DNA and RNA Flashcards
(15 cards)
transcription, translation, replication:
transcription- DNA copies to RNA.
translation- RNA produces proteins.
replication- copying and duplicating a DNA molecule.
DNA:
deoxyribonucleic acid (DNA). expressed graphically in different ways. double helix, base pairs, genes, ATCG.
DNA passes info down generations. some viruses use RNA to perform same function.
how does DNA pass information:
stores information- series of base pairs, triplet code creates amino acids, amino acids form proteins.
protects the information- tightly wound in a double helix, packed onto chromosomes, encased in a protective membrane.
DNA is a long linear polymer of nucleic acids (nucleotides) made up of a pentose sugar, nitrogenous base (the sequence of the nucleic acid) and a phosphate group.
pentose sugar:
pentose sugar: 5 carbon atoms, labelled 1’-5’, 1 oxygen atom, 2’ carbon has missing oxygen- deoxy.
attached to sugar is the nitrogenous base. attached to the 1’ carbon by N-glycosidic bond. exists as 2 parent compounds (groups).
phosphate group:
attached to C5 hydroxyl group. gives the molecule a negative charge. exists in different forms.
nomenclature depends on the number of phosphates:
1 phosphate- nucleoside 5’-phosphate or a 5’-nucleotide eg adenosine 5’-monophosphate (AMP).
2 phosphates- nucleoside 5’-diphosphate or a 5’-dinucleotide eg adenosine 5’-diphosphate (ADP).
3 phosphates: nucleoside 5/=triphosphate pr a 5’-trinucleotide eg adenosine 5’-triphosphate (ATP).
nucleosides and nucleotides:
unit consisting of base bonded to a sugar is a nucleoside.
unit consisting of a nucleoside joined to 1 or more phosphate groups is a nucleotide.
RNA:
another linear polymer of nucleotides. main differences between DNA and RNA- the sugar units are different, uracil in RNA, thymine in DNA.
single and double stranded DNA:
single stranded DNA- nucleotides are linked by phosphodiester bonds. bonds form between 5’ carbon and 3’ carbon. DNA sequence code is always presented in a 5’-3’ direction. maintains integrity of stored genetic material.
double stranded DNA- 2 strands of nucleotides running anti parallel. bonds form between nitrogen bases.
hydrogen bonds:
A and T paired by 2 hydrogen bonds. C and G by 3 hydrogen bonds.
hydrogen bonds in dsDNA- hydrogen bonds are weak. the large numbers of hydrogen bonds within the helix give stability. forms a double helix.
separating the double helix.
separating dsDNA into ssDNA is necessary for- the transcription into mRNA, the copying of the DNA strand during replication and the copying of the DNA molecular during PCR. Separation occurs by disrupting hydrogen bonds between base pairs.
Separation is called melting because it occurs abruptly at a certain temperature. Melting temperature ™ is defined as the temperature at which half the helical structure is lost.
structure of RNA:
ribose not deoxyribose, U instead of T. usually single stranded. fold back on themselves. self complementary regions from hairpin loops which are double helical. random coil.
different types of RNA:
required in protein synthesis- messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA).
required in other functional roles- small nuclear RNA (SnRNA), micro RNA (miRNA)
messenger RNA (mRNA):
active during transcription- complementary to DNA sequence, codes for protein, specific to gene, varies in quantity dependent on gene.
transfer and ribosomal RNA:
tRNA- physical link between mRNA and amino acids. linked to each amino acid. 3 base pair anti codon.
rRNA- forms ribosome with protein. interacts with both mRNA and tRNA. active during translation.
