Th2L01 Nucleic acids (FC)


Medicine Y1 (Theme 2 | Genetics) Flashcards on Th2L01 Nucleic acids (FC), created by Emma Allde on 18/08/2016.
Emma Allde
Flashcards by Emma Allde, updated more than 1 year ago
Emma Allde
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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