GENETICS EXAM 3

when DNA changes but there’s no amino acid change and no protein change what mutation is that?

Silent mutation

different amino acid, DNA change, potential protein function change

Missense mutation

STOP codon, completely altered protein, and DNA change

Nonsense Mutation

Insertion/deletion, Shifts reading frame and is usually severe, completely altered protein

Frameshift Mutation

UUA → CUG, What kind of Mutation?

Silent Mutation

no function at all, is what functional mutation

Null

decreased function (partial loss) is what functional mutation?

Hypomorphic

increased function, is what functional mutation?

Hypermorphic

new function, what functional mutation is this?

Neomorphic

increases effect of another mutation, is what functional mutation?

Enhancer mutation

50% → 20% fertility loss is an example of what functional mutation?

enhancer mutation

What does NER (Nucleotide excision) fix?

it fixes bulky damage (UV)

What DNA repair type cuts out BIG chunk?

NER (Nucleotide excision)

What does BER (Base excision) fix?

it fixes small damage

What DNA repair type fixes ONE base?

BER (Base excision)

What does MMR fix?

it fixes replication mistakes

What DNA repair type uses methylation to detect strand?

MMR

What does HR fix?

it fixes the double-strand break

What DNA repair type uses a template?

HR

What does NHEJ fix?

it fixes the double-strand break

What DNA repair type uses NO template and is error-prone?

NHEJ

What does CRISPR use?

Cas9 + guide RNA

If you want RANDOM mutation, what repair type would you use?

NHEJ

If you want SPECIFIC mutation, what repair type would you use?

add template + HR

what type of testing uses bacteria to test mutagens?

Ames Test

what happens when Rat liver extract = activates chemicals

it makes them mutagenic

what is PCR?

Amplifies DNA

when should you use PCR?

Use when: there’s a small amount of DNA and you need LOTS of DNA

what is Sanger Sequencing?

it Determines DNA sequence

what does sanger sequencing use?

Uses ddNTPs to STOP DNA replication because ddNTPs lack 3’ OH so the DNA can’t extend

what does SNoW DRoP mean?

S→D = Southern Blotting is for detecting DNA

N→R = Northern Blotting is for detecting RNA

o→o = doesn’t stand for anything

W→P = Western Blotting is for detecting Protein

What probe does southern blotting use?

DNA

What probe does northern blotting use?

DNA/RNA, gene expression

What probe does western blotting use?

Antibody

What is molecular cloning?

putting a piece of DNA into a vector so it can be copied inside cells

in molecular cloning what is the DNA you care about considered?

gene of interest

in molecular cloning what is a plasmid (circular DNA) in bacteria?

plasmid vector

in molecular cloning what make lots of copies or express the gene?

goal

what does a Plasmid Vector contain?

• Origin of replication (ORI) which allows copying

• Selectable marker which is the antibiotic resistance gene

• Cloning site where your DNA goes

What does the Selectable Marker confirm?

it confirms that the bacteria has a plasmid.

What’s an example of a selectable marker?

ampicillin resistance gene

what is the Host cell (usually bacteria)?

where DNA gets copied

What happens in Step 1: Restriction digestion?

Restriction enzymes cut BOTH the plasmid and gene of interest at specific sequences.

What is physically broken during restriction digestion?

The phosphodiester backbone of DNA.

What happens in Step 2: Ligation?

DNA ligase joins the gene of interest into the plasmid.

What does DNA ligase form?

Covalent bonds between DNA fragments.

What is the product after ligation?

A recombinant plasmid (plasmid + inserted gene).

What happens in Step 3: Transformation?

Bacteria take up plasmid DNA.

Do all bacteria take up plasmids during transformation?

No—only some bacteria take up plasmids.

What happens in Step 4: Selection (antibiotic plate)?

Only bacteria with the plasmid survive.

What does a selectable marker NOT confirm?

It does NOT confirm the gene of interest is inserted.

Why can bacteria survive without the insert?

the plasmid can re-ligate (close) without inserting the gene.

Selection vs Screening?

• Selection = identifies cells with plasmid

• Screening = identifies cells with correct insert

True or False: Selectable marker guarantees gene insertion

false

True or False: All surviving bacteria contain your gene

false

True or False: Selectable marker confirms plasmid uptake

true

What is a mutation?

A change in DNA sequence.

Which repair pathway does CRISPR rely on for random mutations?

NHEJ

Which repair pathway does CRISPR use for precise edits?

HR

What is confounding (confounding variable)?

A hidden factor that influences results, making it unclear what actually caused the effect.

Example of confounding in twin studies?

Twins share environment and you can’t separate genetics against the environment.

What does overinterpreting heritability mean?

Drawing conclusions that go beyond what heritability actually tells you (e.g., saying a trait is “fully genetic”).

Why is overinterpreting heritability a problem?

Ignores environmental effects and differences between populations.

What is biological determinism?

The idea that genes alone determine traits. (Traits = genes + environment)

What are spandrels?

Traits that exist as side effects, not because they were selected for.

What is gene expression?

Turning a gene ON to produce RNA/protein

What is gene repression?

Turning a gene OFF

What is a repressor?

Protein that binds DNA to block transcription

What is a promoter?

DNA region where RNA polymerase binds to start transcription

What is an operator?

DNA site where repressor binds in an operon.

DNA site where repressor binds in an operon.

Gene that prevents uncontrolled cell growth.

What is a proto-oncogene?

Normal gene that promotes cell growth.

What is an oncogene?

Mutated proto-oncogene causing excessive growth.

What does “dominant mutation” mean in cancer?

One mutated copy is enough (oncogenes)

What does “recessive mutation” mean in cancer?

Both copies must be mutated (tumor suppressors).

What is a screening test?

Test used to detect disease early in a population.

What is a diagnostic test?

Test used to confirm a disease

What is a molecular autopsy?

Genetic testing after death to determine cause.

What is pharmacokinetics?

How the body processes a drug (absorption, metabolism).

What is pharmacodynamics?

How the drug affects the body.

What is a quantitative trait?

Trait with continuous variation (many genes + environment)

What is a qualitative trait?

Trait with discrete categories.

What is absolute risk?

Actual chance of developing a condition

What is relative risk?

Comparison of risk between two groups

What is heritability (h²)?

Proportion of variation due to genetic differences

What is genetic variance (Vg)?

Variation due to genes.

What is phenotypic variance (Vp)?

Total variation (genes + environment).

What is allele frequency?

Proportion of a specific allele in a population.

What is genotype frequency?

Proportion of a specific genotype in a population.

What is Hardy-Weinberg equilibrium?

when there is No evolution and the allele frequencies stay constant.

What is genetic drift?

Random change in allele frequency

What is the bottleneck effect?

Sudden population reduction which means less genetic diversity

What is the founder effect?

New population formed by a small group.

What is fitness (w)?

Reproductive success.

What is selection coefficient (s)?

Measure of selection against a trait (s = 1 − w).

What does “concordance” mean?

Both individuals show the same trait

What does “discordant” mean?

Only one individual shows the trait.

What does “fixed allele” mean?

Allele frequency = 1 (everyone has it)

What does “lost allele” mean?

Allele frequency = 0 (gone).

What are the two core hardy-weinberg equations?

• p + q = 1

• p² + 2pq + q² = 1