Fichas
All IB HL Biology notes on DNA and RNA
Fichas del conjunto (77)
- 1What are DNA and RNA composed of?A pentose sugar
A phosphate group
A nitrogenous base - 24 nitrogenous bases of DNAGuanine
Adenine
Thymine
Cytosine - 34 nitrogenous bases of RNAGuanine
Adenine
Uracil
Cytosine - 4PurinesTwo rings
Adenine and Guanine - 5PyrimidinesOne ring
Thymine and Cytosine - 6Bond linking nucleotidesPhosphodiester bond
(covalent) - 7Phosphodiester bondFormed between the phosphate group attached to the 5'C of one sugar and the hydroxyl (OH) group attached to the 3'C of another sugar
- 8Differences between DNA and RNA- DNA contains deoxyribose
- Bases are A, G, T, C
- A double stranded molecule
- One type of DNA (compared to 3 types
of RNA) - 9Bonds between G and C3 hydrogen bonds
- 10Bonds between A and T2 hydrogen bonds
- 11Strand directionDNA strands are antiparallel to each other. One in 5' to 3', the opposite in 3' to 5'.
- 12ReplicationThe copying of DNA to produce two identical DNA molecules. Occurs during the S phase of the cell cycle.
It is semi-conservative - 13Semi-conservativeEach daughter molecule formed contains one original strand from the parent molecule and one newly synthesized strand
- 14TranscriptionThe process which the information in a strand of DNA is copied into a new molecule of mRNA.
- 15Sense strandDNA strand that is not transcribed.
Has the same sequence of bases as the mRNA molecule - 16Antisense strandDNA strand that is transcribed
Complementary to the mRNA molecule - 17mRNA moleculeForms the template for protein synthesis
Upon leaving the nucleus, it will bind to one or several ribosomes and allowed the translation process to begin. - 18Codon3 bases on the mRNA strand.
Each codon is translated into one amino acid in a polypeptide chain - 19Genetic code is degenerateSome amino acids are encoded by more than one codon
- 20Polymerase Chain ReactionTechnique used to amplify DNA.
Uses cycling heating and cooling of a DNA sample in the presence of primers, DNA nucleotides and Taq polymerase - 21Taq polymeraseA DNA polymerase isolated from Thermus Aquaticus bacterium.
Thermostable, which is required to withstand high PCR temperatures. - 22Transgenic organismPlacing a gene from one organism into a different organism due to the universality of the genetic code.
- 23Meselson and StahlDemonstrated how DNA replication progresses in a semi-conservative way.
Used E.Coli bacteria and 15N and 14N. - 24Eukaryotic DNAAcidic and negatively charged.. Associated with histones.
Prokaryotic DNA is not associated with histones, hence it is described as naked DNA - 25HistonesBasic and negatively charged.
Neutralise the DNA when they bond - 26NucleosomeA length of DNA of about 150 base pairs, wrapped around a core of eight histones and bound with H1 histones.
- 27Uses of nucleosomes- Help supercoil the DNA while still ensuring appropriate access
- Neutralises the DNA - 28Stability of double helix- Hydrogen bonding between purines
and pyrimidines
- Slightly positive charge on T, slightly negative charge on A - 29Initiation of DNA replication in eukaryotesCan be initiated at various points, but can only be started on one position on prokaryotic DNA,
Ensures a faster and more efficient DNA replication in eukaryotes. - 30Rate of replication100 nucleotides per second in eukaryotes
1000 nucleotides per second in prokaryotes - 31HelicaseBinds to the origin of replication and breaks the hydrogen bonds to unwind the DNA double helix.
- 32Single-stranded binding proteinsBind to the single stands formed to keep them apart allowing time for the DNA sequence to be copied.
- 33DNA GyraseRelieves the supercoiling and tension on the region ahead of the helicase
- 34Energy for replicationAs deoxynucleoside triphosphates bind to the template strand, they lose their two extra phosphate groups to generate energy (used to bind the nucleotides to the polynucleotide chain)
- 35Leading strandReplicated continuously in the 5' to 3' direction by DNA polymerase III
- 36Lagging strandReplicated discontinuously in small fragments in the 5' to 3' direction by DNA polymerase III
- 37DNA PrimaseOn the lagging strand, it makes short RNA primers which allow the DNA polymerase III to add deoxynucleotides to the RNA primer.
- 38DNA polymerase IRemoves the RNA primers from the lagging strand and substitutes them with short DNA segments.
- 39DNA ligaseJoins the Okazaki fragments together in the lagging strand
- 40Non-coding DNAAccounts for more than 98% of the human genome. They're DNA sequences within a genome that's not protein coding
- 41Non-coding DNA regions- Regulators of gene expression
- Introns
- Telomeres
- Genes for tRNAs - 42Regulators of gene expressionEg. Promoters are sequences that occur just before genes and can act as a binding point for the RNA polymerase enzymes that catalyst the transcription process
Other eg.'s include enhancers and silencers - 43IntronsDNA base sequences found within genes that get removed at the end of transcription. Hence, they do not contribute to the amino acid sequence of the polypeptide made from the gene.
- 44TelomeresRepetitive sequences that protect the ends of the chromosome.
- 45Tandem repeatsSequence of 2 or more DNA base pairs that is continuously repeated. They form part of the non-coding DNA.
Used for identification purposes at a crime scene - 46DNA SequencingMethod used to deduce the order of the nucleotides.
- 47Rosalind FranklinCarried out X-ray diffraction experiments leading to the determination that DNA was a helical molecule.
- 48Hershey and ChaseProves that DNA was the genetic material, instead of proteins as it was thought at
the time. - 49TranscriptionThe synthesis of mRNA
- 50RNA polymeraseStarts near a region of the gene called the promoter.
- 51Initial part of transcriptionRNA polymerase binds to the DNA and causes the double helix to unwind.
- 52RNA nucleoside triphosphateRNA nucleoside triphosphates are added to the growing mRNA chain
- 53Post-transcriptional modification of mRNAThe mRNA needs to be prepared for translation - the introns are sliced out by
a spliceosome.
A cap and a poly (A) tail are added. - 54EnhancersActivator proteins bind there to increase the rate of transcription
- 55SRepressor proteins bind there to decrease the rate of transcription
- 56AcetylationTails of histones can be acetylated.
This means adding an acetyl group preventing binding between nucleosomes.
This partially unwinds the DNA, allowing RNA polymerase to access it. - 57MethylationTails of histones can be methylated.
This means adding a methyl group, usually causing the gene not to be expressed - 58EpigeneticsThe study of heritable changes in organisms that are brought about by changes in gene expression rather than the modification of the genetic code
- 59TranslationProtein synthesis - mRNA is decoded to produce the specific sequence of amino acids in a polypeptide chain,
- 60SMature mRNA binds to a small ribosomal subunit at the mRNA binding site. The mRNA start codon AUG is linked to the initiator tRNA carrying methionine
- 61InitiationmRNA, small ribosomal subunit, initiator tRNA and large ribosomal subunit assemble to form the translation complex
- 62A, P, E binding sites stands for...Aminoacyl-tRNA binding site
Peptidyl-tRNA binding site
Exit site - 63A siteWhere incoming tRNA with its attached amino acid binds
- 64P siteWhere tRNA from the A site moves to after forming a peptide bond with the growing polypeptide chain.
- 65E siteWhere tRNA moves to after transferring its amino acid to the growing polypeptide chain, ready to be released by the ribosome.
- 66SU
- 67tRNA structureSingle-stranded RNA molecule that folds on itself to form a typical clover-leaf-shaped structure with double-stranded regions held together by hydrogen bonds and 3
hairpin loops. - 68AnticodonContained by one of the loops on tRNA, which can bind to an mRNA codon
- 69Amino acidEach tRNA has its specific amino acid attached at the 3' end of the CCA.
This is transferred to the growing polypeptide chain by forming peptide bonds - 70Proteins translated by free ribosomesDestined to function within the cell.
Once mRNA moves in the cytoplasm, ribosomes attach to it and
translation begins - 71Proteins translated by bound ribosomesDestined to function in lysosomes or secreted outside the cell.
The beginnings of the polypeptide contains a signal sequence recognized by a signal recognition particle.
The SRP binds to the SRP recognition protein on the ER, allowing the polypeptide to enter the rER.
Post-translational modification take place in the lumen of the rER. - 72PA structure occurring when multiple ribosomes attach to the same
mRNA strand - 73Primary structureThe sequence and the number of amino acids in the polypeptide.
Maintained by peptide bonds between
the subunits - 74Secondary structureFormed when the polypeptide chain folds back on itself into alpha helices or beta pleated sheets.
Stabilised by hydrogen bonds between -NH groups and -C=O groups from the
peptide bonds. - 75Tertiary structureFurther folding of the polypeptide.
Stabilised by interactions between R groups.
Eg. Ionic, covalent (eg. disulphide bridges) and hydrogen bonds, as well as hydrophobic interactions between non-polar amino acids - 76Quaternary structureExists in proteins with more than one polypeptide chain.
Subunits are joined together by similar bonds to that of the tertiary structure.
Also have a non-protein molecular unit
(a co-factor or a prosthetic group) - 77Conjugated proteinA protein with a prosthetic group
Información
- Descripción
- This covers the content of 2.6, 2.7, 7.1, 7.2 and 7.3 Enjoy! =)
- Creado por
- Diana Domingues
- Visitas
- 178
- Etiquetas
- Valoración