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Exam 2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

eukaryotic cells

A

cells with a nucleus

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2
Q

plasma membrane

A

controls what goes into and out of the cell

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3
Q

Ribosomes

A

site of protein synthesis

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4
Q

DNA in nucleus

A

contains instructions for making proteins

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5
Q

What do only plant cells have?

A

cell walls

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6
Q

Chloroplasts covert ___ energy to ___ energy

A

light, chemical

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7
Q

Mitochondria break down molecules, generating ___

A

ATP

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8
Q

light microscope (LM)

A

visible light is passed through a specimen and then through glass lenses

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9
Q

Magnification

A

the ratio of an object’s image

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10
Q

Resolution

A

the measure of the clarity of the image, or the minimum distance of two distinguishable points

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11
Q

Contrast

A

visible differences in brightness between parts of the sample

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12
Q

organelles

A

the membrane-enclosed structures in eukaryotic cells

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13
Q

Light microscopes can magnify effectively to about ___ times the size of the actual specimen

A

1000

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14
Q

Scanning electron microscopes (SEMs)

A

focus a beam of electrons onto the surface of a specimen, providing images that look 3-D

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15
Q

Transmission electron microscopes (TEMs)

A
  • focus a beam of electrons through a specimen

- used mainly to study the internal structure of cells

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16
Q

electron microscopes (EMs)

A

used to study subcellular structures

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17
Q

Cryo-electron microscopy (cryo-EM)

A

allows preservation of specimens at very low temperatures

- allows visualization of structures in their cellular environment, with no need for preservatives

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18
Q

cytology

A

the study of cell structure

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19
Q

Cell fractionation

A

takes cells apart and separates the major organelles from one another
- enables scientists to determine the functions of organelles

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20
Q

Only organisms of the domains Bacteria and Archaea consist of ___ cells

A

prokaryotic

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21
Q

Protists, fungi, animals, and plants all consist of ___ cells

A

eukaryotic

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22
Q

Basic features of all cells

A

–Plasma membrane
–Semifluid substance called cytosol
–Chromosomes (carry genes)
–Ribosomes (make proteins)

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23
Q

Prokaryotic cells are characterized by having

A

–No nucleus
–DNA in an unbound region called the nucleoid
–No membrane-bound organelles
–Cytoplasm bound by the plasma membrane

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24
Q

Eukaryotic cells are characterized by having

A

–DNA in a nucleus that is bounded by a double membrane
–Membrane-bound organelles
–Cytoplasm (the region between the plasma membrane and nucleus)
–larger

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25
Q

plasma membrane

A

a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell

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26
Q

As a cell increases in size….

A

its volume grows proportionately more than its surface area

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27
Q

A eukaryotic cell has internal membranes that divide the cell into compartments

A

organelles

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28
Q

nucleus

A

contains most of the cell’s genes and is usually the most conspicuous organelle

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29
Q

nuclear envelope

A

encloses the nucleus, separating it from the cytoplasm

- a double membrane; each membrane consists of a lipid bilayer

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30
Q

pore complex

A

regulate the entry and exit of molecules from the nucleus

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31
Q

nuclear lamina

A

which is composed of proteins and maintains the shape of the nucleus

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32
Q

nuclear matrix

A

a framework of protein fibers throughout the interior of the nucleus

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33
Q

chromosomes

A

In the nucleus, DNA is organized into discrete units
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

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34
Q

Each chromosome contains one DNA molecule associated with proteins, called

A

chromatin

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35
Q

located within the nucleus, is the site of ribosomal RNA (rRNA) synthesis

A

nucleolus

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36
Q

Ribosomes build proteins in two locations:

A

–In the cytosol (free ribosomes)

–On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes)

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37
Q

The endomembrane system consists of:

- These components are either continuous or connected via transfer by vesicles

A 
–Nuclear envelope
–Endoplasmic reticulum
–Golgi apparatus
–Lysosomes
–Vacuoles
–Plasma membrane
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38
Q

endoplasmic reticulum (ER)

A

accounts for more than half of the total membrane in many eukaryotic cells

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39
Q

two distinct regions of ER:

A

–Smooth ER, which lacks ribosomes

–Rough ER, whose surface is studded with ribosomes

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40
Q

Functions of Smooth ER

A

–Synthesizes lipids
–Detoxifies drugs and poisons
–Stores calcium ions

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41
Q

Functions of Rough ER

A
  • Has bound ribosomes, which secrete glycoproteins(proteins covalently bonded to carbohydrates)
    –Distributes transport vesicles, secretory proteins surrounded by membranes
    –Is a membrane factory for the cell
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42
Q

Golgi apparatus

A

–Modifies products of the ER
–Manufactures certain macromolecules
–Sorts and packages materials into transport vesicles

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43
Q

The Golgi apparatus consists of flattened membranous sacs called

A

cisternae

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44
Q

lysosome

A

a membranous sac of hydrolytic enzymes that can digest macromolecules

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45
Q

phagocytosis

A

Some types of cell can engulf another cell

- forms a food vacuole

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46
Q

autophagy

A

Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules

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47
Q

Vacuoles

A

large vesicles derived from the ER and Golgi apparatus

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48
Q

Central vacuoles

A
  • -found in many mature plant cells, contain a solution called sap
  • -it is the plant cell’s main repository of inorganic ions, including potassium and chlorid
  • -The central vacuole plays a major role in the growth of plant cells
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49
Q

Mitochondria

A

are the sites of cellular respiration, the metabolic process that uses oxygen to generate ATP

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50
Q

Chloroplasts

A

found in plants and algae, are the sites of photosynthesis

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51
Q

endosymbiont theory

A
  • It suggests that an early ancestor of eukaryotes engulfed an oxygen-using nonphotosynthetic prokaryotic cell
  • The engulfed cell formed a relationship with the host cell, becoming an endosymbiont
  • The endosymbionts evolved into mitochondria
  • At least one of these cells may have then taken up a photosynthetic prokaryote, which evolved into a chloroplast
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52
Q

Similarities between mitochondria and chloroplasts that support this theory:

A

–Enveloped by a double membrane
–Contain free ribosomes and circular DNA molecules
–Grow and reproduce somewhat independently in cells

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53
Q

mitochondria have a smooth outer membrane and an inner membrane folded into

A

cristae

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54
Q

The inner membrane creates two compartments:

A

intermembrane space and mitochondrial matrix•

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55
Q

are found in leaves and other green organs of plants and in algae

A

chloroplasts

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56
Q

Chloroplast structure includes

A

–Thylakoids, membranous sacs, stacked to form a granum

–Stroma, the internal fluid

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57
Q

The chloroplast is one of a group of plant organelles, called

A

plastids

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58
Q

specialized metabolic compartments bounded by a single membrane
- They contain enzymes that remove hydrogen atoms from various substances and transfer them to oxygen

A

Peroxisomes

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59
Q

Functions of peroxisomes

A
  • Some use oxygen to break fatty acids into smaller molecules, eventually used for fuel for respiration
    –In the liver, they detoxify alcohol and other harmful compounds
    –Glyoxysomesin the fat-storing tissues of plant seeds, convert fatty acids to sugar to feed the emerging seedling
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60
Q

cytoskeleton

A

helps to support the cell and maintain its shape

- It interacts with motor proteinsto produce cell motility

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61
Q

Three main types of fibers make up the cytoskeleton:

A

–Microtubules are the thickest of the three components of the cytoskeleton
–Microfilaments, also called actin filaments, are the thinnest components
–Intermediate filaments are fibers with diameters in a middle range

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62
Q

hollow rods about 25 nm in diameter and about 200 nm to 25 microns long

A

Microtubules

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63
Q

Functions of microtubules:

A

-Shaping the cell
–Guiding movement of organelles
–Separating chromosomes during cell division

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64
Q

In animal cells, microtubules grow out from a __ near the nucleus

A

centrosome

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65
Q

In animal cells, the centrosome has a pair of ___, each with nine triplets of microtubules arranged in a ring

A

centrioles

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66
Q

flagella and cilia

A

microtubule-containing extensions that project from some cells

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67
Q

Difference between flagella and cilia

A
  • Motile cilia are found in large numbers on a cell surface, whereas flagella are limited to one or a few per cell
  • Cilia and flagella differ in their beating patterns
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68
Q

Cilia and flagella share a common structure

A

–A group of microtubules sheathed in an extension of the plasma membrane
–Nine doublets of microtubules are arranged in a ring with two single microtubules in the center
–A basal body that anchors the cilium or flagellum
–A motor protein called dynein, which drives the bending movements of a cilium or flagellum

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69
Q

are solid rods about 7 nm in diameter, built as a twisted double chain of actin subunits

A

Microfilaments

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70
Q

microfilaments form a

A

cortex just inside the plasma membrane to help support the cell’s shape

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71
Q

Microfilaments that function in cellular motility contain the protein __ in addition to actin

A

myosin

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72
Q

pseudopodia

A
  • cellular extensions

- cells crawl along a surface by extending pseudopodia and moving toward them

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73
Q

Cytoplasmic streaming

A

in plant cells, is a circular flow of cytoplasm within cells, driven by actin-protein interactions

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74
Q

Intermediate filaments

A

range in diameter from 8 to 12 nanometers, larger than microfilaments but smaller than microtubules
- support cell shape and fix organelles in place

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75
Q

cell wall

A

an extracellular structure that distinguishes plant cells from animal cells

  • protects the plant cell, maintains its shape, and prevents excessive uptake of water
  • made of cellulose fibers embedded in other polysaccharides and protein
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76
Q

What organisms have a cell wall?

A

Prokaryotes, fungi, and some protists

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77
Q

Primary cell wall

A

Relatively thin and flexible, secreted first

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78
Q

Middle lamella

A

Thin layer between primary walls, containing polysaccharides called pectins

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79
Q

Secondary cell wall(in some cells)

A

Added between the plasma membrane and the primary cell wall

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80
Q

Animal cells lack cell walls but are covered by an elaborate _____

A

extracellular matrix (ECM)

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81
Q

The ECM is made up of glycoproteins such as __, ___, and ___

A

collagen, proteoglycans, and fibronectin

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82
Q

Fibronectin and other ECM proteins bind to receptor proteins in the plasma membrane called __

A

integrins

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83
Q

Extracellular matrix (ECM) function

A
  • can regulate a cell’s behavior by communicating with a cell through integrins
  • influence the activity of genes in the nucleus
  • Mechanical signaling may occur through cytoskeletal changes that trigger chemical signals in the cell
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84
Q

cell junctions

A

Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact

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85
Q

Plasmodesmata

A

channels that connect plant cells

- Through plasmodesmata, water and small solutes (and sometimes proteins and RNA) can pass from cell to cell

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86
Q

Tight junctions

A

membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

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87
Q

Desmosomes (anchoring junctions)

A

fasten cells together into strong sheets

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88
Q

Gap junctions (communicating junctions)

A

provide cytoplasmic channels between adjacent cells

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89
Q

A cell is greater than….

A

the sum of its parts

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90
Q

Alcohol dehydrogenase

A

a protein that breaks down alcohol in the body

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91
Q

What are the structures and functions of the four important classes of biological molecules?

A
  1. carbohydrates
  2. proteins
  3. Nucleic acids
  4. lipids
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92
Q

Macromolecules are __, built from ____

A

polymers, monomers

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93
Q

Large polymers are known as ___

A

macromolecules

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94
Q

polymer

A

a long molecule consisting of many similar building blocks

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95
Q

The repeating units that serve as building blocks are called

A

monomers

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96
Q

Carbohydrates, proteins, and nucleic acids are __

A

polymers

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97
Q

Enzymes

A

specialized macromolecules that speed up chemical reactions such as those that make or break down polymers

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98
Q

A dehydration reaction occurs when…

A

two monomers bond together through the loss of a water molecule

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99
Q

Hydrolysis

A
  • a reaction that is essentially the reverse of the dehydration reaction
  • Polymers are disassembled to monomers by hydrolysis
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100
Q

A huge variety of polymers can be built from a small set of _____

A

monomers

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101
Q

Carbohydrates

A
  • include sugars and polymers of sugars
  • The simplest carbohydrates are monosaccharides, or simple sugars
  • Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks
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102
Q

_____ have molecular formulas that are usually multiples of CH2O

A

Monosaccharides

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103
Q

the most common monosaccharide

A

Glucose (C6H12O6)

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104
Q

Monosaccharides are classified by

A
  • The location of the carbonyl group (as aldose or ketose)

- The number of carbons in the carbon skeleton

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105
Q

disaccharide

A

formed when a dehydration reaction joins two monosaccharides

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106
Q

This covalent bond between two monosaccharides is called a

A

glycosidic linkage

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107
Q

Polysaccharides

A
  • the polymers of sugars
  • have storage and structural roles
  • architecture is determined by its sugar monomers and the positions of its glycosidic linkages
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108
Q

Starch

A
  • storage polysaccharides
  • consists of glucose monomers
    FYI The simplest form of starch is amylose
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109
Q

Glycogen

A

is a storage polysaccharide in animals

  • stored mainly in liver and muscle cells
  • Hydrolysis (chemical breakdown of a compound due to reaction with water) of glycogen in these cells releases glucose when the demand for sugar increases
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110
Q

The polysaccharide cellulose

A
  • a major component of the tough wall of plant cells
  • Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ
  • different ring structures alpha (α) beta (β)
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111
Q

alpha

A

Starch (α configuration) is largely helical

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112
Q

beta

A

Cellulose molecules (β configuration) are straight and unbranched

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113
Q

Chitin

A
  • found in the exoskeleton of arthropods

- provides structural support for the cell walls of many fungi

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114
Q

Lipids

A
  • does not include true polymers
  • consist mostly of hydrocarbon regions
  • important lipids are fats, phospholipids, and steroids
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115
Q

Fats

A

constructed from two types of smaller molecules: glycerol and fatty acids

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116
Q

Glycerol

A

a three-carbon alcohol with a hydroxyl group attached to each carbon

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117
Q

Fatty acids

A

consists of a carboxyl group attached to a long carbon skeleton

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118
Q

triacylglycerol

A

In a fat, three fatty acids are joined to glycerol by an ester linkage

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119
Q

Saturated fatty acids

A

have the maximum number of hydrogen atoms possible and no double bonds
-solid

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120
Q

Unsaturated fatty acids

A

have one or more double bonds

- liquid

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121
Q

Hydrogenation

A

process of converting unsaturated fats to saturated fats by adding hydrogen
TRANS FATS

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122
Q

major function of fats

A

energy storage

123
Q

Humans and other mammals store their long-term food reserves in ___

A

adipose cells

124
Q

phospholipid

A
  • two fatty acids and a phosphate group are attached to glycerol
125
Q

When phospholipids are added to water, they self-assemble into double-layered sheets called

A

bilayers

126
Q

steroids

A

lipids characterized by a carbon skeleton consisting of four fused rings

127
Q

Cholesterol

A

a type of steroid, is a component in animal cell membranes and a precursor from which other steroids are synthesized

128
Q

Enzymes are proteins that act as ___ to speed up chemical reactions

A

Catalysts

129
Q

proteins

A

account for more than 50% of the dry mass of most cells

130
Q

Look at the graphic for proten

A

presentation 5

slide 35

131
Q

Polypeptides

A

unbranched polymers built from amino acids

132
Q

protein

A

a biologically functional molecule that consists of one or more polypeptides

133
Q

Amino acids

A

organic molecules with amino and carboxyl groups

134
Q

Amino acids are linked by covalent bonds called

A

peptide bonds

135
Q

Each polypeptide has a unique linear sequence of amino acids, with a ___ end (C-terminus) and an ___ (N-terminus)

A

carboxyl, amino end

136
Q

The function of a protein usually depends on…

A

its ability to recognize and bind to some other molecule

137
Q

The primary structure

A

of a protein is its unique sequence of amino acids

138
Q

Secondary structure

A

found in most proteins, consists of coils and folds in the polypeptide chain

139
Q

Tertiary structure

A

is determined by interactions among various side chains (R groups)

140
Q

Quaternary structure

A

results when a protein consists of multiple polypeptide chains

141
Q

Sickle-cell disease

A

an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin

142
Q

denaturation

A

loss of a protein’s native structure

143
Q

What Determines Protein Structure?

A

In addition to primary structure, physical and chemical conditions can affect structure

144
Q

Scientists use ___ to determine a protein’s structure

A

X-ray crystallography

- Another method is nuclear magnetic resonance (NMR) spectroscopy, which does not require protein crystallization

145
Q

Diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with

A

misfolded proteins

146
Q

Chronic Wasting Disease in the deer family is also associated with misfolded proteins called

A

prions

147
Q

The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a

A

gene

148
Q

Genes consist of

A

DNA, a nucleic acidmade of monomers called nucleotides

149
Q

Two types of nucleic acids

A
  • Deoxyribonucleic acid (DNA)

–Ribonucleic acid (RNA)

150
Q

gene expression

A

DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis
- Gene expression: DNA → RNA → protein

151
Q

Nucleic acids are polymers called

A

polynucleotides

152
Q

Each polynucleotide is made of monomers called

A

nucleotides

Nucleotide = nucleoside + phosphate group

153
Q

Each nucleotide consists of

A

a nitrogenous base, a pentose sugar, and one or more phosphate groups

154
Q

Nucleoside

A

nitrogenous base + sugar•

155
Q

Two families of nitrogenous bases

A
  • Pyrimidines(cytosine, thymine, and uracil)have a single six-membered ring
    –Purines(adenine and guanine) have a six-membered ring fused to a five-membered ring
156
Q

In DNA, the sugar is ___ ; in RNA, the sugar is __

A

deoxyribose, ribose

157
Q

DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a

A

double helix

158
Q

The backbones run in opposite 5′ → 3′ directions from each other, an arrangement referred to as
(The Structures of DNA and RNA Molecules)

A

antiparallel

159
Q

DNA pair up

complementary base pairing

A

adenine (A) always with thymine (T), and guanine (G) always with cytosine (C)

160
Q

In RNA, thymine is replaced by

A

uracil

161
Q

Bioinformatics

A

uses computer software and other computational tools to deal with the data resulting from sequencing many genomes

162
Q

Analyzing large sets of genes or even comparing whole genomes of different species is called

A

genomics

163
Q

analysis of large sets of proteins including their sequences is called

A

proteomics

164
Q

RNA is ___ stranded

A

single

165
Q

First law of thermodynamics

principle of conservation of energy

A

Energy can be transferred or transformed, but not created or destroyed

166
Q

Second law of thermodynamics

A

Every energy transfer or transformation increases the entropy (disorder) of the universe

167
Q

Metabolism

A
  • the totality of an organism’s chemical reactions

- It is an emergent property of life that arises from orderly interactions between molecules

168
Q

metabolic pathway

A

In a metabolic pathway, a specific molecule is altered in a series of steps to produce a product

169
Q

Catabolic pathways

A

release energy by breaking down complex molecules into simpler compounds

  • ex. Cellular respiration, the breakdown of glucose in the presence of O2
  • “downhill”
170
Q

Anabolic pathways

A

consume energy to build complex molecules from simpler ones

- “uphill”

171
Q

Bioenergetics

A

study of how energy flows through living organisms

172
Q

Energy

A

the capacity to cause change, can be used to do work—move matter against opposing forces, such as gravity and friction

173
Q

Kinetic energy

A
  • is energy associated with motion

- Moving objects perform work by imparting motion to other matter

174
Q

Thermal energy

A
  • the kinetic energy associated with random movement of atoms or molecules
  • transfer from one object to another is called heat
175
Q

Potential energy

A

energy that matter possesses because of its location or structure

176
Q

Chemical energy

A

potential energy available for release in a chemical reaction

177
Q

Thermodynamics

A

the study of energy transformations in a collection of matter

178
Q

Entropy

A

a measure of molecular disorder, or randomness

179
Q

Spontaneous processes

A

occur without energy input; they can happen quickly or slowly

180
Q

Biological Order and Disorder

A

Cells create ordered structures from less organized starting materials
- Complex, ordered structures are also produced from simpler starting materials at the organismal level

181
Q

Free-Energy Change, ΔG

A
  • Gibbs free energy, G, can be simplified and referred to as free energy
  • represents the difference between free energy of the final state and free energy of the initial state
182
Q

Free energy

A

The portion of a system’s energy that can do work when temperature and pressure are uniform throughout the system, as in a living cell

183
Q

ΔH

A

change in enthalpy (total energy)

184
Q

ΔS

A

change in entropy

185
Q

T

A

Temperature in Kelvin (K)

186
Q

ΔG details

A
  • ΔG is negative for all spontaneous processes
    –ΔG is zero or positive for nonspontaneous processes
  • If a reaction has negative ΔG,the system loses free energy and becomes more stable
187
Q

Stable vs unstable ΔG

A

unstable systems (higher G) tend to become more stable (lower G)

188
Q

Equilibrium

A

the point at which forward and reverse reactions occur at the same rate, describes a state of maximum stability
- A process is spontaneous and can perform work only when it is moving toward equilibrium

189
Q

exergonic reaction

A

An exergonic reaction(“energy outward”) proceeds with a net release of free energy to the surroundings
exergonic reactions occur spontaneously

190
Q

endergonic reaction

A

An endergonic reaction(“energy inward”) absorbs free energy from the surroundings
-unspontaniously

191
Q

Breaking bonds during a chemical reaction does not release energy; it ___ energy

A

requires

192
Q

The magnitude of ΔG determines the

endergonic

A

quantity of energy required to drive an endergonic reaction

193
Q

The magnitude of ΔG determines the

exergonic

A

the maximum amount of work an exergonic reaction can perform

194
Q

The chemical reactions of metabolism are ___, but never reach ___ in a living cell

A

Reversible, equilibrium

195
Q

A cell does three main kinds of work:

A

–Chemical work—pushing endergonic reactions
– Transport work—pumping substances across membranes against the direction of spontaneous movement
–Mechanical work—such as beating cilia or contracting muscle cells

196
Q

Reactions in a closed system, such as an isolated hydroelectric system, eventually …

A

reach equilibrium and can then do no work

197
Q

energy coupling

A

Cells manage energy resources to do work through energy coupling, the use of an exergonic process to drive an endergonic one

198
Q

ATP (adenosine triphosphate)

A

is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
- functions as one of the nucleoside triphosphates used to make RNA

199
Q

Energy is released from ATP when the

A

terminal phosphate bond is broken by hydrolysis, the addition of a water molecule

200
Q

How ATP Provides Energy That Performs Work

A

Cellular work (mechanical, transport, and chemical) is powered by ATP hydrolysis
•In the cell, energy from the exergonic hydrolysis of ATP is used to drive endergonic reactions
•Overall, the coupled reactions are exergonic

201
Q

Phosphorylation

A

transfer of a phosphate group from ATP to another molecule, is typically used to power endergonic reactions

202
Q

phosphorylated intermediate

A

The recipient molecule, a phosphorylated intermediate, is more reactive (less stable, with more free energy) that the original molecule

203
Q

ATP hydrolysis

A
  • water is used to split apart adenosine triphosphate (ATP) to create adenosine diphosphate (ADP) to get energy
    Hydrolyze - break things down in the presence of a water molecule
  • Transport and mechanical work in the cell are also nearly always powered by ATP hydrolysis
  • causes a change in protein shape and binding ability
204
Q

The Regeneration of ATP

A

ATP is regenerated by addition of a phosphate group to adenosine diphosphate(ADP)

205
Q

Enzymes speed up metabolic reactions by ___

A

lowering energy barriers

* Spontaneous reactions do not need added energy, but they can be slow enough to be imperceptible

206
Q

catalyst

A

a chemical agent that speeds up a reaction without being consumed by the reaction

207
Q

enzyme

A

a macromolecule (typically protein) that acts as a catalyst to speed up a specific reaction

208
Q

___ provides a barrier that determines the rate of spontaneous reactions

A

provides a barrier that determines the rate of spontaneous reactions

209
Q

The initial energy needed to break the bonds of the reactants is called the

A

Activation energy

210
Q

catalysis

A

the process by which a catalyst selectively speeds up a reaction without itself being consumed

211
Q

The reactant that an enzyme acts on is called the enzyme’s

A

substrate

212
Q

The enzyme binds to its substrate, forming an

A

enzyme-substrate complex

213
Q

Most enzyme names end in

A
  • ase

- For example, the enzyme sucrase catalyzes the hydrolysis of sucrose into glucose and fructose

214
Q

active site

A

the region on the enzyme, often a pocket or groove, that binds to the substrate

215
Q

induced fit

A

results from interactions between chemical groups on the substrate and the active site
- It brings the chemical groups of the active site into positions that enhance catalysis of the reaction

216
Q

Catalysis in the Enzyme’s Active Site

A
  • The substrate is typically held in the enzyme’s active site by weak bonds, such as hydrogen bonds
  • The conversion of substrate to product happens rapidly, and product is released from the active site
217
Q

Enzymes use a variety of mechanisms to lower EA (activation energy)

A

–Substrates may be oriented to facilitate the reaction–Substrates may be stretched to make the bonds easier to break
–The active site may provide a microenvironment that favors the reaction
–Amino acids in the active site may participate in the reaction

218
Q

Effects of Local Conditions on Enzyme Activity

A
  • Enzyme activity can be affected by general environmental factors, such as temperature and pH
  • It can also be affected by chemicals that specifically influence the enzyme
219
Q

Effects of Temperature and pH

A
  • Each enzyme has an optimal temperature at which it catalyzes its reaction at the maximum possible rate
  • Up to this point, the reaction rate increases with increasing temperature; beyond this point the rate of reaction begins to drop
220
Q

Spontaneous reactions do not need __ ___, bu they can be slow enough to be ___

A

added energy, impossible to perceive.

221
Q

Enzymes begin to denature at temperatures beyond their optimum

A

The optimal temperature of an enzyme is dependent on the environment in which it typically functions

222
Q

Cofactors

A

nonprotein helpers that bind to the enzyme permanently, or reversibly with the substrate

223
Q

Organic cofactors are called

A

coenzymes

224
Q

Enzyme Inhibitors

A
  • Certain chemicals selectively inhibit the action of specific enzymes
  • if an inhibitor forms covalent bonds with the enzyme, then the inhibition is usually irreversible
  • Many inhibitors bind to the enzyme by weak interactions, resulting in reversible inhibition
225
Q

Competitive inhibitors

A
  • closely resemble the substrate (the surface or material on or from), and can bind to the enzyme’s active site
  • Enzyme productivity is reduced because the inhibitor blocks the substrate from entering the active site
226
Q

Noncompetitive inhibitors

A
  • Bind to another part of the enzyme, away from the active site
  • Binding of the inhibitor causes the enzyme to change shape, making the active site less effective at catalyzing the reaction
227
Q

__ and ___ are often irreversible enzyme inhibitors

A

toxins and poisons

228
Q

Evolution of Enzymes

A
  • Enzymes are proteins encoded by genes
  • Changes in genes (mutations) lead to changes in the amino acid composition of the enzyme
  • Altered amino acids, particularly at the active site, can result in novel enzyme activity or altered substrate specificity
229
Q

If a mutation results in a new enzyme function that is beneficial to the organism, natural selection will favor the

A

mutated allele

230
Q

Regulation of enzyme activity helps control metabolism

A

Cells can regulate metabolic pathways by switching on or off the genes that encode specific enzymes, or by regulating the activity of existing enzymes

231
Q

Allosteric regulation

A

occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site

232
Q

feedback inhibition

A
  • the end product of a metabolic pathway shuts down the pathway
  • Feedback inhibition prevents a cell from wasting chemical resources by synthesizing more product than is needed
233
Q

How is the chemical energy stored in food used to generate ATP?

A
  • Plant and animal cells break down organic molecules by cellular respiration in the mitochondria
  • The chemical energy in food is transformed into chemical energy in ATP
  • Some energy is released to the environment as heat
234
Q

Energy enters ecosystems as __ and exits as ___

A

light, heat

235
Q

The chemical elements essential to life are recycled

A

–Photosynthesis uses CO2and H2O to make organic molecules and O2
–Cellular respiration uses O2and organic molecules to make ATP; CO2and H2O are produced as waste

236
Q

The breakdown of organic molecules is

A

exergonic

237
Q

Fermentation

A

a partial degradation of sugars that occurs without oxygen

238
Q

Aerobic respiration

A

consumes organic molecules and oxygen and yields ATP

239
Q

Anaerobic respiration

A

similar to aerobic respiration but consumes compounds other than oxygen

240
Q

Cellular respiration

A

a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from oxygen molecules or nutrients into adenosine triphosphate, and then release waste products.
(includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration)

241
Q

Catabolic pathways release stored energy by breaking down

A

complex molecules

242
Q

Catabolic pathways do not directly power work in the cell;

A

they are linked to work by ATP

243
Q

True/False

Cells must constantly regenerate their supply of ATP from ADP and phosphate

A

True

244
Q

Chemical reactions that transfer electrons between reactants are called

A

oxidation-reduction reactions, or redox reactions

245
Q

In redox reactions, the loss of electrons from a substance is called

A

oxidation

246
Q

The addition of electrons to a substance is called

A

reduction

the amount of positive charge is reduced

247
Q

The electron donor is called the ___ __, it reduces the electron acceptor

A

reducing agent

248
Q

The electron acceptor is called the __ ___, it oxidizes the electron donor

A

oxidizing agent

249
Q

Instead of fully transferring electrons, some redox reactions change electron sharing in ___ ___

A

covalent bonds

250
Q

The partial “gain” of electrons by O atoms and the partial “loss” of electrons by their bonding partners constitutes a redox reaction
Ex:

A

For example, electrons are not completely transferred in the redox reaction between methane and O2

251
Q

An electron loses potential energy when it shifts from a ___ electronegative atom toward a ___ electronegative one

A

less, more

252
Q

Redox reactions that move electrons closer to electronegative O atoms __ energy

A

release

253
Q

Cellular respiration is a redox process because:

A

energy is released as hydrogen and electrons are transferred to O atoms

254
Q

The oxidation of glucose transfers electrons from a __ energy state (in glucose) to a __ energy state with O atoms

A

higher, lower

255
Q

electron transport chain

A

consists of a series of molecules built into the inner membrane of the mitochondria (or plasma membrane of prokaryotes)

256
Q

First Stage Cellular Respiration

A

Glycolysis breaks down glucose into two molecules of pyruvate
in mitochondria

257
Q

Second Stage Cellular Respiration

A

Pyruvate oxidation and the citric acid cycle complete the breakdown of glucose to CO2

258
Q

Third Stage Cellular Respiration

A

During oxidative phosphorylation the electron transfer chain and chemiosmosis facilitate synthesis of most of the cell’s ATP

259
Q

The process that generates almost 90% of the ATP is called ___ because ___

A
  • oxidative phosphorylation

- it is powered by redox reactions

260
Q

Some ATP is also formed in glycolysis and the citric acid cycle by

A

substrate-level phosphorylation

261
Q

Substrate-level phosphorylation occurs when:

A

an enzyme transfers a phosphate group directly from a substrate to ADP

262
Q

money as an analogy for cellular respiration:

A

–Glucose is like a larger-denomination bill—it is worth a lot, but it is hard to spend
–ATP is like a number of smaller-denomination bills of equivalent value—they can be spent more easily
–Cellular respiration cashes in a large denomination of energy (glucose) for the small change of many molecules of ATP

263
Q

For each molecule of glucose degraded to CO2 and H2O by cellular respiration, up to ___ molecules of ATP are produced

A

32

264
Q

Glycolysis occurs in the cytoplasm and has two major phases:

A
  • energy investment phase

- energy payoff phase

265
Q

energy investment phase

A

2 ATP are used to split glucose into 2 three-carbon sugar molecules

266
Q

energy payoff phase

A

4 ATP are synthesized, 2 NAD+are reduced to NADH, the small sugars are oxidized to form 2 pyruvate and 2 H2O

267
Q

Glycolysis does not release any __, and occurs whether or not __ is present

A

CO2, O2

268
Q

Pyruvate is converted to ____before entering the citric acid cycle

A

acetyl coenzyme A (acetyl CoA)

269
Q

Pyruvate dehydrogenase catalyzes three reactions:

A
  1. Oxidation of pyruvate’s carboxyl group, releasing the first CO2of cellular respiration
  2. Reduction of NAD+to NADH
  3. Combination of the remaining two-carbon fragment with coenzyme A to form acetyl CoA
270
Q

The citric acid cycle

Krebs Cycle

A
  • oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn
  • Another 2 CO2 are produced as a waste product
  • Because 2 pyruvate are produced per glucose, the cycle runs twice per glucose molecule consumed
271
Q

Citric Acid Cycle steps

A
  • First the acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate
  • The next seven steps decompose the citrate back to oxaloacetate, making the process a cycle
  • The NADH and FADH2 produced by the cycle carry electrons to the electron transport chain
272
Q

Stepwise Energy Harvest via NAD+

A
  • Electrons from organic molecules are transfered to NAD+
  • NAD+ functions as a reducing agent in cellular respiration
  • Each NADH (reduced NAD+) is used to synthesize ATP
273
Q

The Pathway of Electron Transport

A

-Most of the components are proteins which exist

in multiprotein complexes

  • Carriers alternate reduced and oxidized states
  • Electrons drop in free energy as they transfer
  • Finally pass to O2 and form H2O
274
Q

cytochromes

A

(proteins with hemegroups containing an iron atom)

275
Q

Reducing/Oxidizing Agent

A

The compound that loses and electron is call the reducing agent
The compound that gains an electron is the oxidizing agent

276
Q

Location of the Stages of Cellular Respiration

A

Glycolysis - Cytosol of the cell

Citric Acid Cycle - Mitochondrial Matrix

Oxidative Phosphorilation - Mitochondrial Matrix

Electron Transport Chain - Intermembrane space (in mitochondria)

277
Q

What is the Electron Transport Chain doing?

A
  • It is not synthesizing ATP during the chain
  • Each step causes proteins to pump H+into the

intermembrane space

-H+ then flows back out of the membrane through

ATP synthase channels

-ATP synthase uses the exergonic flow of

H+ to drive the phosphorylation of ATP

278
Q

Energy flow seqeunce in cellular respiration

A

glucose → NADH → electron transport chain

→ proton-moative force → ATP

279
Q

chemiosmosis

A

the use of energy in a H+gradient to drive cellular work

280
Q

H+then moves down its concentration gradient back across the membrane, passing through the protein complex ___ ___

A

ATP synthase

281
Q

The H+gradient is referred to as a ___-____ ___, emphasizing its capacity to do work

A

proton-motive force,

282
Q

About __% of the energy in a glucose molecule is transferred to ATP, making about ___ ATP

A

34, 32

283
Q

There are three reasons why the exact number of ATP produced is not known

A
  1. Photophosphorylation and the redox reactions are not directly coupled; the ratio of NADH to ATP molecules is not a whole number
  2. ATP yield varies depending on whether electrons are passed to NAD+or FAD
  3. The proton-motive force is also used to drive other kinds of work
284
Q

Fermentation and anaerobic respiration enable cells to produce ATP without the use of ____

A

oxygen

285
Q

Anaerobic respiration uses an electron transport chain with a final electron acceptor other than ___

A

oxygen

286
Q

Fermentation

A

an extension of glycolysis that oxidizes NADH by transferring electrons to pyruvate or its derivatives

287
Q

alcohol fermentation

A

pyruvate is converted to ethanol in two steps
–The first step releases CO2from pyruvate
–The second step produces NAD+and ethanol
•Alcohol fermentation by yeast is used in brewing, winemaking, and baking

288
Q

lactic acid fermentation

A

pyruvate is reduced directly by NADH to form lactate and NAD+
•There is no release of CO2 in lactic acid fermentation
•Lactic acid fermentation by fungi and bacteria is used to make cheese and yogurt

289
Q

What is responsible for chocolate production?

A

A complex series of fermentation and aerobic respiration carried out by yeasts and bacteria on cacao beans

290
Q

Fermentation and anaerobic and aerobic respiration have some similarities:

A

–All use glycolysis (net ATP = 2) to oxidize glucose and harvest the chemical energy of food
–In all three, NAD+is the oxidizing agent that accepts electrons during glycolysis

291
Q

One major difference is the mechanisms used to oxidize NADH to NAD+:

A

–In fermentation, an organic molecule (pyruvate or acetaldehyde) acts as a final electron acceptor
–In cellular respiration, electrons are transferred to the electron transport chain
- Another difference is the amount of ATP produced per glucose molecule

292
Q

Obligate anaerobes

A

carry out fermentation or anaerobic respiration and cannot survive in the presence of O2

293
Q

Yeast and many bacteria are ___ ____ meaning that they can survive using either fermentation or cellular respiration

A

facultative anaerobes

294
Q

Evolutionary Significance of Glycolysis

A
  • Early prokaryotes likely used glycolysis to produce ATP before oxygen accumulated in the atmosphere
  • Used in both cellular respiration and fermentation, it is the most widespread metabolic pathway on Earth
  • Glycolysis is a metabolic heirloom from early cells that continues to function in fermentation and cellular respiration
295
Q

__ and the ___connect to many other metabolic pathways

A

Glycolysis and the citric acid cycle

296
Q

Glycolysis can use many ___

A

carbohydrates

297
Q

Proteins used for fuel must be digested to amino acids and their amino groups must be removed in a process called

A

deamination

298
Q

Nitrogenous waste is excreted as

A

ammonia (NH3), urea, or other products

299
Q

Fats are digested to ___ and ____

A

glycerol (used to produce compounds needed for glycolysis) and fatty acids

300
Q

Fatty acids are broken down by ___ ___and yield acetyl CoA, NADH, and FADH2

A

beta oxidation

301
Q

Biosynthesis (Anabolic Pathways)

A
  • Organisms use small molecules from food to build macromolecules, such as proteins from amino acids
  • These small molecules may come directly from food, from glycolysis, or from the citric acid cycle
302
Q

Why is feedback inhibition the most common mechanism for metabolic control?

A

because it prevents wasteful production

303
Q

If ATP concentration drops, respiration __; if there is plenty of ATP, respiration ___

A

speeds up, speeds up

304
Q

Regulation of Cellular Respiration via Feedback Mechanisms

Catabolism is controlled by ___

A

regulating the activity of enzymes at strategic points in the pathway

biology (6 decks)

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