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58 Cards in this Set
- Front
- Back
What are the two types of nucleic acids?
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(1) DNA: Deoxyribonucleic acid
(2) RNA: Ribonucleic Acid |
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Where is DNA found?
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Found within the cell nucleus
Uses: - Storage and transfer of genetic information - Passed from one cell to another during cell division (mitosis) |
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Where is RNA found?
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Occurs in all parts of cells
Uses: - Primary function is to synthesize proteins |
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What is chromatin?
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A complex tangle of DNA (a polymer of deoxyribonucleic acid), that carries genetic informations and is twisted around proteins (known as histones)
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During cell division, what does chromatin organise itself into?
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Chromosomes
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What are DNA molecules made up of?
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Genes
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What are genes?
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Individual segments of DNA that contain the instructions that direct the synthesis of a single polypeptide
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What is a Nucleic acid?
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A polymer of nucleotides
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What are Nucleotides?
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A five-carbon sugar bonded to a cyclic amine base and a phosphate group
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What is the sugar present in RNA?
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D-ribose
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What is the sugar present in DNA?
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2-deoxyribose
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What does the prefix "2-deoxy-" mean, present in 2-deoxyribose
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Means that an oxygen atom is missing from the C2 position of ribose
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How many heterocyclic amines are found in nucleic acids?
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5
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What amine is only present in DNA?
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Thymine
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What amine is only present in RNA?
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Uracil
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What is a nucleoside?
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A five-carbon sugar bonded to a cyclic amine base; a nucleotide with no phosphate group.
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What is used to denote the atoms in the sugar of a nucleoside and nucleotides?
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Numbers with primes
*e.g. 5' |
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How is a nucleotide named?
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Nucleotides are named by adding 5'-monophosphate at the end of the name of the nucleoside
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What are nucleotides that contain ribose classified as?
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ribonucleotides
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What are nucleotides that contain 2-deoxy-D-ribose classified as?
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deoxyribonucleotides
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What are nucleotides made up of?
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Nucleic acids
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What type of linkage connects DNA and RNA to nucleotides?
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phosphate diester linkages between the -OH group of C3' of the sugar ring of one nucleotide and the phosphate group on C5' of the next nucleotide
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Where is the free phosphate group located on a nucleotide?
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5' carbon (known as the 5' end)
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Where is a free -OH group located on a nucleotide?
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3' carbon (known as the 3' end)
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How is a nucleotide sequence read?
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Starting at the 5' end and identifying the bases in order of occurene
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In what directions do each strand of the DNA double helix run?
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Opposite directions
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What bases always make up the base pairs in the double helix?
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One pyrimidine base and one purine base
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What type of bonds connect the base pairs in DNA?
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Hydrogen bonds
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What complementary bases are always put together?
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A base opposite a T
C base opposite a G |
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The B form of DNA is the normal right handed form whereas the Z Form is the alternate left-handed form. True or False?
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True
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Where does DNA replication begin?
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Nucleus
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What enzyme catalyzes the the partial unwinding of the double helix when DNA replication begins in the nucleus?
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Helicases
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What occurs in the unravelling of the DNA?
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- Unwinding occurs simultaneously in many specific locations known as origins of replication
- The DNA strands separate, exposing the bases - These branch points, called replication forks, provide a "bubble" into which the replication process can begin |
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What are replication forks?
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Branch points in the unwinding of DNA that provide a "bubble" into which the replication process can begin
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What enzyme facilitates the copying of the single-stranded DNA?
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DNA polymerase
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What is produced during replication of DNA?
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2 identical copies of the DNA double helix; one strand is the template and the other is the newly synthesized strand
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What are Ribosomal RNAs?
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Outside the nucleus but within the cytoplasm of a cell are the ribosomes, small granular organelles where protein synthesis takes place.
Each ribosomes is a complex consisting of about 60% ribosomal RNA (rRNA) and 40% protein |
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What are transfer RNAs (tRNA)?
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Smaller RNAs that deliver amino acids one by one to protein chains growing at ribosomes; each tRNA carries only one amino acid
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What are messenger RNAs?
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Carry information transcribed from the DNA; formed within the cell nucleus and transported out to the ribosomes, where proteins will be synthesised
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Which of the two newly made DNA strands is transcribed during RNA synthesis?
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Template strand
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What molecule is complementary to the template strand during RNA synthesis (transcription)?
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mRNA; makes it an exact RNA-duplicate of the DNA informational strand
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What is a codon?
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nce of hree ribonucleotides in the messenger RNA chain that codes for a specific amino acid; also a three-nucleotide sequence that is a stop codon and stops translation
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What is an exon?
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Small sections of DNA that code for a gene
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What are introns?
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Introns are sections of DNA that do not code for any part of the protein to be synthesised
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What does heterogeneous nuclear RNA refer to?
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The initial mRNA strand that contains both exons and introns.
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Define "Genetic Code"
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The sequence of nucleotides, coded in triplets (codons) in mRNA, that determines the sequence of amino acids in protein synthesis
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What are the three 'stop' codons?
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UAG, UAA and UGA
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What is the 'initiation' codon?
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AUG (also codes for the amino acid methionine)
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What are the three stages of protein synthesis?
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(1) Initiation
(2) Elongation (3) Termination |
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What is a Point Mutation?
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A single base change
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What are the 3 types of Point mutations?
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(1) Silent
(2) Missense (3) Nonsense |
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What is a Frameshift mutation?
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The number of inserted or deleted bases is not a multiple of 3, so that all triplets following the mutation are read differently
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What are the 2 types of Frameshift mutations?
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(1) Insertion
(2) Deletion |
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What is a Silent Point mutation?
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A change that specifies the same amino acid
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What is a Missense Point mutation?
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A change that specifies a different amino acid
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What is a Nonsense Point mutation?
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A change that produces a stop codon
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What is a Insertion Frameshift mutation?
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Addition of one or more bases
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What is a Deletion Frameshift?
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Loss of one or more bases
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