Genetics 311 Exam 3

Transition

purine to purine or pyrimidine to pyrimidine

A to G / G to A

T to C / C to T

Transversion

pyrimidine to purine or purine to primidine

A to C / A to T / G to C / G to T

C to A / C to G / T to A / T to G

Missense (Nonsynonymous) (Point)

changes the amino acid (may alter protein function or protein is nonfunctional)

Neutral (Nonsynonymous) (Point)

a missense mutation that doesn’t affect protein function

Nonsense (Point)

changes codon so that it becomes a stop codon

Synonymous (silent) (Point)

codes for the same amino acid, due to Degeneracy

Readthrough (Point)

Stop codon is changed to a codon that codes for amino acid resulting in a longer protein 

Aneuploidy

Chromosome number is not a multiple of the haploid number, an extra or missing chromosome in a cell

Polyploidy

More than 2 “sets” of chromosomes, 2n=46, 3n=12

Deletions

Terminal (Ends) and Interstitial (Middle)

Duplications

a type of mutation where a segment of a chromosome is copied, resulting in extra genetic material.

Tandem Duplications

copied and inserted directly adjacent

Reverse Tandem Duplications

copied and inserted directly adjacent but reversed

Homobrachial Displaced Duplications

A copied segment on the same are of the chromosome

Heterobrachial Displaced Duplications

A copied segment on the other branch of the chromosome

Inversions

A segment of a chromosome becomes inverted within its original position.

Paracentric Inversions

Inverted area does not include centromere, does not change arm ration

Pericentric Inversions

Inverted area does include centromere, can alter arm ratio

Translocations

genetic rearrangements where a piece of one chromosome breaks off and attaches to another or exchanges segments

Reciprocal Translocations

Two Non-homologous chromosomes exchange arms, no gain or loss of DNA

Nonreciprocal Translocations

A segment from one chromosome is moved to a nonhomologous chromosome, no gain or loss

Robertsonian Translocations

Two telocentric chromosomes combine to make one larger, more meta centric chromosome, some DNA loss

Isochromosomes

Two chromosomes joined are homologs

Structural Genes

Encode proteins that are used in metabolism or play a structural role in the cell

Regulatory Genes

Encode products that interact with other sequences and affect the transcription and or translation of these sequences

Regulatory Elements

DNA sequences that are not transcribed, but play a role in regulating other nucleotide sequences.

Positive Control

Regulator protein (Activator) binds to DNA to stimulate transcription.

Negative Control

Regulator protein (Repressor) binds to DNA to prevent transcription

Inducible Control

Transcription is normally off and is turned on when an effector molecule binds the regulatory protein.

Repressible Control

Transcription is normally on and is turned off when an effector molecule binds the regulatory protein.

Class A

A genes control switch to initiate flower development

Whorl 1 and 2

Sepals and Petals

Class B

Whorl 2 and 3

Petals and stamen

Class C

C genes limit the number of whorls in the flower

Whorls 3 and 4

Stamen and carpels

Monosomic

XXYYZ

Nullisomic

XXYY

Double Monosomic

XXYZ

Trisomic

XXYYZZZ

Tetrasomic

XXYYZZZZ

Double Trisomic

XXYYYZZZ

Autotriploid (Let A and B represent sets of chromosomes)

(AAA)

Allotriploid (Let A and B represent sets of chromosomes)

(AAB)

Autotetraploid (Let A and B represent sets of chromosomes)

(AAAA)

Allotetraploid (Let A and B represent sets of chromosomes)

(AABB)

One gene, One Polypeptide. Why?

Some enzymes have more than one polypeptide

Mutation in one gene seems to interfer with only one reaction

Point Mutation

Results in substitution of one base pair for another

Frameshift Mutation

Occurs in DNA, event leading to the insertion or deletion of one or more base pairs in the gene, shifting the reading frame in all codons, changing stops and starts

Trp Operon under what control?

Negative Repressible