Chapter 1 Flashcards
What did Johann Miescher publish a paper on in 1871?
Nuclein, the viscous substance extracted from cell nuclei, they had no idea the importance of what they extracted at the time.
What is a nucleotide?
A unit of nucleic acid comprised of a phosphorylated ribose sugar and a nitrogen base
What is a nucleoside?
unit of nucleic acid comprised of a ribose sugar and nitrogen base
What are the four nitrogen bases that make up DNA?
adenine, guanine, thymine, and cytosine
What is the bond that forms polymers of nucleotides in DNA?
phosphodiester bonds
How are nucleotides converted to nucleosides?
Hydrolysis
How do the nitrogen base components of DNA stay together in double stranded DNA?
Hydrogen bonds
How many hydrogen bonds does guanine form with cytosine?
3
How many hydrogen bonds does adenine form with thymine?
2
What are pyrimidines?
Nitrogen bases with a single ring structure - thymine and cytosine
What are purines?
Nitrogen bases with a double ring structure- adenine and guanine
What is a gene?
An ordered sequence of nucleotides on a chromosome that encodes a specific functional product
What way is DNA oriented?
5’ to 3’
How do nucleic acid chains grow?
attaching a 5’ phosphate group of an incoming nucleotide to the 3’ hydroxyl group of the last nucleotide on the chain
How are the two strands of connected DNA orientated?
Antiparallel, one is 5’ to 3’ while the other is 3’ to 5’
What is the open reading frame in DNA?
region of DNA comprised of codons coding for an amino acid sequence
What is the promoter region?
DNA sequences that bind RNA polymerase and associated factors
What is a regulatory sequence?
part of a gene sequence that binds factors controlling expression of a gene
What is a structural sequence?
part of a gene sequence that codes for amino acids
In what direction does DNA polymerase read the DNA template?
3’ to 5’
What type of DNA replication is used in humans?
semi-conservative replication, each DNA double helix consists of a parent strand and a newly synthesized strand in the other directiob
What three codons are stop codons?
UAA, UAG, UGA
What are the 4 types of mutations?
Missense, silent, frameshift, and nonsense
What does the phosphodiester backbone of DNA cause?
polarity
What are the 6 steps of DNA replication?
- Enzymes (helicase) unwind the parentla double helix.
- Proteins stabilize the unwound parental DNA
- The leading strand is synthesized continuously in the 5’ to 3’ direction by DNA polymerase.
- The lagging strand is synthesized discontinuously (okazaki fragments) RNA polymerase synthesizes a short RNA primer, which is then extended by DNA polymerase.
- DNA polymerase digests RNA primer and replaces it with DNA
- DNA ligase joins the discontinuous fragments of the strand
