Human Bio Test 1: Organization of Human Body and Homeostasis, Chemistry of Life, Anatomy of the Cell, Plasma Membrane Transport, Cell Cycle, Protien Synthesis

Homeostasis

Maintenance of constant internal environment

• blood delivers nutrients to cells and removes waste

• main sources of intake: respiratory system (take in O2) and digestive system (absorb nutrients)

• main systems of waste removal: respiratory system (remove CO2) and urinary system (removes excess water, salts, and organic waste

Regulation of Homeostasis

Receptor —> Control Center —> Effector

Receptor detects change

Control Center processes information and reports to effector

Effector creates needed change

Feedback

How a process is regulated by the products of the process

2 types: Negative and positive feedback

Negative Feedback

Inhibition of a process by the products of the same process

• stops the process once the products accumulate

• most common form of regulation

• ex: shivering warms you up so you stop shivering

Positive Feedback

Enhancement of a process from the products of the process

• good for creating quick response/exponential production of product

• must have a turn off method

• ex: blood vessel is cut, chemicals trigger clotting which produces more chemicals, accelerating the process, once the blood clot is formed, clotting stops

Elements

Substances made of one type of atom

• building blocks of all molecules

• each has unique chemical properties

• 13 bulk elements in the body: (top 3: Oxygen, Carbon, and Hydrogen)

• 14 trace elements

top 3 bulk elements in the body

Oxygen, Carbon, Hydrogen

Atoms

Smallest unit of matter

• made of protons (+), electrons (-) and neutrons (0)

Electron Shell Rules

1. Lower shells are filled first (Aufbau Principle)

2. 2 electrons per orbital (Pauli Exclusion Principle)

3. 2 e- in first shell, 8 e- in 2nd and 3rd shell

4. if valence shell is filled, the atom is inert

5. # of valence electrons determines behavior/reactivity

Atomic number

number of protons, determines element

Atomic Mass

number of protons and neutrons

Ions

charged atoms that gained or lost e-

• atoms gain or lose e- to fill valence shell

• Cations = positively charged

• Anions = negatively charged

Molecules

Particle formed when atoms chemically bond

Electronegativity

How well an atom attracts electrons

• EN increases across a period as the protons increase, increasing attraction

• decreases down a group as # of shells increase, more shells= more repulsion from internal e- —> less attraction

Ionic Bonds

Chemical Bonds formed by attraction of anions and cations

• an atom with high electronegativity steals the electrons of a an atom with lower electronegativity

• the resulting ions attract

• usually metals and nonmetals

• strongest bond but dissociates in water

Covalent Bonds

Chemical Bonds formed by the sharing of electrons between atoms to fill valence shells

2 types:

• non-polar (uneven charge)

• polar (even charge)

Non-polar Covalent Bonds

Covalent bonds that equally share electrons

• no partial charges

• atoms have equal electronegativity

Polar Covalent Bonds

Covalent bonds that unequally share electrons

• Molecule has partial negatively charged end (towards most electronegative atom) and partial positively charged end (towards least electronegative atom)

• An atom has a higher electronegativity than the other(s)

Hydrogen bonds

Attraction between the partial positive hydrogen end of a polar molecule and the partial negative end (Fluorine, Oxygen, Nitrogen) of a different polar molecule

• SUM EFFECT is biologically significant

Solution

a homogenous mixture

Solvent

Dissolves solute

Solute

Dissolves into solvent

Ionic Compounds Dissociate in water

Ionic compounds are broken into their ionic components in water as the polar charges of water surround the oppositely charged ions of the ionic compound, creating a hydration sphere, seperating the compound

Polar Covalent Compounds Dissolve into water

A compound/matrix of polar covalent bonds do not dissociate, but instead are separated into individual molecules as water’s partial positive and negative charges surround the partial positively charged and negative ends of the molecules, separating the compound

Solute Concentrations Expressions

• Molarity (Mole/Liter): moles of molecule per liter

• Osmolarity (Osmoles/Liter): number of particles a solute dissolves into per liter

• Percentage % (Weight/Volume): grams of solute per 100 mL of solvent 

• Equivalents (Equivalents/Liter): number of moles ionized times valence/charge of ions

Molarity M (moles/liter)

moles of molecule per liter of substance

Osmolarity Osm/L (osmoles/liter)

number of particles a solute dissolves into per liter of solution

• cell osmolarity is 300mOSM

• colligative property: osmolarity dependent on number of particles, not size or charge

• isosmotic = 2 solutions with same molarity

• hyperosmotic = solution has higher osmolarity

• hypoosmotic = solution has lower osmolarity

• hydrostatic pressure:

  • fluid pressure of vessel (osmolarities unequal between 2 solutions)

Percent % (weight/volume)

grams of solute per 100 mL of solvent 

Equivalents (equivalents/ liter)

number of moles ionized times the valence/charge of ion

• for electrolytes

Electrolyte

ionized solute that can conduct electrical currents

• normal blood values of electrolytes are heavily regulated for homeostasis

Proportion of % of body weight

60% of body weight is Total Body Water (TBW)

40% of body weight is Intracellular Fluid (ICF)

20% of body weight is Extracellular Fluid (ECF)

Intracellular Fluid (ICF)

• fluid found inside the cell

• 40% of body weight

Extracellular Fluid (ECF)

• fluid found outside the cell

• 20% of body weight 

• 5% plasma (fluid in blood)

• 15% interstitial fluid (fluid surrounding cells)

Composition of ICF and ECF

Intracellular Fluid: has most K+ (special K cereal)

Extracellular Fluid: has most Ca²+, Na+, Cl-  (salty milk)

Acid

solute that releases H+ when dissociating into solution

Base

solute that removes H+ ions from solutions

pH

measure of H+ ions in solution

• more H+ = more acidic (<7)

• less H+ = less acidic (>7)

Normal pH of blood

pH = 7.35-7.45

Acidosis in blood (too acidic)

pH < 7.35

Alkalosis in blood (too basic)

pH > 7.45

Biomolecules

• Carbon is the most abundant element in organic molecules

• 4 major classes of biomolecules that are macromolecules:

  • Protein (made of amino acids)

  • Lipid 

  • Nucleic Acid (made of nucleotides)

  • Carbs (polysaccharides are made of monosaccharides)

Organic molecules are mostly made of:

Carbon

• because it has 4/8 valence electrons it has a middling electronegativity, meaning it is more likely to form covalent bonds

• because of its tetrahedron structure, it has higher mobility, and makes versatile bonds 

Functional Groups 

Common chemical structures that influence bonding properties and can be used to predict chemical properties 

Ex: 

Hydroxyl group (OH)

Carbonyl group (CO)

Carboxyl group (COOH)

Amino group (NH2)

Carbohydrates

1:2:1 carbon, hydrogen, oxygen ratio

• 3 major classifications 

  • monosaccharides (1 monomer)

  • disaccharides (2 monomers)

  • polysaccharides (3+ monomers)

Carbohydrate Function

• important source of calories

• energy storage

• component of nucleic acids

• structure of cell wall in plants and bacteria

• modifying protein to alter function

• mediate recognition events at cell surface (acts as molecular marker)

Monosaccharide (simple sugars)

• building blocks to construct larger carbohydrates 

  • di= 2 monosaccharides 

  • oligo 3-10 monosaccharides

  • poly = 10+ monosaccharides

• classified by number of carbon atoms

  • 5C = pentose

  • 6C = hexose

• GLUCOSE IS MOST COMMON MONOSACCHARIDE IN DIET

Glycosidic Bonds

• monosaccharides link to form disaccharides

• formed by dehydration synthesis reaction: removal of one water molecule to form a glycosidic bond

• broken apart by hydrolysis reaction (addition of one water molecule to break glycosidic bond 

• REMEMBER

  • sucrose = glucose + fructose (table sugar)

  • lactose = glucose + galactose (milk sugar)

  • maltose = glucose + glucose (malt sugar)

Dehydration Synthesis Reaction

Removal of a water molecule to form a bond

Hydrolysis reaction

Addition of a water molecule to break a bond

Sucrose (table sugar)

glucose + fructose 

Lactose (milk sugar)

glucose + galactose

Maltose (malt sugar)

glucose + glucose

Polysaccharides

• monosaccharides —> monomer (repeating subunit of larger molecule)

• polysaccharides —> polymer (>10 monosaccharides)

types of polysaccharides:

• Starch: glucose storage in plants

• Cellulose: structure component of plant cell walls

• Glycogen: glucose storage in animals

  • branched polymer of glucose

  • found in liver and skeletal muscle

Starch

Storage form of glucose in plants

polysaccharide

Cellulose

Structural component of plant cell walls

polysaccharide

Glycogen

storage form of glucose in animals

• branched polymer of glucose

• found in liver and skeletal muscle

• polysaccharide

Lipids

water insoluble group of organic molecules

• 1:2 carbon to hydrogen ratio (very little oxygen)

• include

  • fatty acids, glycerides, phospholipids and glycolipids, steroids, and eicosanoids

types of lipids

• fatty acids

• glycerides

• phospholipids and glycolipids

• steroids

• eicosanoids

Lipid functions

• energy 

• energy storage 

• structure (ex phospholipid bilayer)

• signaling molecules 

Fatty Acids

type of lipid that is incorporated into larger lipid molecules

• used for energy storage to convert to energy

• Long chain (up to 24 Carbons attached to hydrogens)

• carboxyl group (COOH) on one end and methyl group (CH3) on other

  • include saturated and unsaturated fats

Saturated fatty acids

Fatty acids that have no double bonds and are saturated with hydrogen

Unsaturated fatty acids

Fatty acids with at least 1 double bond. 

Glycerides

• Key functions of triglycerides (glycerol + 3 fatty acids)

  • energy storage 

  • insulation

  • shock absorber

• glycerol + fatty acids

• glycerol = 3 carbon sugar

• formed by dehydration synthesis

• triglycerides stored as lipid droplets in cells of body (adipocytes)

• human body good at making and storing triglycerides

Phospholipids and Glycolipids

• Key functions:

  • Cell membrane structure/ function (phospholipid bilayer)

  • transport of other lipids

• both have glycerol with 2 fatty acids (unsaturated and saturated): diglyceride

• Phospholipids = diglyceride, phosphate group, and nonlipid group

• Glycolipids = diglyceride, carbohydrate (sugar)

• Amphipathic: partially hydrophobic and hydrophilic

Steroid

• Key functions:

  • chemical messengers, cell membrane structure, can span full body

• lipid with many carbons arranged in 4 ring structure 

• Cholesterol make steroid hormones

Eicosanoids

• Key function

  • local chemical signaling 

• 20 carbon compounds derived from arachidonic acid

• produced in small amounts in tissues

• act locally

Proteins

Polymers of amino acids connected by peptide bonds

Protein functions

• Catalysts (enzymes)

• Immune function (antibodies)

• movement (contractile proteins)

• signaling (receptor proteins)

• Structural support (connective tissues)

• oxygen delivery (hemoglobin/myoglobin)

Amino Acids

• components of proteins

• made of carboxyl group (COOH), amino group (NH3), H, and variable R group (differentiates amino acids), attached to central C

  • R groups can be hydrophilic, hydrophobic, acidic, basic

• 20 amino acids in humans

Peptide Bonds

• connect amino acids to form proteins 

• formed by dehydration synthesis 

• Peptides have directionality (OH of COOH terminal binds to H of NH3 terminal)

  • amino terminal (NH3)

  • carboxyl terminal (COOH

• Dipeptide = 2 amino acids

• oligopeptide (short chain) = 3-20 amino acids

• polypeptide = more than 20 amino acids

• >20 amino acid = protein

Protein (polypeptide) structure

• Primary: sequence of amino acids

• Secondary: alpha helix or beta pleated sheet 

• Tertiary: coiling or folding of one polypeptide (can exist without second secondary structure)

• Quaternary: interaction between multiple peptide chains

Protein primary structure

• sequence of amino acids

Protein secondary structure

• Alpha helix or beta pleated sheet

• proteins can be produced without secondary structure

Protein tertiary structure

• coiling and folding of 1 polypeptide

• all proteins have tertiary structures but don’t need secondary structure

Protein quaternary structure

• interactions between multiple polypeptides

Nucleic acids

• polymers of nucleotides

  • bound by sugar phosphate backbone = phosphate bound to free carbon of sugar

  • hydrogen bonds between complementary nucleotides of DNA

  • 5’ - 3’

• Functions 

  • storage and transfer of genetic material 

  • instructions for protein production 

  • energy

• types: DNA deoxyribonucleic acid, RNA ribonucleic acid

Nucleotide structure

• made of phosphate, sugar, nitrogenous base

  • DNA has H in sugar (deoxi = without O)

    • bp: AT, GC

  • RNA has OH in sugar

    • bp: AU, GC

Types of Nucleotides

Purines: double nitrogen ring

• Adenine and Guanine

Pyrimidines: single nitrogen ring 

• Cytosine, Thymine, Uracil

Purines always pair with pyrimidines

• A - T/U

• G - C

ATP (Adenosine Triphosphate)

• currency of energy

• formed by attaching/ phosphate groups to adenosine (adenine + ribose)

  • phosphorylation = adding phosphate group

• tri = 3 phosphate groups

• release energy when ATP (tri) is broken to generate ADP (di)

  • relies on ATPase enzyme

Cell size

10-15um (micrometers)

biggest cell 140 um = oocyte

• cell size is limited due to surface area (r²)  volume ratio (r³)

Mammalian Cells

• Eukaryotic cell = have nucleus 

• cell membrane forms selectively-permeable barrier

Membrane bound organelles in Mammalian cells

• nucleus 

• mitochondria

• golgi apparatus

• endoplasmic reticulum

• lysosomes

• peroxisomes

Nonmembrane bound structures in mammalian cell

• ribosomes

• proteasomes

• cytoskeleton

• centrosome and centrioles

• cilia

Plasma Membrane fluid mosaic model

• fluid: membrane moves

• mosaic: phospholipids, protein, sugar

• Glycocalyx = sugar coat on extracellular surface of membrane (glycolipid, glycoproteins, carbs for cell recognition)

Composition of phospholipid bilayer

• mostly phospholipids 

  • phosphate head is hydrophilic and fatty acid tails are hydrophobic

  • in water, phospholipids naturally form leaflet (sphere shape) to avoid water touching the inner fatty acid tails

• unsaturated fatty acid of phospholipid

Fluidity of phospholipid bilayer

• determined by phospholipids and cholesterol

• because of kinked unsaturated fatty acids, phospholipids are mobile, move laterally, rotate and flex

• cholesterol embedded in bilayer adds to membrane rigidity 

• balance maintains fluidity

Proteins in Plasma Membrane

• Integral Proteins:

  • embedded in plasma membrane or attached via covalent bonds 

    • transmembrane proteins span the plasma membrane

    • embedded proteins within the membrane

    • proteins anchored to membrane by covalent bonds 

• Peripheral Proteins:

  • located at extracellular or intracellular surface of membrane

    • bound to surface or non-covalently bonded to integral proteins

Plasma membrane protein function

• carrier

• channel

• receptor 

• recognition 

• enzymes

• cell-cell interactions

Carrier proteins (plasma membrane)

• integral proteins that transport chemicals across the plasma membrane to both up or down concentration gradient via active transport 

• bind on end, conformational (shape) change, and release

ion channel protein (plasma membrane)

• integral protein that is constantly open to allow ions to pass in and out of the cell down their concentration gradient via passive transport  

• pore

Gated ion channel (plasma membrane)

• integral protein that allows the movement of ions in and out of the cell down their concentration gradient that open and close

Cytoskeleton

made of

• microtubles 25μm

• intermediate filaments 8-10 μm

• microfilaments 5-8 μm

Microtuble

• largest and main component of cytoskeleton

• made of tubulin 

• create highways across cell (moved by motor protein dyenin and kinesin)

• 25 um

• more rigid than microfilaments

• component of spindle fibers, cilia, flagella

• important for fast axon transport of substances in nerve cells

Microfilaments

• smallest component of cytoskeleton

• found just under cell membrane for structure (periphery)

• 2 helix polymers of actin

• help anchor integral plasma membrane proteins to cytoskeleton

• aid in cytokinesis 

• myosin + actin filaments = contraction (ex in muscles)

• track for cargo— myosin motor

• 5-8 um

Intermediate Filaments

• middle sized filaments

• protein composition varies (eg keratin (epithelial), desmin (muscle))

• rope like

• provides structure/ mechanical strength to cell

• 8-10um

Cilia

• generates movement to mix substances at cell surface

• composed of microtubules

• wave-like movement

• basal body = where microtubules grow from

• short

Flagella 

• propel cell

• comprised of microtubules

• whip-like movement

• basal body = where microtubules grow from

• eg sperm

• long

microvilli

• made of microfilaments actin 

• don’t move

Centriole

• component of centrosomes

• 1 microtubule organization center

• single cylinder of 9 groups of microtubule triplets

Centrosome

• microtubule organizing center of the cell

• made of two perpendicular centrioles

• specialized region of cytoplasm by nucleus

• form spindle apparatus during cell division