1.1 The Structure of DNA Flashcards
Describe the structure of inherited genetic material
- Found in DNA
- Contains all the genes that code for proteins
- DNA is in the form of a double stranded helix
- DNA is found in chromosomes most of the time
What is the genotype determined by?
The sequence of bases
What does DNA stand for?
Deoxyribose Nucleic Acid
What are the subunits of DNA called?
Nucleotides
What three components make up a nucleotide?
- Deoxyribose sugar
- Phosphate
- Base
What type of bonds hold the bases together?
Hydrogen bond
What two types of bonding hold DNA in its structure?
Strong chemical bond
Hydrogen Bonds
The base Adenine pairs with what base?
Thymine
What are the base pairing rules?
Adenine - Thymine
Cytosine - Guanine
Why is DNA described as antiparallel?
- The strands run in opposite directions
5’ to 3’ on one strand, 3’ to 5’ on the other
How is DNA organised in prokaryotes?
Single circular chromosomes and plasmids
What are plasmids?
Rings of extra genetic material found in the cytoplasm
Where is DNA found in Eukaryotes?
Nucleus (and mitochondria and chloroplast)
Describe the organelles in Prokaryotes?
No membrane bound organelles
(They have no nucleus, mitochondria or chloroplast)
Describe the organisation of DNA in Eukaryotes
- Linear Chromosomes in Nucleus
- DNA tightly packaged around histones
- Circular chromosomes found in mitochondria and chloroplasts
Do eukaryotes have membrane bound organelles?
Yes
(Nucleus/Chloroplast/Mitchondria)
Do prokaryotes have membrane bound organelles?
No
How is DNA packaged in eukaryotes?
Held in linear chromosomes by tightly wrapping DNA around histone proteins
Why are yeast cells an unusual example of eukaryotic cells?
They contain plasmids in cytoplasm but have linear chromsomes and membrane bound organelles
What are some characteristics of prokaryotic cells?
- Circular Chromosome
- Plasmids in Cytoplasm
- No membrane bound organelles
- No distinct nucleus
