MCB181R Exam 2 Review

Q: What is the central dogma of molecular biology?

A: The flow of genetic information from DNA to RNA to protein.

Q: What is a chromosome?

A: A structure composed of DNA and proteins that carries genetic information.

Q: What role do chromosomes play in cells?

A: They store and organize genetic material, ensuring accurate DNA replication and distribution during cell division.

Q: How do eukaryotic and prokaryotic chromosomes differ?

A: Eukaryotic chromosomes are linear and found in the nucleus, while prokaryotic chromosomes are circular and found in the cytoplasm.

Q: What is the relationship between chromosomes, DNA, genes, alleles, proteins, and traits?

A: DNA makes up chromosomes, which contain genes. Genes have alleles that determine protein production, influencing traits.

Q: What does it mean for a gene to be associated with a disease?

A: A mutation or variation in the gene can contribute to the development of a disease or disorder.

Q: What are homologous chromosomes?

A: A pair of chromosomes, one from each parent, that contain the same genes but may have different alleles.

Q: What are sister chromatids?

A: Identical copies of a chromosome connected by a centromere, formed during DNA replication.

Q: How do homologous chromosomes differ from sister chromatids?

A: Homologous chromosomes have the same genes but may have different alleles, while sister chromatids are identical copies of the same chromosome.

Q: What is a karyotype?

A: A visual representation of an organism's chromosomes arranged by size and shape.

Q: How can a karyotype be used?

A: To detect chromosomal abnormalities such as extra or missing chromosomes.

Q: What is ploidy?

A: The number of sets of chromosomes in a cell.

Q: What is the difference between haploid and diploid cells?

A: Haploid cells have one set of chromosomes (n), while diploid cells have two sets (2n).

Q: What is the purpose of mitotic cell division?

A: To produce genetically identical cells for growth, repair, and asexual reproduction.

Q: How do chromosomes behave during mitosis?

A: They replicate, align at the cell's center, separate, and move into daughter cells.

Q: What is the role of mitosis in single-celled organisms?

A: It allows them to reproduce asexually.

Q: What is the role of mitosis in multicellular organisms?

A: It enables growth, tissue repair, and replacement of dead cells.

Q: How do chromosomes move during meiosis?

A: They undergo two rounds of division, separating homologous chromosomes first, then sister chromatids.

Q: What is the end result of mitosis?

A: Two genetically identical diploid daughter cells.

Q: What is the end result of meiosis?

A: Four genetically unique haploid gametes.

Q: What types of cells are produced by meiosis?

A: Gametes (sperm and egg cells).

Q: What are somatic cells?

A: Body cells that undergo mitosis and contain a diploid number of chromosomes.

Q: What are germ cells?

A: Cells in the reproductive organs that undergo meiosis to produce gametes.

Q: What is crossing over, and when does it occur?

A: The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Q: What is aneuploidy?

A: An abnormal number of chromosomes in a cell, often due to errors in meiosis.

Q: What causes aneuploidy?

A: Nondisjunction, the failure of chromosomes to separate properly during meiosis.

Q: How does meiosis relate to inheritance?

A: It ensures that offspring inherit one allele per gene from each parent.

Q: How can you trace alleles through meiosis?

A: By following homologous chromosomes as they separate and form gametes.

Q: What is genotype?

A: The genetic makeup of an organism, represented by allele combinations.

Q: What is phenotype?

A: The physical expression of a trait based on an organism's genotype.

Q: How are genotype and phenotype related?

A: Genotype determines phenotype, but environmental factors can also influence traits.

Q: What does it mean to be homozygous for a gene?

A: Having two identical alleles for a particular gene (e.g., AA or aa).

Q: What does it mean to be heterozygous for a gene?

A: Having two different alleles for a particular gene (e.g., Aa).

Q: What is a dominant allele?

A: An allele that is expressed in the phenotype even if only one copy is present.

Q: What is a recessive allele?

A: An allele that is only expressed if two copies are present.

Q: How does a Punnett square help predict inheritance?

A: It shows possible allele combinations in offspring from parental genotypes.

Q: What is a pedigree?

A: A chart that tracks inheritance patterns of traits within a family.

Q: What does a filled-in circle or square represent in a pedigree?

A: An individual who expresses the trait being studied.

Q: What is a sex-linked trait?

A: A trait controlled by genes on the X or Y chromosome.

Q: Why do males more frequently express X-linked recessive traits?

A: Males have only one X chromosome, so they cannot mask a recessive allele.

Q: What is codominance?

A: A pattern of inheritance where both alleles are fully expressed in the phenotype (e.g., AB blood type).

Q: What is incomplete dominance?

A: A pattern of inheritance where the heterozygous phenotype is a blend of both alleles (e.g., red + white = pink flowers).

Q: What is a classic Mendelian trait?

A: A trait that follows Mendel's laws of inheritance, typically involving one gene with dominant and recessive alleles.

Q: What is the significance of meiosis in sexual reproduction?

A: Meiosis creates genetic diversity by shuffling alleles and reducing chromosome number, essential for forming gametes in sexual reproduction.

Q: How do sex chromosomes differ from autosomes?

A: Sex chromosomes determine an individual's sex (X and Y chromosomes), while autosomes are all other chromosomes that do not determine sex.

Q: What is the difference between somatic cells and gametes?

A: Somatic cells are body cells with a diploid chromosome number, while gametes are reproductive cells with a haploid chromosome number.

Q: What is the function of DNA in cells?

A: DNA contains the instructions for the development and functioning of all living organisms.

Q: What is a gene?

A: A segment of DNA that codes for a specific protein or trait.

Q: What is an allele?

A: A variant form of a gene that can influence the expression of a trait.

Q: What is the difference between homozygous and heterozygous?

A: Homozygous means having two identical alleles for a gene, while heterozygous means having two different alleles for a gene.

Q: What is the role of mitosis in cell division?

A: Mitosis is responsible for producing two genetically identical daughter cells.

Q: What are the stages of mitosis?

A: Prophase, metaphase, anaphase, and telophase.

Q: What occurs during prophase of mitosis?

A: Chromosomes condense, and the nuclear envelope breaks down.

Q: What occurs during metaphase of mitosis?

A: Chromosomes line up at the cell's equator.

Q: What occurs during anaphase of mitosis?

A: Sister chromatids are pulled apart to opposite sides of the cell.

Q: What occurs during telophase of mitosis?

A: The nuclear envelope reforms around the separated chromatids, and the cell begins to divide.

Q: What is cytokinesis?

A: The division of the cytoplasm to form two daughter cells after mitosis.

Q: What is the role of meiosis in sexual reproduction?

A: Meiosis reduces the chromosome number by half, producing gametes for reproduction.

Q: How does meiosis differ from mitosis?

A: Meiosis produces four genetically diverse haploid cells, while mitosis produces two identical diploid cells.

Q: What is a gamete?

A: A haploid cell, such as sperm or egg, involved in sexual reproduction.

Q: What is a somatic cell?

A: Any cell of the body that is not a gamete, typically diploid.

Q: What are the two types of cell division in humans?

A: Mitosis and meiosis.

Q: What does a diploid cell contain?

A: Two sets of chromosomes, one from each parent.

Q: What does a haploid cell contain?

A: One set of chromosomes, half the number found in diploid cells.

Q: What is a genotype?

A: The genetic makeup of an organism, represented by its allele combinations.

Q: What is a phenotype?

A: The physical expression or traits of an organism, based on its genotype.

Q: What is the purpose of a Punnett square?

A: To predict the possible genetic outcomes of a cross between two individuals.

Q: What is a recessive allele?

A: An allele that is only expressed when two copies are present.

Q: What is a dominant allele?

A: An allele that is expressed in the phenotype even if only one copy is present.

Q: What does it mean for a gene to be linked?

A: Genes that are located close together on the same chromosome tend to be inherited together.

Q: What is a pedigree used for?

A: To track inheritance patterns of traits within a family over multiple generations.

Q: What does a filled square or circle mean in a pedigree?

A: An individual who expresses the trait being studied.

Q: What is a sex-linked trait?

A: A trait determined by a gene located on the X or Y chromosome.

Q: Why are males more likely to express X-linked traits?

A: Because they have only one X chromosome and cannot mask the recessive allele.

Q: What is codominance?

A: A form of inheritance where both alleles are equally expressed in the phenotype.

Q: What is incomplete dominance?

A: A pattern of inheritance where the heterozygous phenotype is a blend of both alleles.

Q: How can genetic variation occur during sexual reproduction?

A: Through the combination of different alleles from two parents and through genetic recombination.

Q: What is the role of meiosis in genetic diversity?

A: It introduces genetic variation through recombination and the independent assortment of chromosomes.

Q: What is the purpose of fertilization?

A: To combine the genetic material from two gametes to form a new organism.

Q: What is aneuploidy?

A: A condition in which a cell has an abnormal number of chromosomes.

Q: What causes aneuploidy?

A: Errors in chromosome separation during meiosis, known as nondisjunction.

Q: How can genetic disorders be inherited?

A: Through dominant, recessive, or sex-linked inheritance patterns.

Q: What is a Mendelian trait?

A: A trait that follows the simple inheritance patterns of dominance and recessiveness.

Q: What does it mean to be homozygous dominant?

A: Having two copies of the dominant allele for a gene.

Q: What is a hybrid genotype?

A: A genotype that contains one dominant allele and one recessive allele (heterozygous).

Q: How does the environment influence phenotype?

A: Environmental factors, such as nutrition and temperature, can impact gene expression and phenotype.

Q: What does it mean for an allele to be expressed?

A: The allele is shown in the organism's physical characteristics or phenotype.

Q: What is the importance of meiosis in maintaining chromosome number?

A: Meiosis halves the chromosome number in gametes, ensuring that the fertilized egg restores the diploid number.

Q: What is the difference between genotype and phenotype?

A: Genotype is the genetic code, while phenotype is the physical trait expressed by the genotype.

Q: How can a pedigree help identify inheritance patterns?

A: By showing the relationships between family members and how traits are passed down through generations.

Q: How does incomplete dominance differ from codominance?

A: In incomplete dominance, the traits blend in the heterozygote, while in codominance, both traits are fully expressed.