Vocabulary Unit 6 1-4

Question 1

Purine

Answer 1

a base (such as adenine or guanine) that is a constituent of DNA or RNA

Question 2

Pyrimidines

Answer 2

a base (such as cytosine, thymine, or uracil) that is a constituent of DNA or RNA

Question 3

Antiparallel

Answer 3

parallel but oppositely directed or oriented

Question 4

Plasmids

Answer 4

an extrachromosomal ring of DNA especially of bacteria that replicates autonomously

Question 5

RNA

Answer 5

any of various nucleic acids that contain ribose and uracil as structural components and are associated with the control of cellular chemical activities

Question 6

DNA

Answer 6

any of various nucleic acids that are usually the molecular basis of heredity, are constructed of a double helix held together by hydrogen bonds between purine and pyrimidine bases (see BASE entry 1 sense 6b) which project inward from two chains containing alternate links of deoxyribose and phosphate, and that in eukaryotes are localized chiefly in cell nuclei

Question 7

Origins of Replication

Answer 7

An origin of replication is a sequence of DNA at which replication is initiated on a chromosome, plasmid or virus.

Question 8

Replication Fork

Answer 8

The point at which the two strands of DNA are separated to allow replication of each strand.

Question 9

Helicase

Answer 9

any of various enzymes that catalyze the unwinding and separation of double-stranded DNA or RNA during its replication

Question 10

Topoisomerase

Answer 10

any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule

Question 11

Primase

Answer 11

an enzyme that synthesizes short RNA sequences called primers, which serve as starting points for DNA synthesis.

Question 12

Primers

Answer 12

a molecule (such as a short strand of RNA or DNA) whose presence is required for formation of another molecule (such as a longer chain of DNA)

Question 13

DNAP III

Answer 13

the primary enzyme complex involved in prokaryotic DNA replication.

Question 14

DNAP I

Answer 14

a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules.

Question 15

Leading Strand

Answer 15

The leading strand is a single DNA strand that, during DNA replication, is replicated in the 3’ – 5’ direction (same direction as the replication fork).

Question 16

Lagging Strand

Answer 16

a single DNA strand that, during DNA replication, is replicated in the 5′ – 3′ direction (opposite direction to the replication fork).

Question 17

Okazaki Fragments

Answer 17

Relatively short fragment of DNA synthesized on the lagging strand during DNA replication.

Question 18

DNA Ligase

Answer 18

An enzyme that closes nicks or discontinuities in one strand of double-stranded DNA by creating an ester bond between adjacent 3’ OH and 5’ PO4

Question 19

Telomeres

Answer 19

the natural end of a eukaryotic chromosome composed of a usually repetitive DNA sequence and serving to stabilize the chromosome

Question 20

Telomerase

Answer 20

a DNA polymerase that is a ribonucleoprotein catalyzing the elongation of chromosomal telomeres in eukaryotic cell division and is particularly active in cancer cells

Question 21

Nuclease

Answer 21

any of various enzymes that promote hydrolysis of nucleic acids

Question 22

Mismatch repair

Answer 22

Describes cells that have mutations (changes) in certain genes that are involved in correcting mistakes made when DNA is copied in a cell.

Question 23

Transcription

Answer 23

the process of constructing a messenger RNA molecule using a DNA molecule as a template with resulting transfer of genetic information to the messenger RNA

Question 24

Gene Expression

Answer 24

the appearance in a phenotype of a characteristic or effect attributed to a particular gene.

Question 25

Template strand

Answer 25

The term template strand refers to the sequence of DNA that is copied during the synthesis of mRNA.

Question 26

Codon

Answer 26

a specific sequence of three consecutive nucleotides that is part of the genetic code and that specifies a particular amino acid in a protein or starts or stops protein synthesis

Question 27

rRNA

Answer 27

RIBOSOMAL RNA

Question 28

tRNA

Answer 28

TRANSFER RNA

Question 29

5’ Cap

Answer 29

In molecular biology, the five-prime cap is a specially altered nucleotide on the 5′ end of some primary transcripts such as precursor messenger RNA.

Question 30

POLY-A tail

Answer 30

The poly-A tail is a long chain of adenine nucleotides that is added to a messenger RNA (mRNA) molecule during RNA processing

Question 31

mRNA

Answer 31

Messenger RNA

Question 32

Redundency

Answer 32

two or more genes are performing the same function and that inactivation of one of these genes has little or no effect on the biological phenotype.

Question 33

Reading Frame

Answer 33

a way of dividing the sequence of nucleotides in a nucleic acid (DNA or RNA) molecule into a set of consecutive, non-overlapping triplets.

Question 34

Alternative splicing

Answer 34

a cellular process in which exons from the same gene are joined in different combinations, leading to different, but related, mRNA transcripts.

Question 35

RNA splicing

Answer 35

The process by which introns, the noncoding regions of genes, are excised out of the primary messenger RNA transcript, and the exons (i.e., coding regions) are joined together to generate mature messenger RNA.

Question 35

Translation

Answer 35

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

Question 36

Anticodon

Answer 36

a triplet of nucleotide bases in transfer RNA that identifies the amino acid carried and binds to a complementary codon in messenger RNA during protein synthesis at a ribosome

Question 37

Stop Codon

Answer 37

a genetic codon in messenger RNA that signals the termination of protein synthesis during translation