ACT Science Section Background

Organelles

parts of cells

Lysosomes

hold enzymes and digest food or break down a cell

Mitochondria

create energy-rich molecules (ATP) for the cell

Cell Nucleus

“brain” of the cell and contains DNA

Chloroplasts

only exist in plant cells and assist in photosynthesis

Cell/Plasma Membrane

holds in all of the cell contents and serves as the barrier between the cell and the outside

Eukaryotic Organism

Organisms whose cells have a nucleus

Protein Synthesis

making proteins/3 step process

DNA

1st Step in Protein Synthesis/found in nucleus/contains genetic information needed for protein synthesis

Messenger mRNA

2nd Step in Protein Synthesis/makes a copy of the sequence of DNA for a specific gene by a process called transcription

3rd Step in Protein Synthesis

mRNA leaves the nucleus and enters the cytosol, where ribosomes bind to mRNA to make proteins of the amino acid sequence coded for in the original DNA in a process called translation

Alleles

genes that come in pairs (one from each parent) that are responsible for particular traits and make up an organisms genotype (dominant or recessive)

Dominant Genotype

dictate observable traits (phenotype); upper-case letter

Recessive Genotype

only dictate observable traits in absence of dominant allele; lower-case letter

Allele Pair Combos using the letter “g”

GG, Gg, gg

Natural Selection

survival of the fittest

Photosynthesis

process by which plants capture sunlight to make food for themselves; consumes 6CO2 + 6H2O, and light energy (C6H12O6 + 6O2); produces glucose and oxygen

Respiration

process by cells break down molecules into usable chemical energy (plants & animals); consumes glucose and oxygen; produces carbon dioxide, water, and chemical energy (ATP)

• C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP.

Taxonomy

science of naming/classifying organisms (kingdom, phylum, class, order, family, genus, species)

Sugar (molecular formula)

C6H12O6

Fats (molecular formula)

C55 H98 O6 (BIG)

Proteins are made up of __

amino acids and contain C, H, O, and N

Nucleic Acids (DNA, RNA)

• contain P, N, C, H, O

• 5-carbon sugar

• phosphate group

• nitrogenous base

Greenhouse Gasses

trap heat in the atmosphere by allowing sunlight to pass through as it heads toward Earth, but then preventing the resulting heat from leaving the atmosphere

6 Examples of Greenhouse Gasses

• Carbon Dioxide (CO2)

• Methane (CH4)

• Nitrous Oxide (N2O)

• Ozone (O3)

• Water Vapor (H2O)

• Chlorofluorocarbons (CFCs)

Melting Point of Water (Celsius)

0 degrees Celsius

Boiling Point of Water (Celsius)

100 degrees Celsius

pH Scale

used to describe how acidic or basic a solution is

Molecular Mass

sum of the mass of the atoms that make up the molecule

Atoms

• Protons (positive)

• Electrons (negative)

• Neutrons (zero charge)

Opposites attractS

Solid Substance

below its freezing (melting) point

Liquid Substance

between its melting and boiling point

Gas Substances

above its boiling point; gasses are generally much less dense than liquids and solids

Solubility

how much/quickly a substance will dissolve

Solute

substance being dissolved

Solvent

liquid in which a substance is being dissolved

Conditions that Affect Solubility

1. higher temperature

2. higher pressure

Ideal Gas Law

PV = nRT (P = pressure, V = volume, n = number of moles, R = a constant, T = temperature (kelvin))

Gravity

downward force acting on objects

Kinetic Energy

results from an objects motion

Potential Energy

results from an object’s position or arrangement

Density

Density = mass / volume (dense objects sink)

Inner (terrestrial) planets

Mercury, Venus, Earth, Mars

Outer (gas giant) planets

Jupiter, Saturn, Uranus, Neptune