AP Biology Review
Unit 1:
1.1
Water
It’s polar
It forms hydrogen bonds
Hydrogen Bonds are found in DNA, RNA, and Protein
It is considered a universal solvent
It is capable of dissolving more substances than any other liquid
This is due to the polarity and hydrogen bonding
Properties: Cohesion, Adhesion, Surface Tension
Water has a high specific heat
1.2-1.3
Many Monomers turn into Polymers
You combine Monomers into Polymers via dehydration synthesis by removing water
Hydrolysis breaks apart Polymers by adding water
1.4
Carbohydrates
Monomer: Disaccharides
Polymer: Polysaccharide
Used for energy and structure
Starch and Cellulose
Cellulose makes cell walls and provides structure
Starch is used by plants to store energy at night during cellular respiration
Lipids
Nonpolar
Made up of Fatty Acids
Saturated Fats: Solid
Unsaturated Fats: Bends/Kinks, Liquid
Used for Energy Storage, Waterproofing (Waxes), Membrane Formation, Signaling (Steroids)
Phospholipids
Hydrophobic tail, Hydrophilic head
This creates the phospholipid bilayer
1.5
Proteins
Used for Motion (Muscle Tissue), Enzymes, Building Structures, Transport, Energy Storage, and Signaling
Made up of: Amino Acid
Structure:
Primary: Amino Acid Sequence
Secondary: creates Alpha Helices and Beta Pleated Sheets by interactions
Tertiary: Overall 3-D arrangement
Quaternary: One or more complete polypeptide chains
1.6
Nucleic Acids
Makes up DNA
Monomer for DNA: Nucleotides
Nucleotide Structure:
DNA is the hereditary molecule
DNA is double stranded and anti-parallel
Anti-parallel: One strand moves in the 5’ to 3’ direction, while the other ones moves in the 3’ to 5’ direction
RNA
Hereditary molecule in some viruses
Transfers Information
Catalyzes Reactions
Single-Stranded
Unit 2:
2.1-2.2
Prokaryotic Characteristics:
Single-celled organisms
Smaller
No Nucleus
Lack Organelles
Encased by a cell wall
Package their DNA through supercoiling
Eukaryotic Characteristics:
Have membrane-bound organelles
Have a nucleus surrounded by a nuclear membrane
Some important Organelles:
Golgi Complex: Packages Proteins into membrane-bound vesicles
Lysosomes: Contain digestive enzymes, breaking down excess or worn-out cell parts
Rough ER: involved with proteins; it has ribosomes attached to it
Smooth ER: involved with lipids, and steroid production; it can detoxify things
Vacuole: Storage and Disposal
(Those Organelles are involved in the Endomembrane System)
2.3
Cell Size
Cells are small in order to maximize surface area: volume ratio
Helps with diffusion
The surface area of cells has resulted in some adaptations:
Gills, Inner-folding of the mitochondria
2.4-2.9
The Membrane is selectively permeable
It allows some things in but keeps others out
Fluid Mosaic: Phospholipids + Proteins + Cholesterol that move around
Cholesterol: Stable at high temperatures, fluid at low temperatures
Membrane Transport
Transport happens through diffusion
Molecules flow down their concentration gradient
Concentration Gradient: A difference in the amount of chemical between two areas
This means that molecules move from higher to lower concentrations spontaneously, requiring no cell energy
Passive Transport:
The cell is allowing diffusion
3 types of passive transport:
Simple diffusion, Facilitated diffusion, Osmosis
Simple Diffusion:
For small, non-polar molecules, lipids (steroids and fats)
Facilitated Diffusion:
Can’t diffuse through bilayer, so it uses protein channels
Osmosis:
Diffusion of water from a higher to lower concentration
Higher concentration of water: less solute
Lower concentration of water: more solute
Water flowers from hypotonic to hypertonic
Active Transport:
molecules moving from actively low to high concentrations
Needs ATP which gets broken down into ADP
Endocytosis: Capturing a molecule and bringing it into the cell
Exocytosis: Releasing content outside the cell
2.10-2.11
Cellular Compartmentalization:
Cellular Functions are compartmentalized to improve efficiency and prevents dangerous molecules from roaming around
Endomembrane System:
Group of organelles that work together to modify, package, and transport lipids and proteins
Endosymbiosis:
Occurred in Mitochondria and Chloroplast
They were believed to be bacteria that were ingested by a larger bacteria
Evidence:
have their own circular DNA
Replicate via Binary Fission
Have ribosomes and perform protein synthesis
Have 2 membranes
Unit 3:
3.1-3.3
Enzymes
Proteins that are catalysts
Catalysts lower the activation energy
Highly Specific
Bind with a substrate
Denatured By:
PH change, temperature, changes in the active site
Inhibition:
Competitive: Non-substrate binds to the active site
Non-competitive: Secondary site where molecule binds
3.4
Cell Energy
Metabolic Pathways is where the product becomes the next reactant in a series of reactions controlled by enzymes
Exergonic Reactions: release energy
Endergonic Reactions: require energy
ATP is made up of:
Ribose, Nitron Base, 3 phosphate groups
3.5
Photosynthesis
Oxygen is released as a waste product
Creates Glucose
Two cycles:
Light Reactions
happen in the thylakoid membrane of the chloroplast
sunlight is converted into chemical energy
the chlorophyll in the plants absorb sunlight and transfer it through photosystems
light is absorbed, electrons get excited, they travel through the electron transport chain, ATP is produced, water is split, oxygen is released, NADPH is produced
Calvin Cycle
occurs in the stroma of the chloroplast
it uses the energy generated by the light reactions to form glucose
this cycle absorbs CO2, converts into glucose, and molecules are regenerated to repeat the cycle
3.6
Cellular Respiration
chemical reactions that break down glucose into ATP
Glycolysis ➡ Krebs Cycle ➡ Electron Transport Chain
Oxidizing food
Creating NADH + FADH2
Those two molecules are electron carriers
Without Oxygen:
An organism would use Anaerobic Respiration and/or Fermentation
Fermentation uses NAD+
Unit 4:
4.1-4.4
Cells constantly communicate via direct touch or signals
Signal are called Ligands
Ligands are complementary to specific receptors
Binding the ligand to the cell results in a cell response
3 Phases:
Reception
Ligands binds to receptor protein
Signal Transduction
This takes one signal and turns it into another signal
A protein will change shape to carry signal inside
Cellular Response
Leads to:
a. Gene Activation
b. Enzyme Activation
G Protein Coupled Receptors:
A ligand binds, activating the G protein.
The G protein activates an enzyme that triggers response
Intracellular: Within the cell
Intercellular: Between cells
Steroid Hormones:
Can diffuse through the bilayer, and bind with cytoplasmic receptors.
It then diffuses into the nucleus, activating genes
4.5
Homeostasis and Feedback
Homeostasis: Maintaining internal conditions at an optimal level
Feedback: Output also becomes the input
Negative Feedback: quiets the system
Positive Feedback: drives the process forward
Cell Cycle
In Eukaryotes, the stages of the cell cycle are divided into two phases:
Interphase
Growth and DNA replication
Most of the cell cycle is spent in interphase
There are checkpoints to prevent errors
G1: Cell Growth
S: DNA synthesis (Makes a complete copy)
G2: More Cell Growth
Miotic
Formation of 2 new cells
The DNA condenses into visible chromosomes that are pulled apart by a mitotic spindle
Four Stages:
Prophase
Metaphase
Anaphase
Telophase
(PMAT)
Cytokinesis: Cytoplasm splits into two, and the cell makes two cells
You would see a cleavage furrow in animal Cells
You would see a cell plate in plant Cells
Cancer: Unregulated cell division
Unit 5
5.1-5.2, 5.6
Meiosis and Chromosomal inheritance
Meiosis:
Diploid (2n) germ cells creates haploid (n) sperm and egg cells
The haploid cells have one chromosome set
Meiosis I: begins with one diploid parent cell and ends in two haploid daughter cells
Meiosis II: starts with two haploid parent cells and ends with four haploid daughter cells
Gamete: reproductive cells
Unlike Meiosis, Mitosis creates clones
Nondisjunction:
Homologous Pairs or Sister Chromatids don’t separate
5.3-5.5
Genetics
Gene:
Basic unit of heredity passed from parent to offspring
Principle Of Segregation of alleles:
Different Alleles of a chromosome bundle will separate into different gametes
Alleles: a variant of a gene controlling a trait
Chromosome: DNA molecule containing genetic material
Monohybrid Cross (Pp x Pp)
Creates a 3:1 phenotypic ratio
1:2:1 genotypic ratio
Phenotype: observable characteristics of an organism
Genotype: genetic makeup of an organism
Incomplete Dominance:
mixes both phenotypes together; neither allele is dominant (red + white flower = pink flower)
Codominance:
phenotype which expresses both traits (brown + white cow = brown and white cow)
Dihybrid:
2 traits at the same time; 4 alleles per parent (RRYY x rryy)
Sex-linked genes: On the X chromosome
Gene can be linked on the same chromosome
Unit 6
6.2
DNA Replication
DNA follow a semi-conservative model
each strand serves as a template
A team of enzymes are used to replicate DNA
Some important ones:
Helicase:
unzips helicase by breaking hydrogen bonds
DNA Polymerase:
adding bases to the DNA strand
Primase:
tells DNA polymerase where to attach
Ligase:
glue Okazaki Fragments together
Replication is fragmentary on the lagging strand, which creates Okazaki Fragments
6.3
Transcription
Makes RNA from DNA template
RNA polymerase unzips helix and adds RNA nucleotides, making RNA
The finished product, the exon, is the coding segment which will leave the nucleus
Transcription happens in the Nucleus
Translation
Produces protein based off of mRNA codon at a ribosome
Three things involved in Translation:
mRNA
Carries copy of a gene to ribosome
tRNA
gets to the ribosome to build amino acid sequence based off of the mRNA’s instruction
rRNA
functional building block of ribosomes tasked with protein assembly
6.5-6.6
Gene Regulation
Cells are different because they express different genes
In Prokaryotes, groups of genes called operons are transcribed in a mRNA molecule
Mutations can appear as:
Silent:
no effect
Nonsense
codes for stop
Missense:
1 amino acid is wrong
However, mutations make evolution possible
Unit 7
7.1-7.3
Natural, Artificial, and Sexual Selection
Natural Selection brings about adaptations through survival of the fittest
Artificial Selection has lead to domesticated animal/plants through humans selecting desirable traits
Sexual selection is where traits are selected for a reproductive advantage, such as physical looks
Effects of Natural, Artificial, and Sexual Selection:
Directional Selection
favors one end of the phenotypic range
Stabilizing Selection
favors the middle of the phenotypic range
Disruptive Selection
favors both outliers of the phenotypic range
(from top to bottom: directional, stabilizing, disruptive)
7.4-7.5
Population Genetics
Demonstrate how allele frequencies change in gene pools
🚫 Common Misconception
Dominant allele is more common than recessive ❌
Dominant alleles can actually be more rare ✅
Factors causing Evolution:
Genetic Drift
Random Change in small population
Natural Selection
Some alleles are harmful/beneficial
Sexual Selection
Some phenotypes are more attractive
Gene Flow
Genes flowing from one population to another
Directional Mutation
One allele mutates to another
7.6-7.8
Evidence for Evolution:
Fossils
Homologous Features
Same structure, different function
Analogous Features
Different structure, same function
Vestigial Features
Features no longer used
Molecular Homologies
Continuing Evolution
Observing a resistance to pesticides, etc…
7.9
Phylogeny
looks at Evolutionary History
Can be expressed using a Phylogenetic Tree/Cladogram
A Phylogenetic Tree is a diagram that represents the evolutionary relationships among species, concluding that they share a common ancestor:
A Cladogram shows relationships among organisms, showing their common traits that have derived from a common ancestor:
7.10-7.12
Speciation, Variation, and Extinction
Biological Species concept:
A species is a group of organism that can interbreed, producing fertile offspring
Some animals that are similar will not be able to mate, which can be called reproductive isolating mechanisms
reproductive isolating mechanisms include:
1a. Prezygotic Barriers, which include:
Habitat Isolation
won’t encounter each other
Temporal Isolation
breeding at different times
Behavioral Isolation
behaviors won’t be considered “good” in the eyes of the organism to mate
Mechanical Isolation
physical difference prevent mating
Gametic Isolation
sperm won’t fertilize
2a. Postzygotic Barriers, which include:
Reduced Hybrid Viability
genes impair development of the hybrid
Reduced Hybrid Fertility
meiosis fails, resulting in a sterile hybrid
Hybrid Breakdown
the first-generation of the hybrid is fine, but the second generation is weaker/less viable
Speciation: One species splits into two
Allopatric Speciation: populations are geographically isolated
Sympatric Speciation: populations are not geographically isolated
Mass Extinctions:
Decrease biodiversity
7.13
Origin of Life
RNA could have been the first genetic material
We could of started out as just monomers
Unit 8
8.2
Energy Flow
Metabolic Rate and Size
The smaller the organism, the higher the metabolic rate
Therefore, smaller organisms need to work harder to maintain their body temperature and to obtain food
Food Webs
made up of many food chains, which shows a more realistic representation of eating relationships in an ecosystem
In a food chain, each organism has a trophic level
Trophic Level: position it occupies on a food chain
90% of energy is lost at each trophic level
8.3-8.4
Population Growth
Exponential Growth Model and Logistic Growth Model
Biotic Potential:
When a species has its highest birth rate and lowest mortality rates
Limiting Factors:
Density Dependent:
Growth rates are regulated by the density of a population
Density Independent:
Any force that would affect the size of a population of living things regardless of the density of the population
ex) natural disasters/catastrophes
8.5
Species Interactions
Competition
Leads to character displacement and niche partitioning
Character Displacement:
2 species competing in the same environment develop divergent traits in order to reduce competition
Divergent traits: differences arising from groups that share a common ancestor
Niche Partitioning:
How an organism makes a living
Keystone Species:
Holds the ecosystem together
Biodiversity:
Includes species richness and species evenness
richness: number of species in a community
evenness: how even species are spread out
Human impact on biodiversity:
Not good; has caused habitat destruction/fragmentation
Miscellaneous
Chi-Square
Null Hypothesis:
what you expect to happen
Alternative Hypothesis
something else that could happen
Symbols:
∑ = sum
O = observed data
E = expected data
Degrees of Freedom:
number of outcomes minus 1
Greater than the critical value: reject the null hypothesis; the groups are significantly different
Less than the critical value: fail to reject the null hypothesis; they groups are not significantly different
Hardy-Weinberg
compares allele frequencies in a given population over time
the frequency of alleles should stay constant unless one or more of the following conditions is not met:
Non-evolving population
infinitely large
No harmful/beneficial alleles
Random mating
No emigration or migration
these conditions do not happen in real life
Symbols:
P = frequency of dominant allele
Q = frequency of recessive allele