Unit 2: Biological chemistry & cell structure Flashcards

1
Q

Learning Objectives

A
  1. Describe the role of the main enzymes involved in digestion & absorption
  2. Describe the different types of digestion (chemical and mechanical) that occur in the small intestine and explain how the structure of the small intestine promotes nutrient absorption.
  3. Explain the role of accessory organs in nutrient absorption.
  4. Describe the life-supporting properties of water and explain how these are related to hydrogen bonding.
  5. Explain why carbon is the ideal molecule for forming large, diverse molecules.
  6. List the four main classes of macromolecules; explain the relationship between monomers and polymers; and compare the processes of dehydration synthesis and hydrolysis.
  7. Describe the structures, functions, properties, and types of carbohydrates, lipids, proteins, and nucleic acids.
  8. Distinguish between the structures of prokaryotic and eukaryotic cells.
  9. Compare and contrast active & passive transport.
  10. Distinguish hypertonic, hypotonic, and isotonic solutions. Describe how and why cells change when placed in these solutions.
  11. Explain how acids and bases affect the pH of a solution and how a buffer functions.
  12. Compare and contrast competitive and non-competitive inhibitors.
  13. Describe the structure and function of the plasma membrane, cell wall, nucleus,
    endomembrane system, smooth & rough ER, Golgi apparatus, lysosomes, vacuoles,
    mitochondria, chloroplasts, ribosomes, and vesicles.
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2
Q

What’s in saliva?

A

Salivary amylase: breaks down starches
Lipase: breaks down lipids
Mucin: protects lining; lubricates food
Buffers: neutralize acid
Antimicrobials: eliminate bacteria

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3
Q

Salivary Amylase
1. Key hormones and enzymes involved in digestion (where is it made)

  1. What is it made out of?
  2. How does it function in digestion?
A
  1. Salivary gland
  2. Protein, enzyme
  3. breaks down carbohydrate
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4
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A
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5
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6
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7
Q

Gastrin

  1. Key hormones and enzymes involved in digestion (where is it made)
  2. What is it made out of?
  3. How does it function in digestion?
A
  1. stomach lining
  2. peptide hormone
  3. Stimulates cells lining stomach to produce HCI
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7
Q

Lipase

  1. Key hormones and enzymes involved in digestion (where is it made)
  2. What is it made out of?
  3. How does it function in digestion?
A
  1. Tongue, gastric lipase -stomach lining
  2. Protein, enzyme
  3. breaks down lipids
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8
Q

Pepsin

  1. Key hormones and enzymes involved in digestion (where is it made)
  2. What is it made out of?
  3. How does it function in digestion?
A
  1. Stomach lining
  2. Protein, enzyme
  3. breaks down proteins into amnio acids
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9
Q

Small intestine

A

Most digestion in duodenum; absorption in jejunum & ileum

Carbs / Proteins / Fats / Nucleic acids

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10
Q

Large intestine

A

Major function → water absorption
Water absorbed → feces compacted
- move via peristalsis

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11
Q

Liver

A

Removes excess glucose → converted to glycogen & stored

Direct access from intestines

Converts nutrients into needed products (plasma proteins, lipoproteins)

Modifies & detoxifies -alcohol, drugs → inactivated

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12
Q

STRONG BONDS

A

Covalent bonds: Sharing the
sandwich

Ionic bonds: One person steals
the sandwich from the other

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13
Q

WEAK BONDS

A

Hydrogen bonds: That sandwich
over there smells pretty good!

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14
Q

The surface tension of a water droplet in glass is an example of…

A. Cohesion
B. Adhesion
C. Both
D. Neither

A

C. Both

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15
Q

Water is the solvent of life

A

Polarity of water allows it to “surround” molecules (acts as solvent)

In a glacier, pollutants trapped in ice remain in solution after glacier melts

In a cell, hydrophilic proteins perform functions in the aqueous environment of the cytoplasm

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16
Q

Water is important for maintaining temperature

A

Heat: amount of energy associated with movement of atoms

Temperature: average amount of energy/average speed of
molecules; intensity of heat

Water resists changes in
temperature

Absorbs heat (bonds break,
faster movement) but only
increases temperature
slightly

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17
Q

Maintaining physiological pH

A

Carbonic acid/bicarbonate system

Phosphate buffer system
(intracellular)

=Maintained by
kidneys &
respiration

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18
Q

Blood pH Levels

A

Death 6-7

Acidosis 7-7.35

Normal 7.35-7.45

Alkalosis 7.45-7.8

Death 7.8-9

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19
Q

Compared with a solution of pH 7, the same volume of solution at pH 4 has _______ times more hydrogen ions (H+).

A. 100
B. 1,000
C.10,000
D.3
E. 3,000

A

B. 1,000

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20
Q

Carbon: Life’s Chemical Backbone

A

Can form 4 covalent bonds (4 unpaired e-)

Tetrahedron spatial orientation

Bonds can rotate freely

Can form long chains that are branched or
ring structures

Carbon is the basis of biological macromolecules!

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20
Q

Double bonds

A

Double bonds between adjacent carbons

shorter than single bonds

no rotation

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21
Q

Isomers

A

Spatial arrangement important

Form/Function relationship
Proteins -> Structure
Sugars -> Taste

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22
Q

What are the 4 categories of biological macromolecules?

A

Lipids

Carbohydrates

Proteins

Nucleic Acids

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23
What are the polymer and monomers forms of each? (four categories of biological macromolecules)
Lipids (fatty acids) Carbohydrates (monosaccharides) Proteins (amino acids) Nucleic Acids (nucleotides)
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What are the linkages between monomers called?
Lipids - ester bonds Carbohydrates - glycosidic bonds Proteins - peptide bonds Nucleic Acids - phosphodiester bonds
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Dehydration
Loss of water molecule during synthesis reaction
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Hydrolysis
Splitting of water molecule to separate polymers
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Carbohydrate storage forms
Storage & function Differ in bond angles, branching All can be broken down for energy ________________________________________ Starch Glycogen Cellulose
28
Fatty acids & glycerol
C & H linked by nonpolar, covalent bonds e- movement leads to slight + and - areas Temporary polarization leads to attraction (van der Waals forces) _________________________________________ Triacylglycerol Glycerol + three fatty acids Great energy storage! 1g fat has more energy than 2g starch! Compact energy storage, insulation
29
Saturated Fatty Acids
Maximum number of H Close packing; solid at RT Promote atherosclerosis Typically animal origin _____________________________ Saturated Fatty Acids chains lack double bonds, resulting in phospholipids with a straight structure that favors tight packing.
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Unsaturated Fatty acids
Not maximum number of H Double bond=kink Loose packing; liquid at RT Typically plant origin __________________________________________ Unsaturated Fatty acids have one or more double bonds that introduce kinks in the phospholipids reducing the tightness of packing.
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Steroids
E.g. cholesterol Provide structure in cell membranes Help maintain fluidity Precursor for hormones like testosterone, estrogen, cortisol
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Phospholipids
2 FA attached to head group Distinct hydrophilic & hydrophobic regions Spontaneously form bilayers in solution Major component of cell membranes
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Nucleic acids RNA and DNA bases
RNA - A, U, C, G DNA - A, T, C, G
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Phosphodiester bonds
Phosphate group (5’) binds to hydroxyl group (3’)
35
DNA structure
Double helix Formed by H bonds between base pairs A:T=2 bonds C:G=3 bonds A = Adenine / T = Thymine G = Guanine / C = Cytosine
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Which of these regions determines the properties of amino acid? A. Amino group B. Alpha carbon C. R group D. Carboxyl group E. All are important
C. R group
37
Peptide bonds
Formed between hydroxyl group and amide group Covalent Dehydration synthesis
38
How many amino acids are in a polypeptide chain with 3 peptide bonds? A. 1 B. 2 C. 3 D. 4 E. 5
D. 4
39
Rank the following molecules in terms of the ease with which they could cross the plasma membrane (phospholipid bilayer). Hint: Consider both SIZE and CHARGE! O2 , K+ , Glucose , CO2 , Glycerol
*easiest to hardest CO2 > O2 > Glycerol > Glucose > K+
39
Elements of the Prokaryotic Cell
- Plasma membrane - Cytoplasm - DNA - Ribosomes - Cell wall - Capsule - Pili - Flagella
40
Prokaryotic: Plasma membrane (common to all bacteria)
This is the outer covering that separates the cell’s interior from its surrounding environment. It is made of phospholipids and proteins and regulates the passage of substances into and out of the cell
41
Prokaryotic: Cytoplasm
This is the jelly-like fluid that fills the cell and contains other cellular components. It is the site of many biochemical reactions that sustain the cell
42
Prokaryotic: DNA (common to all bacteria)
This is the genetic material of the cell that carries the instructions for making proteins and other molecules. It is usually found in a central region called the nucleoid, where it forms a single circular chromosome
43
Prokaryotic: Ribosomes (common to all bacteria)
These are the structures that synthesize proteins from amino acids. They are composed of RNA and proteins and are not enclosed by a membrane. They can be found in the cytoplasm or attached to the plasma membrane
44
Prokaryotic: Cell wall (common to all bacteria)
This is a rigid layer that surrounds the plasma membrane and provides support and protection to the cell. It is made of peptidoglycan, a complex polymer of sugars and amino acids, in most bacteria. Some archaea have cell walls made of other substances, such as pseudopeptidoglycan or polysaccharides
45
Prokaryotic: Capsule
This is a sticky layer of polysaccharides that covers the cell wall of some bacteria. It helps the cell adhere to surfaces or other cells and protects the cell from dehydration and immune system attacks
46
Prokaryotic: Pili
These are hair-like structures that extend from the cell surface of some bacteria. They help the cell attach to other cells or surfaces, or exchange genetic material during a process called conjugation
47
Prokaryotic: Flagella
These are whip-like appendages that protrude from the cell surface of some bacteria and archaea. They help the cell move by rotating like propellers
48
Surface Area: Volume
SA:V decreases as cells become larger At some point, material will not be able to move across membrane fast enough to support life Small size of bacteria allows cell to effectively take in needed materials & eliminate wastes In multi-cellular organisms, SA increased for organ function (e.g. intestines)
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Selective permeability - Hydrophobic Molecules
O2, CO2, N2
50
Selective permeability - Small, uncharged polar molecules
H2O, indole, glycerol
51
Selective permeability - Large, uncharged polar molecules
Glucose, sucrose
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Selective permeability - Ions
Cl-, K+, Na+
53
Out of the four Selective permeabilities which ones can cross the membrane with out help? Which ones can goes through the fastest? 1. Hydrophobic molecules 2. small, uncharged polar molecules 3. large, uncharged polar molecules 4. ions
1. Hydrophobic molecules (fastest) 2. small, uncharged polar molecules
54
Membrane proteins
Transporter (Channel and Carrier) Receptor Enzyme Anchor
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Passive transport: Simple
Diffusion movement of molecules from a higher to a lower concentration - down their concentration gradient molecules are distributed equally.
56
Passive transport: Facilitated
- No energy required - Diffusion: movement from [high] to [low] 2 Types of transmembrane proteins: Channel: open (unless gated) Carrier: regulated
57
Aquaporins are an example of which of the following? A) Active Transport B) Simple Diffusion C) Facilitated Diffusion
C. Facilitated Diffusion
58
Aquaporins
Water moves via osmosis (diffusion of water) Free passage of water across membrane VERY slow Aquaporins facilitate water movement at biologically relevant rate
59
Osmosis
Osmosis is a process that happens when two liquids with different amounts of dissolved stuff (like sugar or salt) are separated by a thin barrier (like a plastic bag or a cell membrane) that only lets water pass through. The water will move from the side with less dissolved stuff to the side with more dissolved stuff until the two liquids have the same amount of dissolved stuff. This is because water likes to be balanced and tries to even out the differences between the two liquids.
60
Active transport = Pump
Movement against concentration gradient E.g. Na/K pump into or out of the cell up an electrochemical gradient Active transport can be powered by ATP (energy) powered …or active transport can be powered by other gradients Active transport maintains cell membrane integrity Active transport used to maintain intracellular [ion] In various non-isotonic solutions, water will move via osmosis
61
(____)tonic list
Hypertonic - higher concentration of solute than another solution (water moves in) [Shrunk] Isotonic - normal Hypotonic - lower concentration of solute than another solution (water moves out) [Swollen] Very hypotonic - much lower concentration of solute, having much water moving out of it. [Lysed]
62
The axolotl lives in fresh water. If you moved it to a tank containing ocean water, what would be the tonicity of the environment in relation to the axolotl’s cells? A)Hypotonic B)Isotonic C)Hypertonic
C)Hypertonic
63
The axolotl lives in fresh water. If you moved it to a tank containing ocean water, what would be the tonicity of the environment in relation to the axolotl’s cells? (answer hypertonic) What would happen to the axolotl’s skin cells? A)Increase in size and burst B)No change C)Shrivel up
C)Shrivel up
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Active transport—Think of it as a Pump
Chemical & electrical gradient across membrane due to proton distribution Protons move from [high] to [low] Proton movement coupled to another molecule (against gradient) Anti- or symporter
65
What is EA? What impact does an enzyme have on EA? How do enzymes exert their effect EA?
EA is the activation energy. The energy needed to reach the transition state Enzymes lower the EA by stabilizing the transition state and lowering free energy
66
What does an enzyme do?
- Enzyme-catalyzed reaction/ - Uncatalyzed reaction - Transition state - EA for each reaction - Energy difference between products and reactants (ΔG)
67
The rate of enzyme-catalyzed reactions depends on several factors. What are some these?
Factors that affect the rate of reaction: These factors cause denaturation = destruction of protein structure * Temperature - enzymes in mammals have optimum of 37°C * pH - Depends on the function and location of enzyme * Pressure Factors that affect rate, but don’t cause denaturation * Enzyme concentration * Substrate concentration