CH2. Chemical bonds and Molecular Bonds In Biology Flashcards

Question

What do amino acids do in proteins?

Answer 1

Amino acids and bonds define the shape and function of the proteins

Answer 2

The shape of the coronavirus allows it to affect us; it makes contact w/ the transmembrane ACE-2 receptor * There are no proteins in the skin that recognize the COVID-19 spike protein. The ACE-2 receptor accumulates in the respiratory system

Answer 3

Thee shape of a protein defines the interacton(s) it will be able to make with other molecules

Answer 4

There are many proteins that are able to facilitate a neuron’s job.

Answer 5

Proteins are made when **covalent bonds** are formed btwn the **COOH group** of the preceding amino acid and a **NH2 group** (**called peptide bonds**) of the following one along the chain. (during the process, one molecule of water is released) All proteins have the same direction…H2N…COOH **(They all have an unbound H2N and, eventually, end at COOH)** * We have as many peptide bonds as are we have amino acids

Answer 6

1. amino group [H2N] 2. carbonyl group [COOH] 3. side chain [R]

Answer 7

(a) Non-covalent chemical bonds within the protein itself also determine the shape of a protein (b) The type of protein folding (e.g. alpha helix, beta sheet) (c) The chemistry of the side chain determines the protein

Answer 8

* hydrophobic interaction happen b/c of hydrophobic side-chains * these usually form the core of a protein (this is like drops of olive oil wanting to group together in water)

Answer 9

Electrons depicted as a continuous cloud b/c there's no way of predicting where they would be in a particular instant The shading of the cloud depicts the probability that electrons will be found there

Answer 10

The density of shading of the cloud is an indication of the probability that electrons will be found there. The diameter of the electron cloud ranges from about 0.1 nm (for hydrogen) to about 0.4 nm (for atoms of high atomic number). The nucleus is very much smaller: about 5 x 1CT 6 nm for carbon, for example.

Answer 11

The concentric black circles represent in a highly schematic form the "orbits" (that is, the different distributions) of the electrons.

Answer 12

The smallest particle of an element that still retains its distinctive chemical properties is an atom. The characteristics of substances other than pure elements—including the materials from which living cells are made—depend on which atoms they contain and the way these atoms are linked together in groups to form molecules.

Answer 13

atomic number The electric charge carried by each proton is exactly equal and opposite to the charge carried by a single electron. Because the whole atom is electrically neutral, the number of negatively charged electrons surrounding the nucleus is equal to the number of positively charged protons that the nucleus contains; thus the number of electrons in an atom also equals the atomic number.

Answer 14

Neutrons have essentially the same mass as protons. They contribute to the structural stability of the nucleus—if there are too many or too few, the nucleus may disintegrate by radioactive decay—but **they do not alter the chemical properties of the atom**. Thus an element can exist in several **physically distinguishable but chemically identical forms, called isotopes**, each having a different number of neutrons but the same number of protons. Multiple isotopes of almost all the elements **occur naturally**,

Answer 15

Carbon 14 undergoes radioactive decay at a slow but steady rate, which allows archaeologists to estimate the age of organic material.

Answer 16

The atomic weight of an atom, or the molecular weight of a molecule, is its mass relative to that of a hydrogen atom.

Answer 17

*Daltons* 1 Dalton = 1 amu = approximate mass of one H atom

Answer 18

1/6x10^23 grams

Answer 19

6x10^23 molecules This if called Avogadro's number

Answer 20

A mole is X grams of a substance, where X is the molecular weight of the substance. A mole will contain 6 x 10 23 molecules of the substance. The concept of mole is used widely in chemistry as a way to represent the number of molecules that are available to participate in chemical reactions. 1 mole of carbon weighs 12 g 1 mole of glucose weighs 180 g 1 mole of sodium chloride weighs 58 g A one molar solution has a concentration of 1 mole of the substance in 1 liter of solution. A 1 M solution of glucose, for example, contains 180 g/l, and a one millimolar (1 mM) solution contains 180 mg/I. The standard abbreviation for gram is g; the abbreviation for liter is L.

Answer 21

The arrangement of electrons in an atom is most stable when all the electrons are in the most tightly bound states that are possible for them— that is, when they occupy the innermost shells, closest to the nucleus.

Answer 22

True: An element's chemical reactivity depends on how its outermost electron shell is filled. All of the elements commonly found in living organisms have outermost shells that are not completely filled with electrons and can thus participate in chemical reactions with other atoms.

Answer 23

Because the state of the outer electron shell determines the chemical properties of an element, when the elements are listed in order of their atomic number we see a periodic recurrence of elements with similar properties: an element with, say, an incomplete second shell containing one electron will behave in much the same way as an element that has filled its second shell and has an incomplete third shell containing one electron.

Answer 24

A molecule is a cluster of atoms held together by covalent bonds, in which electrons are shared rather than transferred between atoms. The shared electrons complete the outer shells of the interacting atoms.

Answer 25

Covalent bonds in which the **electrons are shared unequally** in this way are known as polar covalent bonds.

Answer 26

**When water is present, covalent bonds are much stronger than ionic bonds.** In ionic bonds, electrons are transferred rather than shared, as we now discuss

Answer 27

Ionic bonds are usually formed between atoms that can attain a completely filled outer shell most easily by donating electrons to—or accepting electrons from—another atom, rather than by sharing them. For example, we see that a sodium (Na) atom can achieve a filled outer shell by giving up the single electron in its third shell. By contrast, a chlorine (Cl) atom can complete its outer shell by gaining just one electron. Consequently, if a Na atom encounters a Cl atom, an electron can jump from the Na to the Cl, leaving both atoms with filled outer shells. The offspring of this marriage between sodium, a soft and intensely reactive metal, and chlorine, a toxic green gas, is table salt (NaCl).

Answer 28

These are ions held together by ionic bonds

Answer 29

The statement is correct. The hydrogen – oxygen bond in water molecules is polar, so that the oxygen atom carries a more negative charge than the hydrogen atoms. These partial negative charges are attracted to the positively charged sodium ions but are repelled from the negatively charged chloride ions.

Answer 30

noncovalent bonds

Answer 31

**Attraction caused by a complementary set of charges** The ionic bonds that hold together the Na + and Cl - ions in a salt crystal are a form of noncovalent bond called an electrostatic attraction. **Electrostatic attractions are strongest when the atoms involved are fully charged**, as are Na + and Cl - . But a weaker electrostatic attraction also occurs between molecules that contain polar covalent bonds

Answer 32

**noncovalent, electrostatic interactions** A large molecule, such as a protein, can bind to another protein through complementary charges on the surface of each molecule. In the aqueous environment of a cell, the many individual electrostatic attractions shown would help the two proteins stay bound to each other.

Answer 33

It is because of these **interlocking hydrogen bonds** that water at room temperature is a liquid—with a high boiling point and high surface tension—and not a gas. Without hydrogen bonds, life as we know it could not exist.

Answer 34

In general, a hydrogen bond can form whenever a **positively charged H** atom held in one molecule by a polar covalent linkage **comes close to a negatively charged atom— typically an oxygen or a nitrogen—**belonging to another molecule

Answer 35

A large proportion of the **molecules in the aqueous environment of a cell** fall into this category, including **sugars, DNA, RNA**, and a majority of **proteins**.

Answer 36

Hydrophobic ("water-fearing") molecules are: (1) **uncharged** and (2) **form few or no hydrogen bonds**, and they (3) **do not dissolve in water**.

Answer 37

Because lipids do not dissolve in water, they can form the thin membrane barriers that keep the aqueous interior of the cell separate from the surrounding aqueous environment

Answer 38

False: **Protons move continuously from one water molecule to another in aqueous solutions.** (A) The reaction that takes place when a molecule of acetic acid dissolves in water. At pH 7, nearly all of the acetic acid molecules are present as acetate ions. (B) Water molecules are continually exchanging protons with each other to form hydronium and hydroxyl ions. **These ions in turn _rapidly recombine to form water molecules_.**

Answer 39

A. Yes. Hydronium (H3O+) ions are formed when water dissociates into protons and hydroxyl ions, with each proton forming a hydronium ion by attaching to a water molecule (2H2O—\> H20 + H+ + OH- --\> H3O+ + OH-). At neutral pH, the amounts of H3O+ ions and OH- ions are equal in the absence of an acid that provides more H3O+ ions or a base that provides more OH- ions. We know that the pH at neutrality is 7.0, hence the H+ concentration is 10-7 M. The concentration of H+ is equivalent to the concentration of H3O+. B. We need to know the concentration of water molecules in order to compute the ratio of H3O+ ions to H2O molecules. Water has a molecular weight of 18 (i.e., 18 g/mole), and 1 liter weighs 1 kilogram. The concentration of water is thus 55.6 M (=1000(g/l)/(18 g/mole)), and the ratio of H3O+ ions to H2O molecules is 1.8x10^-9 (=10^-7/55.6): at neutral pH, for example, just two water molecules in a billion are dissociated.

Answer 40

True. The small and large carbon compounds made by cells are called organic molecules. By contrast, all other molecules, including water, are said to be inorganic.

Answer 41

**Sugars, fatty acids, amino acids, and nucleotides** are the four main families of small organic molecules in cells. They form the monomeric building blocks, or subunits, for larger organic molecules, including most of the macromolecules and other molecular assemblies of the cell. Some, like the sugars and the fatty acids, are also energy sources.

Answer 42

(1) They are usually found free in solution in the **cytosol** and have many different roles. Many have more than one role in the cell—acting, for example, as both a **potential subunit for a macromolecule** and as an **energy source**. The small organic molecules are much less abundant than the organic macromolecules

Answer 43

C = black H = white O = red N = blue

Answer 44

**(doesn't have a specific name)** A structural formula in which the atoms are shown as chemical symbols, linked together by solid lines representing the covalent bonds. The thickened lines are used to indicate the plane of the sugar ring and to show that the -H and -OH groups are not in the same plane as the ring.

Answer 45

Another kind of structural formula that shows the three- dimensional structure of glucose in the so-called **"chair configuration."**

Answer 46

A **ball-and-stick model** in which the three-dimensional arrangement of the atoms in space is indicated.

Answer 47

A **space-filling model**, which, as well as depicting the three-dimensional arrangement of the atoms, also gives some idea of their relative sizes and of the surface contours of the molecule

Answer 48

* sugars; carbohydrates * general formula **(CH₂0)_n**_{(n is usually 3, 4, 5, or 6)} * **No, there can be isomers**; glucose can be converted into mannose or galactose) * **Yes, there can be optical isomers**; Each of these sugars, moreover, can exist in either of two forms, called the **D-form** (rotates plane-polarized light to the right) and the **L-form** (rotates plane-polarized light to the left), which are mirror images of each other

Answer 49

**mirror images of isomers; enantiomers** * different molecules “handedness” * same formula * non-superimposable mirror images * the L-isomer if preferred in the body b/c there is an overabundance of L-receptors

Answer 50

* covalent bonds; glycosidic bonds * The way sugars are linked together illustrates some common features of biochemical bond formation. A bond is formed between an -OH group on one sugar and an -OH group on another by a condensation reaction, in which a molecule of water is expelled as the bond is formed. * The bonds created by all of these condensation reactions can be broken by the reverse process of hydrolysis, in which a molecule of water is consumed

Answer 51

**sucrose** (glucose + fructose)

Answer 52

In most cases, the prefix oligo- is used to refer to **molecules made of a small number of monomers**, **typically 2 to 10** in the case of oligosaccharides.

Answer 53

* Because **each monosaccharide has several free hydroxyl groups that can form a link to another monosaccharide** **(or to some other compound)**, sugar polymers can be branched, and the number of possible polysaccharide structures is extremely large. * In **nucleotides** and **peptides** **each unit is joined to the next in exactly the same way**.

Answer 54

* **F: energy source** (when broken down) * **It is broken down** to smaller molecules in a series of reactions, **releasing energy that the cell can harness** to do useful work

Answer 55

**F:** Cells use simple polysaccharides composed only of *glucose* *units*—principally ***glycogen*** in _animals_ and ***starch*** in _plants_—as **long-term stores of** glucose, held in reserve for **energy** production. F: **mechanical support**; the most abundant organic molecule on Earth—the **cellulose** that forms plant cell walls—is a polysaccharide of glucose.

Answer 56

The most abundant organic molecule on Earth—the **cellulose** that forms plant cell walls—is a polysaccharide of glucose.

Answer 57

* F: extraordinarily abundant organic substance, the *chitin* of **insect exoskeletons** and **fungal cell walls**, is also a polysaccharide * in this case, a linear polymer of a sugar derivative called **N-acetylglucosamine**

Answer 58

Other polysaccharides, which **tend to be slippery when wet**, are the main components of slime, mucus, and gristle.

Answer 59

Smaller oligosaccharides **can be covalently linked** to proteins **to form glycoproteins**, or to lipids to **form glycolipids** * Found in cell membranes * F: **protection & help w/ bonding**; differences in the types of cell-surface sugars **form the molecular basis for different human blood groups;** the sugar side chains attached to glycoproteins and glycolipids in the plasma membrane are thought to help protect the cell surface and often help cells adhere to one another.

Answer 60

* found in components of cell membranes; stored in the cytoplasm of many cells * EX) *palmitic acid* (ph=7 in water) * has two chemically distinct regions: ***(1)*** one is a **long hydrocarbon chain, which is hydrophobic** and not very **reactive chemically**. ***(2)*** The other is a **carboxyl (-COOH) group**, which **behaves as an acid** (carboxylic acid) (it is ionized (-COCT), **extremely hydrophilic in an aqueous solution**, and **chemically reactive**.

Answer 61

* **energy is stored** in the long-hydrocarbon tail…EX) gas fire, wax candles, olive oil, butter * **provides fluidity for the cell;** makes up the phospholipid by-layer *(cholesterol)* * **serve as a concentrated food reserve in cells:** they can be broken down to produce about six times as much usable energy, weight for weight, as glucose (Fatty acids are stored in the cytoplasm of many cells in the form of fat droplets composed of **triacylglycerol** molecules). * **triglycerol** (molecules made of three fatty acid chains joined to a glycerol molecule)

Answer 62

**saturated** = no double bonds; solid @ room temp; saturated fats are found in meat and dairy products **unsaturated** = double bonds; bent tails; plant oils, such as corn oil, contain unsaturated fatty acids, which may be monounsaturated (containing one double bond) or polyunsaturated (containing multiple double bonds); this is why plant oils are liquid at room temperature; The **double bonds create kinks in the hydrocarbon tails, interfering with their ability to pack together**,

Answer 63

* 2 hydrophobic fatty acid tails; 1 hydrophilic head that contains a phosphate group (**negatively charged**) With their two hydrophobic fatty acid tails and a hydrophilic, phosphate-containing head, phospholipids are strongly amphipathic. This characteristic amphipathic composition and shape gives them different physical and chemical properties from triacylglycerols, which are predominantly hydrophobic.

Answer 64

the length and saturation of the fatty acid chains they carry

Answer 65

Misfolding = something that happens in proteins that causes diseases

Answer 66

* The **amino** and **carboxyl groups** are responsible for the H-bonds in the peptide. * H-bonds are formed btwn the **O** of the _carboxyl group_ and the **H** of the _amino group_ in peptides The H-bonds happen every 4 amino acids

Answer 67

Side chains determine the nature of each amino acid. The side chains come together to help the **initial steps** of the folding process; THEY DO NOT DETERMINE THE FINAL STRUCTURE

Answer 68

The H-bonds happen every 4 amino acids

Answer 69

\*\*\*see image

Answer 70

**_Levinthal Paradox_ =** the process of protein folding is based on energy; when a protein is folded, the possible # of interactions that can be made is limited; **A process that leads to defined protein structures/shapes,** ***limiting the number of possible interactions*** **among chemical groups in one protein.** * Considering a protein synthesized in the aqueous environment of the cell, and considering the possible interactions that can occur among groups in a protein (H bonds, electrostatic and hydrophobic interaction) leading to a final structure: * It is not possible for this protein to reach the final shape (conformation) by random searches within a feasible amount of time. The number of possibilities would be too high, and the time taken would be… millions of years!!

Answer 71

The higher number of chances to be folded into something is when we haven’t started folding anything As the paper is folded, the number of *possibilities* to fold it in different ways *are reduced***…In protein folding, it is the number of folding possibility.** * The **higher the number of folding possibility,** the **less stable** the protein will be; The amount of **free energy is highest** when the **protein is unfolded** and will decrease when it folds * **In nature**, proteins will fold so that they can reach *their own* **lowest level of free energy** to remain stable ("stable" doesn't mean it can't be modified). * (the image is called the “folding funnel”)

Answer 72

**Native shape** = the _final shape_ that is taken by the protein at the _end of the process of folding_ (it _might change_ a little to interact w/ something)

Answer 73

Molecules—such as fatty acids—that **possess both hydrophobic and hydrophilic regions** are termed amphipathic.

Answer 74

The hydrocarbon tail of **palmitic acid** is saturated: it has no double bonds between its carbon atoms and contains the maximum possible number of hydrogens. Some other fatty acids, such as **oleic acid**, have unsaturated tails, with one or more double bonds along their length.

Answer 75

it is the absence or presence of these double bonds that accounts for the difference between hard (saturated) and soft (polyunsaturated) margarine. Fatty acid tails are also found in cell membranes, where the tightness of their packing affects the fluidity of the membrane. The many different fatty acids found in cells differ only in the length of their hydrocarbon chains and in the number and position of the carbon-carbon double bonds

Answer 76

**Lipids** = loosely defined as molecules that are _insoluble in water but soluble in fat and organic solvents_ such as benzene (they typically contain long hydrocarbon chains, as in the fatty acids, or multiple linked aromatic rings, as in the steroids). * Fatty acids and their derivatives, including triacylglycerols, are examples of lipids. * form the lipid-bilayer

Answer 77

the basis for all cell membranes

Answer 78

**All amino acids have an amino group, a carboxyl group, and a side chain (R) attached to their a-carbon atom. In the cell, where the pH is close to 7, free amino acids exist in their ionized form; but, when they are incorporated into a polypeptide chain, the charges on their amino and carboxyl groups disappear.** The amino acid shown is alanine, one of the simplest amino acids, which has a methyl group (CH 3 ) as its side chain.

Answer 79

The four amino acids shown are linked together by three peptide bonds, one of which is highlighted in yellow. One of the amino acids, glutamic acid, is shaded in gray. The amino acid side chains are shown in red. The two ends of a polypeptide chain are chemically distinct. One end, the N-terminus, is capped by an amino group, and the other, the C-terminus, ends in a carboxyl group. The sequence of amino acids in a protein is abbreviated using either a three-letter or a one-letter code, and the sequence is always read from the N-terminus

Answer 80

This difference in the two ends gives a polypeptide a definite directionality—a structural (as opposed to electrical) polarity. * Regardless of the specific amino acids from which it is made, the polypeptide always has an amino (NH 2 ) group at one end—its N-terminus—and a carboxyl (COOH) group at its other end—its C-terminus (Figure 2-23).

Answer 81

* DNA and RNA are built from subunits called nucleotides. * Nucleosides are made of a nitrogen-containing ring compound linked to a five-carbon sugar, which can be either ribose or deoxyribose

Answer 82

* nucleotide; the **ribonucleotide adenosine triphosphate**, or ATP * (each ) The _nitrogen-containing rings_ of all these molecules are generally referred to as **bases** for historical reasons: under acidic conditions, they can each bind an H + (proton) and thereby increase the concentration of OH - ions in aqueous solution.

Answer 83

C. If we change the conformation, we change the interaction

Answer 84

there can be thermal changes or collisions in the cell

Answer 85

Folding is a continuous mechanism; if chaperones are not present, there would be loss of correct folding

Answer 86

Electrostatic interactions (weak interactions); NOT covalent

Answer 87

beta and gama secretase are responsible for releasing the B-amyloid plaque into the APP molecule

Answer 88

Each of the stretches of B-amyloid turns into a beta sheet from an alpha helix (caused by hydrophobic interactions). An aggregate refers to the beta street structure here?

Answer 89

MIsfolding happens all the side b/c they can be modified constantly by what we have in the cell (our oxygen, zinc, etc…) If the protein is not folding anymore, the folding may not be active and it may turn into something toxic

Answer 90

The intrinsic nature of the B-amyloid causes it to form H--bonds w/ one another; this gives the system rigidity, so it's hard to disassemble aggregates still have free energy, even though they are rigid

Answer 91

As an aggregate is formed, the system of the aggregate reaches a stability that makes it more difficult to change the structure again

Answer 92

oli = “few” mers = “parts” a small aggregate

Answer 93

A larger aggregate of many molecules in a beta sheet

Answer 94

(1) an alpha helix might turn into a beta sheet structure (has rigidity) (2) A change in function (makes it inactive)

Answer 95

Alpha helixs and beta sheets both are made possible by H-bonds a helix is 1 every 4th a beta sheet is many coming in parallel

Answer 96

Protofibrils

Answer 97

diseases associated to misfolding are not specific to brain diseases; they can also affect the heart and the kidneys; this can lead to loss of the organ's function

Answer 98

found in the pulmanergic nuerons; problem w/ Parkingson's disease

Answer 99

Many neurodegenerative diseases caused by alpha helixes that turn into beta sheets

Answer 100

the presence of hydrophobic amino acids can lead to these misfolded beta sheets

Answer 101

Mad cow disease

Answer 102

the addition of a phosphate group to a protein to turn its functions off

Answer 103

She had trouble pronouncing her own name and discovered how the nucleotides are organized. By using beams and an x-ray, she was able to see the diffraction patterns of the DNA on the film

Answer 104

Sugar: what distinguishes nucleic acids

Answer 105

Phosphate group: bound to the 5th carbon of the sugar; this is important b/c it determines how nucleotides come together

Answer 106

The phosphate group of the incoming nucleotide ads to the 3rd part

Answer 107

The very fist nucleotide of any DNA strand has the 5 unbound and leads to the 3 unbound (5' to 3')

Answer 108

No, H--bonds are always btwn an adenine w/ a guanine and a cytosine w/ the thymine A-T is easier to pull apart than C-G

Answer 109

46 23 chromosomes from mom; 23 from dad

Answer 110

Provides the information to generate proteins

Answer 111

Not all DNA is used to store information Some is for structuring of the DNA and some is for packaging of the DNA The two strands are not identical (different information may be stored in each strand; they can be used to store different types of genetic information)

Answer 112

phosphate de-ester bonds

Answer 113

@ position 5…phosphate group is unbound @bosition 3…sugar group is unbound

Answer 114

They are located in a cell's nucleus and they are attached to the nuclear membrane

Answer 115

For most of the life of the cell, the DNA found in the nucleus is slightly dispersed

Answer 116

Genes can be copied into mRNA molecules to generate proteins

Answer 117

The two strands are complementary, not identical; so the two strands can include different genetic information

Answer 118

The DNA wraps around itself and proteins in beads 1. It allows the long DNA molecule to fit into a small place like the nucleus 2. Organization also allows **accessibility** to DNA * This enables the correct copying of DNA * To use the genetic information stored to express proteins

Answer 119

nucleosomes (forms of proteins that are wrapped in disks) \*\*know the Hs (histomes)

Answer 120

But when we look @ thee unwrapped ones, we aree looking at individual nucleosomes. The space btwn the nucleeosomes changes

Answer 121

This sits inside the nucleosomes, making the distance btwn them shorter

Answer 122

histomes make the nucleosomes nucleosomes are made of 4 different kinds of histomes (representeed by two molecules of eact; for a total of 8 molecules)

Answer 123

A tail is a part of the protein that does not directly react w/ everything They are what allows the DNA to become accessable DNA is a negatively charged molecule b/c of the phosphate groups. Histomes are positive, so they are attracted to DNA. This is how it unwrapps the DNA to make it more or less accessible

Answer 124

a chromosome a pair is called “chromatids”

Answer 125

? chromatin

Answer 126

The filament of DNA (147 nucleotides) wraps around twice * this means that each nucleosome has a defined size (the size depends on the protein content of the nucleosome itself)

Answer 127

DNA is organized in a cell's nucleus. It is a supercoiled structure based on DNA stretches wrapped around proteins, called histones.

Answer 128

1. DNA interactions

Answer 129

The histone tails carry positively charged amino acids

Answer 130

It will be more attracted to the nucleosome and make the DNA less accessible

Answer 131

modifications on the histone tails can allow the DNA to become more condensed or more relaxed

Answer 132

Acetylation occurs on the positively charged amino acids The acetylation group covers the positive charge (like putting a HAT on the positive charge) This is like tranfering an acetyl group. Whenever we have an acetylation, we are putting a hat on something with a positive charge. This results in loosening up the DNA from the nucleosome

Answer 133

Histones DeAcetylation These remove the acetyl hat“HAT”

Answer 134

This leads to the generation of DNA that will carry the same modifications (until it hits a barrier DNA sequence)

Answer 135

**ATP chromatin** remodeling **complexes** (formed my many molecules of protein together that can bind to nucleosomes and DNA) require energy They condense and decondense

Answer 136

You will treat your cells with a drug that inhibits Histone Acetylation (an inhibitor of HAT/Histone Acetyl Transferases). Stimulate de-acetylation

Answer 137

* DNA changes in terms of structure and amount in the cell cycle. * The DNA generation carries 1 chromosome from maternal inheritance and 1 chromosome from paternal inheritance * Modifications need to be made on the DNA

Answer 138

The histones carry a positive charge Arginines and lysines Acetylation puts a HAT (histone acetyl transferase) on the positive group → uncoiling of DNA (opens structure) The protein that removes this HAT is HDACs (Histone DeAcetylase) → tight coiling of DNA

Answer 139

chromatin remodeling complexes unwrap the DNA from the chromosome to make chromatin fiber

Answer 140

There are specific areas along the sequence that have a specific function * **telomeres** = prevent damage and cutting of the chromosome (there are no genes here, so this usually remains super compacted) * **centromere** = is employed during cell division (there are no genes here, so this usually remains super compacted)

Answer 141

A and T carry 2 hydrogen bonds G and C carry 3 hydrogen bonds

Answer 142

remains super compacted Telomeres protect the ends of chromosomes from proteins (the mechanisms could randomly start breaking down the ends of the chromosomes)

Answer 143

We need to separate these two strands by breaking the hydrogen bonds between the C-G and T-A * the 1st step is denaturation

Answer 144

B/c DNA synthesis always occurs from the 5' to the 3' direction nucleotides are added to thee 3' end of the last nucleotide of the already-existing growing strand

Answer 145

Whenever we replicate DNA in the test tube, what is one way to denature the DNA? * @ 90 degrees celsius * gets rid of the hydrogen bonds * we can NEVER denature the entire chromosome

Answer 146

DNA replication occurs in interephase

Answer 147

denaturation

Answer 148

The starting strands are called templates/parental DNA A new strand will be synthesized/annealed

Answer 149

DNA is synthesized from 5' to 3'

Answer 150

**Replication origin domains are the regions that enter denaturation first.** **AT nucleotides need to be at the replication origin domains b/c they make 2 Hydrogen bonds**

Answer 151

The figure tells us that synthesis starts as soon as thee replication origin domain is opened

Answer 152

We use replication forks (one that opens on the left and one that opens on the right)

Answer 153

**The opening of the replication origins using forks**; the forks will eventually meet one another while going down the DNA

Answer 154

**Synthesis occurs ONLY in the 5’-to-3’ direction.** This means that the used TEMPLATE DNA strand will be in the 3’-to-5’ direction.

Answer 155

**This is the lagging strand that slows down the synthesis of the DNA** **The lagging strand synthesizes in pieces; the antiparallel strand becomes available to copy one piece at a time;** the first fragment available will be in the middle of the opening; all the Okazaki fragments will, eventually form the “lagging DNA strand” Synthesis follows the direction of the opening of the fork. This means that DNA is synthesized on both template strands AS the template strands separate.

Answer 156

**The Lagging strand is synthesized one little piece at the time!! Each little piece is called Okazaki Fragment. They will be later bound together.**

CH2. Chemical bonds and Molecular Bonds In Biology Flashcards

(189 cards)