theory
general set of principles supported by evidence that explains unified insights of science
-is testable and falsifiable but has no evidence pointing to falsify
-nothing in science is ever really considered "proven" -- it's always open to revision
hypothesis
proposed explanation. testable and falsifiable.
-if/then statements
pseudoscience
claims, beliefs, or info that is portrayed as established scientific theory but lacks objective, repeatable data generated using the scientific method
Scientific method
observation, question, hypothesis, experiment, conclusion, report and publish
Characteristics of life
1. order
2. reproduction
3. growth and development -DNA is inherited
4. energy processing
5. respond to environment
6. constant internal environment (homeostasis: body's ability to remain constant)
7. evolve and adapt
hierarchy of life
- life builds from least complex to most:
atom --> molecule --> organelle --> cell --> tissue --> organ --> organ system --> organism --> population --> community --> ecosystem --> biosphere
producers
provide food (ex: plants)
consumers
eat plants and other animals
decomposers
break matter into simpler mineral nutrients
bacteria
prokaryotes
archaea
extreme prokaryotes (live in very hot/cold environments. won't cause diseases)
Eukarya
animalia, plantae, fungi, protists (multiple kingdoms, only single-celled)
evolution
-biology's chief unifying principle.
-gradual modification of populations of living things over time
-traits allow species to survive in an environment
matter
occupies space and has mass
element
purest form of matter. Cannot be easily broken down.
Defined by the number of protons in nucleus
atom
fundamental unit of matter
ions
different number of electrons than protons.
atomic number
number of protons in nucleus
atomic mass
number of protons and neutrons
proton
- in nucleus
- positive charge
- 1 atomic mass unit
neutron
- in nucleus
- no charge
- 1 atomic mass unit
electron
- around nucleus
- negative charge
- virtually no mass
isotopes
different number of neutrons than original.
same number of protons and electrons
radioactive isotopes
unstable and emits energy
Which particles allow atoms to interact with each other?
electrons
chemical bonding
atoms coming together forming molecules
covalent bond
atoms share electrons
ionic bond
atoms transfer electrons
hydrogen bond
attractions between a positively charged hydrogen and a weak, negatively charged atom (like oxygen)
- weakest bond
-2 polar covalently bonded molecules attracted by electronegativity
polar molecules
unequal sharing of electrons = partially charged atoms
nonpolar molecules
equally sharing of electrons = no partial charges
valence electrons
2+ atoms joined by a chemical bond -- more stable
example: water (h2o)
1st energy level
holds 2 electrons
outer energy levels
holds 8 electrons
octet rule
8 electrons in their outer shell
hydrogen bonding
very strong water surface tension = water insects can walk on those bonds.
high specific heat & heat of vaporization
a lot of energy is needed to heat water --- hydrogen bonds don't break easily
solution
homogenous mixture of 2+ molecules, atoms, or ions
homogenous: same throughout whole mixture
Which is less dense, water or ice?
Ice = floating
frozen water = more hydrogen bonds
solute
compound dissolved in solution.
ex: sugar in water
solvent
compound doing the dissolving.
ex: the water
hydrophilic
love water -- water soluble
- can dissolve in water (polar)
- example: sugar or salt
hydrophobic
hate water - lipid soluble
-can't dissolve in water (nonpolar)
- example: oil or gasoline
acid
release a hydrogen ion when dissolved in water
base
release hydroxide ions when dissolved in water
Logarithmic scale
- 0 to 14
- increases 10 fold: pH of 3 is 10x more acidic than pH of 4
- neutral: 7.0 - pure water
- basic: >7; 14 being the most basic
- acidic: <7; 0 being the most acidic
buffering systems
- resist pH change because most living things function best in near-neutral pH
- example: antacids
carbohydrates
-made of monosaccharides
- sugars
- polysaccharide: glycogen, starch, cellulose, chitin
lipids
- fats
- do not dissolve easily in water
- no monomer
-glyceride, steroids, phospholipids, wax
proteins
- ex: enzymes
- monomer: chains of amino acids
-polypeptide
nucleic acids
- DNA/RNA, ATP
- monomer: nucleotides
dehydration synthesis
build covalent bonds (condensation)
hydrolysis
break covalent bonds (digestion)
meter
human height, length of some nerve and muscle cells
centimeter
chicken egg
millimeter
frog egg
micrometer
human egg, most plant and animal cells, nucleus, most bacteria
nanometer
smallest bacteria, viruses, ribosome, proteins, lipids, atoms
prokaryotic
bacteria or archaea
- do not have a bound nucleus; DNA floats free
-do not have membrane bound organelles
eukaryotic
all other cells (plants and animals)
- DO have bound nucleus with DNA
- DO contain bound organelles
lysosome
- recycling and garbage center of the cell
- digests food in protists
- digests worn out cell parts
- particles get transferred into cytosol to be reused or sent out of the cell
cytoskeleton
- protein filaments
- cell structure, movement, and transport of materials
plant specific organelles
central vacuole, thick cell wall, chloroplasts.
do not have lysosomes or centrioules
gap junctions
allow molecules and electric currents to move from cell to cell
plasmodesmata
series of tiny channels through the cell wall
-cell-to-cell communication in plants
-pass water, nutrients, and wastes
cell theory
every form of life is composed of 1 or more cells
plasma membrane
- many proteins either fixed within it or capable of moving across it
- fluid-mosaic model
phospholipid bilayer
- phosphate group & 2 fatty acid chains
- forms in reaction to water environment in and out of cell
cholesterol in PM
keep smaller molecules from passing
- resists hot and cold temps - fluid PM
proteins in PM
- structural support, recognition, communication, transport
glycocalyx
short carbohydrate on outside of PM.
lubricates area between cells and allows them to adhere when needed
passive transport
no energy needed to move across PM
diffusion
movement of a higher concentration to a lower concentration of that material
concentration gradient
difference btwn highest and lower concentrations of a solute
simple diffusion
direct movement right through PM. No help needed.
examples: oxygen and carbon dioxide
osmosis
movement of water from higher water concentration to a lower concentration.
OR
movement of water from a lower concentration of solute to a higher concentration
active transport
energy (ATP) is needed to move across PM
facilitated diffusion
molecules must pass through a transport protein in PM
- helps polar or charged molecules move through
hypotonic
solution has lower concentration of solutes than the cell = cells swell and lyse
isotonic
osmotic pressure of cell and solution are equal = cells stay normal
hypertonic
solution has a higher concentration of solutes than the cell = cell shrivels
exocytosis
movement of large molecules OUT of the cell through vesicles
endocytosis
movement of large molecules IN to the cell by forming a vesicle with the PM
potential energy
energy is stored
kinetic energy
energy is in motion.
produces heat
once energy is heat, it will not reform
First law of thermodynamics
energy is neither created nor destroyed - only transferred
Second law of thermodynamics
energy transfer will always result in a greater amount of disorder
entropy
measure of the amount of disorder
energy coupling
exergonic reactions power endergonic reactions
- store energy so we can use it later
exergonic (downhill) reactions
reactants contain more energy than products
catabolic reaction: breaking of starches into simple sugars
- stored energy is released for body
endergonic (uphill) reactions
products contain more energy than reactants.
- anabolic reaction: building. glucose form starches
- USES energy
ATP structure
- adenosine group and 3 phosphate groups
- humans transfer food energy into ATP
enzymes
protein that accelerates a chemical reaction
- lowers activation energy
Enzymes fold into what structure?
quaternary, with small pockets
substrate
substance that an enzyme helps transform
active sites
specific "pocket" for each substrate
competitive inhibition
inhibiting molecule binds to the active site
noncompetitive inhibition
inhibiting molecule binds to another spot on the enzyme.
Active site then changes shape (denature) = without a protein's shape, it's nothing
metabolic pathway
series of chemical reactions working together to a common goal
Cellular respiration formula
Glucose + Oxygen ---> Carbon dioxide + Water + 36ATP
reduction
gain electrons
decrease in positive charge
oxidation
lose electrons
increase in positive charge
electron carriers
carry electrons from one part of the process to another
NAD - most important EC
oxidative phosphorylation
NADH + FADH2 bring electrons = LOTS of energy.
glycolysis
location: cytoplasm
- splits glucose into 2 pieces (3 carbons)
- produces 2 pyruvic acid, 2 NADH, 2 net ADP, and 2 H2O
lactic acid fermentation
- animals muscles and microbes
- Glucose --> Lactic acid + ATP + heat
alcohol fermentation
- plants and microbes, like yeast
- Glucose --> Ethanol + 2 CO2 + ATP + heat
aerobic respiration
Krebs & ETC are this.
- need oxygen
Krebs cycle (citric acid cycle)
- mitochondria
- input: 2 acetyl CoA
- output: 6 NADH, 2 FADH2, 2 ATP, 4 CO2
ETC
- oxygen = final electron acceptor
- total of 28 ATP and 4 H2O
prokaryotic aerobic respiration
- no mitochondria = most occurs in cytoplasm
-ETC is on PM
photosynthesis in prokaryotes
- do not have chloroplasts
- some can complete photosynthesis -- use thylakoid membrane fold for electron transport
photosynthesis
turns solar energy into chemical energy.
- plants (autotrophs) make own food from inorganic molecules: feed heterotrophs (consumers)
chloroplasts
filled with chlorophyll
- in mesophyll of plant leaves
- each mesophyll has 30 of these
palisade mesophyll
most photosynthesis occurs here
vein in plants
delivers water/nutrients
stomata
mini pores open and close for gas exchange (CO2 and O2 to enter/leave)
thylakoids
networks of membranes active in photosynthesis
stroma
liquid material in thylakoid and chloroplasts
chlorophyll a
primary pigment of plants.
- in thylakoid membrane to capture light
light dependent reactions
- light energy produces ATP
- water is split
- electrons derived from water are boosted by photons
photosystems
collect solar energy and transform it into chemical energy
Calvin cycle
CO2 + RuBP = G3P (3 carbon sugar)
-occurs in stroma
Plants in hot/dry climates
- lower levels of CO2 and increasing O2
- photorespiration: releases CO2 and uses O2, stopping photosynthesis
- must adapt to survive
c4 plants
- fixes CO2 to a 4-carbon molecule
- saved until optimal
- if stomata is closed, rubisco binds to O2 instead = reducing photosynthesis
- any available CO2 saved
CAM plants
- cacti conserve as much water as possible
- plant's stomata opens at night
- CO2 is saved until sunrise
- sun's rays supply energy needed to power calvin cycle during day
DNA
contains info to make proteins
double helix with 4 bases
genome
collection of an organism's genetic info
- found on DNA as genes
- half of genome comes from mom, other half from dad
gene
basic unit of heredity
karotypes
number and appearance of chromosomes in the nucleus of a eukaryotic cell
chromosomes
long, thin chromatin that folds up into tight coils
chromatin
combo of DNA and protein
homologous chromosomes
chromosome pairs
- humans have 46 chromosomes: 22 homologous pairs of autosomes
sister chromatids
each chromosome is made up of these after going through replication
the cell cycle
cell replication is a repeating pattern of cell growth, genetic replication, and cell division.
consists of interphase and mitotic phase
mitosis
DNA molecules separate (diploid to diploid)
cytokinesis
physical division of cell. starts occurring in anaphase
interphase
consists of G2, S, and G2 phases where cell carries out normal functions, grows, and prepares for cell division
G1
normal functions
S phase
DNA replicates
G2
Prepares for mitosis - normal functions
prophase
nucleus degrades and chromosomes bundle
metaphase
chromosomes line up on metaphase plate
anaphase
sister chromatids pulled apart
telophase
2 nuclear envelopes form. cleavage furrow forms at middle
cytokinesis in plants and animals
animal: cleavage furrow
plant: cell plate
binary fission
- prokaryotes
-circular chromosomes but replicate like animal cells
-septum grows along middle of PM and separates cells
vegetative reproduction
plant cuttings or runners
regeneration
new, complete organism formed from a portion of an existing one
diploid (2n)
cells that contain paired sets of chromosomes
ex: human diploid cell has 23 pairs of chromosomes or 46 total chromosomes
haploid (n)
contains a single set of chromosomes. a human haploid cell (gamete) has 23 chromosomes.
Prophase I
tetrad forms
crossover
Metaphase I
tetrads line up on metaphase plate
Anaphase I
homologous chromosomes pull apart
Telophase I
cytokinesis
Prophase II
same as prophase I.
Brief
Metaphase II
sister chromatids randomly line up at metaphase plate (independent assortment)
spindles attach
Anaphase II
sister chromatids separate and move to each pole
Telophase II
haploid daughter cells forming
Differences between mitosis and meiosis
Mitosis:
- produces 2 cells
- diploid to diploid
- identical cell created
- asexual reproduction
Meiosis:
- produces 4 cells
- tetrads form
- crossing over occurs
- diploid to haploid
spermatogenisis
males produce sperm.
produces 4 identical functioning sperm
oogenesis
females produce oocytes (eggs)
produce 1 functional egg and 3 polar bodies (nonfunctional)
asexual reproduction
-new identical organism
- faster
sexual reproduction
- genetically unique offspring
- diversity: better suited for survival
Gregor Mendel
- used tweezers and paintbrushes to mate peas and observed 7 plant characteristics.
- elements retain character through generations
- without knowledge of DNA or chromosomes
phenotype
physical feature that is seen
genotype
genetic code
dominant
trait that is visible
recessive
trait masked by a dominant gene
homozygous
two identical alleles of a gene for a given characteristic
heterozygous
differing alleles for a characteristic
monohybrid cross
looking at only one trait during crosses
Ratio of heterozygous mating:
phenotype ratio= 3:1 (dominant:recessive)
genotype ratio= 1:2:1 (homozygous dominant:heterozygous:homozygous recessive)
dihybrid cross
looking at 2 traits during crosses
Ratio of heterozygous mating:
9:3:3:1
law of segregation
Differing characters in organisms result from 2 alleles that separate during gamete formation
incomplete dominance
Heterozygote phenotype is an intermediate between both homozygous phenotypes.
Ex: cholesterol in humans.
Ex: Red and white roses mated creating pink roses
codominance
alleles of the same gene can have independent factors.
An organism has 2 alleles with different phenotype effects.
Ex: Blood type. Type A and B carbs that extend from the surface of human red blood cells.
polygenic inheritance
Multiple genes have a small effect on one trait. Populations have many genes with multiple alleles. Allows for genetic diversity.
pleiotropy
one gene has many effects. Example: Fragile-X syndrome.
How does the environment affect alleles?
External influences from environment can cause favorable or unfavorable trait development.
- flower color from soil acidity
- smoking alone does not always cause cancer, but smokers are much more likely to get lung cancer
Autosomal dominant disorders
dominant dysfunction of an allele on an autosome.
Ex: Huntington's disease
Recessive autosomal genetic disorders
recessive dysfunction of an allele on an autosome. Ex: Sickle cell anemia
X-linked disorders
errors carried on X chromosome. More common in males than females because they don't have another X chromosome to cover up the error.
Ex: color blindness
Watson, Crick, Franklin, Wilkins
used x-ray diffraction to detail DNA's structure and proposed a hypothesis of DNA double helix
semiconvservative model
- two DNA strands separate
- each strand is matched using base pairing
- new DNA helix has 1 old strand with 1 new strand
helicase
break hydrogen bonds between nucleotides
DNA polymerase
bind to each strand and add complementary nucleotides to DNA from 5' to 3'
ligase
enzyme that adheres 2 pieces of DNA
-glue
Okazaki fragments
starting pieces of RNA
Explain transcription vs. translation. How are they related?
Transcription: DNA >> mRNA in nucleus by RNA polymerase
Translation: mRNA >> proteins at ribosome
point mutations
mutation in a single base pair in the genome
harmful = can turn into cancer. uncontrolled growth/replication. random mutations are usually non inheritable
mutations in somatic cells
most mutations occur here. they can't be passed on
mutations in germ-line cells (gametes)
can be passed on to offspring
how mutations can be beneficial
could increase survival of an organism
Messenger RNA (mRNA)
code for proteins
Transcription RNA (tRNA)
bring amino acids to ribosome
Ribosomal RNA (rRNA)
make up 2 subunits of ribosomes
Structural difference between RNA and DNA
codon
triplet of mRNA bases that translates to an amino acid
- every 3 mRNA = 1 amino acid
introns
pulled in nucleus. "un-needed" part of sequence
exons
Necessary part of the sequence that codes for proteins.
Exits nucleus
amino acids
building blocks of proteins (20 different of these)
Darwin's contribution
- observed many species
- Galapagos islands = completely isolated = no invasion of species to cross mate
- 13 species of finches evolved
Wallace's contribution
- "co-discover" of evolution
- studied birds and butterflies of South America and Southeast Asia
- presented work in 1858
radiometric dating
determining age based on decay of radioactive elements in bedrock (uranium 238)
fossils
fossils from same time periods are found together in geologic layers
ex: Trilobites went extinct 245 million years ago, fossils show they lived for 500 million years
Morphology/Embryology
study of physical forms & study of embryonic development
ex: homologous features are seen in mammal bone structures: different shapes, sizes, and functions but similar structures
island biogeography
islands isolated for many years
- organisms only found on Madagascar.
- Many species of lemurs live on Madagascar and rarely anywhere else in the world
Gene modification
variations found in the DNA sequences of various organisms
- ex: DNA sequencing compares human DNA to other organisms: some small differences
experiments
experimental demonstrations of evolution have been carried out in the laboratory and in nature
- organisms disappear when a predator is introduced
- organisms thrive when predators are removed: population increases, health decreases due to lack of food so
gene pool
populations have many allele variants of the same gene
population
all members of a single species living in one place
- smallest unit to evolve
microevolution
change of allele frequency in a short amount of time within a population
macroevolution
formation of new species
natural selection
survival = higher mating frequency
mutations
changes in DNA sequences that allow for diversity
gene flow
movement of genes from 1 population to another
migration
movement of individuals from one population to another
genetic drift
chance alternation of allele frequencies
bottleneck effect
change in allele frequencies due to lower population members
founder effect
small subpopulation moves and starts a new population
sexual selection
selection based on success to find mating partners
fitness
success of passing on genes to the next generation = how good you are at mating
- can change with the environment