A1.2 Nucleic Acids Flashcards
2 main functions of nucleic acids
- pass information between generations
- code for protein production
types of nucleic acids
dna rna
types of RNA
tRNA - transfer
rRNA - ribosome
mRNA - messenger
main role of Dna
carries genetic code in all living organisms
passes hereditary information between generations of cells
main role of rna
protein synthesis
codes for making protein
difference between nucleotide bases in RNA and DNA
A C G is the same
in RNA the T is replaced by a U
structure of nucleotides
pentose sugars
structure of DNA
double helix
difference in DNA and RNA structure
there is an extra oxygen in 2’ of RNA
Components of a nucleotide
A pentose sugar (a sugar with 5 carbon atoms)
A nitrogen-containing organic base (with either 1 or 2 rings of atoms)
A phosphate group (this is acidic and negatively charged)
purine bases
Adenine and guanine are purine bases
pyrimidine bases
Cytosine, thymine (in DNA) and uracil (in RNA) are pyrimidine bases
how are the two strands in DNA connected
hydrogen bonds connecting the nucleotide bases
structure of purines
double ringed structures
structure of pyramidines
single ringed structures
how many bonds do A & T have in between them
2 hydrogen bonds
how many bonds do C & G have in between them
3 hydrogen bonds
what is the backbone
sugar - phosphate
polynucleotides
phosphate group of one nucleotide forms a covalent bond to the pentose sugar of the next one
a long unbranched chain of nucleotides as found in DNA and RNA
how are the phosphate groups linked
condensation reaction
where is (mRNA) formed and transported
formed in the nucleus and transported to the ribosomes in the cytoplasm
what is transfer RNA resposible for (tRNA) - function
which is responsible for transporting amino acids to ribosomes during protein synthesis
ribosomal RNA (rRNA)
forms part of ribosomes
anti parallel
DNA molecules are made up of two polynucleotide strands lying side by side, running in opposite directions
direction of strands in dna
5’-3’
3’-5’ - antiparallel
what does 5’ end with
phosphate
what does 3’ end with
pentose
what creates structural support In back bone and why is it necessary?
sharing of electron in the covalent bond between sugar and phosphate - provides strength to structure
strength maintains nucleotides in their specific sequence which is necessary for storing, replication and expression of genetic information
what is complementary base pairing
A with T
C with G
allows genetic information to be replicated and expressed
a
adenine
t
thymine
c
cytosine
u
uracil
g
guanine
genetic code
the order of bases in DNA that determines the sequence of amino acids in a protein
coding strand
the strand that will carry the base sequence to be read by enzymes
codon
triplet of bases which codes for one animo acid
how many bases code for one amino acid
3
how many amino acids are there
20
gene
heritable factor that consists of a length of DNA that codes for a protein
chromosome
length of DNA that carries specific genes in a linear sequence
locus
particular position of a gene on the homologous chromosomes
what does the sequence of amino acids determine
determine the shape and function of the protein that is synthesised from the code
The genetic code is universal
meaning that almost every organism uses the same code (there are a few rare and minor exceptions)
allele
different versions of the same gene
alternative form
homologous chromosomes
pairs of chromosomes one from each parents that carry the same sequences of genes
genome
whole of the genetic information of an organism or cell
mutation
a change in the amount or the structure of DNA of a chromosome
process of decoding a gene consists of
transcription translation
transcription
formation of mRNA molecules from the DNA that makes up a particular gene. first stage of protein synthesis
translation
the later part of protein synthesis when the mRNA is used as a template to which complementary tRNA molecules attach and the amino acids link to form a polypeptide
where is DNA found
nucleus - eukaryotic cell
nucleic or plasmids - prokaryotic
can be found in mitochondria and chloroplasts as well
where is RNA found
made in nucleus during transcription and then transported to cytoplasm
complementary base pairing meaning
base sequence on one DNA strand determines the sequence of the other strand
what does complimentary base pairing allow
allows DNA to be copied very precisely during DNA replication which in turn ensures that the genetic code is accurately copied and expressed in newly formed cells
dna storage ability and why
limitless capacity to store information
because there is a very diverse range of DNA base sequences in DNA molecules of different lengths
