Review for SBI4U Strand 3 Test: Genetics
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1.The two strands of a DNA double helix are "antiparallel" to each other.
2.The building blocks of DNA are called nucleotides.
3.In the green alga, Acetabularia, the cap contains the nucleus and can regenerate the entire organism.
4.Chargaff discovered that in terms of amounts of DNA nucleotides, A=C and T=G.
5.Griffith used bacteriophages and discovered a "transforming factor".
6.Hershey and Chase used radioactive phosphorus (P-32) to label virus DNA.
7.Avery used protein-destroying enzymes (protease) to determine that protein is the genetic material.
8.Watson and Crick used R-strain and S-strain bacteria to determine that DNA is in the form of a double helix.
9.The DNA backbone consists of sugars and phosphate groups.
10.A free hydroxyl group is found on the 3' end of a DNA strand.
11.A nitrogenous base is attached to a deoxyribose sugar.
12.Carbons on deoxyribose are numbered in the counter-clockwise direction.
13.Complementary DNA strands are antiparallel with the 3' end of one strand across from the 5' end of the other strand.
14.A cytosine on one strand binds to a guanine on the complementary strand by covalent bonds.
15.If a DNA molecule contains 30% C, then it also contains 30% G.
16.Watson and Crick made extensive use of x-ray diffraction pictures by Rosalind Franklin to deduce the structure of DNA.
17.3 bases in a row in DNA is called an anticodon.
18.Each codon of mRNA codes for one amino acid.
19.Transcription occurs in the cytoplasm of cells.
20.Elongation is the 2nd stage of translation.
21.During Initiation, the 1st tRNA binds to the P-site on a ribosome.
22.Ribosomes are made of mRNA and protein.
23.Ribosome are made of 3 subunits.
24.During Elongation, amino acids are transferred from the tRNA at the A-site to the tRNA at the P-site.
25.Peptidyl transferase transfers amino acids from one tRNA to another and the amino acids are joined by an ionic bond.
26.During translation, the mRNA moves through the ribosome, 2 codons at a time.
27.ATG is a possible mRNA codon.
28.RNA is mostly in the form of a single helix and contains thymine instead of uracil.
29.Ribose sugar contains an extra oxygen unlike deoxyribose sugar.
30.DNA polymerase synthesizes new DNA strands in the 3' to 5' direction with respect to the new strand.
31.Okazaki fragments are produced during discontinuous DNA replication.
32.Gyrase enzyme joins Okazaki fragments together.
33.Helicase enzyme breaks the hydrogen bonds between complementary bases.
34.A promoter sequence in the lac operon indicates where RNA polymerase should begin DNA replication.
35.A stop codon does not code for any amino acid.
36.Ribonuclease is the enzyme that degrades mRNA after translation.
37.If a DNA triplet is ACG, the tRNA anticodon will be UGC.
38.When the repressor protein in the lac operon binds, it overlaps the structural genes.
39.In the lac operon, RNA polymerase binds to the operator.
40.The 3 enzymes required by bacteria to metabolize lactose are called B-galactosidase, acetylase, and polymerase.
41.The lac operon illustrates eukaryotic gene control.
42.Tryptophan is called an "inducer" in the trp operon because it's presence helps to turn the operon off.
43.The trp operon is turned on in the absence of tryptophan.
44.Introns in mRNA are removed by spliceosomes and exons are attached to produce mature mRNA.
45.mRNA is also modified by addition of a cap and poly-U tail.
46.mRNA may be translated by more than one ribosome creating many copies of the final protein or polypeptide.
47.The "wobble effect" occurs when tRNA's that differ only in the 3rd base can carry the same amino acid.
48.An "inversion mutation" is an example of a specific "point mutation".
49."Deletion mutations" lead to changes in the eventual "reading frame" of mRNA.
50.All gene mutations are harmful.
51.A "translocation mutation" occurs when a gene sequence breaks off of a chromosome and is inserted backwards into the same chromosome.
52.All cells in the body contain identical DNA molecules.
53.DNA is negatively charged and is attracted to the positive terminal during gel electrophoresis.
54.Restriction enzymes cut DNA into fragments of different sizes called PCR fragments.
55.The smallest DNA fragments travel furthest during gel electrophoresis.
56.In DNA fingerprinting, a radioactive label is applied to the DNA just before using restriction enzymes to cut DNA into fragments.
57.Bacterial plasmids are generally long, linear sequences of genes.
58.Recombinant DNA is made by inserting a gene into a bacterial plasmid.
59."Blunt ends" are produced when a restriction enzyme cuts DNA and leaves overhanging, complementary bases on each side of the cut.
60.Restriction enzymes cut DNA at sequences called palindromes.
61.Restriction enzymes are named after the bacteria from which they originate.
62.The probability of a particular 7-base-pair sequence occuring in DNA is 1/74.
63.ddATP, ddGTP, ddCTP, and ddTTP lack an -OH group on the deoxyribose 3' carbon.
64.Addition of a dideoxy nucleotide causes "chain termination" during DNA replication.
65.For a DNA gel prepared by the Sanger Method, the DNA sequence is read from the bottom to top (smallest to largest fragment). The actual sequence of the DNA is the complement to the sequence read.
66.In chromosomes, DNA is coiled around "histones", pos. charged proteins that bind/stabilize neg. charged DNA.