BIOL112 EXAM 1 CARDS (has lectures 1-10)

BIOL112 EXAM 1 CARDS (has lectures 1-10)

What domains are prokaryotes?

Bacteria and Archaea

protists are…

eukaryotes

What is a true nucleus found in?

eukaryotes

Which cells are more complex, eukaryotes or prokaryotes?

eukaryotes

What percentage of the atmosphere is $N_2$ gas?

78%

What makes a covalent bond nonpolar?

equal sharing of electrons

What type of bond holds the two $N$ atoms together in $N_2$?

A triple covalent bond.

Why is atmospheric $N_2$ difficult for most organisms to use?

The $N \equiv N$ triple bond is extremely strong, so atmospheric $N_2$ is unusable to all but a few organisms.

What percentage of the atmosphere is $O_2$ gas?

$$21\%$$

Where does most of the $O_2$ in the atmosphere come from?

Photosynthesis.

What is ozone?

$O_3$, a molecule made of three oxygen atoms.

How does the ozone layer protect terrestrial life?

It blocks UVC and UVB radiation, which can damage living organisms.

What is the greenhouse effect?

When gases in the atmosphere trap heat from Earth, warming the planet

What are greenhouse gases?

Gases in the atmosphere that trap heat, such as CO2 and CH4

Is atmospheric $CO_2$ currently at its highest level in Earth's history?

No.

When was atmospheric $CO_2$ higher according to the lecture?

Paleocene-Eocene Thermal Maximum (PETM)

What happened during the PETM when $CO_2$ was very high?

There were mass extinctions and major sea-level rise.

What is the electronegativity ranking of $H$, $C$, $N$, and $O$ from lowest to highest?

H<C<N<O

What does electronegativity mean?

How strongly an atom pulls on shared electrons

What makes a covalent bond polar?

Unequal sharing of electrons

What is starch?

A polymer of glucose that plants use to store glucose.

What is cellulose?

A carb that is insoluble in water and acts as insoluble fiber in humans

Which atoms are more likely to form polar covalent bonds with each other?

Atoms with different electronegativities, because they will pull on the shared electrons unequally.

What is a hydrogen bond?

Partially pos/neg bond between H with N,O,F

What is ionic bonding?

Attraction between positive and negative charges

What is a hydrophobic interaction?

Nonpolar molecules come together in water

What are Van der Waals forces?

Weak attractions between molecules caused by temporary dipoles

Which four noncovalent bonds/interactions do you need to recognize?

Hydrogen bonds, Ionic bonds, Hydrophobic interactions, van der Waals forces

What is an acid?

A substance that releases H+ into solution.

What is a weak acid?

An acid that only partially dissociates and releases H+

What is a base?

A substance that takes in an H+, therefore reducing H+ in the entire solution

What is a weak base?

A base that is only partially dissociated and has a weak tendency to accept H+

What is protonation?

When a molecule gains an H+

What is deprotonation?

When a molecules looses/gives away an H+

After an acid deprotonates, what charge does it have?

-

After a base protonates, what charge does it have?

+

carbs feel…

sticky

lipids feel…

slippery

Low pH means what?

High acidity and high H+

High pH means what?

Low acidity, low H+ (alkaline)

As pH increases, what happens to $[H^+]$?

H+ decreases.

A solution with pH $3$ has how many times more $H^+$ than a solution with pH $6$?

1000 times more

What is ocean acidification?

the ocean becomes more acidic because it absorbs extra CO2 (therefore more H+) from the atmosphere

What is the equation for $CO_2$ reacting with water?

CO2 + H2O → H+ + H2O

What happens to ocean pH when atmospheric $CO_2$ increases?

Ocean pH decreases.

What is the basic formula for carbohydrates?

(CH2O)n

Are carbohydrates water-soluble or lipid-soluble?

Watersoluble

Are carbohydrates hydrophilic or hydrophobic?

Hydrophilic.

What is the exception to carbohydrates generally being water-soluble?

Cellulose is insoluble in water and is insoluble fiber in humans.

What is the basic formula for lipids?

(CH2)n

Are lipids hydrophilic or hydrophobic?

Hydrophobic.

What is glycogen?

stored glucose/energy in animals

How much glycogen does the human liver store?

Enough to maintain blood sugar for about $11\,\text{hours}$ of fasting.

Why don't we store huge amounts of glycogen?

Because glycogen holds onto a lot of water, making it heavy

What is chitin?

Carb polymer found in arthropod exoskeletons and fungal cell walls.

What does protein folding mean?

The protein folds into its functional 3D shape

What is one of the strongest/most important forces in protein folding according to the lecture?

Hydrophobicity (hydrophobic interactions).

How are alpha-helices and beta-sheets stabilized?

By hydrogen bonds between the protein backbone's O and N atoms.

What four interactions can help stabilize a protein's shape?

Hydrophobic interactions, hydrogen bonding, ionic bonds, disulfide bridges

Which protein-folding interaction is the only covalent bond?

The disulfide bridge.

Where are disulfide bridges found?

In extracellular proteins.

What amino acid forms disulfide bridges?

Cysteine.

Where are hydrophobic R-groups usually found when a protein folds?

On the inside of the protein, away from water.

What is the exception to hydrophobic R-groups being on the inside?

An alpha-helix that spans a lipid bilayer.

Where are the hydrophobic R-groups located in a membrane-spanning alpha-helix?

On the outside of the protein, where they contact the nonpolar lipid bilayer.

Why do they face outward in a membrane-spanning alpha-helix?

Nonpolar–nonpolar contact with the lipid bilayer is the most stable arrangement.

What do some proteins need in order to fold correctly?

Molecular chaperones.

What are intrinsically disordered proteins (IDPs)?

Proteins that do not have a distinct, fixed 3D shape

What is a ligand?

A molecule that binds to a protein and induces a response/reaction

Where does a ligand bind?

At a binding site/active site

What makes a ligand able to bind to a protein/receptor?

Complementary shape and electrostatic contour

Do the amino acids that make up a protein's binding site have to be next to each other in the amino acid chain?

No. Proper folding can bring amino acids from different parts of the chain together to form the binding site.

What is denaturation?

when a protein loses its shape and stops working properly

What can cause protein denaturation?

Changes in temperature, pH, ion concentration, or certain chemicals.

Is protein denaturation always irreversible?

No it can be reversible

Are shape changes that are part of a protein's normal function reversible?

Yes.

Conformational change

a protein changes shape temporarily to do its job

What is the difference between denaturation and a normal conformational change?

Denaturation is when the protein loses its normal shape and function, usually because of a disruptive condition. Conformational change is when a protein changes shape temporarily to do its job, then can return to its original shape

What are the three parts of a nucleotide?

Base, sugar, phosphate

nucleoside

base and sugar

is ATP a nucleotide?

yes

DNA is a ____ strand while RNA is a ____ strand

double, single

What are the two types of nitrogenous bases?

Pyrimidines and Purines

Which bases are pyrimidines?

T U and C (TUC the pyramid)

Which bases are purines?

A and G (Pure As Gold)

How can you recognize a pyrimidine vs. a purine structurally?

Pyrimidine has 1 ring and purine has 2 rings

What sugar is found in RNA?

Ribose

What sugar is found in DNA?

Deoxyribose

What is the 5' carbon associated with?

it forms a covalent bond with the phosphate group

At which carbon do the sugars in DNA and RNA differ?

They differ at the 2' carbon

What makes up the backbone of DNA or RNA?

Sugars + phosphates.

What is the charge of the DNA/RNA backbone?

Highly negative

 

Starch is a _______ of glucose and it is how plants store glucose.

polymer

Nucleic acids are built in the ______ direction.

5’ to 3’

The DNA backbone is highly negative because of the ______

phosphates

Nucleotides are connected by…

Phosphodiester bonds

DNA replication requires an enormous amount of _____ & ______.

nitrogen and phosphorus

What holds the two DNA strands together?

H bonds

What are DNA and RNA?

polymers of nucleotides joined together

What is protein folding?

process where a protein folds into its proper 3D shape