Unit 2 - Topic 9 - Chromosomes, Genes and DNA Flashcards
Definition: Chromosome
Long strand of DNA (genetic structures) located in the nucleus.
Definition: Gene
Short strand of DNA (located on a chromosome) which codes for a particular characteristic or amino acid, which are the building blocks for proteins.
Genes are often described as functional units.
Chromosomes occur in …
Functional pairs
What does DNA stand for?
Deoxyribonucleic acid
Describe the shape of DNA
Double helix
What does DNA consist of?
DNA consists of three sub-units.
Deoxyribose sugar (a pentose sugar)
Phosphate
Bases
What are the four different types of bases?
Adenine
Thymine
Guanine
Cytosine
What type of bond connects the bases of the coding strand to the bases of the anti-coding strand?
Hydrogen bonds
What is the name given to a repeating unit of DNA, consisting of a phosphate, a sugar (deoxyribose) and a base?
A nucleotide
What does adenine bond to?
Thymine
What does thymine bond to?
Adenine
What does guanine bond to?
Cytosine
What does cytosine bond to?
Guanine
Which side of the DNA molecule forms the genetic code?
The coding strand.
How many bases are needed to form an amino acid and what is this hypothesis known as?
Three
Base triplet hypothesis
In theory, how many combinations of amino acids are possible?
4*3 = 64
What do bases code for?
Bases code for amino acids, which are the building blocks of proteins.
Name the scientists who made contributions towards the discovery of DNA.
Erwin Chargaff Rosalind Franklin Maurice Wilkins James Watson Francis Crick
What did Rosalind Franklin and Maurice Wilkins discover and what method did they use?
They discovered the overall 3-dimensional shape of DNA.
X-Ray diffraction (Crystallography).
When did Erwin Chargaff make his discovery?
1950
What did Erwin Chargaff discover?
Erwin Chargaff discovered, through chemical means, that although the arrangement of bases in DNA varied, there was always an equal amount of adenine and thymine. Similarly there was always an equal amount of guanine and cytosine.
When did James Watson and Francis Crick discover the shape of DNA?
1953
What method did James Watson and Francis Crick use to discover the shape of DNA (a double helix)?
Modelling
What is peer review?
When new scientific knowledge is validated by other scientists to confirm its accuracy.
