chapter 2,3, & 4 - overview of chemistry of life

3 primary elements that make up all living things

O, C, and H

atoms are made of…

* protons (+)
* electrons (-)
* neutrons

ionic bonding

* physical exchange of an electron from one atom to another
* results in the production of a cation and anion

covalent bonds

* the sharing of electrons
* different types: single, double, triple

The most electronegative atom in a compound will draw the…

electron density

electrons equally shared?

non-polar covalent bond

electrons not equally shared?

polar covalent bond

hydrogen bonding

weak bond that occurs between a hydrogen atom attached to a very electronegative atom (usually O or N) and another molecule

hydrogen bonding is involved in…

* protein folding
* holding DNA strands together
* dispersing heat (evaporative sweat)
* and much more!

importance of water in the human body

* cohesion: tendency of water molecules to cling together
* adhesion: tendency of water molecules to cling to other molecules
* thermal stability: high heat capacity; takes a lot of energy to raise the temp. of water
* solvency: water is a powerful solvent

hydrophilic

tending to dissolve in water

hydrophobic

tending to fail to mix with water

acids

release H+ ions - “proton donor”

bases

release OH- ions - “proton acceptor”

organic compounds

* carbohydrates
* lipids
* proteins
* nucleic acids

carbohydrates

* sugars & starches
* classified according to size, function according to shape

lipids

* insoluble in water
* fatty acids, triglycerides, phospholipids, steroids

triglycerides

glycerol + 3 fatty acids

saturated fats

* no double bonds - “straight”
* dense fats - tend to clog up arteries & blood vessels

unsaturated fats

* at least 1 double bond - “bent”
* less dense

phospholipids

glycerol (sugar) with 2 fatty acid chains and a phosphate group attached

proteins

* function determined by shape
* most versatile molecule
* made of amino acids

many functions of proteins

* structural
* communication
* transport
* enzymatic
* recognition & protection
* movement
* cellular adhesion

primary structure of proteins

sequence of amino acids joined by peptide bonds

secondary structure of proteins

Alpha helix or beta sheet formed by hydrogen bonding

tertiary structure of proteins

folding and coiling due to interactions among R groups and between R groups and surrounding water

quaternary structure of proteins

association of 2 or more polypeptide chains with each other

denaturation

drastic conformational changes to a protein’s shape

enzymes

* speeds up reactions
* substrate-specific

nucleic acids

* made of nucleotides (DNA & RNA)
* contain ‘genetic code’

all living cells have…

* plasma (cell) membrane
* cytoplasm

intercellular fluid (ICF)

cytosol inside the cell

extracellular fluid (ECF)

fluid surrounding the cell

traits of the cell membrane

* semipermeable
* acts as a boundary
* interactions with other cells often occur at the plasma membrane

structure of the cell membrane

* aka: ‘phospholipid bilayer’ (2 layers = cholesterol + glycolipids + proteins make up the rest)
* surface is hydrophilic
* inside is hydrophobic

membrane proteins are classified as either…

* integral proteins - embedded in the membrane
* peripheral proteins - adhere to inside or outside of membrane

cilia

* short projections
* move objects through the body

flagella

* only found in sperm

pseudopods

* phagocytosis of bacteria

most important organelles to know for A&P…

* membranous organelles
* nucleus
* mitochondria
* lysosomes
* rough & smooth endoplasmic reticulum
* Golgi complex
* ribosomes

types of cells

* squamous
* cuboidal
* columnar
* polygonal
* stellate
* spheroidal
* discoidal
* fusiform
* fibrous

passive (no ATP required) processes

* diffusion
* osmosis
* carrier mediated transport (e.g. facilitated diffusion)

process of facilitated diffusion

* solute particle enters channel of a membrane protein
* solute binds to a receptor on the carrier
* carrier changes conformation
* carrier releases solute on the other side of the membrane

active (ATP required) transport

* primary active transport
* vesicular transport
* carrier method transport (e.g. ion pumps)

diffusion

movement of particles from areas of higher concentration to areas of lower concentration

osmosis

diffusion of water down its concentration gradient

tonicity

the ability of the solution to influence fluid concentration of the cell

hypotonic

water moves into the cell

hypertonic

water moves out of the cell

isotonic

no net change in water concentration

carrier-mediated transport

movement across a membrane using a protein

3 kinds of carrier-mediated transport

1. uniports - 1 molecule
2. symports - multiple molecules, same direction (aka: cotransport)
3. antiports - multiple molecules, opposite directions (aka: countertransport)

function of a receptor (as a membrane protein)

binds to chemical messengers such as hormones sent by other cells

function of an enzyme (as a membrane protein)

breaks down a chemical messenger and terminates its effect

function of a channel protein

constantly open and allows solutes to pass into and out of the cell

function of a gated channel

opens and closes to allow solutes through only at certain times

function of a cell-identity marker

distinguishes the body’s own cells from foreign cells

function of a cell-adhesion molecule (CAM)

binds one cell to another

primary active transport

* uses ATP to push molecules up/against their concentration gradient
* the sodium-potassium pump

vesicular transport

* moves larger particles, droplets of fluid, and numerous molecules through the membrane by creating a plasma membrane pouch that pinches off and produces a vesicle
* endocytosis (aka: phagocytosis)
* exocytosis

endocytosis

move materials into cell

exocytosis

move materials out of cell

gene

a portion of DNA that encodes for an RNA molecule used to make a protein

order of nucleotides in a gene determines the order of amino acids in a…

protein

central dogma of molecular biology

DNA → mRNA → protein

after production, proteins can either be used the cell or transported out of it. either way…

proteins will undergo conformational folding aided by chaperone proteins

if protein is to be packaged or secreted, then…

* post-translation modifications occur in the ER
* carbohydrates are added in the Golgi complex

the regulation of genes implies that…

genes aren’t always turned on

mitosis

the process during which cells reproduce

the cell cycle consists of 2 main processes:

1. interphase
2. M (mitotic) phase

the 3 subprocesses that make-up interphase:

1. G1 phase: growth & normal metabolic roles
2. S phase: DNA replication
3. G2 phase: growth & preparation for mitosis

the 5 subprocesses that make-up M (mitotic) phase:

1. prophase
2. metaphase
3. anaphase
4. telophase
5. cytokinesis (division of the cell’s cytoplasm)