Week 3

Question 1

Central dogma

Answer 1

describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein. Transcription is the synthesis of an RNA copy of a segment of DNA. RNA is synthesized by the enzyme RNA polymerase.

Question 2

Replication

Answer 2

process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritance

Question 3

Transcription

Answer 3

first of several steps of DNA based gene expression in which a particular segment of DNA is copied into RNA by the enzyme RNA polymerase

Question 4

Translation

Answer 4

process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis

Question 5

DNA

Answer 5

a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses

Question 6

RNA

Answer 6

a nucleic acid present in all living cells. Its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins, although in some viruses RNA rather than DNA carries the genetic information

Question 7

Histones

Answer 7

family of basic proteins that associate with DNA in the nucleus and help condense it into chromatin, they are alkaline (basic pH) proteins, and their positive charges allow them to associate with DNA

Question 8

Nucleotide

Answer 8

organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers deoxyribonucleic acid and ribonucleic acid

Question 9

Nucleoside

Answer 9

a nucleobase (also termed a nitrogenous base) and a five-carbon sugar (ribose or 2’-deoxyribose) whereas a nucleotide is composed of a nucleobase, a five-carbon sugar, and one or more phosphate groups

Question 10

Covalent bond

Answer 10

a molecular bond: is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding

Question 11

Base

Answer 11

nitrogen-containing biological compounds that form nucleosides, which in turn are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids

Question 12

Thymine

Answer 12

one of the four nucleobases in the nucleic acid of DNA. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. In RNA, thymine is replaced by the nucleobase uracil

Question 13

Adenine

Answer 13

purine derivative, it is paired with thymine in double-stranded DNA

Question 14

Cytosine

Answer 14

a pyrimidine derivative, pairs with guanine

Question 15

Guanine

Answer 15

binds to cytosine through three hydrogen bonds

Question 16

Phosphate groups

Answer 16

a molecule containing one atom of phosphorus covalently bound to four oxygen residues, two of which may be expressed as a hydroxyl group. They are relatively reactive molecules that readily form phophoester bonds by the interaction with hydroxyl groups

Question 17

Pyrimidines

Answer 17

one of two classes of heterocyclic nitrogenous bases found in the nucleic acids DNA and RNA: in DNA the pyrimidines are cytosine and thymine

Question 18

Purines

Answer 18

heterocyclic aromatic organic compound that consists of two rings in their structure. It is water-soluble

Question 19

Uracil

Answer 19

common naturally occurring pyrimidine found in RNA, it base pairs with adenine and is replaced by thymine in DNA

Question 20

Hydrogen bond

Answer 20

partial intermolecular bonding interaction between a lone pair on an electron rich donor atom, particularly the second-row elements nitrogen, oxygen, or fluorine, and the antibonding molecular orbital of a bond between hydrogen and a more electronegative atom or group

Question 21

Sequence

Answer 21

the order of nucleotides in DNA or RNA

Question 22

Complementary sequence

Answer 22

Nucleic acid sequence of bases that can form a double- stranded structure by matching base pairs

Question 23

Antiparallel

Answer 23

run parallel to each other but with opposite directionality. An example is the two complementary strands of a DNA double helix, which run in opposite directions alongside each other

Question 24

Melting temperature

Answer 24

temperature at which one half of the DNA duplex will dissociate to become single stranded and indicates the duplex stability. Primers with melting temperatures in the range of 52-58°C generally produce the best results

Question 25

Denaturation

Answer 25

process in which proteins or nucleic acids lose the quaternary structure, tertiary structure, and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, an organic solvent

Question 26

Ribozymes

Answer 26

ribonucleic acid (RNA) enzyme that catalyzes a chemical reaction. The ribozyme catalyses specific reactions in a similar way to that of protein enzymes. Also called catalytic RNA, ribozymes are found in the ribosome where they join amino acids together to form protein chains

Question 27

Major groove

Answer 27

occurs where the backbones are far apart

Question 28

Minor groove

Answer 28

occurs where the backbones are close together

Question 29

A-DNA

Answer 29

one of three biologically active double helical structures along with B-DNA and Z-DNA. It is a right-handed double helix fairly similar to the more common B-DNA form, but with a shorter, more compact helical structure whose base pairs are not perpendicular to the helix-axis as in B-DNA

Question 30

B-DNA

Answer 30

most common double helical structure found in nature, the double helix is right-handed with about 10–10.5 base pairs per turn. The double helix structure of DNA contains a major groove and minor groove. In B-DNA the major groove is wider than the minor groove.

Question 31

Z-DNA

Answer 31

one of the many possible double helical structures of DNA. It is a left-handed double helical structure in which the helix winds to the left in a zigzag pattern, instead of to the right, like the more common B-DNA form

Question 32

Mirror like palindrome

Answer 32

in which a sequence reads the same forward and backwards on a single strand of DNA strand. sequence that reads the same forward and backwards, but the forward and backward sequences are found in complementary DNA strands.

Question 33

Inverted repeat

Answer 33

a single stranded sequence of nucleotides followed downstream by its reverse complement. The intervening sequence of nucleotides between the initial sequence and the reverse complement can be any length including zero

Question 34

Hairpin

Answer 34

occurs when two regions of the same strand, usually complementary in nucleotide sequence when read in opposite directions, base-pair to form a double helix that ends in an unpaired loop

Question 35

Stem-loop motif

Answer 35

intramolecular base pairing is a pattern that can occur in single-stranded DNA or, more commonly, in RNA, also called hairpin

Question 36

Gel electrophoresis

Answer 36

technique used to separate DNA fragments according to their size. DNA samples are loaded into wells (indentations) at one end of a gel, and an electric current is applied to pull them through the gel. DNA fragments are negatively charged, so they move towards the positive electrode

Question 37

Agarose

Answer 37

a three-dimensional matrix formed of helical agarose molecules in supercoiled bundles that are aggregated into three-dimensional structures with channels and pores through which biomolecules can pass

Question 38

Polyacrymide

Answer 38

used to separate shorter nucleic acids, generally in the range of 1−1000 base pairs

Question 39

Topisomerase

Answer 39

enzymes that participate in the overwinding or underwinding of DNA

Question 40

Nucleosome

Answer 40

the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundamental subunit of chromatin

Question 41

Chromatin fiber

Answer 41

a complex of DNA and protein found in eukaryotic cells. Its primary function is packaging long DNA molecules into more compact, denser structures

Question 42

Euchromatin

Answer 42

a lightly packed form of chromatin (DNA, RNA, and protein) that is enriched in genes, and is often (but not always) under active transcription. Euchromatin comprises the most active portion of the genome within the cell nucleus. 92% of the human genome is euchromatic

Question 43

Heterochromatin

Answer 43

a tightly packed form of DNA or condensed DNA, which comes in multiple varieties. These varieties lie on a continuum between the two extremes of constitutive heterochromatin and facultative heterochromatin

Question 44

Histones

Answer 44

a family of basic proteins that associate with DNA in the nucleus and help condense it into chromatin, they are alkaline (basic pH) proteins, and their positive charges allow them to associate with DNA. They are found inside the nucleus of eukaryotic cells

Question 45

Transposable elements

Answer 45

a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size

Question 46

Intergenic region

Answer 46

a stretch of DNA sequences located between genes. Intergenic regions are a subset of noncoding DNA. Occasionally some intergenic DNA acts to control genes nearby, but most of it has no currently known function

Question 47

Regulatory region

Answer 47

the region of a gene where RNA Polymerase and other accessory transcription modulator Proteins bind and interact to control RNA synthesis

Question 48

Introns

Answer 48

any nucleotide sequence within a gene that is removed by RNA splicing during maturation of the final RNA product. In other words, introns are non-coding regions of an RNA transcript, or the DNA encoding it, that are eliminated by splicing before translation

Question 49

Exons

Answer 49

any part of a gene that will encode a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term exon refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts