Genetics
90 flashcards by MentisLibrary
Follow the information in DNA from replication through transcription and translation, then into Mendelian crosses, mutations, and population genetics. Ends with the biotechnology that now edits the code directly, including CRISPR.
- What does DNA stand for?
- Deoxyribonucleic acid
- What are the three parts of a DNA nucleotide?
- A deoxyribose sugar, a phosphate group, and a nitrogenous base
- Which bases pair with each other in DNA?
- Adenine with thymine, and guanine with cytosine
- Which bases are purines and which are pyrimidines?
- Adenine and guanine are purines; cytosine, thymine, and uracil are pyrimidines
- What does it mean that the two DNA strands are antiparallel?
- They run in opposite directions, one 5 prime to 3 prime and the other 3 prime to 5 prime
- Who published the double helix model of DNA and in what year?
- James Watson and Francis Crick, in 1953
- What is Chargaff's rule?
- In a DNA sample the amount of adenine equals thymine and guanine equals cytosine
- What did the Hershey and Chase experiment demonstrate?
- That DNA, not protein, is the genetic material
- What did Griffith's 1928 experiment reveal?
- That a transforming substance could pass heritable traits between bacteria
- What is the central dogma of molecular biology?
- Information flows from DNA to RNA to protein
- What does semiconservative replication mean?
- Each new DNA double helix keeps one original strand and one newly made strand
- Which enzyme unwinds the DNA double helix at the replication fork?
- Helicase
- Which enzyme relieves the supercoiling ahead of the replication fork?
- Topoisomerase, also called DNA gyrase in bacteria
- Which enzyme adds new nucleotides during DNA replication and in which direction?
- DNA polymerase, adding only in the 5 prime to 3 prime direction
- Why is a primer needed to start DNA replication?
- Because DNA polymerase can only extend an existing 3 prime end
- What is the difference between the leading and lagging strands?
- The leading strand is made continuously toward the fork; the lagging strand is made in short pieces away from it
- Which enzyme seals the nicks between Okazaki fragments?
- DNA ligase
- What is the end replication problem?
- Linear chromosomes lose a small amount of DNA at each end with every round of replication
- What is proofreading by DNA polymerase?
- Its 3 prime to 5 prime exonuclease activity removes a mismatched base right after it is added
- What are the three main stages of transcription?
- Initiation, elongation, and termination
- Which strand of DNA does RNA polymerase read?
- The template strand, also called the antisense strand
- What is a promoter?
- A DNA sequence upstream of a gene where RNA polymerase and transcription factors bind
- What three modifications turn a eukaryotic pre-mRNA into mature mRNA?
- A 5 prime cap, a poly-A tail, and removal of introns by splicing
- What is the difference between an intron and an exon?
- Introns are removed during splicing; exons are joined together and appear in the mature mRNA
- What is alternative splicing?
- Joining different combinations of exons from one gene to produce multiple protein variants
- What is a codon?
- A group of three mRNA bases that specifies one amino acid or a stop signal
- What is the start codon and which amino acid does it code for?
- AUG, which codes for methionine
- What are the three stop codons?
- UAA, UAG, and UGA
- What does it mean that the genetic code is degenerate?
- Most amino acids are specified by more than one codon
- What is an anticodon?
- The three-base sequence on a tRNA that pairs with a complementary mRNA codon