science terms

science stuff to know for the ACT

lysosomes

• hold enzymes (macromolecules like protein)

they digest food or break down the cell when it dies

mitochondria

they act like a digestive system, which takes in nutrients, breaks them down, and creates energy-rich molecules (ATP) for the cell

cell nucleus

acts as the brain of the cell

• contains the cell’s DNA, or the genetic info., from which proteins are made

• it also helps control eating, movement, and reproduction

chloroplasts

only found in plant cells

• assist in the process of photosynthesis, which is converting light into energy (only plants can do this)

the cell membrane

hold all of the pieces of the cell and serves as the barrier between the cell and other cells

DNA

contains the genetic info. needed for making proteins (protein synthesis)

• DNA acts as the blueprint for protein production

protein synthesis involves..

• DNA

• RNA

• ribosomes

• proteins

messenger RNA (known as mRNA)

makes a copy of the sequence of DNA of a specific gene

• this process is known as transcription and happens in the nucleus

• once the mRNA is made, it leaves the nucleus and enters the cytosol of the cell

ribosomes

use mRNA as a guide to make protein of the same amino acid sequence as the original DNA

• the process of producing protein from the mRNA is referred to as translation

the process of protein synthesis consists pf two steps:

1. DNA to mRNA transcription

2. mRNA to protein translation

natural selection

where in a specific environment, traits that allow organisms to reproduce more effectively will become more common, and traits that reduce reproductive success will become less common\

• also known as “survival of the fittest”

greenhouse gases

gases that trap heat in the atmosphere

• sunlight can pass through them as it goes towards the earth, but greenhouse gases prevent the heat sunlight produces at Earth’s surface from leaving the atmosphere

• this means the heat stays close to Earth, increasing the planet’s temperature

• human activity has caused the amount of greenhouse gases in the atmosphere to increase in recent decades, and they are a major contributor to climate change

the 6 main greenhouse gases are..

1. carbon dioxide (co2)

2. methane (ch4)

3. nitrous oxide (n2o)

4. ozone (o3)

5. water vapor (h2o)

6. fluorinated gases (also known as chlorofluorocarbons or CFCs)

photosynthesis

the process where plants capture sunlight to make food for themselves

• during photosynthesis, the plant takes in carbon dioxide, water, and energy, and it produces glucose (which it consumes to live) and oxygen (which humans and other animals breathe).

formula:

6 CO2 + 6 H2O + light energy —> C6H12O6 + 6 O2

respiration

when cells break down molecule into a type of energy they can use

• only plants go through photosynthesis; both plants and animals go through respiration

in respiration, glucose and oxygen are converted into carbon dioxide, water, and ATP (a chemical that provides energy to cells)

formula:

C6H12O6 + 6 O2 —> 6 CO2 + 6 H2O + ATP

taxonomy

the science of naming and classifying all organisms

• it allows scientists to see how closely different organisms are related and what characteristics they share

• there are 7 taxonomic levels

• if 2 species share one level of taxonomic rank, they also share all of the broader taxonomic ranks above it

• if 2 species are in the same Family, they are also in the same Order, Class, Phylum, and Kingdom

the 7 taxonomic levels are..

1. kingdom

2. phylum

3. class

4. order

5. family

6. genus

7. species

*King Philip Came Over For Good Soup

Alleles

pairs of genes responsible for particular traits

• allele pairs can be made up of 2 dominant genes, 2 recessive genes, or a dominant and recessive gene

dominant genes are usually expressed as capital letters and recessive genes are usually expressed as lowercase letters

the basic molecular structure

C6H1206

contains

• sugar

• fat

• protein

• nucleic acid

the equation above is a sugar molecule

fats

made up of C (carbon), H (hydrogen), and O (oxygen)

• fats have nearly twice the number of H as C and a very small number of O (H is almost twice as big as C and O is really small)

ex. C55H98O6

• fats are much bigger in size than sugar

proteins

composed of amino acids

• all proteins contain C, H, O and N (nitrogen)

nucleic acids

are biomolecules

• DNA and RNA are 2 types of nucleic acids

nucleic acids are made up of 3 parts: a 5-carbon sugar, a phosphate group, and a nitrogenous base

• they are different from sugar, fat, and proteins because they are made up of P (phosphorous) and N in addition to C, H, and O

water freezes at - degrees celsius and boils at — degrees celsius

• 0

• 100

pH scale

a measure of how acidic or basic a substance is

• pH below 7 is acidic

• above 7 is basic

• at 7 is neutral

the mass of a molecule is …

the sum of the mass of its atoms

atoms

composed of 3 types of particles:

1. protons

2. electrons

3. neutrons

like charges repel each other while opposite charges attract each other

protons

positively charged

electrons

negatively charged

neutrons

no charge

(the order of) phase changes

• below freezing point, a material will be in soild form

• just above freezing point, a material will be in liquid form

• above boiling point, liquid becomes gas (is vaporized)

— are generally less dense than —, and — are generally less dense than —

• gases

• liquids

• liquids

• solids

gravity

a downward force that acts on objects, and other forces (like springs) can counteract gravity

density

the degree of compactness of a substance

• formula is mass/volume

main density rule is..

denser objects sink, and less dense objects float

• objects only float when they are less dense than the liquid they are placed in

energy

the ability to do work

kinetic vs. potential energy

• kinetic energy is energy that results from an object’s motion

• potential energy is energy that results from an object’s position or arrangement

for kinetic, an example is when planes are flying or a car driving along the road

for potential, an example is a stretched rubber band or someone sitting at the top of a slide

when a stationary object begins to move, its potential energy is converted to kinetic energy

endotherms

• use internal heat sources for their body temperature

• their bodies stay steady regardless of the environment

ectotherms

• depend on external heat sources

• their body temperature changes with the environment