life 102 EXAM 1

How do atoms fill their valence shell?

Atoms become more stable by filling their outermost electron shell (valence shell).

if an atom Gain electrons

becomes a negatively charged anion

if an atom Lose electrons

becomes a positively charged cation

if an atom Share electrons

form covalent bonds

What elements make up 96% of living matter?

HONC - Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

How can you distinguish one element from another?

By the number of protons in its nucleus.

• Carbon = 6 protons

• Nitrogen = 7 protons

The number of protons is the element's atomic number.

atomic number

number of protons

What are isotopes?

Atoms of the same element that have the same number of protons but a different number of neutrons.

What is a covalent bond?

A covalent bond occurs when atoms share electrons.

Nonpolar covalent bond

electrons shared approximately equally.electrons shared approximately equally.

Polar covalent bonds

electrons shared unequally.

What are electronegative elements?

Electronegative atoms strongly attract electrons.

For example, oxygen is highly electronegative. In a water molecule, oxygen pulls shared electrons closer to itself, creating partial charges.

This produces a polar covalent bond.

How do two atoms share a pair of electrons?

each atom shares an e

How many electrons fill the valence shells of C, H, O, and N?

• H 2

• C 8

• N 8

• O 8

Why are hydrogen bonds important?

They help give biological molecules their shape and stability.

shape…

equals function

What does the law of conservation of mass state?

Matter cannot be created or destroyed during a chemical reaction.

The atoms present before the reaction are still present afterward; they are simply rearranged.

What does reversible mean?

A reversible reaction can proceed in both directions.

A + B ⇌ C + D

Products can be converted back into reactants.

element

substance that cannot be broken down into other substances

ex- gold, copper, oxygen

compound

2 or more different elements combined in a fixed ratio

ex- salt, h20

atom

smallest unit of an element

mass number

protons + neutrons

ion

atom with not equal # of protons and electrons

noble gases

shells filled, very stable

why is # of electrons an element has in its outer shell important

determines what elements it can interact with

valence shell

outer most shell that contains electrons

atoms main goal…

to fill their valence shells and become more stable

strategy one - filling valence shells

donate or accept e from another atom

ionic bond

between oppositely charged ions, atom gives e to other atom

cation

positive charged e donorniona

anion

neg charged e receiver

strategy 2 - filling valence shells

2 atoms can share an electron pair, get close to each other

what bond when 2 atoms share an electron pair/e

covenant bond

polar covalent bond

e not equally shared between the 2 atoms

electronegative

which atom is winning ‘tug of war’ between the e

ionic bonds simple terms

more of borrowing/sharing e

covelant bonds

more of combining to become something

4 important properties of water

1. cohesive

2. moderates temp

3. expands upon freezing

4. excellent solvent

1. cohesive

allows for water to stick to other molecules

surface tension

how hard it is to stretch/break surface of liquid

specific heat

amount of energy required to to change temp

water has high/low specific heat and surface tension

high!

water heats up

hydrogen bonds are broken, heat is absorbed

water cools down

hydrogen bonds form, heat is released

3. expands upon freezing

frozen water floats!

4. excellent solvent (polar solvent)

means that it form hydrogen bonds easily

hydrophilic substances

things that WILL mix/dissolve, water loving bc they're charged

hydrophobic substances

things that don’t mix/dissolve bc not charged

ex- oil and water

solvent

dissolving agent of solution, what makes thing dissolve

ex- water

solute

the substance that is dissolved

ex- salt

pH

measuring how many H+’s water has

pH < 7 (pH lower than 7)

acidic

pH = 7

neutral/pure water

pH > 7 (pH greater than 7)

basic

H+ > OH-

more acidic

H+ = OH-

neutral

H+ < OH-

more basic

carbon compound vary in…

1. carbon skeleton - archetecture

2. side groups - accessories

isomers

made of the same stuff just in a different shape

enantiomers

made of same stuff but mirror like diff shape

ex- left and right hand

polymers

made of many monomers

how are polymers created

dehydration reaction

what happens in a dehydration reaction

removes a water molecule, forming a new bond

how are polymers broken

hydrolysis

hydrolysis

adds a water molecule, breaking a bond

carbohydrates serve as

fuel and building material

polysaccharides

“many sugars”, polymers of monosaccarhides

functions of polysaccharides

1. energy storage(fuel)

starch - plants

glycogen - animals

2. support(structure)

cellulose - plants

chitin - animals

What are lipids

non-polymer macromolecules (fats, phospholipids, steroids)

saturated v.s unsaturated fats

saturated - solid at room temp, no double bonds

unsaturated - liquid at room temp, double bonds

functions of fats

main func - long term energy storage

protection - fat on body

insulation - keeps body warm

what is the structure of proteins - “workhorses” of the cell

polymers of amino acids

how many different amino acids

20

4 diff structures of proteins

1. primary

2. secondary

3. tertiary

4. quaternary

functions of the protein enzymes

break and make chem bonds

functions of the protein antibodies

fight against viruses

denaturation

loss of protein conformation, loss of protein function

if you boil water(denaturation)

it turns the protein into a denatured protein that has lost its function because it becomes straightened out instead of coiled and twisted

2 types of nucleic acid

1. DNA (deoxyribonucleic acid)

2. RNA (ribonucleic acid)

DNA structure

like a slinky, double stranded helix, like a zipper

function of DNA

“blueprint” of the cell, to carry genetic info(genes)

order of DNA,RNA,protein

DNA directs RNA synthesis, RNA directs protein synthesis

RNA: mRNA, rRNA, tRNA functions

mRNA- information to ribosomes

rRNA- component of ribosomes

tRNA- carries individual amino acids to ribosomes

what features/things are common to all cells

plasma membrane, cytosol, chromosomes, ribosomes

prokaryotic cells are in…

bacteria and archaes

eukaryotic cells are in…

plants, animals, humans etc.

prokaryotes

• present in all bacteria

• no nucleus

• no organelles

eukaryotes

• have organelles

• all have a nucleus

organelles

similar to organs, each carries out a specific function, in eukaryotes

nucleus: nuclear envelope

double membrane surrounding the nucleus

nucleus: pore complex

Openings that regulate transport between the nucleus and cytoplasm

nucleus: chromosomes

DNA (genetic info)

ribosomes make…

proteins

instructions to make proteins are in…

DNA in the nucleus

endomembrane system contains:

• nuclear envelope

• endoplasmic reticulum

• Golgi apparatus

• lysosomes

• vacuoles

• plasma membrane

what does the endomembrane system do

connects the nuclear membrane with organelles in the cytoplasm

endoplasmic reticulum has…

• smooth ER

• rough ER

• nucleus

• nuclear envelope

smooth ER

has no ribosomes

rough ER

shredded with ribosomes

endoplasmic reticulum functions

• packs proteins in vesicles

• sends vesicle to next destination