Chapter 4 - Cellular Metabolism Flashcards
1
Q
aer-
A
air
(aerobic respiration)
2
Q
an-
A
without
(anaerobic respiration)
3
Q
ana-
A
up
(anabolism)
4
Q
cata-
A
down
(catabolism)
5
Q
co-
A
with
(coenzyme)
6
Q
de-
A
undoing
(deanimation)
7
Q
mut-
A
change
(mutation)
8
Q
-strat
A
spread out
(substrate)
9
Q
sub-
A
under
(substrate)
10
Q
-zym
A
causing something to ferment
(enzyme)
11
Q
enzyme
A
protein that catalyzes a specific biochemical reaction
12
Q
cellular metabolism
A
the sum total of chemical reactions in the cell
13
Q
What are the two types of metabolic reactions and pathways?
A
anabolic
catabolic
14
Q
anabolism
(anabolic metabolism)
A
synthesis of larger molecules from smaller ones
15
Q
catabolism
(catabolic metabolism)
A
breakdown of larger molecules
16
Q
dehydration synthesis
A
- anabolic process that joins small molecules by enzymatically releasing the equivalent of H₂O
- forms carbohydrates, fats, proteins, and nucleic acids
monosaccharide + monosaccharide ⇄ disaccharide + water
amino acid + amino acid ⇄ dipeptide molecule + water
17
Q
Are metabolic reactions reversible?
A
often, but different enzymes often catalyze corresponding anabolic and catabolic reactions
18
Q
How do enzymes speed metabolic reactions?
A
lower the amount of activation energy required by straining chemical bonds in substrate
substrate + enzyme ⟶ enzyme-substrate complex ⟶ product + enzyme
19
Q
substrate
A
molecule on which an enzyme acts
20
Q
What is catalase, where is it found, and what is its substrate? Give an example.
A
- an enzyme
- in the peroxisomes of liver and kidney cells
- hydrogen peroxide, a toxic by-product of certain metabolic reactions
- EXAMPLE: When hydrogen peroxide is poured on a wound, cells release catalase, and the hydrogen peroxide is broken down, releasing oxygen; the foam removes debris.
21
Q
active site
A
part of an enzyme that temporarily binds a substrate
22
Q
What factors affect the rate of enzyme-catalyzed reactions?
A
- concentration of enzyme or substrate molecules in the cell; higher concentration = faster
- efficiency of the enzyme; some can catalyze only a few reactions per second, some can handle hundreds of thousands
23
Q
metabolic pathway
A
series of linked, enzyme-controlled chemical reactions
24
Q
lipase
A
enzyme that breaks down fat (lipid)
25
protease
enzyme that breaks down protein
26
amylase
enzyme that hydrolyzes polysaccharides (starch, amylum)
27
amylum
starch, polysaccharide
28
What digestive enzyme catalyzes the breakdown of the sugar sucrose?
sucrase
29
What is sucrose, and what is it made of?
* disaccharide
* table sugar
* glucose and fructose
30
maltase
enzyme that splits maltose
31
What is maltose, and what is it made of?
* disaccharide produced by the breakdown of starch
* two glucose molecules
32
lactase
enzyme that splits lactose
33
What is lactose, and what is it made of?
* disaccharide in milk
* made of glucose and galactose
34
hydrolysis
* catabolic process that breaks up large molecules by enzymatically adding a water molecule H₂O
* breaks down carbohydrates, fats, proteins, and nucleic acids
disaccharide + water ⇄ monosaccharide + monosaccharide
dipeptide molecule + water ⇄ amino acid + amino acid
35
What is ATP, what is it made of, and what does it do?
* adenosine triphosphate
* a molecule made of an adenine, a ribose, and three phosphates
* it carries energy in its chemical bonds that is released for use when they are broken
36
What two ways do rate-limiting enzymes affect the rate of a metabolic pathway?
1. they become ineffectual in high concentrations of substrate
2. they are inhibited by the pathway's product (negative feedback)
37
What is ADP, where does it come from, and what happens to it?
* adenosine triphosphate
* when the bonds of ATP's third phosphate group are broken for energy, it becomes ADP
* it is resynthesized into ATP via cellular respiration
38
What is a cofactor, and what does it do?
* a non-protein component
* activates an enzyme by giving the active site an appropriate shape or helping bind enzyme and substrate
39
What is a coenzyme, how does it function, and what are some examples?
* small organic molecule
* acts as a cofactor
* many are vitamins
40
vitamins
essential organic molecules that must come from diet because human cells can't synthesize enough or any
41
What are enzymes made of?
almost all are proteins, but a few are RNA
42
What is energy? Give some examples.
* the ability to do work
* heat, light, sound, electricity, mechanical energy, and chemical energy
43
cellular respiration
a biochemical pathway that releases energy from organic compounds and makes it available for cellular use
44
What are the three series of reactions in cellular respiration?
1. glycolysis
2. the citric acid cycle
3. electron transport chain (oxidative phosphorylation)
45
aerobic
in the presence of oxygen
46
anaerobic
without the presence of oxygen
47
Of the two types of reactions in cellular respiration, which forms more ATP molecules?
aerobic
48
How much energy is captured and how much is lost in cellular respiration?
almost half is captured as ATP; the rest is released as body heat
49
What are the three main events in glycolysis?
1. phosphorylation (two phosphate groups added) and ATP primes the glucose
2. glucose molecule is split in two
3. NADH is produced, more ATP is synthesized, and two pyruvic acid molecules result
50
How many ATP molecules are gained per glucose molecule through glycolysis?
2 are used, and 4 are produced, making the net gain 2
51
glycolysis
the breaking of glucose
52
What does NADH do in cellular respiration? What happens without sufficient oxygen?
* electron carrier produced in glycolysis and recycled in the electron transport chain
* without oxygen, NADH reacts with pyruvic acid
53
How is lactic acid formed? How does it affect cellular respiration?
* When the electron carrier NADH reacts with pyruvic acid in the absence of sufficient oxygen receptors
* inhibits glycolysis, diffuses into the blood and is recycled in the liver when oxygen levels return to normal
54
What two substances are required for the citric acid cycle to begin?
pyruvic acid and oxygen
55
How does the citric acid cycle begin?
acetyl CoA combines with oxaloacetic acid to form citric acid and CoA
56
Name three important consequences of the citric acid cycle.
for each citric acid molecule ...
1. one ATP is produced
2. eight hydrogen atoms with high-energy electrons are transferred to NAD⁺ and related FAD:
NAD⁺ + 2H ⟶ NADH + H⁺
FAD + 2H ⟶ FADH₂
3. as citric acid reacts to form oxaloacetic acid, two CO₂ molecules are produced
57
What happens to the CO₂ produced in the citric acid cycle?
it dissolves into the cytoplasm, diffuses from the cell, enters the bloodstream, and is excreted by the respiratory system
58
What two compounds carry most of the energy from the glucose molecule to the electron transfer chain?
NADH and FADH₂
59
electron transport chain
a series of oxidation-reduction reactions that takes high-energy electrons from glycolysis and the citric acid cycle to form water and ATP
60
Where do the electron transport chain's enzyme complexes lie?
the folds of the inner mitochondrial membranes (cristae)
61
If stretched out, how long is the inner mitochondrial membrane?
could be 45 times as long as the cell membrane
62
What happens to an electron's energy as it moves along the transport chain?
it is gradually transferred to ATP synthase
63
What is ATP synthase, and what role does it play in the electron transport chain? What kind of reactions are these?
* enzyme complex
* uses energy from passing electrons to phosphorylate ADP
* oxidation-reduction
64
The final enzyme in the electron transport chain gives up a pair of electrons that do what?
combine with hydrogen ions (from NADH and FADH₂) and an atom of oxygen to form a water molecule
2e⁻ + 2H⁺ + ½O₂ ⟶ H₂O
65
How many net ATP molecules are produced per glucose molecule by glycolysis, the citric acid cycle, and the electron transport chain?
glycolysis: 2
citric acid cycle: 2
electron transport chain: 32-34
66
What is genetic code and what process is it used in?
* the correspondence between DNA triplets and mRNA codons and the amino acids they specify
* used in protein synthesis
67
chromosomes
threadlike structure built of DNA wrapped around proteins (histones)
68
gene
part of a DNA molecule that encodes information for making a particular protein
69
genome
complete set of genetic instructions for an organism
70
genomics
study of all the genetic information in an individual organism
71
Name DNA's four nitogenous bases and their two possible combinations.
adenine, thymine, cytosine, and guanine
AT and GC
72
complementary base pairs
pairs of nitrogenous bases in DNA
73
purines
adenine and guanine
74
pyrimidines
thymine and cytosine
75
DNA polymerase
enzyme that catalyzes the pairing of nucleotides to form DNA
76
When does DNA replication happen?
during the S phase of interphase
77
Name the four nitrogenous bases of RNA.
adenine, thymine, uracil, and guanine
78
What base does RNA have in place of DNA's thymine, and what does it pair with?
* uracil
* adenine
79
transcription
the process of copying DNA information into an RNA sequence
80
What are the three types of RNA?
messenger RNA, transfer RNA, and ribosomal RNA
81
mRNA
* messenger RNA
* synthesized in nucleus
* carries instructions for synthesizing protein into cytoplasm
82
RNA polymerase
enzyme that binds with DNA, exposes sections of it for RNA nucleotides to pair with, then releases mRNA
83
codons
