- Anatomy and Physiology of a Cell:
o The cells of the human body are surrounded by extracellular fluid, which is mostly water, and an extracellular matrix.
o The plasma membrane is the outer shell of a cell.
o The cytoplasm and nucleus are inside the membrane.
- Plasma Membrane: a phospholipid bilayer that keeps the inside of the cell in and outside of the cell out. Contains cholesterol and a variety of proteins (structural proteins, ion and water channels, and glycoproteins)
o Channel proteins: have a hollow central pore, or channel, that allows water or small, charged particles (sodium, potassium, calcium, chloride) to pass into or out of the cell
o Glycocalyx: layer of carbohydrate groups surrounding a cell which helps cells bind to extracellular substances, which is important for cell recognition
o Membrane Transport: movement of substances across the plasma membrane
Passive Transport: doesn’t require energy
• Diffusion: movement of material from a place where it is concentrated to a place where it is less concentrated
• Channel Proteins: provides pathways across a cell membrane that allow specific substances to diffuse into or out of the cell
Active Transport: requires energy because it makes a substance go where it doesn’t want to go
- Parts of the Cell
o Cytoskeleton: network of proteins that defines the shape of a cell and gives it mechanical strength
3 types of long fibers:
• Microfilaments: thinnest, made of actin subunits, found in most cells (prominent in muscle cells)
• Intermediate filaments: made of keratin, extend across a cell giving the cell strength to resist external pulling forces
• Microtubules: largest, composed of tubulin subunits, helps separate and organize chromosome during cell division
Microvilli: finger like extension that increases the surface area of a cell
Cilia: hair-like projections that actively flex back and forth to move fluid or mucus across the outside of the cell
Centrioles: in the centrosome, area of the cell near the nucleus, helps guide the movement and separation of chromosome during cell division
o Mitochondria: responsible for making ATP, the universal carrier of energy within cells, also known as the powerhouse of the cell
o Golgi apparatus: set of membrane discs in the cytoplasm (usually between the endoplasmic reticulum and the plasma membrane of the cell) that produces small membranous spheres called vesicles
o Ribosomes: large enzymes that make polypeptides
o Endoplasmic Reticulum: network of membranes in the cytoplasm
Rough ER: has ribosomes attached to it, site for protein production and modification
Smooth ER: does not have ribosomes attached to it, sit e where replacement membrane is made for membranous structures in the cell, it is also a cite of steroid hormone production in cells of reproductive organs
o Nucleus: contains the cells genetic information
- Carbohydrates: also known as saccharides are “sugar and starch” molecules
o Function: serves as a source of chemical energy/ fuel which the body can utilize to make ATP
o Simple carbohydrates/sugars made of just one or 2 simple subunits
o Glucose: monosaccharide and is the main form of sugar that circulates in the blood
o Glycogen: polymer of glucose found in plants and animals
Liver and muscles cells make glycogen molecules from glucose
Form of stored fuel
- Proteins: large biological molecules made of chains of dozens to hundreds of amino acids
o Function: helps form the structure of cells, act as carriers (hemoglobin and myoglobin), and enzymes catalyze (speed up) specific biological reactions
o Amino Acids: building blocks of proteins, 20 common amino acids which all share a common design: each has an identical backbone consisting of an amino group, an acid group, and a central carbon in between.
o Peptide Bonds: a bond linking the amino group of one amino acid to the acid group of another.
Polypeptide: a longer chain of amino acids
- Lipids: fats and oils and related molecules
o Facts:
Rich in carbon and hydrogen and contain oxygen atoms and sometimes other types of atoms
Don’t dissolve well in water or blood
o Fatty Acid: hydrocarbon chain with a carboxylic group at one end
Saturated: fatty acids with single bonds
Unsaturated: fatty acids with one or more double bonds
o Steroids: cholesterol is a component of cell membranes and testosterone, and estrogen are hormones that regulate the reproductive system
o Glycerides: composed of a glycerol molecule with 1, 2, or 3 fatty acids attached, to make mono-, di-, and triglycerides.
Important energy storage molecules in the body
o Phospholipids: the phosphate-bearing head is hydrophilic (can form energetically favored hydrogen bonds with water molecules) and the fatty acid tails are hydrophobic (cannot form favorable hydrogen bonds with water)
In a watery environment, phospholipids tend to form bilayer, liposomes, or micelles with the heads facing the water and the tail adjacent to one another
- Nucleic Acids: key information carrying molecules in the cells
o Two kinds of nucleic acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
DNA: double helix, made up of nucleotides containing A, G, C, and T.
RNA: single chain, made up of nucleotides containing A, G, C, and U.
o There are only 5 kinds of nucleotides, the bases are adenine, guanine, cytosine, thymine, and uracil
o Nucleotides: subunits that make up nucleic acids containing a phosphate group, a sugar group, and a nitrogenous (nitrogen-containing) base
o Chromosomes: one DNA molecule and the proteins around, every human cell has 46 chromosomes, 23 from each parent
o Human Genome: DNA sequence of a human
o ATP: adenosine triphosphate, a nucleotide composed of an adenine base, a sugar, and three phosphate groups
Common energy source used in many cellular processes