AP Bio Midterm S1

Units 2, 3, 5, 6, 7

Element

substance that cannot be broken down by a chemical reaction

compound

2 elements mixed in a fixed ratio

4 elements that make up 96% of all living matter

carbon, hydrogen, oxygen, nitrogen (CHON)

Calculate the number of NEUTRONS:

Atomic mass - Atomic #

calculate the ATOMIC MASS

protons + neutrons

isotope

Has different # of neutrons and mass

Periodic table

rows = Number of Shells

columns = Number of Valence Electrons

Which shell has the most potential energy?

(3rd shell) farthest from the nucleus

Van der Waals IMF

attraction/repulsion btwn particles caused by uneven electron distribution

• happens when particles are close together

Strongest to weakest bonds

• ionic

• covalent

• hydrogen

• van der waals

Dynamic Equilibrium

Concentrations stabilize and the ratios remain the same

• Rate of forward = Rate of reverse

cohesion

sticking to itself

adhesion

sticks to something else

Why can someone walk on water?

Water’s high surface tension due to cohesion + hydrogen bonds

• Bonding due to polarity (asymmetry of water)

How does hydrogen bonding contribute to water’s specific heat?

Water needs a lot of heat energy to break hydrogen bonds

Why does ice float?

Ice has a lower density than water

• Ice forms crystalline lattice that takes up more volume but has the same amount of particles —> higher density than H20

solvent

substance that does the dissolving

solute

substance being dissolved

Why is water a good solvent?

Water is polar and surrounds other atoms

ex: NaCl dissociates in H20

hydrophobic

water fearing, dissolves in OIL BASED substances

hydrophilic

water loving, dissolved in H₂0

Why does water not dissolve oil?

LIKE DISSOLVES LIKE

H₂0 — Hydrogen Bonding

Oil — Van der Waals

Acidic

pH < 7, more H+ ions

Basic

pH > 7, more OH-

4 Macromolecules

Carbs, proteins, lipids, nucleic acids

Polymer

long molecule with identical building blocks linked by COVALENT bonds

Dehydration Reaction

Bonds are created by removing water

• Each reactant provides hydroxyl group (OH- and H+ to make H₂0)

Hydrolysis

Water is added to break bonds

Is glucose a monomer or polymer?

monomer

What is the monomer of all carbs?

monosaccharides

Monosaccharide ratio

1 - 2 - 1

CH₂O

• Ex: Glucose

Isomer

same chemical formula, different structure

What is an example of a hexose sugar?

Glucose

• Carbon chain forms ring

• unlabeled corners = carbon

Glycosidic Linkage

covalent bond formed between 2 monosaccharides = polymer via dehydration

What are the 2 functions of a polysaccharide?

storage and structural support

Storage Polysaccharide

plants/animals store sugars for later

• starch (monomer = glucose) and glycogen (muscle and liver)

Structural Polysaccharide

plants/animals build strong materials

• cellulose supports the plant wall

Why can humans not digest cellulose

we lack the enzymes

What structural polysaccharide gives cockroaches their “crunch”?

chitlin

Which polysaccharide has 1-4B glucose linkages

cellulose

What characteristic do all lipids share?

all lipids are hydrophobic

What is a fat composed of?

Glycerol + 3 Fatty Acids

• C-H makes fats hydrophobic

How are fats assembled?

dehydration reactions

What is an ester linkage (in fats)?

hydroxyl (OH) + carboxyl (C)

to form a fat, how many water molecules are removed?

3 (b/c there are 3 fatty acids that bond to glycerol)

Saturated Fats

Animal Fats, NO double bonds

• solid at room temp

  ex: lard

Unsaturated Fats

Plant Fats, double bonded and less flexible to condense/harden

• Liquid at room temp

  ex: oils

What is the charge of a phospholipid head and tail?

head = negative (hydrophilic)

tail = neutral (hydrophobic)

What does cholesterol (steroid) look like?

steroid = sex hormones, anabolic steroid

What are amino acids made of?

R-Group, Amino Group, carboxyl group (C—O)

What varies in amino acids?

the R-Group

peptide bond

bond between amino acids

polypeptide

polymer created by amino acids

Primary protein structure

Primary Protein Structure

Linear amino acid chain (composed of multiple polypeptide chains)

• each has 127 amino acids (20 types)

Secondary Protein structure

Hydrogen bonds stabilize atoms on the polypeptide backbone

• alpha helix and beta pleated sheet

Tertiary Protein Structure

amino acid R-group interactions —> 3d folding

Quaternary Protein structure

polypeptide subunits are combined to protein

Which 2 molecules make up the “uprights” of DNA?

phosphate + sugar

What is a nucleic acid made of?

phosphate group, nitrogenous base, sugar (RIBOSE)

What is the smallest organelle broken up during cell fractionation?

ribosomes

Which 2 domains consist of prokaryotic cells?

bacteria and archea

Which cell type has a membrane bounded nucleus

eukaryotic

Parts of a prokaryotic cells

• cell wall

• plasma membrane

• bacterial chromosome

• nucleotide

• cytoplasm

• flagella

Relationship between cell size and SA: Volume ratio

inversely proportional: as cells increase in size, SA: Volume decreases

What connects the layers of the nuclear envelope?

pore complexes

nuclear lamina

protein networks that maintain shape of nucleus by supporting envelop

nuclear matrix

framework of protein fibers w/in nucleus

What are ribosomes composed of?

rRNA + Protein

Free ribosomes

suspended in cytosol

ex: enzymes

Bound ribosomes

attached to the outside of the rough ER

ex: lysosomes

Smooth ER

no ribosomes

• synthesizes lipids

• detoxifies

• stores Ca²⁺

Rough ER

“membrane factory”, has ribosomes

• synthesizes PROTEINS (glycoproteins)

• distributes vesicles

lysosome

membrane-bound sac of hydrolytic enzymes that digests macromolecules

phagocytosis

food is digested when food vacuole fuses with lysosome (INTRACELLULAR DIGESTION)

Difference between rough ER’s cisface and transface

transface - ships vesicles

cisface - receives vesicles

Contractile vacuole

pumps excess H₂0 out of cell

• maintains ion Equilibrium

central vacuoles in plants

responsible for plant waste and growth

cytoskeleton

fiber network that supports cell and enables motility (of motor proteins)

microtubules

shape and supports cell, makes up tubulin

centrosomes

located by nucleus, organizes microtubule assembly in plants

Cilia V. Flagella

Cillia - more abundant, shorter

Flagella - singular, longer

3 parts of a cell wall

1. middle lamella

2. primary cell walls

3. secondary cell walls

Integrin Proteins

transmembrane linkers that enables the cells to grip the matrix

How does cholesterol act at high temps?

temp restrains phospholipid movement —> hardens

How does cholesterol act at low temps?

low temp = buffer, fluidity is difficult to reach

peripheral proteins

loosely bound to membrane surface (NAME TAG + ID)

carrier proteins

Molecule must be a specific size to fix

channel proteins

hydroPHILIC channel used by ions/molecules

How do non-polar molecules travel through the membrane?

non-polar molecules are attracted to polar heads —> passive diffusion

how do polar molecules travel through the membrane?

polar molecules are repelled by polar heads —> facilitated diffusion

Active Transport

facilitated diffusion that requires energy (carrier proteins NOT channel proteins)

Sodium Potassium Pump

1. 3 Na⁺ bind to pump

2. Phosphorylation occurs (ATP is created)

3. Protein shape is changed

4. 3 Na⁺ leave, 2 K⁺ enter

What are 2 forces that drive the diffusion of ions across the membrane?

chemical (concentration gradient) + electrical (membrane potential) = electrochemical gradient

endocytosis

macromolecules are taken into the cell in vesicles

exocytosis

vesicles fuse with the membrane and release their contents outside the cell

ex: insulin

cotransport

downhill diffusion drives uphill diffusion

phagocytosis

“cellular eating” - cell engulfs another food/particle

• food digestion

pinocytosis

“cellular drinking” - cell “gulps” fluid into vesicles

• not selective!