the plasma membrane. Structure is important for many cellular activities General Anatomy: The Plasma Membrane

Structure:  Two lipid layers arranged “tail to tail”  Mostly phospholipids but some of it is cholesterol  “lipid bilayer”  Protein molecules “float” between the tails

General Anatomy: The Plasma Membrane Polar heads  Hydrophilic (water loving)  Attracted to water  Main component of intracellular and extracellular fluid Nonpolar tails  Hydrophobic (water fearing)  Lineup inside the membrane This structure is self orientating and allows for quick reseal if the membrane is torn

General Anatomy: The Plasma Membrane Proteins are scattered throughout the membrane  Many are receptors for hormones or for other chemical messengers  Some are binding sites to anchor to other surfaces  MOST have a transport function for items going in and out  Protein channels

General Anatomy: The Plasma Membrane Glycoproteins  Proteins have branching sugar groups  Think of them like tiny fuzzy structures all over the cell  Functions  Determine your blood type  Act as receptors for certain types of bacteria/toxins/viruses can bind to  Act as signaling towers for that other cells recognize

Specialties of the Cell Membrane Microvilli!  “little shaggy hairs”  Tiny fingerlike projections that line the hollow organs  Increase the cell surface area for more absorption ability  This also speeds up the absorption process

Specialties of the Cell Membrane Membrane junctions – where the membranes meet  Tight junctions- impermeable junctions that bind cells together - you shall not pass!  Desmosomes- button-like anchoring junctions that prevent cells from being torn apart.  Normally membranes are thickened in these areas  Gap junctions- allows communication through membrane with chemical molecules (ions, nutrients, hormones etc)  Neighboring cell connected with a connexon! – hollow tube composed of proteins

We made it to Cytoplasm! Cytoplasm- the cellular material outside the nucleus and inside the plasma membrane Three components  Cytosol  Organelles  inclusions

Components of Cytoplasm Cytosol  Semitransparent fluid that suspends the other components  Mostly water Inclusion bodies (proteins that miss fold)  Most are stored nutrients or products from the cell  Lipid drops in fat cells, glycogen abundant in liver and muscle cells, pigments such as melanin in skin and hair cells, mucus and other secreted products etc.  Aggregate inside the cell and can be used sometimes as markers for disease  Aggregates of inclusion bodies in the brain = markers for dementia or Parkinson's

Organelles

Organelles- Mitochondria “Power-house” of the cell Inner membrane has shelf- like structures called cristae. Enzymes dissolved in the fluid within the mitochondria carry out reactions to break down food.  Energy will be released as this occurs and most is lost as heat  What isn't lost is used to form ATP molecules

Organelles- Mitochondria Cells that are metabolically “busy” like liver and muscle cells require a lot of ATP and so have A LOT of mitochondria in the cells

Organelles- Ribosomes Tiny bodies made of protein Ribosomes are the site of protein synthesis Some float free in the cytoplasm and make protein Others are bound to membranes (like the endoplasmic reticulum)

Organelles- Endoplasmic Reticulum “ER” – system of fluid filled canals used as a “circulatory system” to carry proteins around the cell  Rough ER- has ribosomes bound to it  Proteins made on the ribosome and transported via the rough ER  Smooth- no protein making but does help in lipid break down and breakdown of drugs/pesticides- liver cells are full of rough ER

Organelles- Golgi Apparatus Stack of flattened sacs close to nucleus and is the “traffic director” for cellular proteins sent from the ER  Modifies, packages, and ships proteins

Organelles- Lysosomes “break down bodies”- different sizes within cell Bags full of digestive enzymes that breakdown foreign material and non- usable cell structures  Demolition sites in the cell Abundant in phagocyte cells that engulf debris/bacteria

Organelles- Cytoskeleton Elaborate protein network throughout the cytoplasm  “cells bones” – internal framework  Intermediate filaments- form desmosomes to resist pulling apart  Microfilaments (actin/myosin) are involved in cell motility  Microtubules- determine shape of the cell and how organelles are distributed

Organelles- Centrioles Are close to the nucleus Rod shaped structures that create microtubules for cell division