Flashcards in Nucleotides and Nucleic acids Deck (27)
What three components make up a nucleotide?
A phosphate group, a pentose sugar and a base
Draw the basic nucleotide structure
What is the pentose sugar in DNA
Name the 4 bases in DNA and what 2 pairs they are in
Adenine and Thymine
Cytosine and Guanine
What is the change in the four bases in RNA
Thymine is replaced by Uracil
What is the basic structure of purine?
2 carbon rings
(adenine and gyanine)
What is the basic structure of a pyrimidine?
1 carbon ring
(cytosine, thymine and uracil)
What structure does ADP have?
Two phosphate groups
What structure does ATP have?
Three phosphate groups
What is it called when nucleotides join together and what bond is formed?
What is DNA composed of?
Two polynucleotide strands forming a double helix
How many bonds are formed between C and G?
How many bonds are formed between A and T
What is meant by antiparallel and how does this effect DNAs structure?
Strands run in opposite direction
This causes the strand to twist and form a double helix
How is DNA purified?
It can be purified by a precipitation reaction
Why does DNA replicate?
Before cell divisions o each new cell can have a full amount of genetic information
This is important in passing genes generation to generation
How is DNA replicated?
1. DNA helicase breaks hydrogen bonds between the strands, forming two single strands
2.Each original strand acts as a template. Free floating DNA nucleotides join to exposed bases
3. DNA polymerase joins them together forming hydrogen bonds
What is a gene?
It is a sequence of DNA nucleotides that codes for a polypeptide.
What is a codon?
Three bases making up a amino acid
What is a single polynucleotide called?
What is the function of mRNA?
Made in transcription.
It carried genetic code from the DNA in the nucleus to the cytoplasm where it is used to make protein during translation
What is the function of tRNA?
Carried the amino acids that are used to make proteins to the ribosomes
What is the function of rRNA?
The rRNA in the ribosome helps to catalyse the formation of peptide bonds between the amino acids
What is transcription?
The first stage of protein synthesis. Where mRNA makes a copy of a gene
How does transcription take place?
1. RNA polymerase attaches to the DNA
2. Complementary mRNA is formed
3. RNA polymerase moves down the DNA strand
4. mRNA leaves the nucleus
What is translation?
This is the second stage of photosynthesis.
It takes place in the ribosomes in the cytoplasm.
Amino acids are joined together by a ribosome to make a polypeptide chain (protein)