Girl Genius Clipboard

2006-10-29T15:30:00.000-08:00

10/27/06 & 10/28/06

Prokaryotes
General structure - no membrane-bound nucleus or organelles; cell wall composed of pepidoclycan disaccharides & peptide fragments; flagella, fimbriage (short fibers that aid in attachment)

Nutrition

obligate anaerobes - cannot grow in presence of oxygen
facultated anaerobes - can grow with or without oxygen present (but prefer to be without)
autotrophic - can synthesize organic molecules from inorganic molecules; includes photoautotrophs and chemoautotrophs (use H2, H2S, NH3)
heterotrophic - must take in organic molecules for nutrition

Three Different Shapes of Bacteria

spiral - helical
rods - baccilli
round/spherical - cocci

Archae - different from bacteria

contain different rRNA sequences
more similar to eukaryotic rRNA
contain similar enzymes to eukaryotes

Pathogen - disease-causing agents:

Bacterial pathogens

anthrax - bacillus anthracis
the plague - yersinia pestic

Viral pathogens

small pox
rabies

Protists - eukaryotic, mostly unicellular organisms

Green algae - photosynthetic
ex: chlamydomas (unicellular), spirogyra (filamentous), volvox (colonial)

Red algae - marine, unicellular, photosynthetic
ex: gelidium

Brown algae - marine, photosynthetic
ex: kelp

Diatoms - marine, unicellular, phytoplankton
ex: cyclotella

Dinoflagellates - photosynthetic, unicellular
ex: gonyaulax

Euglenoids - fresh water, unicellular
ex: euglena

Zooflagellates - no photosynthesizing, can be symbiotic or parasitic
ex: trypanosomes (causes African sleeping sickness), giardia lamblia (causes severe diarrhea)

Ameoboids - protists with pseudopodia ("false foot") for locomotion and obtaining food

Ciliates - protists with cilia
ex: stentor, paramecium

Sporozoans
ex: pneumocytic carnii (causes pneumonia), plasmodium vivax (malaria)

Fungi

Structure

mycelium -network of filaments (called hyphae) that absorb nutrients
non-motile
multicellular

Fungi's Reproduction (both sexual and asexual)

spore - reproductive cell that develops into a new organism identical to the original without needing another reproductive cell
budding - fragmentation of mycelium
two hyphae contact and fuse

Phylum Zygomycota (zygospore fungi)

ex: rhizopus (black bread mold)
sporangium - capsule that produces spores
zygospore - structure formed through sexual reproduction

Phylum Axcomycota (sac fungi)

ex: neurospora (red bread mold)
axcus - finger-like sac, develops during sexual reproduction (contains ascospores)

Phylum Basidiomycota (club fungi)

ex: 'shrooms...
basidia - club-shaped structures that produce basidiospores

Phylum Deutromycota (imperfect fungi)

ex: penicillin
reproduce asexually
conidiospores - spores produced for asexual reproduction
mode of sexual reproduction is yet unknown

Plantae

Plant Parts

root system - anchors plant in soil; gives support; absorbs nutrients and water
stem - contains tissue for production of leaves; transports minerals, water, and products of photosynthesis
leaves - photosynthesis; broad blade (good surface area)

Plant tissues - all derive from meristem at tips of stems, which leads to growth of plant

epidermal tissue - outer protective covering; contains epidermic cuticle, stomata (small opening on underside of leaves, for gas exchange)
ground tissue - fills interior of plant
vascular tissue -also interior, aid in transport of water and nutrients; also provides support

Two major types of vascular tissue

xylum - transports water and nutrients from roots to leaves
phloem - transports sucrose and other compounds from leaves to roots

Plant reproduction - "alternation of generations" (there's a snazzy picture for this, which I can't figure out how to put in here)

Four Major Plant Groups

Nonvascular - no vascular tissue for water transport
ex: hornworts, liveworts, mosses
Seedless vascular - contain specialized tissue for water transport
ex: club mosses, ferns
Gymnospermns - seed plants that produce pollen grains and seeds for reproduction
ex: conifers
Angiosperms - flowering plants, reproduce by way of pollen grains and seeds
ex: any flower (daisies, water lilies, etc.)

Must know how to ID these under microscope

amoeba
spirogyra
paramecium
volvox
trypanosoma
bacteria
diatoms
rhizopus
aspergillus
mushroom

2006-10-23T17:22:00.000-07:00

10.20.06 & 10.21.06

Origin of Life (Chemical & Biological evolution)

Chemical evolution

increase in complexity of chemicals that could have led to the first cells
containing things like H2, H2O, NH3, CH4, CO2
this is an abiotic process that created small organic molecules

Biological evolution

evolution of self-replecating system
these complex macromolucules could have produced proto cells

Proto cell ("first cell") - structures containing a protein-lipid membrane, that also carries out energy metabolism

Evolution of a "true cell" could have occurred with formation of genes in RMA

were probably prokaryotic
these cells then evolved in photosynthetic cells, which would have added O2 to the atmosphere

Eukaryotic cells came about how?...

endosymbiotic hypothesis - the evolution of a eukaryotic cell by phagocytosis of prokaryotes, which then became organelles (such as, perhaps, mitochondria)

Factors that influence evolution

Continental drift - movement of continents over Earth's surface, change in biogeography
Mass extinction - disappearance of many species, brought on by environmental changes

Evolutionary Thought

Darwin's Contributions

species change over time in response to environment
all living things share characteristics because they have common ancestry
Natural Selection - mechanism of evolution caused by environmental selection of organisms most fit to reproduce; results in adaptation to environment...

...such as...

random variations caused by genetic mutations and recombination of alleles
struggle for existence due to food source (think Thomas Hobbes)

Fitness - ability for an organism to reproduce, compared to another organism in same environment

Some Evidence/Support/Etc.

Fossil evidence - history of life recorded from remains of the past (such as equus)
biogeographical evidence - distribution of organisms (related organisms starting in one location evolve differently in different environments)
anatomical difference - anatomical similarties among different organisms
biochemical evidence - organisms contain a lot of the same biochemical structures (such as DNA and proteins); many organisms also contain similar genes

Re: similar structures:

homologous structures - anatomically similar becauase they were inherited from common ancestor
analogous structures - serve the same function but do not look similar or have a common ancestor (such as the wings on a bird vs. the wings on a housefly)

Human Evolution

Primate adaptations for arboreal life (livin' in the trees)

opposable thumbs
nails
produce (typically) 1 offspring per reproductive cycle
binocular vision
large, complex brain
learned behavior

Primate evolution

Prosimians - lemor
Anthropoids - new world monkeys (spider monkeys) and old world monkeys (baboons, rhesus monkey)
Hominoids - apes and humans

Humans got it - Apes don't

Spine enters from center
Spine is S-shaped
Bowl-shaped pelvis
Femurs angle inward to the knees
Knee can support weight
Feet are arched

Homonoid evolution

Australopithecus - "Lucy" - low forehead, projecting face, 400 cc brain
Homo Habilis - forehead a little higher, projecting face, 700 cc brain
Homo Erectus - even higher forehead, almost flat face, 800 cc brain
Homo Sapiens - high forehead, flat face, 1000 cc brain

Homo Sapiens

Neanderthals - homo neanderthalenis - advanced culture, complex tools, use of fire
Cro-magnons (homo sapiens sapiens) - culturally advanced; men hunt, women have the kids; compound tools; hunt cooperatively, language (verbal & written)

Classification of Living Things

Taxonomy - branch of biology concerned with identifiying, naming, and classifying organisms
Characteristics - structural/chromosomal/molecular feature that distinguishes one group from another

Domain (bacteria, archaea, eukarya)
Kingdom (monera, protista, plantae, animalia, fungi)
Phylum
Class
Order
Family
Genus
Species

Viruses are another story...

non-cellular, parasitic agents, consisting of:

Capsid - outer covering composed of protein
Nucleic acid - DNA or RNA

Viral reproduction -obligate, intracellular parasites - cannot reprouce out of a living cell

Reproductive Mechanism

Attachment
Fusion
Uncoating
Reverse transcription RNA --> cDNA
Integration --> into host DNA
Replication
Biosynthesis
Maturation
Release

Other Infectious Particles

Prions - only protein; causes mad cow disease and chronic wasting disease
Viroid - only RNA, doesn't even have a capsid

2006-10-23T17:02:00.000-07:00

10.13.06 & 10.14.06

Detailed crap on DNA replication (I did not follow this incredibly well, feedback please):

Double helix - this form is fantastic because it's stable

Along the "backbone" are a sugar and a phosphate group

First carbon atom attached to the base is 1' (one prime); exposed carbon atom on the last nucleotide will always be either a 3' or a 5'.

These run anti-parallel
3' ---------------5'
5'----------------3'

DNA replication is semi-conservative

each new cell will a get an old strand and a new strand
new strand will be filled in by reading its nucleotides' bases and matching the correct nucleotides based on the base...basically

DNA polymerase (the suffix -ase means it's an enzyme) - enzyme that joins complimentary nucleotides to the DNA template; has proof-reading abilities

DNA helicase - facilitates opening the DNA by holding itself in place, while binding proteins keep the strands apart

Polymerase reads a strand, pulling in correct nucleotides; must start at a 3' and read towards the 5' end, which means...

...one strand (the leading strand) does all of this fairly quickly and...

...the other (the lagging strand) requires a primase, which lays down an RNA primer; RNA primer acts as a 3' for the polymerase to attach to [this is also very confusing to me]

Replication Errors

Genetic mutations - change in sequence of bases during replication; can happen if DNA polymerase lays down the wrong nucleotide (only once every 100,000 base pairs)
DNA polymerase proofreading - it can go back, remove the wrong one, and replace with a correct match, making its error rate really only one in a billion base pairs

Environmental Factors - UV light, tabacco smoke, pesticides

DNA --> mRNA --> Protein

Type of RNA involved

mRNA (messenger) - made from DNA template that encodes a protein
tRNA (transfer) - transfers an amino acid to a ribosome
rRNA (ribosomal) - makes up a ribosome; contains a large sub-unit and a small sub-unit

Overview of Steps for DNA --> mRNA --> Protein

DNA, in the nucleus - transcription occurs in nucleus to become mRNA
mRNA moves to cytoplasm - translation occurs in cytoplasm to make a protein

Transcription (in the nucleus)

RNA polymerase
promoter region - defines the start of a gene
terminator - defines the end of a gene, causes release of RNA polymerase, newly synthesized mRNA

Translation (in the cytoplasm)

Genetic code - codon - three base pair sequence in the mRNA, codes for a particular amino acid
tRNA has an anticodon that pairs to the codon

2006-10-05T17:58:00.000-07:00

Friday 9/29/06

Meiosis - two nuclear divisions, producing four haploid cells from an initial diploid cell

Structures & Definitions

Gamete - haploid cell (such as a sperm or egg) for sexual reproduction
Zygote - diploid cell (2n) produced by fusion of male and female gamete (one of each) ... or, to put it simply, a fertilized egg
Homologou chromosomes - in a diploid cell, chromosomes occur pairs (paternal & maternal); these are homologoug

Phases of Meiosis I

Prophase I
Metaphase I
Anaphase I
Telophase I ... (2 cells - 2n)

Phases of Meiosis II

Prophase II
Metaphase II
Anaphase II
Telophase II

"Crossing over" - swapping of small parts of paternal & maternal chromosomes ... that's crazy and cool

Meiosis in dudes...

Spermatagonesis - development of sperm

Primary spermatocyte

...meiosis...

Secondary spermatocyte

Spermatids (n)

...maturation...

sperm (n)

In chicks...

Oogenesis - formation & maturation of eggs in ovary

Primary oocyte (2n)

...meiosis...

Secondary oocyte & first polar body

...meiosis II...

egg (n) & second polar body

...fertilization...

zygote (2n)

That's right, no maturazation without a male.
Seems like it should be the other way around, doesn't it?

Intro to Genetics

Gregor Mendel - constructed inheritance experiments with pea plants, and discovered info contrary to the then-popular "blending theory"

Gregor developed Laws of Segregation

Each individual has two factors for each trait
Factors segregate during formation of gametes
Each gamete contains only one factor for each trait
Fertilization gives each new individual two factors for each trait

Modern Genetics

gene - region of DNA that controls hereditary characteristics
gene locus - specific location of a gene on homologous chromosomes
alleles - one of a set of alternative forms of a gene

Dominant [allele] - this allele is expressed in phenotype; noted with an upper-case letter
Recessive [allele] - this allele is not expressed in phenotype; noted with a lower-case letter
homozygous - an organism containing two of same alleles for same trait (such as TT or tt)
heterozygous - organism containing two different alleles for a single trait (Tt)
genotype - what genes an organism has
phenotype - what organism looks like; its manifested traits

2006-10-04T07:03:00.000-07:00

Last weekend's notes coming soon. Should be up by the end of this evening.

Hm, when exactly is "the end" of an evening? It is when morning comes again? Or right at midnight? Or does it end when you feel like going to sleep? "Survey says..."

2006-09-25T19:54:00.000-07:00

Saturday 9/23/06

Apparently, those who attended Friday's lecture left off with haploid and diploid cells

Haploids: sperm and egg
Diploids: all others

Steps of Meiosis (very cool, super-special eukaryotic division):

G1 - a pause (for suspense), preparing to replecate
S - growth and DNA replication
G2 - growth and final preparation for division
M - mitosis

Mitosis (Let's stick with 5 steps); cell division/reproduction

Interphase - Meiosis, essentially
Prophase - centrioles begin moving to opposite poles; spindle fibers begin extending from poles; nuclear envelope breaks apart; spindal fibers attach to centromer region chromosome
Metephase (this step is shorter than the last one and I like it better) - chromosomes align in middle of cell
Anaphase - sister chromatids are pulled apart to create daughter chromosomes; each set of daughters are pulled to opposite poles
Telophase - nuclear envelope appears around each daughter

Cytokinesis: divions of cytoplasm into two distinct cells

Prokaryotic Cell Division (binary fission; it even sounds gross) - asexual reproduction, producing two identical cells

Color results and the pigments they respresent (from Lab)

Orange/Yellow-ish: beta cerotene
Yellow: xanthrophyll
Blue green/Green: chlorophyll A
Olive green: chlorophyll B

2006-09-25T19:13:00.000-07:00

I was not in class on Friday, September 22. I also did not get notes from anybody, but after all, I am awesome and a girl genius. So, here's my summation of what I think we all should have learned in my absence...

Autotrophs - produce nutrition using inorganic sources of energy (like light), and get carbon from carbon dioxide

Heterotrophs - require organic substrates for same; we're consumers

Photosynthesis (literally translated: "putting together light")

requires light, carbon dioxide, and water
method of grubbin' used by plants, algae, some bacteria and protists
6 CO2 + 12 H2O + light ---> C6H12O6 + 6 O2 + 6 H2O

Chlorophyll in photosynthesis: colors absorbed, color reflected...those are very good questions...

ATP questions that I need to work on:

why it's the "energy currency" of the cell, and not glucose
structure of ATP and ADP
ATP cycle

Cellular Respiration - process of converting molecules (like, say, glucose) into useful energy; every cell technically respirates

Aerobic respiration - requires oxygen (anything else I should know?)

Anaerobic respiration / Fermentation - Some sort of definition-esque thing should go here.

in animals and their friends - C6H12O6 --> 2 lactic acid + ATP (energy)
in plants, bacteria and yeast, attorneys at law -
C6H12O6 --> 2 alcohol _ 2 CO2 + ATP (energy stuff)

Okay, so my notes from this Friday totally suck and I am not a girl genius. At all. I'm just a girl who missed class and has lousy notes...and can't hide it because I've been proclaiming my meager Bio knowledge from the rooftops via the internet. Sue me.

Actually, don't sue me. Just comment and leave me suggestions, so I can stay in business. Thanks.

2006-09-18T16:33:00.000-07:00

9/16/06 Saturday

Regarding chemical reactions...

Two outcomes for chemical reactions - release or conversion of energy

Release! (reactants broken down) - exergonic reaction; in the body this is catabolism (breaking macromolecules down into molecules)
Conversion - requires input of energy (most religious experiences do) - endergonic reaction; in the body this is anabolism (large molecules synthesized from small molecules)

Picture of ATP: http://en.wikipedia.org/wiki/Adenosine_triphosphate

ADP + P + energy --> ATP

ATP --> ADP + P + energy

^ They happen close by for each other's benefit.

Cells also need...

Enzymes - protein that acts to speed reactions by physically holding reactants together; these guys have specific active sites that they respond to surrounding molecules with. So, no square pegs in round holes.

Factors affecting enzymatic activity:

Temperature
pH - neutral for the most part, except for a cell's lysosomes (low-pH cellular garbage disposal)

2006-09-16T18:09:00.000-07:00

9/15/06 Friday

Cell Membrane (Plasma membrane)

No charged molecules pass through
No macrmolecules (big dudes) get through

Fluid-mosaic model: a cell's membrane is fluid, embedded with proteins that span whole membrane or part of it

Functions of Plasma Membrane

Protection / Concentration gradient - separates outside environment from inside
Support - cholesterol deposits (among fatty acids in phospholipid bi-layer) stiffien membrane, regulate fluidity
Cell-to-cell signaling / Adhesion - glycolipids (phospholipids w/ carb chains) and glycoproteins (proteins w/ carb chains)

Mechanism of Transport

Diffusion - Molecules' tendancy to move from high concentration to low concentration until there's equal distribution...like communism
Osmosis - Diffusion across semi-permeable membrane
Facilitated transport (for molecules too big to pass membrane) - use of carrier proteins, still moving from high to low concentration; requires no exertion of energy
Active transport - still using carrier proteins; molecules "pumped" from low to high concentration; requires exertion of energy
Membrane transport - movement in/out of cell by using vesicles (small membrane-bound sacks containing molecules); exocytosis - vesicle formed inside cell fuses w/ plasma membrane and releases content outside cell; endocytosis - vesicle formed around outside molecules and is brought inside

Metabolism: Enzymes & Energy

Lawn of Thermodynamics

Energy cannot be lost, but can be converted from one form to another: potential energy and kenetic energy
Energy cannot change from one form to another without the loss of useful energy (Hint: heat is not useful energy, since it just floats away and is lost to the environment.)

ATP (Adenosine Triphosphate): contains two high-energy bonds between phosphate groups, give us all energy (all of us...you...me...chimps....whales...strep throat critters...etc...)

We need this crap for:

Chemical work (building of macromolecules)
Mechanical work (muscle contraction, nerve impulses)

2006-09-16T10:02:00.000-07:00

Friday 9/8/06

Organelles in Eukaryotic cells:

Endoplasmic reticulum (reticulate, adj. = something that's part of and involved in networking)

both prokaryotic and eukaryotic cells have ribosomes
but euk.'s have them organized, the rough part has embedded ribosomes and the smooth is involved in synthesizing phospholipids and steiroids

Golgi

sorts and packages proteins & lipids, which are then ready for secretion

Mitochondria

most of cell's energy made here
has a double membrane (outer one is "normal" and inner membrane is squiggly, so it has more surface area to work on - makes sense)
produces energy through chain reactions - "cell respiration"

carb + oxygen --> "ATP"

Lysosome

low pH, digestive enzymes
Down with the foreign antigens; kill them all!

Cilia (hairy-type things) and Flagella (tail) - structures for movement

2006-09-05T18:06:00.000-07:00

Week Two

Polar molecules dissolve in water (attraction of partially positive/negative molecules to hydgrogen in the water)

Nonpolar examples: fats, oils

Properties of Water

High heat capactiy (because of hydrogen bonds), slow changes in temp
High heat of vaporization (H bonds broken easily)
Solvent
Cohesive & Adhesive
Surface tension
Less dense when frozen than when fluid (this is how ice floats on liquid water)

pH: indication of solutions' acidity or alkalinity
acidity: high concentration of hydrogen ions (atom w/ a charge)

ex: HCl (hyroclauric acid), in water, becomes: H+ and Cl-

pH 1-6 : acidic (stomach acid: 1)
pH 7 : neutral (water)
pH 8-14: basic (ammonia: 14)

ex: NaOH in water: Na+ and OH- <-- makes solution basic

Organic Molecules: containing both carbon and hydrogen

Carbon is important because: it can form 4 covalent bonds; 2 in first shell, 4 in second, it wants 4
more: very unique

Four classes of Organic Molecules: carbohydrates, lipids, proteins, nucleic acids

Carbs: sugars used as an energy source

monosaccaride: one sugar molecule (in carbs - glucose, simple sugar)
disaccaride: two sugar molecules (such as glucose + fructose = sucrose)
polysaccaride: polymer of monosaccarides

in plants: starch
in animals: glycogen
(long-term storage molecules)

Lipids

Triglycerides: fats & oils; fat molecule is made up of glycerol and 3 fatty acids

unsaturated fats: double H-bonds
saturated fats: H-saturated, pack together well (artery-clogging power of doom)

long-term energy storage: holds more than glycogen & starch

Phospholipid: out of all living cells, phospholipid bi-layer

Phosphate group ("head"): polar - hydrophillic
Fatty acids ("tail"): non-polar - hydrophobic

They form a bi-layer which is the plasma membrane around all cells, with hydrophbic fatty acids facing in and hydrophillic phophate groups facing out.

Steiroids: in plasma membrane
Waxes: for protection (plants)

Proteins: polymer made of amino acid monomers

polypeptide: chain of aa's = protein, linked together by polypeptide bond

Structure of Proteins:

Primary: polypeptide
Secondary: form alphahelices and beta-pleated sheets
Tertiary: globular structure
Quaternary: big messy protein thing

Nucleic Acids: its monomer is a nucleotide

Prymadines (one ring):

C - cytosine
T - thymine
U - uracil

Purines (two rings)

A - adendine
G - guanine

DNA (deoxyribonucleic acid): for replication, info to make proteins, shape of a double helix,
a polymer of C, T, A and G
complimentary pairs: C with G
A with T
deoxyribose: sugar in DNA
H bonds in DNA: important for cell replication
DNA contains: sugar, phosphate group, and a base (C, T, A or G)

RNA: ribonucleic acid: involved in protein synthesis, single stranded, base of C, G, A and U

Protein Functions:

Support (such as keratin in hair & nails; callogen in ligaments & tendons)
Enzymes (such as amylese for digestion)
Transport (plasma membrane, channel & carrier proteins)
Defense (antibodies)
Hormones (cell-to-cell signalers, such as insulin)
Motion (such as actin & myosin for muscle contraction)

Cells: smallest unit of living matter, two broad types:

Prokaryotic: no membrane-bound nucleus
Uekaryotic: nucleus, membrane-bound

Prokaryotic (bacteria): plasma membrane, cytoplasm (semifluid - contains DNA, enzymes, and
other shit), DNA has one chromosome and is circular
Eukaryotic (protists, fungi, plants, animals): made up of organelles - compartment enclosed by
a membrane with distinct structure & function

Celcius = 5/9 (F-32)
Farenheit: 9/5 C + 32

2006-09-05T17:34:00.000-07:00

Week One

Characteristics of life

organization
response to environment (stimulus --> response)
obtain materials and energy
development/reproduction (sexual or asexual)
ability to adapt

energy: capacity to do work
metabolism: chemical reaction within cells; need essential molecules obtained from food to
perform these reactions
homeostasis: maintenance of normal internal conditions in a cell/organism by means of
self-regulating (such as body temp, pH balance)
adaptation: genetically determined characteristic that enhances ability of individual to
copy with environment
evolution: descent of organisms from common ancestor with development of genetic and
phenotypic changes over time that make them better-suited to environment
phenotypic: physical manifestation of genetic change
natural selection: mechanism of evolution by environmental selection of organisms most
fit to reproduce; results in adaptation; "form fits function"

Unity & Diversity of Life: united in descent from common ancestor, diversified by different
environments

Levels of Biological Organization

atom: smallest unit
molecule: smallest unit of a compound
cell: smallest unit of a living thing
tissue: group of cells with common function
organ: tissues combined for common task
organ system: organs combined for common task
organism: an individual
population: several individuals
community: interacting populations
ecosystem: community + environment
biosphere: Earth

Scientific Method

Observation leads to a Question
Makes an educated guess: a Hypothesis
Experimentation
leads to a Conclusion

A conclusion can turn the experiment right back into more experimentation, or a theory is developed

Scientific Theory: group of ideas that are accepted because of results
Law: theory accepted by many scientists

What an Experiment Needs:

Experimental variable
Dependent variable
Results (organize the data)
Then a conclusion can be formed: analyzing, determining what's significant, etc.

matter: anything that takes up space
element: substance that cannot be broken down into substances with different properties
molecule: two or more of same element
compound: two or more of different elements

elements' subatomic partices: protons, neutrons, electrons

On the Periodic Table

protons + neutron = mass number
protons = atomic number

They want to be electronically stable

Key elements for Bio purposes (these make up 98% of all life):

C - carbon
N - nitrogen
O - oxygen
P - phosphorus
S - sulfur
H - hydrogen

"Organic" = contains carbon

electrons e ` (negative charge): 2 in first shell, as many as 8 in each one after it

octet rule: outermost shell is most stable when it contains exactly 8 electrons;
atoms can give up, accept, or share electrons to fulfill the octet rule
noble gases: stable all by themselves

Chemical Bonds: ionic, covalent, hydrogen bond

Ionic: weak: occurs when electrons are transferred from one atom to another

ex: NaCl (sodium chloride). One electron from outermost shell of sodium (2 +8 +1) transfers to a chlorine atom, which needs one more electron (2 + 8 + 1). Creates a negative ion (Cl) and a positive ion (Na), which attract.

Covalent: very strong, requires energy to break them; occurs when two atoms share electrons

H - H (two hydrogen atoms each sharing an electron with the other)
O = O (two oxygen atoms each sharing two electrons with the other)

Hydrogen: partially negative or positive, creates a polar molecule; very unstable, weak bond;
this is how water is fluid