Chapter 4 Flashcards
What are the properties of DNA in prokaryote cells?
- short
- circular
- not associated with proteins
What are the properties of DNA in eukaryotes?
- long
- linear
- associated with proteins called histones
- forms chromosomes
In eukaryotes cells, what other 2 organelles have DNA?
- mitochondria
- chloroplasts
What is a gene?
base sequence of DNA that codes for
- amino acid sequence
- functional RNA (tRNA and ribosomal RNA)
Where is a gene found on a DNA molecule?
a gene occupies a fixed position called a locus on a DNA molecule
What is a sequence of 3 DNA bases called?
a triplet that codes for a specific amino acid
- genetic code is degenerate, universal and non-overlapping
What are
- introns
- exons?
- introns = non-coding base sequences
- exons = coding base sequences
What is a genome?
the complete set of genes in a cell
What is a proteome?
the full range of proteins a cell can code for
What is transcription?
the production of an mRNA copy of a gene from DNA - in eukaryotes it takes place in nucleus
What are the stages of transcription?
- RNA polymerase breaks hydrogen bonds between DNA strands unwinding double helix structure
- ons strand used as a template
- free nucleotide bases in nucleus attach to their complementary base pairs (ATP)
- RNA polymerase joins bases together forming mRNA
- when RNA polymerase gone hydrogen bonds reform
What is the result of transcription in prokaryotes and eukaryotes?
- porkaryotes = mRNA
- eukaryotes = pre-mRNA then spliced to mRNA
What is mRNA?
- made in transcription
- short, single polynucleotide strand
- takes genetic code from DNA to ribosomes where proteins are made
What is tRNA?
- involved in translation
- carries amino acids to ribosomes
- single polynucleotide strand folded into clover shape held together by hydrogen bonds
- amino acid binding site
- specific sequence of bases called anticodon
How do 2 polynucleotide strands become a double-helix?
hydrogen bonds form between bases of 2 strands
A-T = 2 hydrogen bonds
C-G = 3 hydrogen bonds
