Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
What is the central dogma of of molecular biology?
|
DNA > RNA > Protein
|
|
|
What is the problem with the central dogma?
|
does not take into account that RNA is sometimes the finished product (rRNA, tRNA, iRNA, miRNA)
|
|
|
What are Ribozymes?
|
RNA's that have cralytic activity, function LIKE enzymes. Accociated with translation in making the peptide bonds.
|
|
|
What are Retroviruses? Can it occur normally?
|
Transcribe RNA into DNA, also known as reverse transcription.
Yes example Telomearse enzyme. |
|
|
What are Nucleotides and what made of?
|
They are subunits of nucleic acids. Consist of sugar (ribose or deoxyribose, lacks an O), phosphate and nitrogenouse base (Pyrimidines & Purines).
|
|
|
What is a Pyrimidine?
|
Single Ring three types: Uracil (RNA), Cytosine, and Thymine (DNA)
|
|
|
What is the difference between Thymine and Uracil, Cytosine and Uracil?
|
Thymine has a methyl group and Cytosine has an Amine group.
|
|
|
What are Purines?
|
2 ring structure, Adeine and Guanine. And Adenine like cytosine has an Amine group.
|
|
|
What happens if Cytosine or Adenine is deaminated?
|
Turns into Uracil, which is picked up easily because DNA does not have Uracil. Same with Adeine forms hypoxanthine.
|
|
|
What if Cytosine gets methylated and deaminated?
|
If a bunch in one area then shuts down gene expression. When you deaminate a methulated cytosine turns into Thymine harder to repair and take out.
|
|
|
Describe Phosphates role in Nucleotides?
|
Up to 3 attached to 5' Carbon inan ester link. Each phosphate has a negative charge which gives DNA and RNA a negative charge.
|
|
|
What makes up DNA and what is the polarity?
|
Nucleotides strung together by phosphodiester bonds
Both RNA and DNA are polar. |
|
|
What are complementary base pairs?
|
Adenine is always paried with Thymine/Uracil and Gaunine alsway aoired with cytosine.
|
|
|
How many hydrogen bonds pair A-T and G-C?
|
A-T have two hydrogen bonds and G-C have 3. Areas of seperation or Origin of Replication occrus at A-T rich b/c easier to seperate.
|
|
|
What are the advantages of an alpha helix?
|
Make it more compact, more thermodynamically stable, more surface area for proteins to recognize it.
|
|
|
What is the difference between the sequence of the two stands and the two strands?
|
The sequence are complementary and the two strands are antiparallel
|
|
|
Where does protein recognition occur?
|
In the Major Groove between two turns (particular structure) and the Minor Groove between two strands (particular nucletide sequence)
|
|
|
What is chromatin?
|
DNA in the nucleus combined with proteins (histones), that make up chromosomes
|
|
|
Whare is Heterochromnatin?
|
Most compacy form of chromatin particulary compact area is nucleoli whare ribosomes are synthesized
|
|
|
What is Euchromatin?
|
Most open form of chromatin, has to do with whether of not DNA is being actively used or not.
|
|
|
What is the nuclear envelope?
|
Double membrane that separates the nucleus form the cytosol.
|
|
|
What are Nuclear Pores and how are they used in RNA processing?
|
Where molecules travel between the cytosol and nucleus protected by proteins.
Important in RNA processing will not let RNA out of nucleus into cytosol until fully processed. |
|
|
What are Histones?
|
small POSITILVELY charged proteins that DNA wrap around nearly tice to form NUCLEOSOME BEADS.
|
|
|
How are Histones linked together/seperated?
|
They are seperated by about 50 base pairs of DNA called LINKER DNA which is bound together by HISTONE H1.
|
|
|
How do you seperate the two stands to use for replication/transcription?
|
Post-Transitonal Modification
Lysine AA on termnmal end of Histone have + charge and interact with - charge of phosphate on DNA. They are neutralized by addion of acetyl group (acetylation). This weakens the attraction. Done by the ENZYME HAT |
|
|
Once replication / transcription is finished what happens with histone interaction?
|
The acetyl group is removed and histone can re-bind to DNA dpme ny tje Emzyme HDAC.
|
|
|
When is nuclear DNA replicated?
|
Only during a discrete phase called the S Phase.
|
|
|
What is Mitosis?
|
When the cell actually divides
|
|
|
What is proto-oncogenes?
|
Protein that stimulates cell cycle progression
|
|
|
What is Tummor Suppressors (p53)?
|
Products of the this inhibit cell cycle progression.
Control checkpoints where cell checks that everthing was done beofore moving on. |
|
|
When are regions of the genome actively transcribed and when are untranscribed regions replicaed?
|
Regions of the genome that are actively transcribed are replicated early in S phase
Untranscribed regions are replicated later in S |
|
|
What are cell cycle events controlled by?
|
Controlled by proteins called cyclins and cyclin dependent kknases (CDK's)
|
|
|
What is semiconservative?
|
It is in DNA replication where each daughter cell contain one parental strand and one newly synthesized strand.
|
|
|
What direction does DNA synthesis occur and in what direction and from where?
|
Only in the 5' to 3' direction
There are multiple origins along a chromosome and more bi-directional |
|
|
What is the replication fork and the replication bubble?
|
The region of trnasition between the unwound parent duplex and the newly replicaed daughter DNA
Unwound region is the bubble |
|
|
When does cell licensing occur and what is it?
|
Occurs in G1
It is when "licensed" to replicate and when Cdc6 binds ORC and recruits Mcm to form pre-RC |
|
|
What does Mcm contain?
|
It contains helicase activity whcih separates two stands of DNA and migrates with the replication fork
|
|
|
When does the origin fire?
|
When it is phosphorylated by S-Cdk (Cdc6) in the S phase
|
|
|
What prevents positive supercoiling and what are the 2 types?
|
Topoismerase make reversible nicks and then reseal the gap
Type I = make single stranded nicks Type II = make double stranded nicks |
|
|
Decribe DNA synthesis by DNA Polymerase:
|
Both parental stands are used as templates
Complementary nuclotides are added one at a time t othe 3' OH DNA Polymerase requires pre - existing 3' OH, provided by an RNA primer by the primase Joined by phosphodiester bonds |
|
|
What direction is DNA synthesized and what dierction does it move along the template?
|
Synthesized in the 5' to 3' and DNA Pol. moves along the template in 3' to 5'
|
|
|
How does DNA Pol. proofread?
|
DNA pol. has 3' to 5' exonuclease activity and excise the last nucleotide if it doesnt base pair correctly with the template strand
|
|
|
What does the RNA primer (primase) do?
|
Provides the 3' OH for DNA pol. so DNA synthesis can begin. RNA pol. does not have this requirement
|
|
|
How does the proofreading remove an unwanted nucleotide?
|
Failure to form a proper ase pair triggers a conformational change in the DNA pol. so falls into hte exonuclease pocket where the last nucleotide is removed
|
|
|
What is the leading strand?
|
moves forward in the smae direction the forks
away from the origin contineous |
