DNA to Protein Translation and Mutation

Define mRNA

Messenger RNA directs synthesis of protein (has uracil instead of thymine)

Define rRNA

Ribosomal RNA joins with ribosomal proteins to make ribosomes

Define tRNA

Transfer RNA binds to an amino acid and holds it in place on a ribosome until it is incorporated into a protein during translation

One end binds with amino acid and the other has an anticodon (matches to codon on mRNA)

Describe process of transcription

An RNA polymerase copies a specific region of DNA is transcribed to produce an mRNA strand

Describe process of translation

mRNA leaves the nucleus and attaches to a ribosome (large and small ribosomal subunit joint to form bonding site) - strand is translated into a sequence of amino acids to form a protein

Read in base triplets (codon) and each codon corresponds to a specific amino acid

Define genetic code

The set of rules that relate the base triplet sequence of DNA to the corresponding codons of RNA and the amino acids they specify

State the start and stop codon/s

Start = AUG

Stop = UAA, UAG and UGA (no matching transfer RNA anticodon)

Define mutation

Changing in DNA sequence for a gene (can be single or multiple nucleotides changed, or a loss/gain of nucleotide/s)

State outcomes of mutations (changed nucleotide/s)

Produce a functional protein

Produce a protein that does not function to full extent

Cannot produce functional protein or an insufficient amount of protein

State outcome of mutations (loss/gain of nucleotide/s)

Wrong protein produced or early STOP codon - produce protein that will not likely function

Are mutations lethal?

Mutations are often lethal if it changes necessary protein products, however, if its not lethal, it stays in the population as a new allele

Describe dominant vs recessive inheritance

Phenotype will express the dominant allele and mask expression of recessive allele (when alleles are heterozygous)

Only one dominant allele needs to be present to express dominant trait

Must be homozygous recessive to show recessive trait

Dominant = capital letter, recessive = lower case letter

Define co-dominance

When two alleles are dominant over a recessive allele (both phenotypes of dominant alleles are expressed

Define sex-linked mutation

Sex-linked mutations are disease alleles present on the X-chromosome

Describe sex-linked mutations

Can be inherited by both males and females

Most are recessive (therefore, more likely in males because they don’t have a second X chromosome to potentially cancel out the disease allele)

Define a carrier

Person who has dominant normal allele but carries recessive disease allele (usually females)