BIO STUDY SET

Central Dogma

The flow of genetic information in a cell: DNA → mRNA → protein

DNA

Stores genetic information

Transcription

Process of making mRNA from DNA

Translation

Process of making a protein from mRNA

mRNA

Messenger RNA that carries instructions from DNA to make a protein

COVID-19 mRNA Vaccine Example

Vaccine delivers mRNA that makes COVID proteins, allowing the immune system to recognize them and build immunity

Exception to Central Dogma

Some viruses can convert RNA back into DNA

Reverse Transcriptase

Enzyme that converts mRNA into DNA

Integrase

Enzyme that inserts viral DNA into the host genome so it is not destroyed

Herpes Virus Example

Enters as mRNA, converts to DNA, and integrates into host DNA

Ionic Bond

One atom gives electrons to another, creating charged atoms that attract each other

Ionic Bond Example

Sodium chloride (NaCl)

Covalent Bond

Atoms share electrons to stay together

Covalent Bond Example

Water (H2O)

Polar Covalent Bond

Electrons are shared unevenly, creating partial positive and negative charges

Cause of Polar Bonds

Difference in electronegativity

Nonpolar Covalent Bond

Electrons are shared evenly with no charges

Nonpolar Covalent Example

Oxygen gas (O2)

Electronegativity

Ability of an atom to attract electrons

Most Electronegative (Bio)

Oxygen

Least Electronegative (Bio)

Hydrogen

Electronegativity Difference < 0.5

Nonpolar covalent bond

Electronegativity Difference 0.5–2.0

Polar covalent bond

Electronegativity Difference > 2.0

Ionic bond

Hydrogen Bond

Weak electrostatic attraction between a slightly positive hydrogen and a slightly negative atom (usually oxygen or nitrogen)

Hydrogen Bond Example

Attraction between water molecules

Covalent vs Hydrogen Bond

Covalent bonds share electrons; hydrogen bonds are weak attractions

Covalent Bonds in Water

Bonds within one H2O molecule

Hydrogen Bonds in Water

Attractions between separate water molecules

Bond Strength Order

Ionic → Covalent → Hydrogen

Strong Electron Overlap

Stronger bonds

Hydrophobic

Does not like water; nonpolar molecules

Hydrophobic Example

Oils

Hydrophilic

Likes water; polar or ionic molecules

Hydrophilic Example

Salt

Amphipathic

Has both hydrophilic and hydrophobic regions

Amphipathic Example

Phospholipids

Cohesion

Hydrogen bonds holding water molecules together, creating surface tension

Properties of Life

Reproduce, adapt/evolve, grow and develop, maintain homeostasis, process energy, respond to stimuli

Cell Theory

All living things are made of cells; cells come from pre-existing cells; cells are the basic unit of life

Three Domains of Life

Bacteria, Archaea, Eukarya

Prokaryotes

Bacteria and Archaea

Eukaryotes

Animals, plants, fungi, protists

Functions of Cells

Store genetic information, process energy, respond to stimuli, communicate, grow and develop

Prokaryotic Cells

Simple cells without membrane-bound organelles

Prokaryotic Characteristics

Usually unicellular with simple structure

Prokaryotic Structures

Cell wall, cell membrane, ribosomes, chromosome (DNA), nucleoid region, flagellum, pili

Prokaryotic Cell Wall

Made of peptidoglycan

Why Antibiotics Work

They target peptidoglycan in bacterial cell walls

Eukaryotic Cells

Complex cells with membrane-bound organelles

Eukaryotic Organisms

Animals, plants, fungi, protists

Nucleus

Membrane-bound organelle that contains DNA

Plant Cell Special Structures

Cell wall, chloroplasts, large vacuole

Plant Cell Wall

Made of cellulose