4.1 - DNA, Genes & Chromosomes Flashcards
What are the 3 components of nucleotides?
- deoxyribose pentose sugar
- phosphate group
- organic base
Describe the structure of DNA.
Made up of a deoxyribose pentose sugar, a phosphate group, and one of four organic bases (adenine, thymine, cytosine & guanine). It is double-stranded, and hydrogen bonds between the bases form a helix shape.
What is the role of DNA?
To carry genetic information
To determine our inherited characteristics
What are the three components of RNA?
- ribose pentose sugar
- phosphate group
- an organic base
How do the organic bases in RNA differ from those in DNA?
They both have the 3 organic bases: adenine, guanine and cytosine.
But DNA has thymine, whereas RNA has uracil.
What is the role of RNA?
To transfer genetic information from DNA to ribosomes for protein synthesis.
What is meant by a purine base?
A double-ringed base.
Includes adenine & guanine
What is meant by a pyrimidine base?
A single-ringed base
Includes cytosine, thymine & uracil.
How is DNA stored in eukaryotic cells?
-DNA is long and linear
-found in the nucleus
-wound around proteins called histones, then coiled, to make a chromosome
How is DNA stored in prokaryotic cells?
- DNA is shorter and circular
- condenses to fit in the cell by supercoiling
What is special about mitochondria & chloroplasts?
They have their own DNA.
Similar to prokaryotic DNA.
As its circular and short.
It doesn’t associate with histone proteins.
What is the genetic code?
The order of bases on DNA.
Consists of codons
What is a codon?
A triplet of bases that code for a particular amino acid.
Identify feature of the genetic code.
- non-overlapping
- degenerate
- universal
What is meant by the genetic code being non-overlapping?
Each triplet (codon) is only read once.
