types of mutations and the sources: translation- lecture 3 Flashcards
how can just 4 bases encode 20 amino acids
A triplet code would be the smallest set of four bases capable of encoding all 20 amino acids. In other terms, it is a specific set of three consecutive nucleotides that functions as a part of the genetic code and specifies a certain amino acid in a protein or initiates or terminates protein synthesis
you lose the frame if you remove one or two, but if you remove 3 or add 3 the frame is preserved so it works in 3 amino acids
the genetic code for rna is made of amino acids, and each triplet is called a
codon (64 codons)
1- there are stop codons
2) there are differing levels of redundancy, ranging from 6 (serine) to 1 (methionine)
-most redundancy found in third position of the codon
nirenberg used what for his experiement
poly u
transfer rna
a small RNA molecule that plays a key role in protein synthesis. Transfer RNA serves as a link (or adaptor) between the messenger RNA (mRNA) molecule and the growing chain of amino acids that make up a protein
transfer RNA (tRNA), small molecule in cells that carries amino acids to organelles called ribosomes, where they are linked into proteins
structure: molecules are composed of one short chain of RNA, 70-90 nucleotides in length, folded into a trefoil shape
how does trna work
ribosome
A ribosome is an intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell. The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins
start codon
aug-methionine
initiation of translation in eukaryotes is at the blank prime cap
5’
explain how translation works
are mrna and amino acids to protein 1 to 1 ratio (as in, you can make multiple proteins from one mrna)
no, you can make multiple protein molecules from the same mrna
single nucleotide polymorphism (snips)
A DNA sequence variation that occurs when a single nucleotide (adenine, thymine, cytosine, or guanine) in the genome sequence is altered and the particular alteration is present in at least 1% of the population
which mutations are passed on to the next generation and which ones arent
germ cell mutations are passed on to the next generation while somatic cell mutations arent
what are somatic cells
somatic cells are any cell of a living organism other than the reproductive cells
mutations occurring in somatic cells arent passed on to the next generation (affect the body in which they occur but dont pass on)
mutations in germline cells (cell that generate gametes) are passed on
gamete
a mature male or female germ cell usually possessing a haploid chromosome set and capable of initiating formation of a new diploid individual by fusion with a gamete of the opposite sex
unfertilized reproductive cells (one from each parent, Each of those gametes had 23 chromosomes, so that after the union of those gametes, when you were just a single cell, you had 46 chromosomes. Or, 23 pairs of chromosomes)
zygote
fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell becomes subdivided into smaller cells
why are somatic mutations bad
they dont contribute to future generations but they can be problematic
cancer is caused by the loss of proper cell cycle regulation and may be caused by the accumulation of mutations affecting a few key genes
Somatic & Germline Mutations
Germline mutations are changes to your DNA that you inherit from the egg and sperm cells during conception. Somatic mutations are changes to your DNA that happen after conception to cells other than the egg and sperm
A known mutation causing cystic fibrosis
cystic fibrosis, deletion of amino acid phe (need that amino acid to make sure the molecule is stable enough to leave and get translated, so protein is unstable and degrades before reaching membrane)