Carson Ticer Flashcards
Genetics 210- Riddle
In humans, 20 percent of the bases in DNA are cytosine, what percentage of the bases are Thymine?
Cytosine and Guanine are in equilibrium. That being said, Cytosine and Guanine each have values of 20 percent, adding up to 40 percent. As Thymine and Adenine are in equilibrium, they will amount to the remaining 60 percent of the total 100 percent, which makes both Thymine and Adenine 30 percent.
Relations to DNA
DNA strands are antiparallel, contain Thymine (as opposed to RNA which contains Uracil), consists of a 5 carbon sugar, a deoxyribose sugar ( RNA consists of a ribose sugar), and the synthesis occurs from 5’ to 3’)
Euchromatic characteristics
Gene rich, Early Replicating, Recombines during meiosis, transcribed, and contains chromosome arms.
How is DNA packaged?
DNA is tightly wound around a histone complex (and octamer) as well as an H1 histone. (H1 histones are composed of chromatin in eukaryotic cells)
What will happen to a linear chromosome that lacks a telomere at one end?
The end of the chromosome will degrade very quickly and become unstable. This occurs because telomeres are used as protectants.
What are hairpin structures, where are they usually found, and what is their purpose?
It is a structure where a loop is formed usually with complementing base pairs lining up with a loop at the end. They are usually found in RNA. They usually serve as recognition sites for proteins.
Endosymbiotic theory and its significance to life today
This theory states that once the mitochondria and the chloroplasts were free-living organisms that got engulfed by eukaryotic cells. This theory is backed by the fact that both mitochondria and chloroplasts have their own DNA.
Why does replication within the cells have to be extremely accurate?
Since cells replicate so much, even a small percent of errors are fatal to the cells.
What does semiconservative mean? DNA replication is semi-conservative. Explain-
Semiconsevative means half preserved. A DNA strand is held apart and new strands are built onto the old strands. In the end you will have 2 new strands, one old and one new.
What are the products of theta replication
2 circular DNA molecules
What are the products of eukaryotic DNA replication
2 linear DNA molecules
What is the difference between a leading and lagging strand?
The leading strand is synthesized all in one piece and the lagging strand is synthesized in small fragments since DNA can only be synthesized in the 5’ to 3’ direction.
Okazaki fragments
They are small fragments that are built onto the lagging strand. They are later pieced together with DNA ligase.
Enzyme functions- DNA helicase
unwinds DNA at the replication fork
Enzyme functions- DNA gyrase
Moves ahead of the replication fork and works to break some bands and reduce torque
Enzyme functions- DNA primase
Synthesizes a short RNA primer to provide a point of attachment for the DNA nucleotides
Enzyme functions-DNA poly 1
Removes RNA primer and replaces with DNA
Enzyme functions-DNA poly 2
Elongates the nucleotide sequence
Enzyme functions-DNA poly 3
Elongates the nucleotide sequence
Enzyme functions-DNA ligase
glues together the Okazaki fragments from the lagging strand.
If there is a malfunction in the way DNA ligase works, what would be the outcome?
The lagging strand would exist in a bunch of small pieces and would not be able to function properly and would not be able to code for any important genes or proteins which would be fatal.
Is DNA or RNA more stable? Why?
DNA is more stable as it is double stranded which is more stable. Also the ribosome sugar in RNA molecules is more unstable than the deoxyribose sugar in DNA molecules.
Is the promoter region downstream or upstream of the coding region?
Upstream
Which strands are genes transcribed from?
Genes can be transcribed from either leading or lagging strands.
Where are all the different Polymerases found?
RNA poly 1-3 all Eukaryotes RNA poly 4-5 plants
How does the process of translation begin? What are the key players as it comes to translation?
- The process begins as the MRNA exits the nucleus in eukaryotes and the small subunit of the ribosome binds to the mRNA strand which starts the whole process. You need a AUG codon to begin.
- The key players within this process are mRNA, the ribosomal units, and tRNA.
What codon is absolutely needed to start the process of translation?
The AUG codon is needed which is also referred to as the start codon which codes for amino acid methionine.
What are the three sites located on the ribosome for the tRNA and what happens to each of these sites?
a. The three sites are A, P, and E.
b. The A site is the first site that the new tRNA molecule will bind to. This is where the peptide bond is formed between the chain at the P site and the amino acid at the A site. The P site is where elongation occurs. The tRNA that contains the polypeptide chain happens here. The E site contains a tRNA molecule which no longer has an amino acid. This is also referred to as the exit site where tRNA molecules leave the ribosome.
What initiates the process of termination?
A stop codon (UGA,UAG,UAA) on the mRNA comes into the ribosome which tells the ribosome that there is no more code that is needed to be translated.
What is a polyribosome?
This is when the same strand of the mRNA has multiple ribosomes that are translating to make the same protein.
coding purposes formula
4^b
Primary, secondary, tertiary, and quanterary structures of protein
- Primary- the amino acid sequence
- Secondary- The alpha helices or beta pleated sheets
- Tertiary- protein folding in on itself
- Quanterary- Two or more polypeptide chains associating
What does the core structure of an amino acid include?
- an amino group
- hydrogen
- carboxyl group
- R group (radical group) side chain
How many amino acids do humans need to function?
Humans need 20 amino acids in order to function..
What is a peptide bond and where in a protein are they formed?
A peptide bond is a covalent bond that is present between amino acids.
B- This bond is formed between the carboxyl group of one amino acid to the amino group in the adjacent amino acid. This is what links the amino together to create the polypeptide chain.
What is a codon? What is the significance of a codon?
A codon is a triplet RNA code. The significance is that the codon codes for an amino acid which makes up proteins
What is meant by the genetic code being universal?
The same codons code for the same amino acids in all forms of life. This is why you can take a human gene, insert it into bacteria, and get the same resulting protein.
What does wobbling refer to?
The first two mRNA nucleotides in a codon/anticodon pairing are more important that the third in attracting the correct tRNA because hydrogen bonding at the third position is less constrained and follows more relaxed rules. Wobbling allows there to be only 30-50 tRNAs. As the same anticodons on a tRNA can be bound to different codons without the needing to be 61 anticodons to match the 61 codons on the mRNA.
What is the structure of ribosomes and what are the differences between prokaryotes and eukaryotes?
Ribosomes consisted of two subunits with one larger than the other. They are composed of rRNA and proteins, E, P, and A are 3 major sites on the ribosomes
