6067781
Description
Flashcards by Emma Allde, updated more than 1 year ago
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Created by Emma Allde
over 7 years ago
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| Question | Answer |
| Pharmacogenomics | When our DNA sequence determines whether you respond to a particular drug treatment |
| WHO studied virulent (Smooth) and non-virulent (Rough) strains of Streptococcus pneumonia in mice and demonstrated the principle of transformation | Griffith (1928) |
| What is the concept of transformation | Modification of a cell or bacterium by the uptake and incorporation of exogenous (foreign) DNA |
| What is the transforming factor in eukaryotic genetics | DNA |
| Which radioisotope is used to label protein | 35S can be used to label protein (no sulphur in DNA) |
| Which radioisotope is used to label DNA | 32P can be used to label DNA (no phosphorus in protein) |
| WHO experimented with radioactively lableled bateriophages (virus that infects bacteria) showing that DNA is the transforming factor | Hershey and Chase (1952) |
| What are the strongest type of bonds | covalent |
| What binds with adenine | thymine (DNA) and uracil (RNA) |
| What binds with guanine | cytosine |
| A molecule that can be written as several resonance structures of approx. equal energy have greater _________ than those without resonance structures | stability |
| Sugar in sugar-phosphate unit is attached to how many phosphates | two |
| What charge to phosphates carry | negative |
| What are the purines | guanine, adenine |
| What are the pyrimidines | cytosine, thymine, uracil |
| Nitrogenous base with two ring structure | purines |
| Nitrogenous base with single ring structure | pyrimidines |
| What is the nucleic acid composition | 9 purine or 6 pyrimidine atoms + amine (NH2) + methyl (CH3) or carbonyl (C=O) group |
| How is uracil different from thymine | Only found in RNA Demethylated form of thymine |
| What makes up a nucleotide | sugar, base, phosphate |
| What does ATP stand for | deoxydenosine triphosphate |
| Nucleotides can be attached to WHAT of other nucleotides | 3' OH groups |
| Nucleotide attachments are catalysed by what enzyme | polymerases |
| At 3' 5' - phosphodiester bonds are formed liberating what molecule | inorganic pyrophsphate (PPi) |
| 5' end of polynucleotide chains contain | phosphate |
| 3' end polynucleotide chains contain | hydroxyl group |
| Criteria for DNA structure (3) | ○ capable of storing info. ○ replication mechanism ○ capable of mutation |
| Who solved that DNA has a three dimensional structure | Watson and Crick (1953) |
| Whose experimental findings that served as basis for Watson and Crick's hypotheses | Chargaff and Franklin & Wilkins |
| What are Chargaff's rules (1947) (3) | ○ the amount of guanine = cytosine (G=C) ○ the amount of adenine = tyrosine (A=T) ○ the composition of DNA varies from one species to another, with respond to relative amount of A, G, T and C bases (hint to molecular diversity) |
| Percentage of bases in humans | 30.9% A; 29.4% T; 19.9% G; 19.8% C |
| Who discovered that DNA was helical and the molecule has a diameter of 2 nm and makes a complete turn on the helix every 3.4 nm i.e. RNA has a regular, repeating structure; helical structure; width and spacing of nitrogenous bases | Franklin and Wilkin |
| What is the intronucleotide distance | 0.34nm |
| What is the distance of one full twist of DNA in nt. and nm | 10 nucleotides per turn; 3.4nm |
| What is the diameter of the helix | 2.0nm |
| DNA strands are what | in anti-parallel |
| Bases are ________ to the helical axis | perpendicular |
| Information in DNA is stored as what | a sequence of bases |
| Who discovered: ○ Replication mechanism of DNA - semi-conservative ○ One DNA strand acts as a template for the building of a new strand in replication ○ The parent molecule unwinds and the two new daughter strands are assembled based on base-paring rules (semi-conservative) | Mesleson and Stahl (1958) |
| Compression of DNA is mediate by what | proteins |
| What is the chromosome composition | DNA + protein |
| Number of chromosomes in humans | 46; 22 pairs and XX or XY |
| Number of nucleotide pairs in humans | 3 x 10^9 |
| Meters of DNA in every nucleus | 1.8m |
| Diameter of nucleus | 5 micro meters |
| What is the building block of chromatin | Nucleosome |
| What is nucleosome | 146bp of DNA wrapped around a protein core of 8 histones which are chromosomal proteins |
| What are the 8 histones | 2x (H2A, H2B, H3, H4) |
| What is special about H1 (histone) | ○ Not part of nucleosome ○ Helps assemble nucleosomes into the 30nm fibre ○ Non-chromosomal protein; changes that path DNA takes as it exists the nucleosome core, allowing it to become more compact |
| What is chromatin fibre | many nucleosomes packed together; arranged as loops; form chromosome scaffold |
| What is linker DNA | DNA between nucleosomes (up to 80 nt) |
| What is the composition of a histone | Made of up a high proportion of positively charged amino acids (lysine and arginine) |
| What about histone composition is important to DNA structure | The positive charge helps the histones bind tightly to the negatively charged sugar-phosphate backbone; their amino acid sequence is highly conserved amongst eukaryotes They also have a long N-terminal amino acid tail which influences chromatin structure |
| What is condensing chromatin | 30nm fibre is folded into a series of loops, which are further condensed to produce interphase chromosomes |
| What is the net result of packaging chromatin | Each DNA molecule has been packaged into a mitotic chromosome that is 10K shorter than its extended length |
| What are chromatin-remodelling complexes | Proteins that use ATP hydrolysis to change the position of DNA wrapped around the nucleosome |
| What is the main role of chromatin-remodelling complexes | loosening the chromosomal DNA by pushing it along the histone core, this repositioning (sliding) of the nucleosome, exposes the DNA to other DNA-binding proteins |
| What is the role of RNA polymerase | links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template. |
| What is the role of Histone acetyltransferase (HAT) | Recruit transcriptional co-activators, act in large complexes, recruit RNA polymerase, turn on gene expression Lead to the uncoiling of chromatin |
| What is the role of Histone deacetylase (HDAC) | remove acetyl groups from histones, which closes chromatin conformation and decreases gene expression |
| What is Heterochromatin | DNA that is densely packed around histones |
| Describe the genes in heterochromatin | The genes in heterochromatin are generally inaccessible to enzymes and are turned off |
| What is Euchromatin | DNA that is loosely packed around histones |
| Describe the genes in Euchromatin | This DNA is more accessible to enzymes and the genes in euchromatin can be activated if needed. |
| What is Methylation | chemical modification of DNA makes that gene less likely to be expressed |
| Number of human genes | 23,000 |
| Average size of a gene (in bases) | 2,000 bases |
| Humans genes make up about how many nts. | 4.6 x 10^7 nucleotides |
| What are exons | Genome expressed sequence of DNA |
| Where are exons found | in mature DNA |
| What are introns | Sequence of DNA that is not involved in coding for a protein |
| Where are introns found | immature DNA |
| What is repetitive DNA | Nucleotide sequences, usually noncoding, that are present in many copies in a eukaryotic genome |
| What are the untranscribed regions near genes | ca. 2% of non-coding regions of DNA Areas flanking genes, esp. at the 5' end are important regulatory elements that control the production of mRNA |
| What are two kinds of Retrotransposable elements | LINES and SINES |
| What are LINES | Viral retrotransposable elements Long Interspersed Elements |
| What are SINES | Non-viral retrotransposable elements Short Interspersed Elements |
| What is Satellite DNA | short sequences of DNA that are tandemly repeated as many as 10 million times in the DNA |
| Where is most satellite DNA located | in the telomeres |
| What is the role of satellite DNA | structural properties of DNA |
| What is the clinical significance of satellite DNA | Provides genetic fingerprint Used in paternity testing and forensic science |
| Uncharacterised/junk DNA is what | non-coding |
| Human genome size | 3 billion bp |
| Amoeba genome size | 22x larger than human 670 billion bp |
| What is the key structure difference between deoxyribose and ribose | In DNA H' is at the 2' position In RNA OH' is at the 2' position |
| DNA forms ________ outside biological symptoms | sponatenously |
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