DNA UNIT 2 Flashcards
(26 cards)
Each nucleotide is made from which type of sugar
Pentose (with 5 carbon atoms)
How is DNA replicated
Semi-conservative method
DNA nucleotides join together to form…..
Polynucleotide strands
What join to form polynucleotide strands
2 nucleotides
2 polynucleotide strands join together to form…..
A double helix
The nucleotides join up between…..
The phosphate group of one nucleotide and the sugar of another, creating a sugar-phosphate backbone
How is a sugar-phosphate backbone created
Nucleotides join between the phosphate group of one and the sugar of another
How do polynucleotide strands join together
By hydrogen bonds between the bases
Where do the hydrogen bonds in the polynucleotide strands form
Between the bases
What is specific bases pairing
Each base can only join with one particular partner
What are genes
They are sections of DNA. They code for proteins as they contain the instructions to make them
Proteins are….
Polypeptides, made from amino acids
Different proteins have a different…..
Number and order of amino acids
What does the order of nucleotide bases in a gene determine
The order of amino acids in a particular protein
Each amino acid is coded for by a sequence of…
Three bases (triplet code) in a gene
Why does DNA copy itself before cell division
So that each new cell has the full amount of DNA
What does degenerate mean
Different bases can code for the same amino acid
Why do eukaryotes have longer DNA than prokaryotes
They are more complex so require a longer DNA base sequence
What is the function of the DNA bases
To provide sequence of amino acids
How does chiasmata occur
Chromosomes in each homologous pair twist around each other, crossing over many times.The chromatids break and rejoin to chromatid on sister chromosome
A DNA sequence has a specific number of bases. Why might there be more bases than this number?
Introns present
Addition of bases through mutations
What happens in meiosis 1
The chromosomes arrange themselves into homologous pairs, which then separate, halving the chromosome number
What happens in meiosis 2
The pairs of sister chromatids are separated. 4 genetically different haploid cells are produced
What are chromatids
2 copies of each chromosome
