DNA, genes and protein synthesis Flashcards
What is a locus?
Position of a gene on a chromosome
What does it mean that the genetic code is degenerate?
Most amino acids are coded for by more than one triplet
What does it mean that the genetic code is universal?
The same triplet codes for the same amino acid in all organisms.
What does it mean by the genetic code is non-overlapping?
Adjacent codons do not overlap, so each base is only part of one codon and read only once.
What is a histone?
Proteins that DNA wraps around to make chromatin.
What is the difference between a chromosome and a chromatid?
A chromosome is one molecule of DNA. A chromatid is half the chromosome when it has been copied and is held to another chromatid by centromere.
What is a homologous pair?
Two chromosomes that carry the same genes, each from a different parent
What is an allele?
Version of a gene so it is occupied at the same locus
What is DNA wrapped around in prokaryotes?
Not associated with proteins but wraps tightly around itself.
What are the differences beween DNA and mRNA?
mRNA is single stranded, mRNA has uracil, has no hydrogen bonds. The pentose sugar in mRNA is ribose and is smaller than DNA
Give one way that tRNA is like DNA
Both have hydrogen bonds
What are the two enzymes involved in transcription and their function?
DNA helicase separates the two strands by breaking hydrogen bonds.
RNA polymerase adds RNA nucleotides together by joining the sugar phosphate backbone
What happens between transcription and translation?
Splicing of pre-mRNA to make mRNA. This removes introns
Where does translation take place?
Ribosomes in the cytoplasm
How many tRNA molecules bind to the mRNA transcript at any time?
3
What is the role of the tRNA molecule?
Carry amino acids and bind to the complementary codon sequence
What is the role of ribosomes?
Allow the amino acids carried by tRNA molecule to come close enough to each other to form a polypeptide chain.
What is the anticodon?
Sequence of bases on the tRNA which complementary base pairs to a specific sequence on the mRNA and it also determine which amino acid tRNA will carry
How is ATP used in protein synthesis?
To attach an amino acid to tRNA and to form the peptide bond between two amino acids
What is a polysome?
Multiple ribosomes translating the same molecule of mRNA
