Chapter 20 Flashcards
What are genes made of?
DNA
What is the Frederick Griffith experiment?
it was comparing two strands of Streptococcus there was an S strain is virulent and a
R strain is nonvirulent. when a variant was dead the mouse lived but with a cocktail of live and dead cells the animal died.
what did Avery, MacLeod, & McCarty process of the experiment?
first they repeated Griffith’s experiment, then they found out that Removal of all protein from the transforming material did not destroy its ability to transform R strain cells, DNA-digesting enzymes destroyed all transforming ability, and lastly Supported DNA as the genetic material, at least in bacteria
what was the Hershey & Chase experiment?
they were able to separate the phages into radioactive sulfur-containing protein ghosts and radioactive phosphorus-containing DNA. They found that the radioactive sulfur protein ghosts could attach to bacterial membranes while the radioactive phosphorus DNA could not
How are monomers linked?
monomers are linked by Phosphodiester bonds
how are phosphodiester bonds formed
Formed between the phosphate group of one nucleotide and the 3′ —OH of the next nucleotide
what is the Structure of a single strand of DNA?
Phosphodiester backbone and a 5’ to 3’
Erwin Chargaff determined that:
Always an equal proportion of two-ringed purines (A and G) and single-ringed pyrimidines (C and T) Amount of adenine = amount of thymine amount of cytosine = amount of guanine The ratio of A-T and G-C varies by species
what did Rosalind Franklin discover?
she discovered that the molecule has a diameter of 2 nm and makes a complete turn of the helix every 3.4 nm she used Maurice Wilkins’
James Watson and Francis Crick discover?
Deduced the structure of D N A using evidence from Chargaff, Franklin, and others, Strands
connected via hydrogen bonds between bases on opposite strands, Result is specific base-pairs: A-T and G-C, Helix has a consistent diameter, is stable because of additive property of thousands of low-energy hydrogen bonds
Pattern of base-paring is
complementary
Two strands of single DNA molecule are _____ identical
not
each strand specifies the other by ____
base-pair complementarity
Conservative DNA is
semiconservative DNA is
dispersive DNA is
what was the Meselson and Stahl experiment for round 1?
Round 1 = 1 density band
Conservative model rejected
Dispersive & Semiconservative supported
what was the Meselson and Stahl experiment for round 2?
Round 2 = 2 bands
Semiconservative supported
Dispersive rejected
what are the stages of DNA replication?
Initiation, Elongation, Termination,
central dogma steps
Transcription = D N A → R N A (both nucleic acids)
Translation = R N A → protein (from nucleic acid to protein)
Retroviruses violate this order using reverse transcriptase to convert their R N A genome into DNA
Transcription = D N A-directed synthesis of _____
RNA
the template strand is:
Only one strand of DNA copied as RNA
the coding strand is:
Strand of DNA not used as template
mRNA used to direct _____ of polypeptides
synthesis
Messenger RNA
intermediate form of information from nucleus to cytoplasm for processing
Ribosomal RNA
class of R N A found in ribosomes, is essential for their function in protein production
Transfer RNA
intermediary adapter molecule between mRNA and amino acids during protein synthesis
Small nuclear RNA
part of machinery involved in processing of “pre-mRNA” in splicing
Signal recognition particle RNA
mediator for proteins synthesized on the rough endoplasmic reticulum
Small RNAs
– involved in control of gene expression
Start codon Codon ______ used to signify the start of translation
AUG
Stop codons
Three codons used to terminate translation
UAA, UGA, UAG
Many eukaryotic genes contain sequences that are ___represented in mRNA
Not
Introns
non-coding sequences
Exons
sequences that will be translated
exon shuffling
introns suggests exons are functional domains and intron-exon arrangements represent shuffling of those domains over evolutionary timescale
Some support from genetic data, but _____
not universal
Promoter
forms recognition and binding site for RNA polymerase( where start site is located)
Start site
actual site where RNA synthesis begins
All RNA is synthesized from a DNA template by _____
transcription
Sequences the “stop” signal to RNA polymerase
RNA–DNA hybrid within the transcription bubble dissociates
R N A polymerase releases the DNA
DNA rewinds
_______ bonds are weakest bonds, results in dissociation of RNA from DNA in transcription bubble
A-U
Can form a hairpin, which causes RNA polymerase to pause at ______
uracil
what are the differences of Procaryotes and eukaryotes replication
procaryotes: Prokaryotes have operons,
Operon
A single mRNA may contain multiple genes
RNA polymerase I transcribes what?
rRNA
RNA polymerase II transcribes what?
mRNA and some snRNA
RNA polymerase III transcribes what?
tRNA and some other small RNAs
Each R N A polymerase recognizes its own_____
promoter
RNA Pol II promoters:
Consist of a “core promoter” that can be composed of a number of elements, including the TATA box (TATA sequence upstream of start site)
RNA Pol III promoters
Most are found within the gene itself
Elongation complex factors coordinated by structural feature called
carboxyl terminal domain
explain Eukaryotic initiation complex
proteins or protein complexes involved in the initiation phase of eukaryotic translation. These proteins help stabilize the formation of ribosomal preinitiation complexes around the start codon and are an important input for post-transcription gene regulation.
_____ is added to 5′ end, with GTP modified by addition of
_______ group, called methyl-G cap
Involved in ________ initiation, RNA stability, and further processing
GTP, methyl, translation
Transcriptome
all the RNAs produced from a genome
Proteome
all the proteins produced from a genome
How is it possible for one gene to produce multiple transcripts or proteins?
Alternative splicing, processes of a single primary transcript being spliced into different mRNAs by including different sets of exons, can account for deviation from balanced ratio
