dna, rna and protein synthesis Flashcards
What is eukaryotic DNA?
Eukaryotic DNA consists of linear DNA molecules that exist as chromosomes, wound around proteins called histones, which help to support DNA. The DNA and proteins are then coiled very tightly to make compact chromosomes.
What is prokaryotic DNA?
Prokaryotic DNA also carries DNA as chromosomes, but the DNA is shorter and circular. It has no histones and condenses by supercoiling.
What is a gene?
A gene is a sequence of DNA bases that codes for either a polypeptide or functional RNA. Each amino acid in a polypeptide is coded by 3 bases in a gene called a triplet.
What are introns?
Introns are sections in genes that code for polypeptides but do not code for amino acids. The coding sections are called exons, and introns are removed during protein synthesis.
What are alleles?
Alleles are different forms of a gene. The order of bases in each allele is different, leading to the coding of different polypeptide chains.
How many chromosomes do humans have?
Humans have 23 pairs of chromosomes, with pairs of matching chromosomes called homologous pairs.
What is messenger RNA (mRNA)?
mRNA is made during transcription and carries the genetic code from the DNA to the ribosomes for protein synthesis. It is a single polynucleotide strand with groups of 3 bases called codons.
What is transfer RNA (tRNA)?
tRNA carries amino acids to the ribosomes for protein synthesis. It is a single polynucleotide strand folded into a clover shape, with specific sequences of 3 bases at one end called an anticodon.
What is transcription?
Transcription is the process where RNA polymerase attaches to DNA at the start of a gene, breaks hydrogen bonds, and uses one strand as a template to form mRNA.
What happens during transcription in eukaryotes?
In eukaryotes, both introns and exons are copied into mRNA. A process called splicing occurs, where introns are removed and exons are joined together in the nucleus.
What happens during transcription in prokaryotes?
In prokaryotes, mRNA is produced directly from DNA, and there are no introns in prokaryotic DNA.
What is translation?
Translation is the process where mRNA attaches to a ribosome, tRNA carries amino acids to it, and peptide bonds form between amino acids to create a polypeptide chain.
What does it mean that the genetic code is non-overlapping?
The genetic code is non-overlapping, meaning each base triplet is read in sequence, separate from the triplet before and after it.
What does it mean that the genetic code is degenerate?
The genetic code is degenerate, indicating that there are more possible combinations of triplets than there are amino acids, so some amino acids can be coded for by more than one base triplet.
What does it mean that the genetic code is universal?
The genetic code is universal, meaning the same specific base triplets code for the same amino acids in all living organisms.
