MT1

Question 1

what kind of environment do plants and animals prefer? (hypotonic, isotonic, hypertonic)

Answer 1

animals - isotonic; plants - hypotonic

Question 2

at resting membrane potential, is the inside or outside of the cell relatively positive?

Answer 2

outside of the cell is relatively positive at resting membrane potential

Question 3

T or F: diffusion needs no cell energy

Answer 3

T; diffusion doesn’t need cell energy

Question 4

T or F: hydrogen bonds keep the temperature in oceans and cells constant

Answer 4

T: hydrogen bonds stabilize the water; each bond formation releases heat and prevents temperature from dropping further. Increased heat energy is absorbed by energy bonds.

Question 5

T or F: H bonds prevent the formation of ionic bonds

Answer 5

T

Question 6

Does water interact with non-polar molecules, like fats?

Answer 6

No

Question 7

Describe surface tension of water (surface tension measures how hard it is to break the surface of something)

Answer 7

Water forms many H-bonds at the surface and just beneath the surface, making it hard to break the surface of the water

Question 8

Glycogen and starch examples of ____saccharides

Answer 8

polysaccharides

Question 9

T or F: a chloroblast is a type of amyloblast

Answer 9

T

Question 10

Where can an ester linkage be found?

Answer 10

Between a fatty acid and a glycerol on a lipid molecule;

o-c=o

Question 11

Fats take up _____space and more ______ energy than carbohydrates

Answer 11

Fats take up LESS space and more ENERGY than carbohydrates

Question 12

Why are saturated fats more closely packed?

Answer 12

They have single C-C covalent bonds, so are very flexible and can pack closely

Question 13

Why are unsaturated fats more rigid?

Answer 13

Their double C=C bonds produce a liquid, oily substance that doesn’t pack closely

Question 14

Hydrophilic portions point towards the ____ portion of a membrane

Answer 14

Outer; they want to interact with water molecules. The hydrocarbon fatty-acid tail is non-polar and hydrophobic

Question 15

What can proteins do?

Answer 15

1) speed up chem rxns (enzymes), 2) move in/out cell (membrane transporters) 3) support cells (cytoskeleton), 4) fight microbes (antibodies), 5) allow movement (shorten + contract muscles)

Question 16

Can all amino acids be produced by the body?

Answer 16

No, 9 amino acids must be consumed

Question 17

What are the 3 parts of a nucleotide?

Answer 17

1) deoxyribose sugar (5-C sugar) 2) -vely charged phosphate group on 5’-C of deoxyribose sugar, 3) nitrogenous base attached to the 1’-C of the deoxyribose sugar

Question 18

Enzymes add nucleotides to the ____ end of the DNA

Answer 18

Enzymes add nucleotides to the 3’ end of the DNA, copying them from 5’ to 3’

Question 19

Name some differences between RNA and DNA

Answer 19

DNA: larger, always double-stranded helix; deoxyribose (2’-C), GCAU

RNA: smaller, linear, oxyribose, GCAU, more versatile than DNA, enzymes

Both: store genetic information

Question 20

Why is RNA less stable than DNA?

Answer 20

OH group (RNA) is more EN than H group (DNA) and so the C-O (RNA) is more polar and less stable than the C-H (DNA)

Question 21

unzipping DNA involves breaking what kind of bonds?

Answer 21

H bonds between nitrogenous bases

Question 22

What is primase responsible for?

Answer 22

Primase is responsible for creating and attaching an RNA primer to the DNA strand (complementary base-pairs RNA nucleotides , then joins them together with a phosphodiester bond) - always between sugar and phosphate in backbone of any genetic material; writes from 5’ to 3’

Question 23

What does DNA polymerase do?

Answer 23

1) removes primer, fills gap with DNA nucleotides
2) attach to 3’ end, add nucleotides; when it sees a RNA primer, it detaches and re-attaches at junction to keep creating nucleotides
3) builds lagging and leading strands simultaneously, with a complex that has 2 DNA polymerases connected together

Question 24

What does DNA ligase do?

Answer 24

Connects DNA fragments - forming phosphodiester bonds between sugar and phosphate backbones

Question 25

Why are telomeres important?

Answer 25

As the ‘ends of DNA’, they are short, non-coding segments that protect essential genes in middle of DNA. DNA polymerase needs a 3’ end to add nucleotides (but when RNA primer is removed, there is no 3’ end) - eventually DNA polymerase eats away at telomeres, then at essential genes, then the cells die. This is why we age!

Question 26

What is PCR? Polymerase Chain Reaction? Name the steps.

Answer 26

1) method of making specific pieces of DNA
2-1) DNA is denatured using heat to break complementary strands (H-bonds)
2-2) Annealing; lab-created DNA primers is bound to ends of DNA that need to be copied
2-3) Extension; reheating the solution for DNA polymerase to lengthen the DNA primer in a 5’ to 3’ direction

each round of heating-cooling-heating doubles the amount of DNA to be copied each time

Question 27

How can you stop DNA sequencing?

Answer 27

Adding small amounts of a modified dideoxynucleotide can stop DNA polymerase and end replication - there is no 3’ end in this modified nucleotide!!!

Question 28

What is a plasmid?

Answer 28

Small, circular piece of DNA found in bacteria

Question 29

What does a restriction enzyme do?

Answer 29

Cuts a plasmid (circular bacterial DNA) to allow for complementary extensions joined by DNA ligase – result: recombinant DNA

Question 30

How does CRISPR work?

Answer 30

1) RNA strand is made in lab, complementary to target DNA
2) RNA is linked to a protein, guides protein to the target DNA
3) protein cuts the target DNA
4) desired gene introduced
5) desired DNA is incorporated into its own genome during the repair process

Question 31

What holds the plasma membrane together?

Answer 31

Van der waals interactions between fatty acids of phospholipid bilayer - allows membrane to move, and add/subtract things

Question 32

What direction does fluidity affect?

Answer 32

The ability of proteins to move/drift sideways

Question 33

Which portion of the membrane regulates passage?

Answer 33

The central, nonpolar region of the phospholipid bilayer decides what gets in/out - this is what decides the packing/spacing (permeability)

Question 34

How does cholesterol buffer fluidity?

Answer 34

As a non-polar steroid, cholesterol creates space between fatty acids, prevents membrane from becoming solid, also fills in the middle nonpolar region when many gaps exist

Question 35

A synthetic membrane composed of only phospholipids; organize from most easily to least easily penetrable (galactose, chloride ion, testosterone, atmospheric nitrogen, water, maltose)

Answer 35

atmospheric nitrogen (small, gaseous), testosterone (non-polar molecule), water (small molecule) galactose (monosaccharide), maltose (disaccharide)

chloride ions would need a channel to cross membrane

Question 36

How do plant cells adjust to changing environments in terms of membrane?

Answer 36

They use cholesterol to adjust the barrier, can adjust saturation/unsaturation of components

Question 37

Is pinocytosis active transport?

Answer 37

Yes - it involves bringing something from a lower concentration to a higher concentration. Therefore, active transportation.

Question 38

What concentration is most important to pay attention to in osmosis?

Answer 38

The free water concentration - the most solute you have, the less “free water” you have

Question 39

A plant cell is surrounded by a dead cell wall. A plant cell would be unable to take in materials through…

a) facilitated diffusion
b) simple diffusion
c) pinocytosis
d) phagocytosis
e) receptor-mediated endocytosis

Answer 39

d) phagocytosis

Question 40

Do Van der Waal interactions happen between polar or nonpolar molecules?

Answer 40

nonpolar molecules - induced charge repulsion

Question 41

How does cholesterol contribute to fluidity?

Answer 41

At high temperatures, cholesterol decreases fluidity. As a nonpolar molecule, it forms VDW interactions with neighbouring phospholipids, restricting their movement.

Question 42

The presence of protein transporters affects ______ permeability

Answer 42

Selective Permeability; they move ions and polar molecules across the membrane; preventing charged particles from interacting with middle nonpolar portion of membrane