Genetics Foundations: Chromosomes, Cell Cycle, and Inheritance Patterns

What are sister chromatids?

Identical copies formed during DNA replication, joined at the centromere.

What are homologous chromosomes?

A maternal and paternal pair, same genes but may have different alleles.

What is the function of the centromere?

The DNA region that holds sister chromatids together.

What is the function of the kinetochore?

The protein structure that forms on the centromere and attaches to spindle fibers.

How many chromosomes are present in a diploid organism at this stage?

2

How many chromatids are present in a diploid organism at this stage?

4

How many chromosomes were present prior to DNA replication?

2

How many chromatids were present prior to DNA replication?

2

What are the three main stages of the cell cycle?

Interphase, Mitosis, Cytokinesis.

Why is G0 not included in the phases of the cell cycle?

Cells in G0 have exited the cycle and are not actively preparing to divide.

What happens during S phase of interphase?

DNA is replicated; each chromosome becomes two sister chromatids.

During which phase does the cell prepare for mitosis?

In G2 phase.

What happens during prophase/prometaphase?

Chromosomes condense; nuclear envelope breaks down.

What happens during metaphase?

Chromosomes line up along the center of the cell.

What happens during anaphase?

Sister chromatids separate and move toward opposite poles.

What happens during telophase?

Nuclear envelope reforms; chromosomes decondense.

What happens during cytokinesis?

Cytoplasm divides into two daughter cells.

What is the M checkpoint?

The spindle assembly checkpoint that ensures all chromosomes are properly attached to spindle fibers before separation.

When does the M checkpoint occur?

At the end of metaphase, before anaphase begins.

What could happen if the M checkpoint is bypassed?

The cell could divide with unequal chromosome distribution, leading to aneuploidy.

What protein complex holds sister chromatids together before anaphase?

Cohesin proteins.

What happens if cohesin is non-functional?

Chromatids could separate too early or unevenly, causing chromosome mis-segregation.

What is synapsis and crossing over?

Homologous chromosomes pair and exchange DNA segments during prophase I.

What is independent assortment?

Homologous chromosome pairs align randomly at the metaphase plate during metaphase I.

What happens during anaphase I of meiosis?

Entire homologous chromosomes separate and move to opposite poles.

What is reduction division in meiosis?

The process where the cell goes from diploid to haploid after anaphase I and telophase I.

What is the outcome of meiosis II?

Four genetically distinct haploid gametes are produced.

What is the difference between mitosis and meiosis regarding daughter cells?

Mitosis produces 2 identical diploid daughter cells, while meiosis produces 4 genetically unique haploid gametes.

What is the role of the spindle assembly checkpoint?

To ensure proper attachment of chromosomes to spindle fibers before separation.

What happens during the S phase of the cell cycle?

DNA replication occurs, resulting in sister chromatids.

What is the significance of the G2 phase?

The cell prepares for mitosis by synthesizing proteins and organelles.

What is the significance of the anaphase in mitosis?

Sister chromatids are separated and pulled to opposite poles.

What is the significance of the telophase in mitosis?

Nuclear envelope reforms and chromosomes decondense.

What is the significance of cytokinesis?

It divides the cytoplasm, resulting in two daughter cells.

What is the process that determines the types of gametes formed from a genotype?

Meiosis

What are the possible gametes produced from the genotype AABB?

AB

What are the possible gametes produced from the genotype AaBBgg?

ABg, aBg

What does Mendel's Law of Segregation state?

Alleles for a trait separate during gamete formation, and each gamete receives only one allele.

What are the genotype(s) of the F1 generation when a true-breeding tall pea plant is crossed with a dwarf pea plant?

All are Tt; heterozygous.

What are the phenotype(s) of the F1 generation when a true-breeding tall pea plant is crossed with a dwarf pea plant?

Tall

What are the genotype(s) and phenotype(s) of the offspring when a Tt plant is crossed with a true-breeding dwarf plant?

Genotypes: Tt, tt (1:1); Phenotypes: Tall and Dwarf (1:1).

What is the probability of a child inheriting sickle cell anemia if both parents are carriers?

Yes, they should be concerned because each parent could pass down one recessive allele.

What is the probability of a child inheriting sickle cell anemia if one parent is affected and the other has no family history?

None will be affected, but all will be carriers.

What is the genotype of parents if they have 24 children with a 17:7 ratio of brown to blue eyes?

Both parents are likely heterozygous.

What does Mendel's Law of Independent Assortment explain?

Alleles for different traits are inherited independently.

What is the probability of producing purple, starchy corn kernels from a dihybrid cross?

9/16.

What are the possible genotypes for producing purple, starchy corn kernels?

RRTT, RrTT, RRTt, RrTt.

What is the probability of producing yellow, sweet corn kernels?

1/16.

What are the possible genotypes for producing yellow, sweet corn kernels?

rrtt.

What is the probability of producing guinea pigs with black and rough fur?

9/16.

What are the possible genotypes for guinea pigs with black and rough fur?

BBRR, BbRR, BBRr, BbRr.

What is the probability of producing guinea pigs with white and smooth fur?

1/16.

What are the possible genotypes for guinea pigs with white and smooth fur?

bbrr.

What is the probability of the F1 generation being aa Bb Cc Dd Ee from the parent generation Aa Bb Cc dd Ee and Aa bb Cc Dd ee?

1/64.

What is the probability that a female carrier of hemophilia has a child with a male hemophiliac?

50% affected.

What is the product rule in probability?

Probability of two independent events occurring together.

What is the addition rule in probability?

Probability of either of two mutually exclusive events.

What is the probability of rolling a 2, 4, and 6 on three six-sided dice?

1/216.

What percentage of kittens will be black and male if a calico female cat mates with a black male?

25%.

What percentage of kittens will be calico and male from a calico female cat?

0% (males cannot be calico).

What is the probability that a child of two cystic fibrosis carriers will not have cystic fibrosis?

75%

What is the probability that a child of two cystic fibrosis carriers is a carrier?

2/3

What is the probability that four out of five hatchlings from two heterozygous brown-eyed dragons will have blue eyes?

0.015

What is the null hypothesis for the Chi-square analysis of yellow and green seed phenotypes in peas?

The offspring phenotypes follow the Mendelian 3:1 ratio for a monohybrid cross with complete dominance.

What is the alternative hypothesis for the Chi-square analysis of yellow and green seed phenotypes in peas?

The offspring phenotypes do not follow a 3:1 ratio; deviations are too large to be explained by chance alone.

What conclusion can be drawn from a Chi-square value of 12.328 with 1 degree of freedom?

Reject H₀; the data do not fit the predicted 3:1 Mendelian ratio.

What is the null hypothesis for the inheritance of cotyledon color and pod shape in garden peas?

No significant difference; data fits the phenotypic ratio of complete dominance with no gene linkage.

What is the alternative hypothesis for the inheritance of cotyledon color and pod shape in garden peas?

Significant difference; data shows this cross must be another type of inheritance or the genes are linked.

What conclusion can be drawn from a Chi-square value of 0.36 with 3 degrees of freedom?

Accept H₀; data is consistent with the expected 9:3:3:1 ratio.

How is the rainbow horn trait inherited in unicorns?

It is inherited as autosomal recessive.

What is the probability that a blue-horned unicorn with a rainbow-horned sibling is a carrier?

2/3

If a rainbow-horned unicorn mates with a rainbow carrier, what fraction of their offspring are expected to be rainbow-horned?

1/2 rainbow, 1/2 blue.

What is the most likely inheritance pattern for the extra layer of scales in dragons?

X-linked dominant.

What fraction of daughters and sons would be affected if an affected female (heterozygous) mates with an unaffected male?

Daughters: 1/2 affected, Sons: 1/2 affected.

Could two unaffected parents have an affected child under the X-linked dominant inheritance model?

No, they would produce only unaffected children.

What does a Chi-square test determine in genetics?

Whether deviations between observed and expected values are due to chance.

What is the expected phenotypic ratio for a dihybrid cross in peas?

9:3:3:1.

What is the probability of a child being affected if both parents are carriers for a recessive trait?

25%.

What is the expected ratio of affected to unaffected offspring in a cross between a heterozygous and a homozygous recessive?

1:1.

What is the significance of a Chi-square value greater than the critical value?

It indicates that the observed data significantly deviates from the expected data.

What is the probability of having a calico male kitten from a specific genetic cross?

0%.

What is the expected outcome of a cross between two heterozygous individuals for a trait?

A 3:1 phenotypic ratio.

What does it mean if a trait skips generations in a pedigree?

It suggests that the trait is likely recessive.

What is the expected ratio of phenotypes in a monohybrid cross?

3:1.

What is the significance of observing equal affected males and females in a pedigree?

It suggests the trait is likely autosomal.

What is the expected ratio of offspring from a dihybrid cross with independent assortment?

9:3:3:1.

What is the probability of an unaffected child being a carrier if both parents are carriers?

2/3.

What does a Chi-square value of less than 0.05 indicate?

There is a significant difference between observed and expected values.

What does it mean if a trait shows vertical transmission in a pedigree?

It suggests the trait is likely dominant.