DNA, genes and protein synthesis Flashcards
Describe the structure of DNA
Deoxyribose sugar
Phosphate group
4 organic bases:
Adenine, Cytosine, Guanine, Thymine
Double helix
H bonds between bases
Describe the structure of RNA
Ribose sugar
Phosphate group
Same 4 organic bases as DNA but replace Thymine with Uracil
Single stranded
How does the DNA differ in eukaryotes and prokaryotes?
Eukaryotes: Prokaryotes:
found in nucleus short and circular
histone proteins form chromosomes not associated with proteins
long and linear
Explain some of the features of the genetic code
Non-overlapping = each triplet is read once
Degenerate = more than one triplet codes for an amino acid
Universal = same bases / sequences used by all species
What is a gene?
Sequence of bases that codes for a specific sequence of amino acids
Also codes for functional RNA
What is a locus?
Fixed position on a DNA molecule
Occupied by a gene
What is an allele?
Different versions of the same gene
What are the regions of DNA that code for amino acids known as?
Exons
What is a genome?
Complete set of genetic info in the cell
What is a proteome?
Complete set of proteins produced by a cell
Describe the structure of mRNA
Long, single strand
Base sequence is complementary to DNA it was transcribed from
Describe the structure of tRNA
Single strand folded into clover leaf shape
Anticodon on one end
Amino acid binding site on other end
Outline the process of transcription
- DNA helicase causes H bonds to break
- One DNA strand acts as a template
- RNA nucleotides align by complementary base pairing
- Uracil used in place of thymine
- RNA polymerase joins nucleotides by phosphodiester bonds
- Pre-mRNA spliced (removing introns to form mRNA)
Outline the process of translation
- mRNA attaches to ribosomes
- (tRNA) anticodons bind to complementary (mRNA) codons
- tRNA brings specific amino acid
- Amino acids join by peptide bonds
- With the use of ATP
- tRNA released
- Ribosome moves along mRNA to form the polypeptide
