TOPIC 4 - DNA GENES CHROMOSOMES Flashcards
describe the structure of DNA?
-deoxyribose sugar
-phosphate group
-organic base ( ATCG)
-double stranded
-H bonds between bases which form helix shape
what are three components of nucleotides?
phosphate group , sugar , base
describe the role of DNA?
carries genetic information, determines our inherited characteristics
describe the structure of RNA?
- ribose sugar
-phosphate group
-organic base (AUCG)
-single stranded
describe the role of RNA?
transfers information from DNA to ribosomes during protein synthesis
which bases are purine and pyrimidine?
purine - double ring - AG
pyrimidine - single ring - TCU
how is DNA in eukaryotic cells different from in prokaryotic cells?
Eukaryotic cells -
- found in nucleus
- long and linear
- bound by histone proteins to form chromosomes
- mitochondria and chloroplast contain prokaryotic -like DNA
Prokaryotic cells-
- short circular
- not associated with proteins
what is the genetic code?
the order of bases on DNA. Consists of codons - triplets of bases which codes for a particular amino acid
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 location of a particular gene on a chromosome
what is an allele?
different forms of the same gene found at the same locus of 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 amino acids. Found in eukaryotic DNA not prokaryotic. It is spliced (removed) our of mRNA molecules.
where are introns
between exons
within genes
identify features of the genetic code?
Non overlapping
Degenerate
Universal
what does DEGENERATE mean?
more than one triplet base codes for 1 Amino Acid.
64 possible triplets for 20 amino acids
Advantage - if point mutation occurs, it may still code for the same Amino Acid and therefore have no effect
