3.4.1 DNA , Genes and Chromosomes Flashcards
What are 3 components of nucleotides?
Pentose sugar , Phosphate group and Organic base
Describe the structure of DNA
Consists of a Phosphate group , Deoxyribose sugar and 1 of 4 Organic bases (Adenine , Thymine , Gaunine and Cytosine)
- It’s double stranded
- Hydrogen bonds between bases form a helix shape
Describe the role of DNA
Carries genetic information and determines our inherited characteristics
Describe the structure of RNA
Consists of a Phosphate sugar , ribose sugar and 1 of 4 Organic bases (Adenine , Uracil , Guanine and Cytosine)
- It’s single stranded
Describe the role of RNA
Transfers genetic information from DNA to ribosomes for protein synthesis
How is DNA in eukaryotic cells different from in prokaryotic cells?
Eukaryotic: found in the nucleus long and linear. Associated with histone proteins to form chromosomes. Mitochondria and chloroplast contain prokaryotic like DNA.
Prokaryotic: short and circular and not associated with histone proteins.
What is the Genetic code?
Order of bases on DNA. Consists of codons (triplets of bases that code for particular amino acid)
Identify features of the Genetic code
Non-overlapping: each triplet is only read once.
Degenerate: more than one triplet codes for the same amino acid.
Universal: same bases and sequences are used by all species.
What is a Gene?
A base sequence of DNA that codes for the same amino acid sequence of a polypeptide or a functional RNA
What is a Locus?
The fixed position on a DNA molecule that is occupied by a gene
What is an Allele?
A different version of the same gene , found at the same locus on a chromosome
What are Exons?
Regions of DNA that code for an amino acid sequence separated by 1 or more Introns
What are Introns?
Regions of DNA that don’t code for anything
Where are Introns found?
Between exons and within genes
