1What are the three main components of a nucleotide?
phosphate, a 5-carbon sugar, and a nitrogen-containing base
2DNA is made up of what four bases?
adenine (A), thymine (T), guanine (G), and cytosine (C)
3RNA is made up of what bases?
adenine (A), uracil (U), guanine (G), and cytosine (C)
4Why do you think it was suspected that DNA was a replicating molecule?
because of Franklin's X-ray diffraction data which showed DNA to be a helix with some portions repeating over and over; also Watson and Crick's model
5Chargaff's Rules
1. The amount of A, T, G, and C in DNA varies from species to species
2. In each species, the amount of A = T and the amount of G = C
6DNA strucutre
deoxyribose sugar and phosphate molecules are bonded, forming the sides. with the bases making up the rungs of the ladder; hydrogen bonding between the bases holds the halves of the helix together
7What three main enzymes are needed for DNA replication?
primase, DNA polymerase, DNA ligases, helicase
8primase function
attaches to a short strand called a primer, which shows DNA polymerase where to work
9helicase function
the unzipping enzyme, breaks through the hydrogen bond holding the 2 bases together
10DNA polymerase function
begins adding complementary bases; enzymes that synthesize new copies of DNA. BUILDS the new strand of DNA
11DNA ligase function
seals any breaks in the sugar-phosphate backbone (the glue)
12What is a primer?
a short nucleic acid sequence that serves as the starting point for DNA synthesis
13How is a massive eukaryotic DNA molecule replicated so quickly?
replication bubbles; bubbles spread in both directions until they meet
14semiconservative
each new DNA molecule is made of one parent strand and one new strand
15How is RNA different from DNA?
uses uracil instead of thymine, and is single-stranded
16What are the three types of RNA?
messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA)
17messenger RNA (mRNA)
produced in the nucleus from DNA template, carries genetic message to ribosomes
18transfer RNA (tRNA)
carrier of amino acids and transfers them to complemntary bases on mRNA, connecting anticodons to codons (all in ribosomes); helps operate translation
19ribosomal RNA (rRNA)
produced in the nucleolus of the nucleus from DNA template, joins with proteins to form ribosomes (which are a mixture of protein and RNA); responsible for protein synthesis
20central dogma of molecular biology
information flows from DNA to RNA to protein
21codon
3 nucleotide sequence in mRNA, a codon encodes a single amino acid
22transcription
mRNA is formed from the DNA coding strand; DNA -> RNA; transcribing a messenge (mRNA)
23translation
mRNA along with ribosomes, directs the sequence of amino acids which make up a protein. tRNA assists with this process by carrying amino acids to the ribosome; RNA -> protein; protein synthesis
24What are the three phases of translation?
initiation, elongation, termination
25initiation
mRNA binds to small subunit of ribosmoe at start codon AUG. the tRNA that complements this codon carries methionine or Met. large subunit then joins
26elongation
peptide lengthens one amino acid at a time
27termination
occurs when one of the stop codons are encountered (UAA, UAG, or UGA). the growing polypeptide is released and the ribosome subunits dissociate and leave mRNA
28anticodon
group of 3 bases complementary to a specific codon of mRNA
29What is the start codon, and what amino acid does it code for?
the initiation signal for translation, typically AUG and codes for methionine
30What are the three stop codons, and do they code for amino acid?
the signal for chain termination: UAA, UAG, and UGA. they do not code for amino acid
31How is the transcription product different from replication?
replication forms 2 daughter strands and transcription forms different kinds of RNA: mRNA, tRNA, rRNA