dna, genes and chromosomes Flashcards
What are the 3 components of nucleotides
- Pentose sugar
- Phosphate group
- Organic base
Describe the structure of DNA
- Deoxyribose sugar
- Phosphate group
- One of four organic bases (A, T, C, G)
- Double-stranded
- Hydrogen bonds between bases form a helix shape
Describe the role of DNA
Carries genetic information, determines our inherited characteristics
Describe the structure of RNA
- Ribose sugar
- A phosphate group
- 1 of four organic bases (A, U, C, G)
- Single-stranded
Describe the role of RNA
Transfers genetic information from DNA to ribosomes for protein synthesis
Which bases are purine and which are pyrimidine?
Purine (2x ring) = adenine, guanine
Pyrimidine (1x ring) = cytosine, thymine, uracil
How is DNA in eukaryotic cells different from in prokaryotic cells?
- Eukaryotic DNA is found in the nucleus and is long and linear, associated with histone proteins to form chromosomes
- Prokaryotic cells are short and circular, not associated with histone proteins
What is the genetic code?
The order of bases on DNA, consists of codons
Define codons
Triplets of bases that code for a particular amino acid
Identify features of the genetic code
- Non-overlapping so each triplet is only read once
- Degenerate so more than one triplet code for the same amino acid
- Universal because the same bases and sequences are used by all species
Define 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
Define locus
The fixed position on a DNA molecule occupied by a gene
Define an allele
Different versions of the same gene found at the same locus on a chromosome
What are exons?
Exons are sections of a gene that do code for an amino acid
What are introns?
Introns are sections of DNA that don’t code for amino acids