Genetics and Sex Determination Quiz

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Questions and Answers

What is the likelihood that offspring from a BbCc x bbcc cross will have both white fur and black eyes?

50%

10%

25% (correct)

75%

Which gene pairs are most likely to be linked?

G and H with an RF of 15%

A and B with an RF of 10%

E and F with an RF of 30%

C and D with an RF of 2.5% (correct)

What type of bonds form between complementary nitrogenous bases in DNA?

Ionic bonds

Covalent bonds

Peptide bonds

Hydrogen bonds (correct)

What is the source of energy used to form phosphodiester bonds in DNA?

Hydrolysis of nucleotide triphosphates Signup and view all the answers

Why is DNA replication referred to as semi-conservative?

Each new molecule consists of both old and new strands Signup and view all the answers

Which of the following is NOT a potential result of errors during DNA replication?

Protein synthesis enhancement Signup and view all the answers

Which part of a nucleotide identifies it as a deoxyribonucleotide?

Deoxyribose sugar Signup and view all the answers

Which enzyme is primarily responsible for synthesizing new DNA strands during replication?

DNA polymerase Signup and view all the answers

What role does the Cas9 enzyme play in gene editing?

It makes a cut in the DNA for editing purposes. Signup and view all the answers

How do bacteria typically obtain antibiotic resistance?

By mutation and horizontal gene transfer. Signup and view all the answers

What method is used to determine the antibiotic susceptibility of bacteria?

Disk diffusion method or Kirby-Bauer test Signup and view all the answers

What is the impact of injecting human genes into bacteria for hormone production?

It allows for mass production of critical hormones. Signup and view all the answers

How does herd immunity protect vulnerable populations?

By reducing pathogen spread through community vaccination. Signup and view all the answers

Which characteristic of vaccines enables them to prevent severe infections?

They train the immune system to recognize pathogens. Signup and view all the answers

What immediate action does innate immunity take against pathogens?

It offers a fast, non-specific defense mechanism. Signup and view all the answers

What accelerates the development of antibiotic resistance in bacteria?

Overuse of antibiotics in medical settings. Signup and view all the answers

What is a major advantage of sexual reproduction?

Genetic diversity for better adaptation Signup and view all the answers

Which sex-determination system is NOT found in sexually reproducing organisms?

XX system Signup and view all the answers

How did the Y chromosome evolve according to scientific understanding?

From an ordinary autosome that lost genes Signup and view all the answers

What is the primary reason that X and Y chromosomes do not typically cross over during meiosis?

They are largely non-homologous except for small regions Signup and view all the answers

In a Bb x bb mouse cross, what is the probability of producing an offspring with a white fur genotype?

50% Signup and view all the answers

Which of the following is NOT a disadvantage of sexual reproduction?

Faster population growth Signup and view all the answers

Which reproductive mechanism is one way sex determination has evolved in certain species?

Environmental temperature dependency Signup and view all the answers

What elements are primarily lost from the Y chromosome during its evolution?

Protein coding genes Signup and view all the answers

Study Notes

Genetics

Sexual reproduction introduces genetic diversity; essential for adaptation.
Recombination of genes during meiosis creates unique offspring.
Sexual reproduction is energetically costly, requires a mate; slower population growth than asexual reproduction.
Potential for passing on genetic mutations or harmful alleles.

Sex Determination

Not all sexually reproducing organisms have XY chromosomes.
Mammals use XY; other organisms use different systems (ZW, temperature-dependent).
Y chromosome evolved from an autosome, lost genes, became smaller.
X and Y chromosomes typically do not cross over during meiosis, except in pseudoautosomal regions (PARs).

Mouse Crosses

White fur in a Bb x bb cross has a 50% probability.
Probability of white fur and black eyes in a BbCc x bbcc cross is 25%.

Pedigrees

Pedigrees analyzed for dominant, recessive, autosomal, or sex-linked inheritance patterns.
Autosomal recessive disorder appears in offspring when both parents are carriers.

DNA Replication and Transcription

Nucleotides bond through hydrogen bonds (A-T, G-C).
Energy for phosphodiester bonds comes from hydrolysis of nucleotide triphosphates.
DNA replication is semi-conservative (one old, one new strand).
Tautomeric shifts can cause mispairing during DNA replication.
DNA replication errors can lead to mutations (point mutations, insertions, deletions).
Single-stranded binding proteins (SSBs) prevent DNA reannealing.
Helicase unwinds DNA; primase synthesizes RNA primers.

Gene Regulation in Prokaryotes

Lac operon is in prokaryotes like E. coli.
Default state is off; repressor blocks transcription.
Lactose inactivates repressor; RNA polymerase transcribes operon.
Glucose suppresses transcription.
7 ways gene expression can be regulated: DNA methylation, histone modification, transcription factors, RNA splicing, mRNA stability, translation control, protein modification.

Cell Differentiation

Process by which a cell becomes specialized to perform a specific function.
Selective expression of genes.

Stem Cells

Embryonic stem cells are pluripotent (differentiate into almost any cell type).
Adult stem cells are multipotent; differentiate into a limited cell type.
Induced pluripotent stem cells (iPSCs) are adult cells reprogrammed to be pluripotent.

CRISPR-Cas9

Bacterial immune system adapted for gene editing.
Guide RNA targets specific DNA sequences.
Cas9 enzyme cuts DNA; allows for gene editing.

Gene Technology for Hormones

Gene technology produces hormones (e.g., insulin, human growth hormone).
Mass production possible.

Antibiotic Resistance

Bacteria develop resistance through mutations and acquiring resistance genes.
Horizontal gene transfer (conjugation, transformation, transduction) spreads resistance quickly.
Overuse of antibiotics accelerates this process.

Vaccines

Vaccines train immune system to recognize and remember pathogens.
Vaccinations create herd immunity, protecting immunocompromised individuals.
Innate immunity provides immediate, non-specific defense.
Adaptive immunity involves specialized responses through B and T cells.

Bacterial Susceptibility Testing

Disk diffusion or Kirby-Bauer test identifies bacteria's antibiotic susceptibility.
Zones of inhibition indicate susceptibility or resistance based on bacterial growth response.

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Description

Test your knowledge on genetics, sexual reproduction, and sex determination systems. This quiz covers gene recombination, probability in mouse crosses, and analyzing pedigrees for inheritance patterns. Challenge yourself to understand how these concepts contribute to genetic diversity and evolution.