genetics final...

AAAAH

aneuploidy

one extra or missing chromosome

polyploidy

extra full sets of chromosomes (that is, every single chromosome has an extra copy, not just one)

Why is polyploidy less deleterious than aneuploidy?

Because all the product concentrations are increasing together, so genetic balance is still present. In aneuploidy, there is genetic imbalance

Why does chromosome size affect effects of aneuploidy?

Smaller chromosomes have less genes and so less genetic imbalance.

How are chromosomes numbered?

By size

Does X aneuploidy have an effect on gene expression?

Not much because X inactivation of all but one copy occurs usually. Sometimes the extra copy will evade X inactivation but symptoms are mild

Why are polyploidic plants advantageous in agriculture?

They have more DNA and to accommodate that the cells are bigger so the plants are bigger

What polyploids can make viable gametes?

2n

What polyploids can’t make viable gametes?

2n+1

Which arm is the long arm?

Q arm

Which arm is the short arm?

P arm

Pericentric inversion

break and inversion includes centromere

Paracentric inversion

break and inversion does not include centromere

What are two reasons inversions can disrupt gene function?

Interruption of a gene at the breakpoint, or movement of an enhancer farther from the gene in a way that it cannot do what it is supposed to

Alternate segregation

You either get 2 non-translocated chromosomes and everything is awesome, or you get 2 translocated chromosomes that balance each other out and everything is oh-so-chill

Adjacent segregation I, 50%

You get 2 centromeres, 1 from chromosome A and 1 from B (as you should), but either A or B is translocated with a segment of the other and the normal one is, well, normal. So you have duplication of the translocated region which is not good

Adjacent segregation, rare

Both centromeres come from 1 chromosome, either A or B, and you get a LOOOOT of either chromosome whichever one it is

Name three things supporting the endosymbiotic theory.

Mitochondria and chloroplasts don’t have the histone activity present in eukaryotes, and neither do prokaryotes.

Mitochondria and chloroplasts have prokaryotic transcriptional and translational machinery not found in cell nuclei.

Organelle genome is circular as opposed to the linear nucleic genome.

How does heteroplasmy arise?

Prokaryotic DNA polymerase doesn’t proofread nearly as much as eukaryotic and mtDNA is 10x as likely to mutate and pass on the mutation.

Why might these mtDNA mutants stick around?

Hyperproduction to compensate for reduced function. The same way if your alcohol is lower concentration you have to drink more of it

Or shorter mtDNA (deletion mutants) replicate faster

Or ya know. Random chance at replication

What type of effect do mtDNA mutations most commonly have?

Muscular dystrophy, usually heart, eyes, and other muscles

If a mutation is paternally imprinted, is it silenced or active when passed down from the father?

SILENCED

Where does methylation of a gene change depending on the sex of the individual it is in?

during gametogenesis

What reproductive difference accounts for the difference between the maternal and paternal haploid genomes?

The maternal genome primarily evolves to protect the health of the mother and conserve her resources, while the paternal one primarily evolves to protect the health of the child because his purpose is mainly to reproduce strong offspring.

Example: 2 maternal pronuclei give a poor placenta because they are conserving the mother’s resources instead of giving them to child. Paternal pronuclei give good placenta and poor embryo because placenta is meant to give offspring nutrients and protect it rather than the mother.

What sequence usually gets methylated?

5’-CpG-3’ (C next to G, with p representing connecting phosphate group)

How do methylation patterns that were inherited stay maintained in the offspring?

DNA methyltransferase follows behind DNA polymerase during synthesis and matches the methylation on the parent strand.

1˚ DMR, ICR

imprinting control region, which is methylated in the gametes

2˚ DMR

secondary DMR, which is methylated after fertilization based on the methylation pattern at the ICRs

What is responsible for the G1-S checkpoint to be fulfilled?

CDK-cyclin complexes which phosphorylate RB which then stops inhibiting E2F and lets it continue with S phase of the cell cycle

What happens if the DNA is damaged?

p53 is activated, activates p21, which inhibits the CDK-cyclin complex responsible for phosphorylating RB and halts the cell cycle

What triggers p53 activation?

UV or radiation damage to DNA

What type of gene is p53?

Transcription factor

Why is p53 relevant to cancer?

When p53 is mutated the cell cycle cannot halt with mutated DNA, so cells divide uncontrollably and accumulate mutations

What class of gene is p53? (not type)

Tumor suppressor gene

What is a proto-oncogene?

gene that stimulates cell growth and division

What happens to a proto-oncogene when it is mutated?

It creates mutant that is overexpressing growth factor and causing unnecessary cell division.

Are proto-oncogene mutations dominant or recessive?

Dominant

Why are they dominant?

Gain-of-function mutation: excessive function as opposed to loss of function

How do viruses cause cancer?

Viral genomes hide in host genome, when it is excised some host genome goes with it, which then gets transmitted into ANYTHING the virus affects. In a virus, host genome proto-oncogenes can mutate easily and become dominant oncogenes

Are tumor suppressor mutations dominant or recessive?

Recessive

Cause for cancer specificity of tumor suppressor mutations?

tissue-specificity of gene expression, such as ESR1, or environmental effects such as UV damage to skin over other organs

Signs of familial cancer?

Relatives with same type of cancer

Vertical transmission of cancer

Cancer at early age

Bilateral cancer

Multiple types of cancer

Atypical sex

Can you inherit a cancer?

No, only a predisposition for cancer.