Midterm 1 (chapters 1-6)

Question 1

What are the 5 fundamental characteristics of life?

Answer 1

Energy, genetic information, cells, replication, evolution

Question 2

What are the three main theories in biology?

Answer 2

evolution, chromosomal theory, cell theory

Question 3

What is the cell theory? Who is associated with it?

Answer 3

Dr. Virchow; all organisms are made of cells & cells come from pre-existing cells

Question 4

What is the theory of evolution? Who is associated with it?

Answer 4

Darwin; species are related by common ancestors. species characteristics modified from generation to generation.

Question 5

What is the chromosomal theory? Who is associated with it?

Answer 5

Sutton & Boveri; hereditary information is encoded in genes found in chromosomes (your traits come from your parents)

Question 6

What is the order of the central dogma of molecular biology? (DNA to traits)

Answer 6

DNA -> mRNA -> proteins

Question 7

What did Dr. Woese do?

Answer 7

created phylogeny= evolutionary relationships between species (he compared RNA relatedness between organisms to create a phylogenetic tree), & he defined the 3 domains of life= bacteria, eukaryote & archaea

Question 8

What are the common elements of life?

Answer 8

carbon, hydrogen, oxygen & nitrogen

Question 9

What is the structure of an atom

Answer 9

protons & neutrons in nucleus, electrons on the shells

Question 10

What is a proton?

Answer 10

has a positive charge, located in nucleus, & it’s the atomic number which doesn’t change

Question 11

What’s an electron?

Answer 11

has a negative charge, located on the shells, elements need to be stable so they will share / gain or lose electrons to reach the octet rule (8 in valence shell, 1st shell only needs 2 electrons)

Question 12

What is the valence shell? What is the valence number?

Answer 12

Valence shell= outermost shell & Valence number= number of unpaired electrons in the valence shell

Question 13

What are the 3 kinds of bonds?

Answer 13

covalent, ionic, hydrogen

Question 14

What is a covalent bond?

Answer 14

forms when atoms share electrons in order to satisfy the octet rule (if carbon has 4 electrons, and hydrogen has 4 electrons = methane)

Question 15

What is an ionic bond?

Answer 15

forms when atoms are held together by the attraction between the opposite charge (ex: sodium chloride: chloride has 7 electrons (slightly negative bc gained an electron), sodium has 1 electron (slightly positive bc one electron lost) -> table salt)

Question 16

What is a hydrogen bond?

Answer 16

caused by polar covalent bonds if those partical charges are opposite

Question 17

What is the difference between polar & non-polar?

Answer 17

polar has a charge & nonpolar doesn’t have a charge

Question 18

What is the difference between hydrophobic & hydrophillic?

Answer 18

hydrophobic= has a charge (polar), water soluble, lipophobic (doesn’t like lipids)
hydrophillic= no charge (non-polar) , doesn’t like water (bc no charge), lipophilic (likes lipids)
ex: water (polar) + oil (non-polar) = doesn’t mix because oil is hydrophillic

Question 19

What are the properties of water?

Answer 19

water can be used as a solvent (the ability to dissolve other substances in a solution), 75% of a typical cell volume is water. Solid water is less dense so it can float on water. Life thrives with water.

Question 20

What is the difference between cohesion & adhesion?

Answer 20

Cohesion= water is attracted to water (other hydrogen bonds)
Adhesion= water is attracted to other charged/polar molecules

Question 21

What is electronegativity?

Answer 21

Formula: O>N>S=C=H=P
when shared electrons in a bond are pulled towards the nucleus

Question 22

What chemical reaction puts all 4 of the macromolecules together?

Answer 22

dehydration/condensation

Question 23

What chemical reaction separates all 4 macromolecules?

Answer 23

hydrolysis (water is added to break poly into mono)

Question 24

What is the basic chemical structure of an amino acid?

Answer 24

an amino group, central carbon, hydrogen, carboxyl group, r-group (only thing that changes between all the amino acids)

Question 25

What are the 4 levels of protein structure?

Answer 25

primary= sequence of amino acids
secondary= what’s in common with the amino acids (the backbone)
teritary= the r-group
quaternary= proteins binding to other proteins (like hemoglobin)

Question 26

What is sickle cell?

Answer 26

changes the 6th amino acid to valence (unable to hold oxygen)

Question 27

What are the 4 groups of amino acids?

Answer 27

polar, non-polar, positive charge, negative charge

Question 28

What is a non-polar amino acid?

Answer 28

all have non-polar covalent bonds (hydrophobic), no presence of oxygen (O) or nitrogen (N) b/c they are electronegative

Question 29

What is a polar amino acid?

Answer 29

hydrophilic, has electronegative elements like oxygen & nitrogen so it has a partial charge

Question 30

What is a negatively charged amino acid?

Answer 30

has a negative charge (can see it on diagram)

Question 31

What is a positively charged amino acid?

Answer 31

has a positive charge (can see it on diagram)

Question 32

What are the 3 parts of a nucleotide?

Answer 32

nitrogenous base (A,T,G,C) + sugar (glucose) + phosphate group

Question 33

What are pyrimidines? Purines?

Answer 33

pyrimidine= cytosine & thymine
purines= adenine & guanine

Question 34

Which nucleotides bind together?

Answer 34

A+T
G+C

Question 35

What are the differences between RNA & DNA?

Answer 35

1. DNA is a double stranded helix (constant in structure) & RNA is single stranded so it can fold over to create different structures
2. DNA has thymine (A+T) while RNA has uracil (A+U)
3. DNA has deoxyribose which has an absence of one oxygen molecule & RNA has ribose which has that extra oxygen molecule thats why DNA is called deoxyribonucleic acid & RNA is called ribonucleic acid
4. DNA just carries genetic traits while RNA is multifunctional (can be an enzyme)

Question 36

What did Watson & Crick do?

Answer 36

they took what Chargaff & Franklin discovered, and found that DNA is an anti-parallel double-stranded helix

Question 37

What does DNA replication achieve?

Answer 37

reproduction of cells, creates proteins which determine physical traits

Question 38

What is a monosaccharide? Disaccharide? Polysaccharide?

Answer 38

mono= 1 sugar
di= 2 sugars
poly= multi-sugars

Question 39

What are the 3 main monosaccharides?

Answer 39

glucose, fructose, galactose

Question 40

What are the 3 main disachharides?

Answer 40

sucrose= glucose + fructose
lactose= glucose + galactose
maltose= glucose + glucose

Question 41

What are the 5 main polysaccharides?

Answer 41

starch= stores energy in plants
glycogen= stores glucose energy in animals/humans
cellulose= support for plants
chitin= support for insects & crustaceans (in their exoskeletons)
peptidogylcan= support for bacteria

Question 42

What are the covalent bonds called in all 4 macromolecules?

Answer 42

amino acids= peptide bonds
dna= phosphodiester bonds
carbohydrates= glycolistic linkage
lipids= ester linkage

Question 43

What are healthy fats vs unhealthy fats?

Answer 43

saturated fats= unhealthy
unsaturated fats= healthy

Question 44

What are saturated fats?

Answer 44

• straight & closely packed
• unhealthy
• solid at room temp
• blocks arteries & stays solid in the bloodstream can lead to heart attack or stroke

Question 45

What are unsaturated fats?

Answer 45

• has a kink to it
• liquid at room temp
• healthy

Question 46

What is a lipid? What is a phospholipid?

Answer 46

Lipid= 3 fatty acids + glycerol
Phospholipid= has a hydrophilic head (phosphate & glycerol), 3 fatty acids (saturated and/or unsaturated) [hydrophobic tail]

Question 47

What is the layers of lipids?

Answer 47

extracellular space= hydrophilic head
phospholipid bilayer= 2 layers of phospholipids w hydrophobic interior & hydrophilic exterior
cytoplasm= hydrophilic head

Question 48

What are the characteristics of the phospholipid bilayer?

Answer 48

-it has selective permeability, allows certain things into our cells
-high selective permeability= gases (CO2 & N2)
-low selective permeability= ion with a charge to it (bc the tails are hydrophobic so it has no charge to it so it won’t allow charged ions in)
-its affected by the temperature
-increase= more fluidity / movement
-decrease= less movement -> freezes

Question 49

What is diffusion?

Answer 49

the random movement of molecules from high concentration to low concentration until equilibrium (equal concentration) is reached [doesn’t need energy]; can’t happen with every molecule

Question 50

What is osmosis & tonicity?

Answer 50

osmosis= diffusion of water across semipermable membrane
tonicity= determines the direction in which osmosis occurs

Question 51

The effects of hypertonic, hypotonic & isotonic solutions

Answer 51

water moves from hypotonic to hypertonic or from high to low. water follow the ion concentration between the membrane. while others follow its own concentration.

hypertonic= a solution with greater solute concentration than that in another solution
hypotonic= a solution with lower solute concentration than that in another solution
isotonic= a solution with same solute concentration than that in another solution