Exam 2 Content (pt 2)

Question 1

what happens once the large ribosomal unit is assembled?

Answer 1

• a new tRNA enters the A site
• a peptide bond forms between the previous & the next amino acid

Question 2

what kind of molecule catalyzes the peptide bond formation in elongation?

Answer 2

rRNA

Question 3

what is released when a stop codon is encountered?

Answer 3

release factor

Question 4

which site on the large ribosomal unit does the release factor enter?

Answer 4

A site

Question 5

what happens to the polypeptide when a release factor enters the large ribosomal unit?

Answer 5

it is released from the tRNA located in the P site and enters the E site

Question 6

when does the termination phase start in translation?

Answer 6

when the small ribosome encounters the stop codon (UAG)

Question 7

what does the large ribosomal unit do that signals the end of termination phase (or the translation process)?

Answer 7

it dissociates from the mRNA strand

Question 8

what are the processes by which inactive proteins can be activated?

Answer 8

• cleavage
• posttranslational modification

Question 9

not all genes are going to be expressed, therefore only a certain part of the gene (DNA) will be accessed by transcription factors

Answer 9

true

Question 10

why do transcription & translation rapidly occur in prokaryotes?

Answer 10

they lack a nucleus that allow for separation of these processes within the cell

Question 11

what is a common organelle between eukaryotes & prokaryotes?

Answer 11

ribosomes

Question 12

what are the requirements of a cell?

Answer 12

• cellular membrane
• means to encode & transmit information
• ATP

Question 13

where does ATP store its energy?

Answer 13

in weak covalent bonds of its phosphate groups

Question 14

what are the metabolic classifications of life?

Answer 14

• phototrophs
• chemotrophs
• autotrophs
• heterotrophs

Question 15

what are the metabolic classifications grouped by?

Answer 15

• energy source
• carbon source

Question 16

where do autotrophs obtain their carbon?

Answer 16

inorganic compounds

Question 17

organic compounds are the carbon source for which type of metabolic classification?

Answer 17

heterotrophs

Question 18

definition

anabolism

Answer 18

the process of building macromolecules from smaller units that requires the input of ATP

Question 19

definition

catabolism

Answer 19

a process that produces ATP from breaking down macromolecules into its smaller subunits

Question 20

what makes ATP have the highest potential energy out of the other types of energy?

Answer 20

it has more bonds where energy can be stored

Question 21

definition

Gibbs Free Energy

Answer 21

the amount of energy available to do work

Question 22

where do DNA replication & DNA transcription occur in the cell?

Answer 22

nucleus

Question 23

definition

difference in free energy

Answer 23

the amount of free energy between reactants & products

Question 24

endergonic reactions require an energy input

Answer 24

true

Question 25

***exergonic reactions*** *release* energy

Answer 25

true

Question 26

what will be the *sign* of **∆G** when the free energy of *products* is ***greater than*** that of *reactants*? | *recall characteristics*

Answer 26

**positive** | endergonic reaction; nonspontaneous; **anabolic**

Question 27

# definition **ATP hydrolysis**

Answer 27

an **exergonic reaction** of H₂O *breaking down* *ATP* into ***ADP*** & ***phosphate***

Question 28

why do cells perform **energetic coupling** with *endergonic* & *exergonic* reactions?

Answer 28

to drive **nonspontaneous reactions** *(-∆G)*

Question 29

how do **enzymes** increase the *rate of reaction*?

Answer 29

by lowering the **activation energy**

Question 30

what do **enzymes** stabilize during a reaction?

Answer 30

**intermediates** *(transition state)*

Question 31

what is the *process* that forms an **active site**?

Answer 31

**protein folding**

Question 32

what is the result of **protein folding**?

Answer 32

an **active site** formed by amino acids

Question 33

why are **amino acids** that form the *active site* located far apart from each other on the protein's *primary structure*?

Answer 33

when the protein folds into its *secondary structure* they are able to properly form the site

Question 34

what are the factors that *affect* **enzyme activity**?

Answer 34

* temperature * pH * activators * inhibitors

Question 35

types of **inhibitors**

Answer 35

* competitive * noncompetitive

Question 36

what does a **noncompetitive inhibitor** do ?

Answer 36

* binds to a site other than the active site * *changes the shape* of the enzyme * *reduces the rate* of reaction

Question 37

how does a **competitive inhibitor** *reduce* the reaction rate?

Answer 37

* binds to the active site * competes with the substrate

Question 38

what happens when an **allosteric enzyme** changes its shape as it is bound to a *molecule*?

Answer 38

it is either **inhibited** or **activated**

Question 39

# definition **negative feedback**

Answer 39

the process in which the *final product* ***inhibits*** the *first step* of a reaction

Question 40

where does **carbon** come from in *cellular respiration*?

Answer 40

**carbohydrates** from food

Question 41

what are the stages of **photosynthesis**? | (2)

Answer 41

* light capture * carbon fixation

Question 42

what is the *purpose* of **carbon fixation**?

Answer 42

convert inorganic molecules into organic molecules

Question 43

which **organelle** in a plant cell *captures light*?

Answer 43

**chloroplast**

Question 44

what **molecule** is contained in the chloroplast that *actively* absorbs light?

Answer 44

**chlorophyll pigments**

Question 45

where is the **chlorophyll pigment** embedded in?

Answer 45

**thylakoid membrane**

Question 46

where does **carbon fixation** occur?

Answer 46

**stroma**

Question 47

where is the **stroma** located? | hint: it’s a name for the “space”

Answer 47

between the chloroplast's **inner membrane** & the **thylakoid membrane**

Question 48

what gives leaves their green color?

Answer 48

**chlorophyll** merely reflecting back the *green wavelength*

Question 49

what happens to the **electrons** when *chlorophyll* absorbs light?

Answer 49

they transition to a **higher energy state**

Question 50

what happens when **chlorophyll pigments** become close to one another?

Answer 50

the **energy** from the electrons transitioning states are *transfered*

Question 51

what is the name for **chlorophyll pigments** that transfer *energy*?

Answer 51

**antenna chlorophyll**

Question 52

where is the *energy* from **antenna chlorophyll** transfered to?

Answer 52

**reaction center**

Question 53

what is the **reaction center**?

Answer 53

*paired chlorophyll molecules* located within ***Photosystem I*** & ***Photosystem II***

Question 54

where does **Photosystem II** receive an *electron*?

Answer 54

**water**

Question 55

what happens when **Photosystem I** receives *light energy*?

Answer 55

**NADP+** is reduced to **NADPH**

Question 56

why cannot **NADPH** from *Photosystem I* leave the *chloroplast*?

Answer 56

it is needed for **Carbon fixation** wherein the carbon gets fixed into *carbohydrates*

Question 57

where does **Photosystem I** receive electrons for *reduction*?

Answer 57

**Photosystem II**

Question 58

what happens to **H₂O** when Photosystem II receives its *electron*?

Answer 58

oxidation (**H+** & **O₂**)

Question 59

which *atom* **drives** *ATP synthesis*?

Answer 59

**H+**

Question 60

what kind of *enzyme* synthesizes **ATP**?

Answer 60

**ATP synthase**

Question 61

where does **ATP synthesis** occur?

Answer 61

**stroma**

Question 62

where do **protons** accumulate during *photosynthetic electron transport*?

Answer 62

**thylakoid lumen**

Question 63

where are the **protons** derived from when ATP is being synthesized?

Answer 63

* oxidized **water** * **proton pumps** *(Pq & Cytb6f)*

Question 64

**ATP** synthesized in the *chloroplast* cannot leave

Answer 64

true

Question 65

where will be the **ATP** used for after synthesis?

Answer 65

**Calvin cycle**

Question 66

what is the ultimate *product* of **Calvin cycle**?

Answer 66

**Carbohydrates**

Question 67

what *first* happens when **CO₂** from cellular respiration enters ***carbon fixation***?

Answer 67

carboxylation of **RuBP** | *(carbon dioxide)* is added to RuBP

Question 68

which *enzyme* catalyzes **carboxylation**?

Answer 68

**Rubisco**

Question 69

how many *carbons* does **RuBP** have?

Answer 69

**5**

Question 70

how many **ATP** does *carboxylation* require?

Answer 70

**none**

Question 71

how many *carbons* are a result from **carboxylation**?

Answer 71

**6**

Question 72

what are the steps of the **Calvin cycle**?

Answer 72

* carboxylation * reduction * regeneration of RuBP

Question 73

what is the *product* of **reduction** in the *Calvin cycle*?

Answer 73

**triose phosphate**

Question 74

what is the premise of **photosynthesis**?

Answer 74

absorption of light by the *chlorophyll* in order to convert it to energy

Question 75

which is the *only* step in **cellular respiration** that uses _oxygen_?

Answer 75

**oxidative phosphorylation**

Question 76

which is the _only_ step in **cellular respiration** *that does not generate ATP*?

Answer 76

**pyruvate oxidation**

Question 77

what is the premise of **Calvin cycle**?

Answer 77

it uses the *ATP* generated from light absorption in the chlorophlast to **synthesize carbohydrates**

Question 78

both the **electron transport chains** in the *mitochondria* & *thylakoid* _require_ ***proton pumps***

Answer 78

true

Question 79

what happens to **NADH** & **FADH₂** when the cell has no oxygen?

Answer 79

they cannot be _oxidized and regenerated_ into **NAD+** & **FAD**

Question 80

where does **glycolysis** occur?

Answer 80

**cytoplasm**

Question 81

what kind of reaction is **cellular respiration**?

Answer 81

**spontaneous exergonic**

Question 82

what kind of **electron carriers** are used in _cellular respiration_?

Answer 82

* NAD+ * FAD

Question 83

what is the premise of **cellular respiration**?

Answer 83

_carbohydrates_ are broken down by using *oxygen* in order to **produce carbon dioxide**

Question 84

what are the products from *oxidizing* **glucose**?

Answer 84

**2 pyruvates**

Question 85

how many **carbons** are in 1 *pyruvate molecule*?

Answer 85

**3**

Question 86

how many **carbons** are in 1 *glucose molecule*?

Answer 86

**6**

Question 87

**oxidized** state of *electron carriers*

Answer 87

* NAD+ * FAD

Question 88

**reduced** states of *electron carriers*

Answer 88

* NADH * FADH₂

Question 89

what are the *steps* in **cellular respiration**? | (4)

Answer 89

* glycolysis * pyruvate oxidation * citric acid cycle * oxidative phosphorylation

Question 90

which *step* in **cellular respiration** gets rid of all the _carbons_?

Answer 90

**Citric acid cycle**

Question 91

why do **electron carriers** make *cellular respiration* a more efficient process?

Answer 91

they prevent energy from being lost as heat

Question 92

what is the premise of **glycolysis**?

Answer 92

breaking down glucose *(oxidizing)* into 2 pyruvate molecules

Question 93

how much **ATP** does *glycolysis* cost?

Answer 93

**2**

Question 94

what are the **products** of *glycolysis*?

Answer 94

* 4 ATP * 2 NADH * 2 pyruvate

Question 95

what are the *steps* in cellular respiration that occur in the **mitochondria**?

Answer 95

* pyruvate oxidation * citric acid cycle * oxidative phosphorylation

Question 96

what is the **ATP** *net gain* _after_ glycolysis?

Answer 96

**2**

Question 97

where in the *mitochondria* does **pyruvate oxidation** occur?

Answer 97

**mitochondrial matrix**

Question 98

what happens to **one** of the carbons in _pyruvate_?

Answer 98

it gets released as **carbon dioxide**

Question 99

what kind of functional group are the other **two** carbons from _pyruvate_ attached to?

Answer 99

**acetyl** | COCH3 *(note the 2 carbons)*

Question 100

what is **triose phosphate**?

Answer 100

it is a building block for **carbohydrates**