DNA & Protein Sythesis Flashcards
What is a mutation?
A change in DNA
What 3 molecules were thought to be possibilities for being the genetic material?
Proteins, RNA, or DNA
What happened to Griffith’s mice when R cells were injected into them?
Lived
What happened to Griffith’s mice when S cells were injected into them?
Died
What happened when dead S cells, along with live R cells were injected into Griffith’s mice?
Died
What kind of cells are found in the blood of mice when dead S cells, live R cells, and DNAase are injected?
Live R Cells
What kind of cells are found in the blood of mice when dead S cells, live R cells, and RNAase are injected?
Live S cells
What kind of cells are found in the blood of mice when dead S cells, live R cells, and Protease are injected?
Live S cells
If one strand of DNA has the following sequence of nucleotides, what would the other strand look like? GCCTAAGCCTA
CGGATTCGGAT
What are the monomers of DNA and what is one of these units made of?
Nucleotide is made of a phosphate group, 5 carbon sugar (deoxyribose), & a nitrogenous base
Name the 4 nitrogen containing bases
Adenine, Guanine, Thymine, Cytosine
Who officially discovered the helical structure of DNA?
Watson and Crick
What makes up the backbone of DNA?
Sugar and Phosphate
What makes up the rungs of DNA?
Nitrogenous Bases
What always joins with Adenine in DNA?
Thymine
What always joins with Cytosine?
Guanine
What holds the 2 strands of DNA together (they are found between bases that are paired together).
Hydrogen Bonds
Briefly describe DNA replication (ensure to include ALL enzymes involved).
Helicase (an enzyme): unzips and untwists DNA, separating DNA into two complimentary “ parent strands”. This happens at many “origins of replication” along a chromosome
Single-stranded Binding Protein: attach to each separate parent strand & stabilize them Each parent strand can now act as a template for new complimentary “daugher strands”.
Primase (an enzyme): adds a short sequence of complimentary RNA to the DNA. This short piece of RNA is called a Primer.
Topoisomerase: as helicase unwinds DNA, pressure builds up where DNA is unwinding. Topoisomerase relieves this pressure by breaking DNA, swivelling it, and re-joining it
Problem with DNA Polymerase III only being able to add to the 3’ end of the growing piece of DNA?
DNA is antiparallel which means that DNA polymerase III can only add nucleotides to one strand continuously. (Leading Strand)
The other strand needs to have little short pieces of DNA at a time. This strand is called the (Lagging Strand). These pieces of DNA are called Okazaki Fragments
Formation of Okazaki Fragments:
RNA Primase adds RNA primers to start fragments
DNA Polymerase III adds nucleotides to the 3’ end of the RNA primers
DNA Polyermase I replaces the RNA primers with DNA
Ligase attaches the last nucleotide of each fragment to the next one (It glues the fragments together)
What is a replication fork?
Where DNA synthesis begins.
What is a point mutation?
A mutation involving 1 or few nucleotides
What kinds of point mutations are there?
Substitutions; Insertions & Deletions
What kind of mutation is considered to be a “frameshift” mutation?
Insertions and deletions
List the types of chromosomal mutations that exist & briefly explain what each one is
Deletion – part of chr omosome is deleted
Duplication – chromosome is duplicated
Inversion – part of chromosome is reversed
Translocation – part of chromosome breaks off & attaches to another chromosome
State 3 differences between DNA & RNA
DNA has deoxyribose, RNA has ribose
DNA has 2 strands, RNA has 1 strand
DNA has thymine, RNA has uracil
If a coding strand of DNA is 18 - nucleotides, & all 18 nucleotides are transcribed into mRNA:
How many codons will be in the mRNA?
How many amino acids will be in the resulting protein (assuming that the first 3 nucleotides in the m RNA formed are AUG)
6
6
What’s the function of mRNA?
To take a copy of the genetic code of a gene out of the nucleus to ribosomes (takes copy of DNA to ribosomes)
What’s the function of tRNA?
To match proper amino acids with appropriate codons on mRNA
What’s a codon?
3 bases on mRNA that encode for a specific amino acid
What’s an anticodon?
The 3 bases on tRNA that match up with a codon
Briefly describe the process of transcription.
RNA polymerase binds to the initiation site on DNA (a specific sequence of bases). RNA polymerase separates DNA and uses one of the 2 strands as a template to make a single strand of mRNA. When the terminator of the gene is reached (specific sequence of bases on DNA) then RNA polymerase falls off & so does the mRNA. The mRNA then leaves the nucleus through nuclear pores.
Briefly describe the process of translation (Include what happens at the different sites found on the ribosomal subunits).
A small & large ribosomal subunit bind at the AUG (start) condon on mRNA. The tRNA with methionine attaches at the P site of the ribsome. Next a tRNA with the proper amino acid and anticodon that fits with the next codon on mRNA attaches at the A site. Whatever amino acids are in the P site hop onto the new amino acid that just came into the A site. The ribosome then moves up the mRNA 3 base knocking the now empty tRNA that had methione out and it opens up the A site, because what WAS in the A site is now in the P site. The process continues until a stop codon is reached. Remember….tRNA with new amino acids come in at the A site and whatever amino acids were already in the P site hop onto the new amino acids that come in at the A site.
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