4.1 DNA, genes and Chromosomes Flashcards
What are the three components of nucleotides?
A pentose sugar, a phosphate group, an organic base
Describe the structure of DNA
Made up of a deoxyribose sugar, a phosphate group, and one of four organic bases (A,C,G,T). It is double-stranded, and hydrogen bonds between the bases form a helix shape
Describe the role of DNA
Carries genetic information, determines our inherited characteristics
Describe the structure of RNA
Made up of a ribose sugar, a phosphate group, and one of four organic bases (A,C,G,U).It is single stranded
Describe the role of RNA
Transfer genetic information from DNA to ribosomes for proteins synthesis
Which bases are purin and which are pyrimidine?
Purine (double ring) = adenine, guanine.
Pyrimidine (single ring) = cytosine, thymine, uracil
How is DNA in eukaryotic cells different from in prokaryotic cells
DNA in eukaryotic cells are found in nucleus and are long and linear. Associated with histone proteins to from chromosomes.
Prokaryotic cells contain short and circular DNA similar to mitochondria and chloroplasts . Not associated with proteins
What is the genetic code?
The order of bases on DNA consisting of codons (triplets of bases that code for a particular amino acid)
Identify features of the genetic code
Non-overlapping meaning each triplet is only read once
Degenerate so more than one triplet codes for the same amino acid
Universal so the same bases and sequences used by all species
What is a gene
A sequence of bases on a DNA molecule that codes for a specific sequence of amino acids to make a polypeptide. Can also code for functional RNA
What is a locus
The fixed position on a DNA molecule occupied by a gene
What is an allele
Different versions of the same gene, found at the same locus on a chromosome
What are exons and introns
Exons = regions of DNA that code for amino acid sequences. Separated by one or more introns
Introns= regions of DNA that do not code for anything
Where are introns found
Between exons within genes
