4.1 DNA, Genes and Chromosomes Flashcards
what are the three components of nucleotides?
pentose sugar
phosphate group
an organic base
Describe the structure of DNA
made up of deoxyribose sugar, phosphate group and an organic base.
Double-stranded and hydrogen bonds between the bases to form a helix shape
Describe the role of DNA
carries genetic information, determines our inherited characteristics
Describe the structure of RNA
made up of
. ribose sugar
. phosphate group
. one of the four organic bases (a, u, t, 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 (double ring) = adenine, guanine
Pyrimidine ( single ring) = cytosine, thymine, uracil
How is DNA in eukaryotic cells different from in prokaryotic cells?
Eukaryotic cells = found in nucleus, long and linear. Associated with histone proteins to form chromosomes. Mitochondria and Chloroplasts contain prokaryotic-like DNA.
Prokaryotic cells = short and circular. Not associated with proteins.
What is the genetic code?
The order of bases on DNA.
Consists of codons
Identify features of the genetic code
Non-overlapping = each triplet is only read one.
Degenerate = more than one triplet code can base for the same amino acid
Universal = same bases and sequences used by all species.
What is a gene?
Sectionof DNA on a chromosome coding for one or more polypeptide
What is a locus?
the position of a gene on a chromosome
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
