Structure of DNA Flashcards
What is the essence of DNA?
DNA is a molecule that holds instructions for growth and development in every living thing
What is the shape of DNA and how is it held together?
Double-Stranded Helix, with complimentary base pairs
What are the basic units of DNA?
Nucleotides
What do the basic units of DNA consist of?
Deoxyribose sugar, phosphate and base
What do all basic units (nucleotides) have in common?
All nucleotides are identical except from the base
What are the bases and how do they pair together?
Adenine and Thymine (A-T), Guanine and Cytosine (G-C)
What do these basic units (nucleotides) do with each other when forming a DNA strand?
The basic units are linked together via strong covalent bonds between the deoxyribose sugar of one nucleotide and the phosphate of another nucleotide, forming a strong sugar-phosphate back bone
What are the ends of a DNA strand called?
5’ end (said 5 prime end) at the phosphate end, and the 3’ end at the deoxyribose end
How do the two DNA strands run in relation to each other and how do they bind together?
Anti-parallel, so one strand runs 5’ to 3’ and the other runs 3’ to 5’, this forms the twisting double helix shape we see, the two strands are linked together via weak hydrogen bonds between the bases
How do all cells store their genetic information?
In the base sequence of DNA
What is determined by the sequence of bases?
The Genotype
What is DNA present in?
Every living thing
What does the organisation of DNA differ in?
Different types of organisms
What two groups can we put DNA into based on the way they organise themselves?
Eukaryotes and Prokaryotes
What are Prokaryotes?
Bacteria
What is different about the prokaryote cell’s nucleus and DNA?
They do not have a membrane bound nucleus and their DNA is free in the cytoplasm
How are the genes held in a prokaryote cell?
They have a singular circular chromosome in the centre of the cell that holds all the genes needed for that bacterium
What are plasmids and what has them?
Additional circles of DNA, bacteria prokaryotes
What are Eukaryotes?
Animals, plants and fungi
What is different about the eukaryote cell’s nucleus and DNA?
It has a membrane bound nucleus and their chromosomes are linear rather than circular, however in some cells small circular genetic information can additionally be found
How is DNA stored in eukaryotes in the nucleus?
The DNA found in linear chromosomes within the nucleus is tightly coiled around special proteins called histones
What organism is a eukaryote but has plasmids like a prokaryote?
Yeast cell
Where does the numbering start on the carbons in a nucleotide sugar and in what direction?
from the point where the base is connected and clockwise
What is the name of the detail of all the organelles inside a living cell?
An Ultrastructure
