exam 3

What is the p arm?

Short arm of chromosome

What is the q arm?

Long arm of chromosome

What is the centromere?

Region where sister chromatids are held together

What determines chromosome morphology?

Centromere position

Metacentric chromosome?

Centromere in middle (equal arms)

Submetacentric?

Slightly off center

Acrocentric?

Very off center (one very short arm)

Telocentric?

Centromere at end

What are the 4 structural mutations?

Deletion, duplication, inversion, translocation

Deletion = ?

Loss of DNA segment

Duplication = ?

Extra copy of DNA segment

Inversion = ?

Segment flipped 180°

Translocation = ?

Segment moved to another chromosome

Which mutations change DNA amount?

Deletion + duplication

Which changes orientation?

Inversion

Which changes location?

Translocation

Why is deletion irreversible?

DNA is lost

Acentric chromosome?

Missing centromere

Cri-du-chat cause?

Deletion of chromosome 5

Cri-du-chat key feature?

Cat-like cry

Prader-Willi cause?

Deletion on chromosome 15

Prader-Willi symptom shift?

Poor feeding → overeating

Tandem duplication?

Copy placed next to original

Reverse tandem?

Copy reversed

Terminal duplication?

Copy at end of chromosome

What is gene dosage?

Amount of gene product

Why are duplications harmful?

Unbalanced gene dosage

Paracentric inversion?

Does NOT include centromere

Pericentric inversion?

Includes centromere

Do inversions lose DNA?

No

What forms in meiosis with inversion?

Inversion loop

Nonreciprocal translocation?

One-way transfer

Reciprocal translocation?

Exchange between chromosomes

What structure forms in meiosis?

Cross-shaped configuration

Alternate segregation result?

Normal/balanced

Adjacent segregation result?

Unbalanced

What happens to small fragment?

Lost

What is a Robertsonian translocation?

Fusion of chromosomes + loss of small fragment

Aneuploidy?

Gain/loss of individual chromosomes

Euploidy?

Change in full sets

Trisomy?

2n + 1

Monosomy?

2n - 1

Tetrasomy?

2n + 2

Nullisomy?

2n - 2

Polyploidy?

More than 2 sets

Autopolyploidy?

Same species

Allopolyploidy?

Different species

Allotriploid?

3 sets from different species

Autotriploid?

3 sets from same species

Transition?

Purine ↔ purine OR pyrimidine ↔ pyrimidine

Transversion?

Purine ↔ pyrimidine

Silent mutation?

Same amino acid

Missense?

Different amino acid

Nonsense?

Stop codon

Frameshift?

NOT multiple of 3

In-frame?

Multiple of 3

Suppressor mutation?

Masks another mutation

Intragenic suppressor?

Same gene

Intergenic suppressor?

Different gene

Replication model?

Semiconservative

Direction of synthesis?

5’ → 3’

Leading strand?

Continuous

Lagging strand?

Discontinuous

Okazaki fragments?

Short DNA fragments

Helicase?

Unwinds DNA

SSB proteins?

Prevent re-annealing

Gyrase (topoisomerase)?

Relieves supercoiling

Primase?

Makes RNA primer

DNA pol III?

Adds DNA nucleotides

DNA pol I?

Removes primers + replaces

Ligase?

Seals backbone

Tautomeric shift?

Base form change → mispairing

Depurination?

Loss of purine

Strand slippage?

Insertions/deletions

Radiation effect?

Increases mutations

Pyrimidine dimer?

T-T bonding blocks replication

Frameshift ALWAYS causes?

Major protein change

Which mutation is LEAST harmful?

Silent

Which mutation stops protein early?

Nonsense

Which mutation subtly changes protein?

Missense

Duplication vs trisomy difference?

Duplication = DNA segment → Trisomy = whole chromosome

Allotriploid chromosome count formula?

(n₁ + n₂ + n₃)