| How are the parts of nucleotides bonded? | C'1 of pentose to N'9 of purines and N'1 of pyrimidines. the bond is called N-glycosidic bond. And phosphate is bonded to pentose in C'3, or C'5. |
| What are RNA? | single-stranded molecule that consists of one chain of ribonucleotides complementary to one of the DNa strands (transcribed) enzyme that synthesizes it is called RNA polymerase. |
| What is the difference between DNA and RNA (sugar/base/molecule/localization)? | sugar (deoxyribose/ribose)
base (thymine/Uracil)
molecule (double helix,long/ single stranded, short)
localization--eukaryotes (nucleus mitochondria chloroplast/nucleus, cytoplasm and mitochondria)
---prokaryotes (cytoplasm BOTH) |
| How does ligase function? | after removal of RNA primers,DNA polymerase polymerizes the gaps until a side of phosphate is present then the ligase ligates the two adjacent strands with phosphodiester bonds |
| What are the different types of RNA? | mRNA (messenger) single stranded that specifies aa in polypeptide chains through transcription and translation. it is synthesized on template transcribed non coding DNA strand it is the only coding RNA.
tRNA (transfer) single stranded, particular arrangement resembles shape of cloverleaf. used in protein synthesis as an adapter between mRNA and aa, each tRNA is linked to an aa covalently and is so called charged tRNA
rRNA; located in ribosomes. |
| What is gene expression? | process by which a gene product is produced. |
| What are the steps of gene expression? | transcription (copying genetic info through RNA)
if the transcript RNA is mRNA, then the second step is translation into peptides. |
| What is the result of transcription? | single stranded mRNA complementary to one of the DNA strands. |
| Talk about the process of transcription | DNA sense strand (or coding ) is the strand that is the same as the mRNA but the difference is in T and U, it contains promoters (with 5' end) which makes it impossible to be transcribed given that RNA polymerase reads only from 3'-5'. |
| What is the point of transcription? | first RNA nucleotide is transcribed at a point, designated vy "+1" |
| What is a gene consisting of in terms of organizaton? | exons and introns, exons are the coding sequences while introns are not coded by RNA, a gene always begins and ends with an exon, exons and introns are separated by termination sequences. (terminators) |
| What are UTR sequences? | genes that are transcribed but not translated, constituting the opening frame. |
| Is the whole DNA sequence transcribed? | Yes, but not all mRNA sequences are translated (only exons) |
| Describe the transcription process. | Intiation: RNA polymerase recognizes promoter binds to it and starts transcribing the template starting from transcription start site.
Elongation: RNA are inserted to complement the transcribed strand and linked by amide bonds, from 5' to 3', direction of the DNA stranded is 3' to 5'
Termination: when it encounters a specific nucleutide sequence acting as a termination signal, enzyme terminates, RNA is released from transcribed strand. |
| What is the difference between transcription of eukaryotes and prokaryotes? | Eukaryotes (in nucleus, has to go to ribosomes in the cytoplasm, processing (changes to make RNA possible to polymerize proteins)
prokaryotes (no need for any additional processes d8re transcription translation. |
| What was the original view over genetic material carriers? | Originally, scientists didn't know whether chromosomes are made up of proteins or nucleic acids, so there was no idea of which carries the genetic material. |
| Who was the first do discover about carriers of genetic material? Name the experiment | Fredrick Griffith - Transportation experiment |
| What cells did Griffith use? | a bacterium called streptococcus pneomoniae which was responsible for pneumonia and death of mice |
| What are the kinds of the bacteria Griffith used? how do they differ? | two kinds S which is virulent and is capsuled by a polysaccharide capsule and the stains form smooth colonies, and R which was avirulent and not capsuled and stains form rough colonies. |
| Talk about the procedures of the experiment of Griffith | Mice were injected first with living S and R bacterium, the one who was injected with S died whereas the one with R survived. Then a mice was injected with heat killed S bacterium, the mouse survived.
Lastly the mouse was injected with both R and heat killed S bacterium, the mouse died |
| What conclusions can be made by Griffiths experiment? | Substances inside heat killed S bacterium caused the R bacterium to transform into S bacterium, forming a capsuled virulent bacterium which killed the mouse. |
| After the transportation experiment, Who were the scientists that made a breakthrough? | Avery, Macleod and McCarty |
| What was the aim of their experiments? | to discover the substance that caused the transformation in Griffith's experiment |
| Talk about the procedure of Avery, Macleod and McCarty's experiment. | First S cell extracts was isolated, heat killed, then added with R cells, then some S cells were added into R cells but with protease that digest proteins, then they added them with RNase which digest RNA, then with DNase which digest DNA. |
| What results were obtained and what conclusions were discovered? | transformation occurred in all tubes except the one with DNase, meaning that the substance that carries genetic information are DNA, however they were inconclusive since DNA might still just be catalyzing agents |
| In general, what is DNA? | DNA is deoxyribonucleic acids that carry genetic information , a polymer of two helical anti-parallel chain that are essential for the cell's life |
| What are nucleosides? | The combination of a nitrogenous base and pentose |
| WWhat are nucleotides? | They are the main subunits that polymerize to form DNA. they are made up of nitrogenous bases, pentose and phosphate. |
| What are the main kinds of nitrogenous bases? | nine member double ring purine (Adenine and Guanine), and six member single ring pyrimidines (Cytosine, Thymine, Uracil). |
| What is the main difference between RNA and DNA? | The difference is in the pentose, where in C'2 of DNA the carbon is bonded to two hydrogen atoms however in RNA it is bonded to one hydrogen and one hydroxyl group. So RNA contains ribose, while DNA contains Deoxyribose. |
| How are nucleotides named(TWO WAYS) | they are named according to the nitrogenous base attached (adenylic acid- guanylic acid- cytidylic acid- deoxythymidylic acid- uridylic acid) or nucleoside mono-tri-diphosphate. |
| How are nucleosides named | (adenosine- cytidine- guanosine) |
| How are mononucleotides bonded together? | Through phosphodiester bond between phosphate and two sugars of both mononucleotides one at C-3' and one on C-5'. |
| What are the two types of bonded nucleotides? | oligonucleotides (30 mono and less) and polynucleotides. |
| Who was first to discover about the process of genetic material functionality? | Erwin Chargaff |
| What conclusions did Chargaff give concerning DNA structure? | A & T are equal, C & G are equal , (A+G)=(C+T), (A+T)!=(C+G) |
| Who were first to discover the real structure of DNA? | Watson and Crick |
| What is the main structure of DNA? | Two long antiparallel polynucleotide chains coiled around a central axis (hydrophobic nitrogenous bases) forming a right-handed double helical shape, H-bonded in the middle, distance between two nucleotides is 0.34 nm, distance of a complete turn in helical structure is 3.4nm (10 nucleotides) diameter of 2nm |
| What is the mode of DNA replication? | Semi-consevative |
| Describe the process of replication | helicase unwinds helical shaped of DNA forming the origin of replication.
Primase adds RNA primers on with 3'-OH ends necessary for the commencation of DNA polymerase to be able to synthesize DNA.
DNA polymerase starts synthesizing DNA complement of both strands of parents, Because the two strands are antiparallel, continuous synthesis in the direction of the replication fork is possible along only one strand called the leading strand, whereas in the other strand the synthesis is discontinuous called lagging strand.
RNA primers are removed by ligase, gaps temporarily created must be filled with DNA polymerase leaving some gaps.
The gaps left after synthesis are filled and must be joined to the adjacent DNA strand by ligase. |
| What is the origin (eye) of replication? | The sum of both forks done by helicase to unwound the DNA helix shape |
| How is the replication process? and why? | Bidirectional, since replication forks are expanding in both directions of the replication bubble |
| How is DNA synthesis catalyzed? | By DNA polymerase III |
| Describe the DNA synthesis process. | Helical shape of double strands is unwitted by helicase, then RNA primers attach to the cite of polymerizing for the DNA polymerase to act. Synthesis occurs on one direction at first because the two strands are bidirectional, the other strand is complemented discontinously. |
| What do we call the strand that gets polymerized first? the one that gets discontinously? | Leading strand, Lagging strand |
| What is the direction for polymerizing of strands? | 5'-3' |
| What does DNA ligase do? | it attaches the nucleotides by phosphodiester bonds without polymerizing new nucleotides |
| what are primers? | primers are ribonucleic acids (oligonucleotides) that are nessecary for the initiation of polymerizing complementary nucleotides to the old strands. |
| What is primase? | They are enzymes that adds RNA primers with 3'-OH ending for DNA polymerase to start |
| What are Okazaki fragments? | The fragments of lagging strand that get polymerized discontinously |
