BIOL 1115 CHAPTER 16

What is the central dogma?

DNA ----> RNA ----> PROTEIN

What is transcription?

- the process of using a DNA template to make a complementary RNA

What is translation?

- the process of using the information in mRNA to synthesize a protein

What is reverse transcriptase?

- synthesizes DNA from an RNA template

- information flow is: RNA → DNA

How many amino acids are there? How many nucleotides are there in DNA?

- 20 amino acids

- 4 nucleotides

What is the triplet code?

- series of non-overlapping, three-nucleotide words

What are the traits of the genetic code?

- redundant but not ambiguous

- conservative

What are the 5 traits of the genetic code and what are their definitions?

1. Redundant = multiple codons can code for the same amino acid

2. Unambiguous = each codon specifies only one amino acid

3. Non-overlapping = there is no overlap between triplet codes; each triplet code is separate from the other triplets in the chromosome

4. Nearly universal = the same genetic code is used by almost all living organisms on Earth

5. Conservative = if the first two base pairs of the mRNA are the same but the third is different, there is a high likelihood (but not an absolute certainty), that the will code for the same amino acid

What is a mutation? What are the 2 types of mutations?

- any permanent change in an organism's DNA

1. Point mutations

2. Chromosome-level mutations

What 3 impacts can mutations have?

1. Beneficial - increase fitness of an organism

2. Neutral - do not affect an organism's fitness

3. Deleterious - decrease fitness of an organism

What are the 3 point mutations?

1. Silent mutation - have no effect on the amino acid produced by a codon because of redundancy in the genetic code

2. Missense mutations - code for a different amino acid

3. Nonsense mutations - change an amino acid codon into a stop codon

- when the stop codon is encountered, translation stops, resulting in a truncated polypeptide

- nearly all truncated proteins are nonfunctional and unstable

What effects can chromosome mutations have?

- may change chromosome number or structure

What term is used to describe a cell that has too many or too few chromosomes?

- aneuploidy

What term is used to describe cells that have too many sets of chromosomes?

- polyploidy

What is inversion?

- a segment of a chromosome breaks off, flips around, and rejoins

What is translocation?

- A section of a chromosome breaks off and becomes attached to another chromosome