Biology Chapter 13-14 Flashcards

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Questions and Answers

What are genes?

Genes are segments of DNA located on chromosomes that determine distinct traits.

What are alleles?

An allele is an alternative form of a gene located at a specific position on a chromosome.

What is the purpose of mitosis?

Mitosis produces identical cells with a complete set of DNA.

What is the purpose of meiosis?

Meiosis produces gametes, or sex cells, such as sperm and eggs. Signup and view all the answers

What are the subphases of interphase?

G1, S, and G2. Signup and view all the answers

Name the subphases of mitosis.

Prophase, Metaphase, Anaphase, Telophase. Signup and view all the answers

What is asexual reproduction?

A mode of reproduction where offspring arise from a single parent. Signup and view all the answers

What is an autosome?

Any chromosome not involved in sex determination. Signup and view all the answers

What are sex chromosomes?

Chromosomes usually designated X or Y, determining sex and sex-linked characteristics. Signup and view all the answers

Who is Gregor Mendel?

The 'father of genetics' who formulated the Law of Segregation. Signup and view all the answers

What is the restriction point in the cell cycle?

It is a point where the cell decides to proceed with the cell cycle or not. Signup and view all the answers

What is a Barr body?

An inactive X chromosome. Signup and view all the answers

What is a centrosome?

An organelle that serves as the main microtubule organizing center in animal cells. Signup and view all the answers

What are spindle fibers?

Structures that separate chromosomes during cell division. Signup and view all the answers

What is polygenic trait? Give an example.

A trait affected by many genes. Example: skin color. Signup and view all the answers

What are differences between cell plates and cleavage furrows?

Cell plates occur in plant cells, while cleavage furrows are in animal cells. Signup and view all the answers

In humans, the haploid number of chromosomes is ____.

23 Signup and view all the answers

In humans, the diploid number of chromosomes is ____.

46 Signup and view all the answers

What is the difference between phenotype and genotype?

Phenotype is the observable traits, while genotype is the genetic code. Signup and view all the answers

Match the following human disorders with their chromosome abnormalities.

Down's Syndrome = Trisomy 21 Turner's Syndrome = Monosomy X Klinefelter Syndrome = XXY Signup and view all the answers

Study Notes

Genes and Alleles

Genes are segments of DNA on chromosomes that determine traits.
Alleles are alternative forms of a gene located at specific positions on chromosomes.
Traits are passed from parents to offspring through alleles, as clarified by Gregor Mendel's law of segregation.

Cell Division: Mitosis and Meiosis

Mitosis produces identical diploid cells, functioning as body cells with one division resulting in two identical cells.
Meiosis produces haploid gametes (sperm and eggs) through two divisions, resulting in four cells that each have half the genetic material.

Mitosis Phases

Prophase: Chromosomes condense; centrioles move apart; spindle fibers form; nuclear membrane dissolves.
Metaphase: Chromatids align at the metaphase plate; kinetochores face opposite poles.
Anaphase: Chromatids separate to opposite poles, becoming individual chromosomes; cell elongates.
Telophase: Chromosomes decondense; spindle fibers dissolve; nuclear envelope reforms; cytokinesis begins.

Chromosome and Cell Characteristics

Autosomes are non-sex chromosomes that occur in pairs in somatic cells.
Sex chromosomes (X and Y) determine an individual's sex; XX is female, XY is male.
Haploid cells have 23 chromosomes; diploid cells have 46 chromosomes.

Genetic Disorders

Aneuploidy refers to abnormal chromosome numbers, such as trisomy (e.g., Down syndrome) and monosomy (e.g., Turner syndrome).
Disorders can arise from deletions (e.g., Smith-Magenis) and exhibit incomplete dominance (e.g., Tay-Sachs).

Concepts of Dominance

Complete Dominance: One allele masks the expression of another.
Incomplete Dominance: The phenotype is a blend of both alleles (e.g., red and white flowers produce pink).
Co-dominance: Both alleles are expressed simultaneously (e.g., red and white spotted flowers).

Cell Structure and Function

The centrosome organizes microtubules and plays a role in cell division.
Chromatin is uncondensed DNA; chromosomes are condensed chromatin.
Spindle fibers separate chromosomes during cell division.

Reproductive Genetics

A monohybrid cross involves one trait, while a dihybrid cross involves two traits.
Test crosses determine an individual's genotype based on a dominant phenotype.

Genetic Variability

Polymorphism results from variations in genes influencing traits (e.g., skin color as a polygenic trait).
Pleiotropic effects occur when one gene affects multiple phenotypes (e.g., Sickle Cell trait offers malaria resistance).

Regulation of Cell Division

Cyclins and cyclin-dependent kinases (Cdks) regulate the cell cycle.
Growth factors provide external signals to control cell division.

Tumors and Cancer

Benign tumors are non-cancerous; malignant tumors are cancerous.
Metastasis is the spread of cancer, while transformed cells lose anchorage dependence and density inhibition.

Genetic Phenomena

Norm of reaction describes the environmental impact on phenotype.
Multifactorial traits are influenced by both genetics and environment.

Inheritance Patterns

Genomic imprinting refers to genes being expressed differently based on parental origin.
Wildtype organisms exhibit typical phenotypes, while mutants show variations.

Human Chromosome Tolerance

Humans can tolerate extra X and Y chromosomes due to mechanisms such as X-chromosome inactivation (Barr bodies) in females.

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Test your knowledge with flashcards covering key concepts from Biology Chapters 13 and 14. This quiz includes essential terms such as genes and alleles, along with their definitions and significance in inheritance. Perfect for reinforcing your understanding of genetic principles!